Fig 1: Renal senescence and aging are improved in IL‐33+/− and ST2+/− DN mice and. αIL‐33‐treated WT DN mice. WT mice considered diabetic were intraperitoneally injected with IgG or αIL‐33 twice a week for 12 weeks and maintained with HFD feeding. IL‐33+/− and ST2+/− DN mice were maintained with HFD feeding for 26 weeks. (A) The circulating IL‐33 level was measured by ELISA. (B and C) FBG and renal‐body ratio. (D‐F) Renal function was measured by Scr, BUN, and ACR. (G) Representative images of H&E, PAS staining (scale bar: 20 µm), and transmission electron microscopy (scale bar: 1 µm). (H) The statistics of pathological indicators in the glomeruli included glomerular area, PAS‐positive areas, GBM thickness, and foot process width. (I and J) Renal tubular injury score and KIM‐1 protein level were used to measure renal tubular changes. *p < 0.05, **p < 0.01, ***p < 0.001.
Fig 2: Partial reduction of IL‐33 alleviates cell injury and senescence, and cellular senescence mediates the role of IL‐33 in vitro. (A and B) KIM‐1 expression and LDH release in cells treated with different doses of αIL‐33 (10 or 50 ng/mL) and rIL‐33 (10 or 50 ng/mL) for 10 days. (C and D) cellular senescence‐related changes including the ratio of SA‐β‐gal+ and EdU+ cells, and fold change in nuclear area and γH2AX expression. (E) The protein levels of p53, p21, and p16 in HK‐2 cells. (F–H) Cell damage‐related (KIM‐1 expression and LDH release) and cellular senescence‐related changes (SA‐β‐gal, EdU, nuclear area, and γH2AX) in rIL33‐treated (50 ng/mL) cells with p16 and p21 silencing respectively or simultaneously. (I–K) SA‐β‐gal, Hochest (marked apoptotic cells), and LDH analyses of HK‐2 cells exposed to HG for 17 days and ABT‐263 (10 µM) for 1 day. Scale bar: 20 µm. *p < 0.05, **p < 0.01, ***p < 0.001.
Fig 3: Mechanism flow chart. Sustained hyperglycemic stimulation leads to an increased production of IL‐33, which in turn accelerates senescence in tubular epithelial cells. The senescent cells then release SASP components, including IL‐33 and prostaglandins, which further amplify cellular senescence and exacerbate renal lesions.
Fig 4: IL‐33 and ST2 levels are increased in human participants and animals with DN. (A) Western immunoblot analysis for IL‐33 and ST2 in kidney of DN mice (HFD+STZ), ZDF rats, or ApoE−/− mice fed with HFD and respective control animals. GAPDH served as a loading control. The third blot shows the shorter IL‐33. (B and C) Serum IL‐33 levels and the expression levels of IL‐33 and ST2 mRNA in DN mice (HFD+STZ) and control mice (ND). (D) The protein expression of IL‐33 and ST2 in the paracancerous kidneys and the kidneys of DN patients was shown by immunohistochemistry (scale bar: 20 µm). (E) Fold change of IL‐33 mRNA levels in DN‐related models compared with control kidney tissue. Data from the GEO database. (F) At 2, 4, and 8 months, renal mRNA levels of IL‐33 in OVE26 diabetic mice and its control group (n = 4–7). (G) At 10 and 20 weeks, IL‐33 mRNA levels in the kidney of STZ‐induced diabetic rats and its control group (n = 3). (H) Renal IL‐33 mRNA expression in non‐diabetic, early‐stage, and advanced DN individuals. *p < 0.05, **p < 0.01, ***p < 0.001.
Fig 5: rIL‐33 exacerbates renal senescence and aging in DN mice. (A) Representative images of kidney tissue stained with SA‐β‐gal and Ki67. The statistical data were the ratio of positive area. (B) The protein levels of senescence markers were determined by immunoblots. Densitometric analysis of p53, p21, p16, ATM, and γH2AX. (C and D) Representative fluorescence colocalization images of IL‐6 (red) and NF‐κB (red) with SA‐β‐gal (C12FDG, green) in renal tissue. Colocalization statistics were shown as Pearson's correlation coefficient. (E) Protein levels in the cell apoptosis pathway, including AKT, p‐AKT, Bcl‐2, Bax, and Caspase‐3. (F) Colocalization of the prosurvival protein Bcl‐2 (red) with SA‐β‐gal (green). (G) The extent of fibrosis (Masson staining) and the level of oxidative stress in the kidneys (ROS fluorescent probe, 10 µM). (H) Fibrosis‐related protein levels including Collagen I and CTGF. (I) Correlation of p16 expression with IL‐33 and ST2 level in DN patients. Scale bar: 20 µm. *p < 0.05, **p < 0.01, ***p < 0.001.
Supplier Page from MedChemExpress for IL-33 Protein, Mouse