Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: CDC42 -/- A549, Rac1 -/- A549, ArpC2 -/- A549 and ArpC4 -/- A549 cell lines.

Article Snippet: TEM results could directly show that the number of bacteria invading ArpC2 -/- A549 cells by 73-OR and ATCC 25238 was not reduced, and the volume of the macropinosomes formed was larger ( ).

Techniques:

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC2 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC2 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC2 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC2 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC2 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC2 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC2 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC2 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: TEM results could directly show that the number of bacteria invading ArpC2 -/- A549 cells by 73-OR and ATCC 25238 was not reduced, and the volume of the macropinosomes formed was larger ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: CDC42 -/- A549, Rac1 -/- A549, ArpC2 -/- A549 and ArpC4 -/- A549 cell lines.

Article Snippet: The invasion assay suggested bacterial counts of M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC2 -/- A549 cells showed no significant difference compared to wild-type A549 cells ( ).

Techniques:

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of CDC42 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. CDC42 -/- A549 cells. Data are presented as mean ± standard error (SE) from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and CDC42 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and CDC42 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and CDC42 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into CDC42 -/- A549 cells compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and CDC42 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and CDC42 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. CDC42 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay suggested bacterial counts of M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC2 -/- A549 cells showed no significant difference compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of Rac1 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. Rac1 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and Rac1 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and Rac1 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and Rac1 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into Rac1 -/- A549 compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and Rac1 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection.Wild-type (WT) and Rac1 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. Rac1 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay suggested bacterial counts of M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC2 -/- A549 cells showed no significant difference compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC2 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC2 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC2 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC2 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC2 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC2 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC2 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC2 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay suggested bacterial counts of M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC2 -/- A549 cells showed no significant difference compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC4 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC4 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC4 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC4 -/- A549 cells. Invasion counts for M.catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC4 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC4 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC4 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC4 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three to four independent biological replicates (n=3-4). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay suggested bacterial counts of M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC2 -/- A549 cells showed no significant difference compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: CDC42 -/- A549, Rac1 -/- A549, ArpC2 -/- A549 and ArpC4 -/- A549 cell lines.

Article Snippet: Among them, the invasion assay results showed that compared with wild-type A549 cells, the number of bacteria invading Rac1 -/- A549 cells by 73-OR and ATCC 25238 decreased significantly ( ); For the 73-OR strain, invasion counts were substantially lower in Rac1 -/- A549 cells (Mean:9,833 ± 3,436 CFU/well) compared to WT A549 cells (Mean: 76, 562 ± 53, 978 CFU/well).

Techniques:

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of Rac1 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. Rac1 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and Rac1 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and Rac1 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and Rac1 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into Rac1 -/- A549 compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and Rac1 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection.Wild-type (WT) and Rac1 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. Rac1 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: Among them, the invasion assay results showed that compared with wild-type A549 cells, the number of bacteria invading Rac1 -/- A549 cells by 73-OR and ATCC 25238 decreased significantly ( ); For the 73-OR strain, invasion counts were substantially lower in Rac1 -/- A549 cells (Mean:9,833 ± 3,436 CFU/well) compared to WT A549 cells (Mean: 76, 562 ± 53, 978 CFU/well).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: CDC42 -/- A549, Rac1 -/- A549, ArpC2 -/- A549 and ArpC4 -/- A549 cell lines.

Article Snippet: Both M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC4 -/- A549 cells demonstrated no significant difference compared to wild-type A549 cells.

Techniques:

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of CDC42 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. CDC42 -/- A549 cells. Data are presented as mean ± standard error (SE) from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and CDC42 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and CDC42 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and CDC42 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into CDC42 -/- A549 cells compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and CDC42 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and CDC42 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. CDC42 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: Both M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC4 -/- A549 cells demonstrated no significant difference compared to wild-type A549 cells.

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of Rac1 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. Rac1 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and Rac1 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and Rac1 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and Rac1 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into Rac1 -/- A549 compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and Rac1 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection.Wild-type (WT) and Rac1 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. Rac1 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: Both M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC4 -/- A549 cells demonstrated no significant difference compared to wild-type A549 cells.

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC2 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC2 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC2 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC2 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC2 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC2 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC2 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC2 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: Both M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC4 -/- A549 cells demonstrated no significant difference compared to wild-type A549 cells.

