The beneficial effects of renin–angiotensin system inhibitors (RASI) on IgA nephropathy with tubulointerstitial lesions categorized by Oxford classification

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.

Randomized clinical study to evaluate the effect of personalized therapy on patients with immunoglobulin A nephropathy

Background

Randomized controlled trials (RCTs) have been conducted, stratifying idiopathic immunoglobulin A nephropathy (IgAN) patients based on the laboratory findings [serum creatinine, estimated glomerular filtration rate (eGFR) and daily proteinuria]. In contrast, data from kidney biopsy have been used only for clinical diagnosis. Therefore, IgAN patients with active or chronic renal lesions have been receiving the same therapy in experimental and control arms of randomized clinical trials (RCTs).

Methods

Our clinical study of IgAN (CLIgAN) is a multicentre, prospective, controlled and open-label RCT based on patients' stratification at the time of their kidney biopsy. We will consider, first, the type of renal lesions, followed by serum creatinine values, eGFR and proteinuria. Primary and secondary endpoints will be monitored. Then, we will determine whether personalized therapy can slow the decline of renal function and delay end-stage kidney disease.

Results

We will enrol 132 IgAN patients with active renal lesions (66 patients per arm) in the first RCT (ACIgAN). They will receive corticosteroids combined with renin-angiotensin system blockers (RASBs) or only RASBs. A total of 294 IgAN patients with chronic or moderate renal lesions at high or very high risk of chronic kidney disease (147 patients per arm) will be enrolled in the second RCT (CHRONIgAN), in which they will receive dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, combined with RASBs, or RASBs alone.

Conclusion

Using this approach, we hypothesize that patients could receive personalized therapy based on renal lesions to ensure that the right drug gets to the right patient at the right time.

Evaluation of appropriate treatment for IgA nephropathy with mild proteinuria and normal renal function

BACKGROUND

Tonsillectomy and steroid pulse therapy (TSP) for immunoglobulin A nephropathy (IgAN) is frequently employed in many Japanese institutions; however, performing this invasive treatment in patients with mild IgAN is controversial. This study aimed to evaluate the appropriate treatment for IgAN patients with mild proteinuria.

METHODS

In this retrospective cohort analysis, 122 IgAN patients with mild proteinuria (0.5-1.0 g/day) and estimated glomerular filtration rate of ≥ 60 mL/min/1.73 m² were classified into three groups as follows: patients treated with TSP (n = 32), oral prednisolone (oPSL, n = 33), and conservative therapy (CONS, n = 47). The clinical and histological backgrounds, 5-year remission rates of urinary findings, and 10-year renal survival rates were analyzed.

RESULTS

The backgrounds were similar among the three groups. The remission rates of hematuria, proteinuria, and both were significantly higher for TSP and oPSL than for CONS; however, they were similar for TSP and oPSL. In the multivariate Cox regression analysis, TSP and oPSL were independent factors for the remission of urinary findings compared with CONS; however, the relapse rates of urinary abnormalities were similar among the three groups. No patient progressed to end-stage renal disease (ESRD) within 10 years. Adverse effects of corticosteroid therapy were significantly more frequent in oPSL than in TSP.

CONCLUSION

In IgAN patients with mild proteinuria and stable renal function, similar to oPSL, TSP showed higher remission rates of hematuria and/or proteinuria than CONS, and no case progressed to ESRD regardless of the treatment methods. Therefore, appropriate treatments should be carefully considered for each patient.

Long-term blood pressure behavior and progression to end-stage renal disease in patients with immunoglobulin A nephropathy: a single-center observational study in Italy

BACKGROUND

Antihypertensive treatment by the use of RAAS inhibitors (RAAS-is) is of paramount importance in the management of slowly progressive IgA nephropathy (IgAN). With the aim of better understanding the relationship between BP behavior and progression, we looked at time-averaged SBP and time-averaged proteinuria and renal outcome in a single-center cohort of IgAN patients.

METHODS

Among 248 consecutive patients referred to the Clinic of Nephrology of San Martino Hospital from 1996 to 2018 for native renal biopsy with a diagnosis of IgAN, we retrospectively analyzed 145 with available data at baseline and during follow-up. All patients received Supportive Care, 39% were on RAAS-is alone, 45% plus steroids, and 16% plus steroids and immunosuppressors. Renal replacing treatment (RRT) was the primary endpoint.

RESULTS

During a mean follow-up of 67 ± 6 months, 23% of study patients (n = 33) progressed to RRT and 6% (n = 9) died. Patients who reached the renal endpoint, had lower baseline eGFR and higher proteinuria and proteinuria indexed at baseline. Moreover, they had higher TA-SBP (139 ± 17 vs. 130 ± 13, P = 0.0016). The incidence of RRT was higher in IgAN patients in the highest time-averaged SBP tertile as compared with the others (32 vs. 23 vs. 9%, χ 6.8, P = 0.033). After adjusting for baseline SBP, baseline and time-averaged proteinuria indexed, MEST-C score, and treatment, the association between TA-SBP and RRT persisted.

CONCLUSION

Time-averaged low BP values were independently associated to a decreased risk of renal progression in IgAN with no evidence of a J-curve relationship even at SBP levels below 125 mmHg.

Perspectives on how mucosal immune responses, infections and gut microbiome shape IgA nephropathy and future therapies

Infections have been considered to play a critical role in the pathogenesis of IgA nephropathy (IgAN) because synpharyngitic hematuria is a common feature in IgAN. However, how infections participate in this process is still debated. More recent studies have also revealed that the alteration of the gut microbiome exerts a profound effect on host immune responses, contributing to the etiology or progression of autoimmunity. Considering IgA as the first line of defense against bacterial and viral antigens, this review evaluates the relationships among intestinal infections, gut microbiome, and IgA for a better understanding of the pathogenesis of IgAN. Moreover, as a prototype of IgA immunity, we provide detailed clarification of IgAN pathogenesis to shed light on other diseases in which IgA plays a role. Finally, we discuss potential therapies focusing on microbes and mucosal immune responses in IgAN.

The impact of tonsillectomy combined with steroid pulse therapy in patients with advanced IgA nephropathy and impaired renal function

BACKGROUND

Preventing progression to end-stage renal disease (ESRD) in advanced IgA nephropathy (IgAN) patients with impaired renal function remains challenging. We analyzed the efficacy of tonsillectomy combined with steroid pulse therapy (TSP).

METHODS

In this retrospective analysis, IgAN patients with proteinuria > 0.5 g/day and estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² were divided into three groups: patients treated with TSP (TSP group; n = 23), oral prednisolone (oPSL group; n = 41), and conservative therapy (CONS group, n = 51). We analyzed the clinical and histological backgrounds, remission of urinary findings, and renal survival rate to a 25% decline in eGFR from baseline, and incidence of ESRD.

RESULTS

There were significant differences in the patients' backgrounds among the groups. Therefore, we adjusted the background using propensity score marching between TSP group and oPSL or CONS group. The 5-year remission rate of hematuria was significantly higher in the TSP group than in the oPSL group, and that of both hematuria and proteinuria was significantly higher in the TSP group than in the CONS group. The 10-year renal survival rate was significantly higher in the TSP group than in the oPSL and CONS groups. In a multivariate Cox regression analysis, TSP was found to be an independent factor for the 25% decline in eGFR in entire cohort. The adverse effect frequency in the TSP group was similar to the CONS group.

CONCLUSIONS

TSP can effectively induce remission of urinary abnormality and improve the prognosis without frequent adverse effects in IgAN patients with impaired renal function.