The role of hypertriglyceridemia and treatment patterns in the progression of IgA nephropathy with a high proportion of global glomerulosclerosis

The causal effect of triglyceride and high blood pressure on IgA nephropathy: a Mendelian randomization study

Background

It has been reported that high blood pressure (HBP) and triglyceride (TG) are considered risk factors in immunoglobulin A nephropathy (IgAN). This study aimed to explore the causalities between HBP and TG, and IgAN on the basis of Mendelian randomization (MR) analysis.

Methods

Firstly, the genome-wide association study (GWAS) summary data of IgAN (GCST90018866) and two exposure factors, TG (ukb-d-30870_raw) and HBP (ukb-a-437), were sourced from the GWAS Catalog and Integrative Epidemiology Unit (IEU) OpenGWAS databases, respectively. In this study, five methods were utilized to perform MR analysis after picking out single nucleotide polymorphisms (SNPs) as instrumental variables, including MR-Egger, weighted median, simple mode, weighted mode, and inverse variance weighted (IVW), followed by the sensitivity analysis containing the heterogeneity, horizontal pleiotropy test and leave-one-out (LOO) analysis. Finally, the enrichment analysis and interaction network construction of genes corresponding to SNPs of HBP and TG were performed.

Results

The univariate MR results revealed that HBP and TG regarded as risk factors were causally related to IgAN [TG: p = 0.046, odds ratio (OR) = 1.065, 95% confidence interval (CI) = 1.001-1.133; HBP: p = 7.09 × 10-7, OR = 1.970, 95% CI = 1.507-2.575] based on random-effect IVM method, of which TG had a weaker impact. The reliability of these univariate MR results was certified by the sensitivity analysis, in which there was no horizontal pleiotropy and exaggerated influence of each SNP. Furthermore, HBP was markedly causally related to IgAN (p = 0.000512) with the help of multivariate MR analysis, rather than TG (p = 0.332). Therefore, when HBP and TG occur simultaneously, HBP is a direct influencing factor on IgAN. Ultimately, a total of 208 and 153 genes separately corresponding to SNPs of TG and HBP were included in enrichment analysis, and thereinto, genes relevant to TG were mainly enriched in lipid homeostasis and cholesterol metabolism, while genes concerned with HBP played their roles in regulation of cell growth, aldosterone synthesis and secretion and so forth.

Conclusion

TG and HBP as risk factors were causally connected with IgAN, of which HBP was strongly related to the onset of IgAN, providing more reliable evidence for further exploring the relationship between TG and HBP and IgAN.

Prognostic significance of the extent of tubulointerstitial lesions in patients with IgA nephropathy

PURPOSE

IgA nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide. However, the effect of the degree of tubulointerstitial lesions (TIL) on the renal prognosis of these patients is uncertain.

METHODS

All biopsy-proven primary IgAN patients from a single center (≥ 14 years old) were retrospectively examined from January 2006 to December 2011. According to the Oxford classification for tubulointerstitial lesions in IgAN, eligible patients were assigned to T0 or T1/2 groups. The clinicopathological features of these groups were compared and multivariate models were used to identify the effect of tubulointerstitial lesions on renal prognosis. The composite endpoint was end-stage renal disease or doubling of serum creatinine.

RESULTS

We initially identified 1570 patients with IgAN and examined 988 patients who completed follow-up examinations (mean: 49 months). There were 506 patients in the T0 group (51.2%) and 482 in the T1/2 group (48.8%). The 1-year, 3-year, and 5-year incidences of the composite endpoint were 0.2%, 1.5%, 7.7% in the T0 group, and 1.9%, 9.9%, 18.1% in the T1/2 group. An adjusted multivariate model indicated the hazard ratio for reaching the composite endpoint was 9.3 for patients with T1/2 rather than T0 (reference group). A multivariate logistic analysis of the T1/2 group indicated the independent risk factors for reaching the composite endpoint were decreased eGFR, hypertension, hyperlipidemia, proteinuria, global glomerulosclerosis, and segmental glomerulosclerosis.

CONCLUSION

More severe tubulointerstitial lesions (> 25%, T1/2) were an independent predictor of poor renal prognosis in patients with IgAN.

Dyslipidemia may be a risk factor for progression in children with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is often chronically progressive and commonly accompanied by dyslipidemia. However, the intrinsic relationship between dyslipidemia and IgAN remains to be elucidated. This study aimed to investigate the impact of different types of dyslipidemia on clinical and pathological characteristics in children with IgAN.

