Predictors and histopathological characteristics of non-diabetic renal disorders in diabetes: a look from the tubulointerstitial point of view

Relationship between complement and macrophage markers with kidney survival in patients with diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease (ESKD) worldwide. Macrophages and the complement system have interrelated roles in DN. We aimed to determine associations between macrophage and complement markers with the progression of DN.

METHODS

This retrospective cohort study included patients diagnosed with sole DN by kidney biopsy. Using immunohistochemistry, CD68+ and CD163+ cells and complement markers were counted in glomerular and tubulointerstitial areas. The primary outcome was evolution to ESKD and/or doubling serum creatinine (SCr).

RESULTS

Forty-six patients were included. The median SCr at baseline was 2.7 (1.41-3.1) mg/dL. During the median follow-up of 32 months (range 6-54), 50% of patients reached the primary outcome. Most of the clinical and histological findings were comparable between progressors and non-progressors, while progressors had a higher median number of glomerular CD68+ cells and a higher percentage of glomerulosclerosis. After adjustments for age, sex, and SCr, the median glomerular CD68+ cell number was the sole independent predictor of progression. Glomerular C4d was associated with nephrotic-range proteinuria but not with the progression of kidney failure.

CONCLUSIONS

Glomerular CD68+ cell count may serve as a promising predictor of kidney disease progression among patients with DN. Glomerular C4d was associated with nephrotic-range proteinuria but not with the progression of kidney failure.

Non-diabetic nephropathy in diabetic patients: incidence, HbA1c variability and other predictive factors, and implications

PURPOSE

Diabetes mellitus (DM) is the leading cause of chronic kidney disease (CKD) in the population. In patients with diabetes mellitus, the incidence of non-diabetic nephropathy (NDNP) has been estimated to range from 3% to 69.5%. Personal judgment is frequently employed while deciding whether or not to do a kidney biopsy (KB) on diabetic patients. NDNP alters the prognosis and course of treatment for people with DM. In our study, we examined the incidence of NDNP concurrent with the progression of diabetes mellitus, as well as the laboratory and clinical indicators that could be utilized to forecast it.

METHODS

A retrospective analysis of 76 diabetic patients who underwent KB was conducted. Based on the pathological diagnoses of these patients, they were categorized as DNP (diabetic nephropathy) or NDNP. The definition of HbA1c variability was determined by calculating the mean HbA1c and the average value of the HbA1c measurements, as well as the standard deviation (SD) for each participant.

RESULTS

NDNP was detected in 50% of 76 patients. Among patients with NDNP, 36.8% had focal segmental glomerulosclerosis (FSGS), 23.6% had membranous glomerulonephritis, and 7.8% had IgA nephritis. The NDNP group exhibited significantly higher rates of female gender, absence of diabetic retinopathy, shorter time to diagnosis of diabetes mellitus, chronic kidney disease, and proteinuria, less intensive medication for diabetes mellitus, presence of hematuria and leukociduria, immunological serological marker positivity, and non-HbA1C variability. Risk factors for predicting non-diabetic nephropathy, as determined by multivariate analysis, included female gender, the absence of diabetic retinopathy, non-HbA1c variability and a positive immunological serological test.

CONCLUSION

In this study, a significant number of diabetic patients with chronic kidney disease were diagnosed with NDNP. Identifying these patients allows for treatment of the specific underlying disease. Factors such as the absence of DR, non-HbA1c variability, female gender, and immunological serological test positivity can predict NDNP and guide the clinician's decision on kidney biopsy. Further prospective studies are warranted to validate the efficacy of potential predictive factors like HbA1c variability.

Non-Diabetic Renal Diseases in Diabetic Patients with Emphasis on Infection-Related Glomerulonephritis

Background:

Non -diabetic renal diseases (NDRDs) in diabetics are treatable and therefore have better prognosis. Infection-related glomerulonephritis (IRGN) is being frequently reported as NDRD.

Objective:

We attempt to study the clinicopathologic spectrum of diabetic patients with biopsy proven IRGN.

Materials and Methods:

This was a retrospective analysis of renal biopsies performed in diabetic patients from January 2014 to June 2021. Demographic data, clinical features, and other laboratory findings were collected. The renal biopsies were classified into diabetic nephropathy (DN) and NDRD. The patients with diagnosis of IRGN were studied in detail.

Results:

Of the 1972 renal biopsies done in diabetic patients, 537 were NDRD and 1233 were DN. The commonest NDRD was tubulo-interstitial nephritis (n = 173) followed by IRGN (n = 74). The IRGN cases were in the age range of 5-78 years (median-53.5) with M: F = 3.4:1. The median duration of diabetes was six years, with median HbA1c = 7.5. Proteinuria ranged from 0.041 to 13 g/day (median = 1.95) with median serum creatinine of 3.7 mg%. History of preceding infection was present in nine cases. These patients presented with rapidly progressive renal failure (RPRF, 17), nephritic syndrome (27), nephrotic syndrome (27), and asymptomatic proteinuria (3). Median C3-level was 47 mg/dl. The biopsies showed classic endocapillary hypercellularity with neutrophils in mesangium, 45 cases had associated DN. Immunofluorescence performed in 54 cases showed coarse granular deposits of C3C.

Conclusions:

IRGN should be kept in mind in diabetic patients presenting with RPRF or nephrotic proteinuria. The biopsy and immunofluorescence helps in accurate diagnosis.

