Background and objectives Several studies have suggested that activation of the complement system is a contributing pathogenic mechanism in IgA nephropathy (IgAN). C4d staining is an inexpensive and easy-toperform method for the analysis of renal biopsies. This study aimed to assess the clinical and prognostic implications of C4d staining in IgAN.Design, setting, participants, & measurements This retrospective cohort study included 283 patients with IgAN in 11 hospitals in Spain who underwent a renal biopsy between 1979 and 2010. The primary predictor was mesangial C4d staining. Secondary predictors included demographic, clinical, and laboratory characteristics, and Oxford pathologic classification criteria. The primary end point was the cumulative percentage of patients who developed ESRD, defined as onset of chronic dialysis or renal transplantation. C4d was analyzed by immunohistochemical staining using a polyclonal antibody. Kaplan-Meier and Cox proportional hazards analyses were performed to evaluate the effect of C4d staining on renal survival.Results There were 109 patients (38.5%) and 174 patients (61.5%) who were classified as C4d positive and C4d negative, respectively. Renal survival at 20 years was 28% in C4d-positive patients versus 85% in C4d-negative patients (P,0.001). Independent risk factors associated with ESRD were as follows: proteinuria (hazard ratio [HR] per every 1 g/d increase. 1.16; 95% confidence interval [95% CI], 1.03 to 1.31; P=0.01), eGFR (HR per every 1 ml/min per 1.73 m 2 increase, 0.96; 95% CI, 0.94 to 0.97; P,0.001), T2 Oxford classification (tubular atrophy/ interstitial fibrosis, .50%; HR, 4.42; 95% CI, 1.40 to 13.88; P=0.01), and C4d-positive staining (HR, 2.45; 95% CI, 1.30 to 4.64; P=0.01).Conclusions C4d-positive staining is an independent risk factor for the development of ESRD in IgAN. This finding is consistent with the possibility that complement activation is involved in the pathogenesis of this disease.

In patients with resistant hypertension and OSA, CPAP treatment for 3 months achieves reductions in 24-h BP. This effect is seen in patients with ABPM-confirmed resistant hypertension who use CPAP more than 5.8 h.

The STARMEN trial indicates that alternating treatment with corticosteroids and cyclophosphamide is superior to sequential treatment with tacrolimus and rituximab in primary membranous nephropathy.

IgA nephropathy (IgAN), a frequent cause of chronic kidney disease worldwide, is characterized by mesangial deposition of galactose-deficient IgA1-containing immune complexes. Complement involvement in IgAN pathogenesis is suggested by the glomerular deposition of complement components and the strong protection from IgAN development conferred by the deletion of the CFHR3 and CFHR1 genes (Δ). Here we searched for correlations between clinical progression and levels of factor H (FH) and FH-related protein 1 (FHR-1) using well-characterized patient cohorts consisting of 112 patients with IgAN, 46 with non-complement-related autosomal dominant polycystic kidney disease (ADPKD), and 76 control individuals. Patients with either IgAN or ADPKD presented normal FH but abnormally elevated FHR-1 levels and FHR-1/FH ratios compared to control individuals. Highest FHR-1 levels and FHR-1/FH ratios are found in patients with IgAN with disease progression and in patients with ADPKD who have reached chronic kidney disease, suggesting that renal function impairment elevates the FHR-1/FH ratio, which may increase FHR-1/FH competition for activated C3 fragments. Interestingly, Δ homozygotes are protected from IgAN, but not from ADPKD, and we found five IgAN patients with low FH carrying CFH or CFI pathogenic variants. These data support a decreased FH activity in IgAN due to increased FHR-1/FH competition or pathogenic CFH variants. They also suggest that alternative pathway complement activation in patients with IgAN, initially triggered by galactose-deficient IgA1-containing immune complexes, may exacerbate in a vicious circle as renal function deterioration increase FHR-1 levels. Thus, a role of FHR-1 in IgAN pathogenesis is to compete with complement regulation by FH.

The long-term outcome of patients with IgA nephropathy who present with normal renal function, microscopic hematuria, and minimal or no proteinuria is not well described. Here, we studied 141 Caucasian patients with biopsy-proven IgA nephropathy who had minor abnormalities at presentation and a median follow-up of 108 months. None of the patients received corticosteroids or immunosuppressants. We reviewed renal biopsies using the Oxford classification criteria. In this sample, 46 (32%) patients had mesangial proliferation, whereas endocapillary proliferation, focal glomerulosclerosis, and tubulointerstitial abnormalities were uncommon. Serum creatinine increases .50% and .100% were observed in five (3.5%) patients and one (0.7%) patient, respectively; no patients developed ESRD. After 10, 15, and 20 years, 96.7%, 91.9%, and 91.9% of patients maintained serum creatinine values less than a 50% increase, respectively. Using Cox proportional hazards regression, the presence of segmental glomerulosclerosis was the only factor that significantly associated with a .50% increase in serum creatinine. Clinical remission occurred in 53 (37.5%) patients after a median of 48 months. Proteinuria.0.5 and .1.0 g/24 h developed in 21 (14.9%) and 6 (4.2%) patients, respectively. Median proteinuria at the end of follow-up was 0.1 g/24 h, with 41 (29.1%) patients having no proteinuria. At presentation, 23 (16.3%) patients were hypertensive compared with 30 (21.3%) patients at the end of follow-up; 59 (41.8%) patients were treated with reninangiotensin blockers because of hypertension or increasing proteinuria. In summary, the long-term prognosis for Caucasian patients with IgA nephropathy who present with minor urinary abnormalities and normal renal function is excellent.