Fig 1.
CIH-induced systemic inflammation and attenuation by JAK1 inhibition.
(A) Serum levels of IL-6 and (B) TNF-α in normoxic control (Sham) and chronic intermittent hypoxia (CIH) groups. CIH exposure for 8 weeks significantly increased both cytokines compared to Sham (**p < 0.01). Data expressed as mean ± SEM; n = 8/group.
Fig 2.
Activation of JAK1-STAT1 signaling in lung tissues after CIH.
(A-B) Western blot analysis showing phosphorylated JAK1 protein expression (representative bands and quantitative data). (C-D) Western blot analysis showing phosphorylated STAT1 (Tyr701) levels (representative bands and quantitative data). (E-F) Immunohistochemical staining and quantification of p-JAK1-positive cells. (G-H) p-STAT1 immunostaining and positive cell counting. Data expressed as mean ± SEM (n = 8 rats/group). *p < 0.05, **p < 0.01 vs Sham group (unpaired t-test). Scale bars: 20 μm. Arrows indicate nuclear localization of target proteins in CIH group.
Fig 3.
Therapeutic effects of JAK1 inhibitor Filgotinib on CIH-induced inflammation and JAK1-STAT1 pathway activation.
(A-B) Serum levels of IL-6 and TNF-α. (C-F) Western blot analysis of p-JAK1 and p-STAT1 protein expression in lung tissues (representative bands and quantitative data). (G-J) Immunohistochemical staining and quantification of p-JAK1 and p-STAT1 positive cells in lung sections. Data expressed as mean ± SEM (n = 8). **p < 0.01 vs Sham group; ##p < 0.01 vs CIH group (one-way ANOVA with Tukey’s post hoc test). Scale bars: 20 μm.
Fig 4.
Histopathological improvements in lung tissues after JAK1 inhibition.
(A) Representative H&E-stained lung sections (200 × magnification). Arrows indicate leukocyte infiltration. (B) Quantitative analysis of lung injury scores (0-4 scale). (C) Representative Masson’s trichrome-stained lung sections from Sham, CIH, and CIH+Filgotinib groups. Collagen fibers are stained blue. Scale bars: 20 μm. (D) Quantitative analysis of collagen deposition. The area of blue-stained collagen was measured as a percentage of total tissue area in 10 randomly selected fields per section using ImageJ software (NIH). Data are expressed as mean ± SEM (n = 8). ***p < 0.001 vs. Sham group; ##p < 0.01 vs. CIH group (one-way ANOVA with Tukey’s post hoc test). Data expressed as mean ± SEM (n = 8). ***p < 0.001 vs Sham group; ##p < 0.01 vs CIH group (one-way ANOVA with Tukey’s post hoc test). Scale bars: 20 μm.
Fig 5.
Correlation between JAK1-STAT1 activation and systemic inflammation.
(A) Positive correlation between p-STAT1 levels in lung tissues and serum IL-6 (r = 0.86, p < 0.001, Pearson correlation, n = 15). (B) Positive correlation between p-STAT1 levels and serum TNF-α (r = 0.82, p < 0.001, n = 15). (C) Airway resistance measured by forced oscillation at baseline and after methacholine challenge. Data are presented as mean ± SEM (n = 8 per group). Baseline resistance (open bars) did not differ among groups. Post-methacholine resistance (solid bars) was significantly elevated in the CIH group compared to the Sham group (***p < 0.001). Filgotinib treatment significantly attenuated this increase (###p < 0.001 vs. CIH group; one-way ANOVA with Tukey’s post hoc test). (D) Analysis of STAT3 pathway activation in lung tissues. Representative Western blot bands and quantitative analysis of total STAT3 and phosphorylated STAT3 (p-STAT3, Tyr705) protein levels in the Sham and CIH groups. β-actin was used as a loading control. Data are expressed as mean ± SEM (n = 8 per group). No statistically significant difference was found between the two groups (p > 0.05, unpaired t-test).