METHODS

In our retrospective cohort study from January 2006 to January 2021, 276 children with IgAN were ultimately included in the baseline analysis, and 169 were included in the follow-up analysis. The clinical and pathological features of different types of dyslipidemia and their effect on kidney prognosis were analyzed.

RESULTS

Children in the dyslipidemia group had more severe clinical characteristics (higher blood urea nitrogen, serum uric acid, and 24-h proteinuria; higher proportion of hypertension; and lower serum albumin and estimated glomerular filtration rate) and pathological changes (higher proportion of Lee grades IV-V and E1, S1, and C2 in MEST-C). Furthermore, the clinical and pathological characteristics were worse in the mixed hyperlipidemia group. Multivariate logistic analysis showed that hypertension, steroid treatment, lower serum albumin, severe proteinuria, and segmental glomerulosclerosis were independent risk factors for dyslipidemia in children with IgAN. The Kaplan-Meier analysis revealed that the probability of kidney survival in children with dyslipidemia was lower than that in those without dyslipidemia, with a median follow-up of 5.9 years.

CONCLUSIONS

Children with IgAN and dyslipidemia, especially mixed hyperlipidemia, are prone to more severe clinical and pathological changes. Our study provides further insight into dyslipidemia as a potential risk factor in children with IgAN. A higher resolution version of the Graphical abstract is available as Supplementary information.

Hypercholesterolemia Correlates With Glomerular Phospholipase A2 Receptor Deposit and Serum Anti-Phospholipase A2 Receptor Antibody and Predicts Proteinuria Outcome in Idiopathic Membranous Nephropathy

Background

The anti-phospholipase A2 receptor (PLA2R) antibody is a non-invasive diagnostic tool and prognosis predictor of idiopathic membranous nephropathy (IMN). Baseline hypercholesterolemia independently predicts proteinuria outcomes in IMN patients. Thus, we investigated whether hyperlipidemia is correlated with anti-PLA2R and pathological indicators.

Methods

A total of 495 IMN patients identified by kidney biopsy in Wuhan Tongji Hospital, China, from January 2016 through December 2020 were enrolled in this study. Data on clinical features, pathology findings, and outcomes were collected.

Results

Total cholesterol (TC), non-high-density lipoprotein cholesterol (non-HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) were positively related to proteinuria, indicating damage to the renal glomerulus [Spearman’s rank correlation coefficient = 0.432, 0.462, 0.315, and 0.289, respectively, P < 0.001 for all]. In univariate logistic regression, low HDL-C [odds ratio (OR): 0.856; 95% CI: 0.778–0.939; P = 0.001] and high TG [OR: 1.025; 95% CI: 1.006–1.044; P = 0.011] were correlated with tubular atrophy, suggesting lesions on tubules. Increased TC [adjusted OR: 1.285; 95% CI: 1.119–1.475; P < 0.001], non-HDL-C [adjusted OR: 1.284; 95% CI: 1.113–1.482; P = 0.001], and LDL-C [adjusted OR: 1.178; 95% CI: 1.009–1.376; P = 0.039] independently predicted glomerular PLA2R deposit; similar results were observed for lipids in predicting the seropositivity of anti-PLA2R antibodies. After treatment, increased HDL-C [adjusted hazard ratio (HR): 1.764; 95% CI: 1.241–2.507; P = 0.002] and decreased non-HDL-C [adjusted HR: 0.884; 95% CI: 0.795–0.983; P = 0.022] independently predicted proteinuria remission.

Conclusion

Hypercholesterolemia is a potentially useful biomarker for disease severity, serum anti-PLA2R antibody, glomerular PLA2R deposit, and proteinuria outcome of IMN.

Utility of non-HDL-C in predicting proteinuria remission of idiopathic membranous nephropathy: a retrospective cohort study

Background

Idiopathic membranous nephropathy (IMN) may have various clinical outcomes. Hyperlipidemia is quite common in IMN. However, the utility of the lipid profile in predicting outcomes remains unknown. This study aimed to explore the correlation between hyperlipidemia and proteinuria remission in IMN.

Methods

256 patients who diagnosed with IMN confirmed by renal biopsy in Wuhan Tongji Hospital from January 2016 to October 2020 were included in this study. The end point was defined as a combination of partial and complete remission. Cox proportional-hazards regression analysis and Kaplan–Meier curve were applied to assess the prognostic value of the lipid profile for proteinuria remission.

