Higher density of CD4+ T cell infiltration predicts severe renal lesions and renal function decline in patients with diabetic nephropathy

Abstract

Background: More evidence have shown that the combination of immune and inflammatory mechanism was critical in diabetic nephropathy (DN). However, the relationship between CD4+ T cells and the development of DN is still unclear. Therefore, this study will focus on this issue from the perspective of clinicopathology.

Methods: From September 2019 to December 2022, a total of 112 adult patients with DN were enrolled in the study. According to the density of CD4+ T cell infiltration based on immunostaining, the patients were divided into high-CD4 group (56 patients) and low-CD4 group (56 patients). Another 25 diabetic patients with minimal change disease (non-diabetic nephropathy, NDN) was reviewed as control group in clinical and molecular analysis. The clinical parameters, morphological features, and molecular characteristics were compared. The predictive value of CD4+ T cells for DN prognosis was also investigated.

Results: DN patients in the high-CD4 group suffered from higher proteinuria and lower estimated glomerular filtration rate (eGFR) level than those in the low-CD4 group and NDN patients. Renal biopsy in the high-CD4 group presented with more severe glomerular lesions, higher density of interstitial inflammation, and more severe tubular atrophy/interstitial fibrosis than in the low-CD4 group. Multivariate logistic analysis indicated that the density of CD4+ T cell infiltration could independently predict the severity of tubular atrophy/interstitial fibrosis. In addition, more severe mitochondrial damage of renal tubular epithelial cells and a more obvious expression of Bcl6, IL-6, STAT3, and TGFβ1 were observed in DN patients of the high-CD4 group, indicating the possible mechanism of CD4+ T cells involving the progression of DN. Multivariate Cox regression analysis revealed that a higher intensity of interstitial CD4+ T cell deposition remained as an independent predictor of the double endpoint with doubling of baseline serum creatinine or end-stage renal disease.

Conclusion: The high density of CD4+ T cell infiltration was associated with renal function decline and severity of renal lesions and predicted poor renal survival for DN patients.

Keywords: CD4+ T cells; clinicopathological analysis; diabetic nephropathy; interstitial fibrosis; tubular atrophy.

Figure 1

Histological features of the high-CD4 and low-CD4 groups (A–C) and CD4 immunohistochemical results (D–F). The histological features of the high-CD4 group (A, D) showed heavier interstitial inflammatory cell infiltration, more severe renal tubular atrophy, and interstitial fibrosis than those in the low-CD4 group (B, E) and non-diabetic nephropathy group (C, F).

Figure 2

Characteristics of mitochondria in proximal tubular epithelial cells of diabetic nephropathy patients grouped by CD4 immunostaining results (A–F). Compared with the patients in the low-CD4 group (C, D), patients in the high-CD4 group (A, B) harbored more severe mitochondrial damage manifested by more obvious rupture of the mitochondrial cristae, fewer mitochondrial number (E), and more obvious mitochondrial swelling (smaller aspect ratio) (F). ****p < 0.0001.

Figure 3

Immunostaining results of some molecules among different groups. (A–L) Immunohistochemical results of Bcl6 (A–C), IL-6 (D–F), STAT3 (G–I), and TGFβ1 (J–L) in the high-CD4, low-CD4, and non-diabetic nephropathy (NDN) groups (scale bar = 100 μm; red arrows indicate partial positive expression). (M–P) The expression of Bcl6, IL-6, STAT3, and TGFβ1 in renal tissue was more obvious in the high-CD4 group than in the low-CD4 and NDN groups (data was shown as mean ± SD, five cases in each group; ns, not significant; *p < 0.05, **p < 0.01, ***p < 0.001).

Figure 4

Kaplan–Meier survival curves for renal outcome according to the CD4 immunostaining results. (A) Kaplan–Meier survival curves for renal outcome stratified by the severity of CD4+ T cell infiltration in the total of 112 diabetic nephropathy patients. (B) Kaplan–Meier survival curves for renal outcome stratified by the severity of CD4+ T cell infiltration in 72 patients with severe glomerular lesions.