Huangkui capsule in combination with metformin ameliorates diabetic nephropathy via the Klotho/TGF-β1/p38MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huangkui capsule (HKC), extracted from Abelmoschus manihot (L.) medic (AM), as a patent proprietary Chinese medicine on the market for approximately 20 years, has been clinically used to treat chronic glomerulonephritis. Renal fibrosis has been implicated in the onset and development of diabetic nephropathy (DN). However, the potential application of HKC for preventing DN has not been evaluated.

AIM OF THE STUDY

This study was designed to investigate the efficacy and underlying mechanisms of HKC combined with metformin (MET), the first-line medication for treating type 2 diabetes, in the treatment of renal interstitial fibrosis.

MATERIALS AND METHODS

A rat model of diabetes-associated renal fibrosis was established by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg) combined with a high-fat and high-glucose diet. The rats were randomly divided into five groups: normal control, DN, HKC (1.0 g/kg/day), MET (100 mg/kg/d), and HKC plus MET (1.0 g/kg/day + 100 mg/kg/d). Following drug administration for 8 weeks, we collected blood, urine, and kidney tissue for analysis. Biochemical markers and metabolic parameters were detected using commercial kits. Histopathological staining was performed to monitor morphological changes in the rat kidney. High-glucose-induced human kidney HK-2 cells were used to evaluate the renal protective effects of HKC combined with MET (100 μg/mL+10 mmol/L). MTT assay and acridine orange/ethidium bromide were used to examine cell proliferation inhibition rates and apoptosis. Immunofluorescence assay and Western blot analysis were performed to detect renal fibrosis-related proteins including Klotho, TGF-β1, and phosphorylated (p)-p38.

RESULTS

Combination therapy (HKC plus MET) significantly improved the weight, reduced blood glucose (BG), blood urea nitrogen (BUN), total cholesterol (T-CHO), triglycerides (TG), low-density lipoprotein (LDL) and increased the level of high-density lipoprotein (HDL) of DN rats. Combination therapy also significantly reduced urine serum creatinine (SCR) and urine protein (UP) levels as well as reduced the degrees of renal tubule damage and glomerulopathy in DN rats. Combination therapy ameliorated renal fibrosis, as evidenced by reduced levels of alpha-smooth muscle actin and fibronectin and increased expression of E-cadherin in the kidneys. Moreover, HKC plus MET alleviated the degree of DN in part via the Klotho/TGF-β1/p38MAPK signaling pathway. In vitro experiments showed that combination therapy significantly inhibited cell proliferation and apoptosis and regulated fibrosis-related proteins in high-glucose (HG)-induced HK-2 cells. Further studies revealed that combination therapy suppressed cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway.

CONCLUSIONS

HKC plus MET in combination suppressed abnormal renal cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway. Collectively, HKC combined with MET effectively improved DN by inhibiting renal fibrosis-associated proteins and blocking the Klotho/TGF-β1/p38MAPK signaling pathway. These findings improve the understanding of the pathogenesis of diabetes-associated complications and support that HKC plus MET combination therapy is a promising strategy for preventing DN.

Insights into the Role of Renal Biopsy in Patients with T2DM: A Literature Review of Global Renal Biopsy Results

INTRODUCTION

Renal biopsy performed in patients with type 2 diabetes mellitus (T2DM) for atypical or suspected diabetic kidney disease (DKD) reveals one of three possibilities: diabetic nephropathy (DN, pathological diagnosis of DKD), nondiabetic kidney disease (NDKD) and DN plus NDKD (mixed form). NDKD (including the mixed form) is increasingly being recognized worldwide. With the emerging concept of DKD and the complexity of routine application of renal biopsy, the identification of "clinical indicators" to differentiate DKD from NDKD has been an area of active research.

METHODS

The PubMed database was searched for relevant articles mainly according to the keyword search method. We reviewed prevalence of the three types of DKD and different pathological lesions of NDKD. We also reviewed the clinical indicators used to identify DKD and NDKD.

RESULTS

The literature search identified 40 studies (5304 data) worldwide between 1977 and 2019 that looked at global renal biopsy and pathological NDKD lesions. The overall prevalence rate of DN, NDKD and DN plus NDKD is reported to be 41.3, 40.6 and 18.1%, respectively. In Asia, Africa (specifically Morocco and Tunisia) and Europe, the most common isolated NDKD pathological type is membranous nephropathy, representing 24.1, 15.1 and 22.6% of cases, respectively. In contrast, focal segmental glomerulosclerosis is reported to be the primary pathological type in North America (specifically the USA) and Oceania (specifically New Zealand), representing 22% and 63.9% of cases, respectively. Tubulointerstitial disease accounts for a high rate in the mixed group (21.7%), with acute interstitial nephritis being the most prevalent (9.3%), followed by acute tubular necrosis (9.0%). Regarding clinical indicators to differentiate DKD from NDKD, a total of 14 indicators were identified included in 42 studies. Among these, the most commonly studied indicators included diabetic retinopathy, duration of diabetes, proteinuria and hematuria. Regrettably, indicators with high sensitivity and specificity have not yet been identified.

CONCLUSION

To date, renal biopsy is still the gold standard to diagnose diabetes complicated with renal disease, especially when T2DM patients present atypical DKD symptoms (e.g. absence of diabetic retinopathy, shorter duration of diabetes, microscopic hematuria, sub-nephrotic range proteinuria, lower glycated hemoglobin, lower fasting blood glucose). We conclude that renal biopsy as early as possible is of great significance to enable personalized treatment to T2DM patients.