Results

A total of 153 (59.8%) patients achieved remission and 103 (40.2%) did not. The levels of total cholesterol, low-density lipoprotein, and non-high-density lipoprotein were significantly lower in the remission group than in the non-remission group. Non-high-density lipoprotein level revealed the strongest correlation with proteinuria (Spearman’s rho = 0.42; P < 0.001). The multivariate analysis demonstrated that serum total cholesterol [hazard ratio (HR): 0.883; 95% confidence interval (CI): 0.813–0.958; P = 0.003] and non-high-density lipoprotein cholesterol (HR: 0.892; 95% CI: 0.820–0.970; P = 0.007) levels were independent markers to predict proteinuria remission in IMN.

Conclusions

Among the lipid profile, the non-high-density lipoprotein level exhibited the strongest correlation with proteinuria in IMN. Moreover, elevated serum cholesterol and non-high-density lipoprotein cholesterol concentrations at baseline predicted probability of proteinuria non-remission in IMN.

Hypertriglyceridemia Is Associated with More Severe Histological Glomerulosclerosis in IgA Nephropathy

IgA nephropathy (IgAN) is a globally well-known primary glomerular nephropathy. Hypertriglyceridemia (HTG) is one factor contributing to atherosclerosis and is a common complication of renal failure. HTG is a significant risk factor for decreased renal function in patients with IgAN. We evaluated the association of HTG with the histopathological features of IgAN patients. A total of 480 patients diagnosed with IgAN via kidney biopsy from eight university hospitals affiliated with the College of Medicine of the Catholic University of Korea were included in the final cohort. Pathological features were evaluated by eight expert pathologists with hospital consensus. HTG was defined as a serum triglyceride (TG) level of ≥150 mg/dL. In the study population analysis, the HTG group was older, with more males; higher body mass index (BMI), low-density lipoprotein cholesterol (LDL-C) and spot urine protein ratio; and lower estimated glomerular filtration rate (eGFR). In the lipid profile analysis, eGFR was negatively correlated with TGs/ high-density lipoprotein cholesterol (HDL) and triglyceride-glucose index (TyG). Proteinuria positively correlated with TGs/HDL, non-HDL/HDL, LDL/HDL, TyG, TGs and LDL. The percentages of global sclerosis (GS), segmental sclerosis (SS) and capsular adhesion (CA), and the scores for mesangial matrix expansion (MME) and mesangial cell proliferation (MCP), were more elevated in the HTG group compared to the normal TG group. Multivariable linear regression analysis showed that the percentages of global sclerosis, segmental sclerosis and capsular adhesion, as well as the scores for mesangial matrix expansion and mesangial cell proliferation, were positively associated with TG level. In binary logistic regression, the HTG group showed a higher risk for global sclerosis and segmental sclerosis. In conclusion, HTG is a significant risk factor for glomerulosclerosis in IgAN.

The predictive value of Oxford MEST-C classification to immunosuppressive therapy of IgA nephropathy

PURPOSE

To analyze the efficacy of immunosuppressive therapy in IgA nephropathy and investigate the value of all clinicopathologic indicators.

METHOD

One hundred and one eligible IgA nephropathy patients were retrospectively studied. All the patients received immunosuppressive treatment and were then grouped according to the treatment outcome. The endpoint was a composite outcome (halving eGFR, end-stage renal disease (ESRD) or death due to kidney disease). The outcomes of immunosuppressive therapy were evaluated, and the factors influencing the outcomes of immunosuppressive therapy were analyzed by logistics regression. The independent significance of clinicopathologic indicators on renal outcome was then analyzed by multivariable Cox regression.

RESULTS

Multivariate logistic regression analysis showed that S1 and M1 were the risk factors for the immunosuppressive treatment effect in IgAN patients, and eGFR was the protective factor for the immunosuppressive treatment effect in IgAN patients. Kaplan-Meier analysis revealed that outcomes of immunosuppressive therapy were significantly associated with poor renal outcomes. Multiple Cox regression analysis further confirmed that M1, T2, and the initial level of eGFR were independent predictive factors for poor renal outcomes.

CONCLUSIONS

M, S scores and initial eGFR are independent predictors of outcomes of immunosuppressive therapy. Only M, T scores can effectively predict poor renal outcomes after immunosuppressive therapy. Nonetheless, stable eGFR and low proteinuria can protect renal outcomes.

