Effect of cathepsins on the amount of CD4-positive cells in lungs. The number of CD4-positive cells (A) was more than a 5-times higher in lungs of Apoe-/- mice as a result of HFD-feeding (B). Apoe-/- Ctsk-/- mice did not reveal a significant difference in its CD4 population, whereas Apoe-/- Ctsl-/- mice showed less dramatic accumulation of CD4+ cells when compared to Apoe-/- mice (* - p < 0.05 between Apoe-/- mice on HFD and Apoe-/- mice on normal diet; * - p < 0.05 when compared to Apoe-/- mice on HFD). Cathepsin S inhibitor treatment resulted in a significant reduction of CD4+ cells in lungs of mice on HFD (C, * - p < 0.05 when compared to mice on HFD without inhibitor). (A), Scale bar 30 μm.