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC4 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC4 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC4 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC4 -/- A549 cells. Invasion counts for M.catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC4 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC4 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC4 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC4 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three to four independent biological replicates (n=3-4). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: Both M. catarrhalis strains 73-OR and ATCC 25238 invading ArpC4 -/- A549 cells demonstrated no significant difference compared to wild-type A549 cells.

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: CDC42 -/- A549, Rac1 -/- A549, ArpC2 -/- A549 and ArpC4 -/- A549 cell lines.

Article Snippet: The invasion assay showed the bacterial counts of 73-OR and ATCC 25238 strains invading CDC42 -/- A549 cells were significantly reduced compared to wild-type A549 cells ( ).

Techniques:

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of CDC42 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. CDC42 -/- A549 cells. Data are presented as mean ± standard error (SE) from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and CDC42 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and CDC42 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and CDC42 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into CDC42 -/- A549 cells compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and CDC42 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and CDC42 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. CDC42 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay showed the bacterial counts of 73-OR and ATCC 25238 strains invading CDC42 -/- A549 cells were significantly reduced compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of Rac1 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. Rac1 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and Rac1 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and Rac1 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and Rac1 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. Both 73-OR and ATCC 25238 strains showed a significant reduction in invasion into Rac1 -/- A549 compared to WT cells. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and Rac1 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection.Wild-type (WT) and Rac1 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs. Rac1 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay showed the bacterial counts of 73-OR and ATCC 25238 strains invading CDC42 -/- A549 cells were significantly reduced compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC2 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC2 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC2 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC2 -/- A549 cells. Invasion counts for M. catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC2 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n =3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC2 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC2 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC2 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay showed the bacterial counts of 73-OR and ATCC 25238 strains invading CDC42 -/- A549 cells were significantly reduced compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing

Journal: Frontiers in Immunology

Article Title: The Rho GTPase signaling pathway modulates Moraxella catarrhalis invasion into human respiratory epithelial cells by regulating actin polymerization

doi: 10.3389/fimmu.2026.1730864

Figure Lengend Snippet: Critical role of ArpC4 in the Rho GTPase signaling pathway during M. catarrhalis invasion into A549 cells. (A) Comparison of invasion counts of M. catarrhalis strains 73-OR and ATCC 25238 into WT A549 cells vs. ArpC4 -/- A549 cells. Data are presented as mean ± standard error (SE)from three independent biological replicates (n=3). Statistical significance was determined using an unpaired Student’s t-test. To accurately assess the magnitude of the impact given the limited sample size, effect sizes (Cohen’s d) and mean differences are reported alongside P-values. (B) Transmission electron micrographs (TEM) of 73-OR and ATCC 25238 invading WT A549 cells and ArpC4 -/- A549 cells. (C) TEM quantification of M. catarrhalis invasion into wild-type and ArpC4 -/- A549 cells. Invasion counts for M.catarrhalis strains 73-OR and ATCC 25238 were quantified by counting the number of bacteria internalized within wild-type (WT) and ArpC4 -/- A549 cells via Transmission Electron Microscopy (TEM). Data represent the mean ± standard error(SE) from three independent biological replicates (n=3). Within each biological replicate, three random microscopic fields at the same magnification were selected and counted. Statistical significance between groups was determined using the non-parametric Mann-Whitney U test. (D) Quantitative comparison of F-actin/G-actin ratios in WT A549 cells and ArpC4 -/- A549 cells post-infection with M. catarrhalis strains 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three independent biological replicates (n=3). Statistical comparison between groups was performed using an unpaired Student’s t-test. (E) Immunofluorescence analysis of F-actin polymerization in A549 cells post-infection. Wild-type (WT) and ArpC4 -/- A549 cells were challenged with M. catarrhalis strains 73-OR and ATCC 25238, fixed, and stained. Blue: nuclei; Green: F-actin. (F) Analysis of microfilament expression levels in WT A549 cells vs ArpC4 -/- A549 cells following infection with 73-OR and ATCC 25238. Data are presented as the mean ± standard error(SE) from three to four independent biological replicates (n=3-4). Statistical comparison between groups was performed using an unpaired Student’s t-test.

Article Snippet: The invasion assay showed the bacterial counts of 73-OR and ATCC 25238 strains invading CDC42 -/- A549 cells were significantly reduced compared to wild-type A549 cells ( ).

Techniques: Comparison, Transmission Assay, Bacteria, Electron Microscopy, MANN-WHITNEY, Infection, Immunofluorescence, Staining, Expressing