Hyperuricemia and hypertriglyceridemia indicate tubular atrophy/interstitial fibrosis in patients with IgA nephropathy and membranous nephropathy

PURPOSE

Hyperuricemia (HUA) and hypertriglyceridemia (HTG) were very common in chronic kidney disease (CKD) and associated with accelerated progression of CKD. This was a retrospective, cross-sectional study which aimed to explore the relationship between serum uric acid levels or triglyceride levels and tubular atrophy/interstitial fibrosis (proven by renal biopsy).

METHODS

The present study enrolled 229 CKD individuals who included 127 biopsy-proven primary IgA nephrology (IgAN) patients and 102 biopsy-proven primary membranous nephropathy (MN) patients. The baseline characteristics at the time of the kidney biopsy were collected. According to the serum uric acid (UA) or triglyceride (TG) whether it exceeds the normal reference range, patients were divided into non-HUA (n = 127), HUA (n = 102), non-HTG (n = 119), and HTG group (n = 110). Based on the extent of tubular atrophy/interstitial fibrosis, patients were divided into no/mild injury (T0, n = 127), moderate injury (T1, n = 102). Multivariable logistic regression for factors predicting moderate tubular atrophy/interstitial fibrosis was performed.

RESULTS

There were 127 IgAN and 102 MN cases among 229 patients in the present study. The prevalence of HUA was 44.5% (n = 102), 40.9% (n = 52), and 49.0% (n = 50) in all patients, IgAN patients and MN patients, respectively (P = 1.49). The prevalence of HTG was 48.0% (n = 110), 29.9% (n = 38), and 70.6% (n = 72) (P < 0.001), respectively, as well. Multivariate logistic regression analysis showed that HUA and HTG were independent risk factors for moderate tubular atrophy/interstitial fibrosis (HUA OR = 2.335, 95% CI = 1.147-4.755, P = 0.019; HTG OR = 2.646, 95% CI = 1.289-5.432, P = 0.008). The area under curve (AUC) of model 1 (HUA + eGFR + HTG + age + serum globulin + 24 h urinary protein, AUC = 0.876) was larger than the other two models; however, there was no significant difference among these models (all P > 0.05).

CONCLUSIONS

Hyperuricemia and hypertriglyceridemia, which were prevalent in CKD patients, were the independent risk factors for moderate tubular atrophy/interstitial fibrosis. HUA together with HTG could improve the value of diagnosis for moderate tubular atrophy/interstitial fibrosis to some extent.

The role of urine IgG in the progression of IgA nephropathy with a high proportion of global glomerulosclerosis

BACKGROUND

IgA nephropathy (IgAN), the most common glomerulonephritis in the world, is an important cause of end-stage renal disease (ESRD). It is necessary to explore new prognostic markers for predicting the activity and progress of IgAN. There are few studies on new prognostic markers in IgAN patients with high proportion of glomerulosclerosis. This study aims to explore the value of urine IgG in predicting the prognosis of IgAN patients.

METHODS

The primary end point of this retrospective study was a composite event with a reduction in estimated glomerular filtration rate (eGFR) of  ≥ 50% or ESRD or death. This study assessed the association between urinary IgG and clinicopathological parameters, as well as the prognosis of a high proportion of patients with global glomerulosclerotic IgAN.

RESULTS

This study included 105 IgAN patients with high proportion of global glomerulosclerotic. The level of urinary protein IgG was significantly correlated with clinical prognostic factors. The level of urinary protein IgG was positively correlated with urinary protein excretion (rs = 0.834, P < 0.001), CRP (rs = 0.375, P < 0.001), and C4 (rs = 0.228, P = 0.019), and negatively correlated with eGFR (rs =  - 0.307, P = 0.001). In addition, the level of urinary IgG increased with the increase of tubulointerstitial injury rate, which was positively correlated with endothelial cell proliferation and crescent (all P < 0.05). Prognostic analysis using the Cox proportional hazard regression model and Kaplan-Meier survival curve further determined that urine IgG is an independent risk factor for the prognosis of IgAN with high proportion of global glomerulosclerosis.

CONCLUSIONS

This study determined that urine IgG can be used as a useful predictor of the prognosis of IgAN patients with high proportion global glomerulosclerosis. The mechanism of urine IgG trends in IgAN with high proportion of glomerulosclerosis needs further study.