The level of urinary secretory immunoglobulin A (sIgA) of patients with IgA nephropathy is elevated and associated with pathological phenotypes

Abstract

SummaryRecent studies have demonstrated deposition of secretory immunoglobulin A (sIgA) in glomeruli of some patients with IgA nephropathy (IgAN). The aim of this study is to investigate the levels of urinary sIgA in IgAN patients with different pathological phenotypes and whether it could be used as a noninvasive biomarker for assessment of kidney injury in IgAN. Urine samples from 202 patients with IgAN were collected on the day of renal biopsy. Forty-eight fulfilled the histopathological criteria of Haas-I or II (group 1), 60 fulfilled Haas-III (group 2) and 94 patients fulfilled Haas-IV or V (group 3). Urine samples from 60 healthy sex-and age-matched volunteers with negative urinalysis were collected as normal controls. Urinary sIgA was detected by sandwich enzyme-linked immunosorbent assay and was corrected by urinary creatinine. In comparison with normal controls, the levels of urinary sIgA were significantly higher in IgAN [2·22 (0-43·82) mg/mg Cr versus 1·08 (0-16·49) mg/mg Cr, P < 0·001]. The levels of urinary sIgA were significantly higher in group 3 than that in group 2 and group 1 [3·54 (0-43·82) mg/mg Cr versus 1·63 (0-15·88) mg/mg Cr versus 0·91 (0-11·79), P < 0·001], and group 2 than group 1 (P = 0·014). The levels of urinary sIgA were associated positively with proteinuria (r = 0·443, P < 0·001), serum creatinine (r = 0·376, P < 0·001) and histopathological parameters, such as ratio of global sclerosis (r = 0·356, P < 0·001), ratio of total crescents (r = 0·339, P < 0·001) and ratios of cellular crescents (r = 0·231, P < 0·001). The levels of urinary sIgA were associated closely with histopathological phenotypes of IgAN and might be used as a non-invasive biomarker to evaluate kidney injury in IgAN.

Stone former urine proteome demonstrates a cationic shift in protein distribution compared to normal

“…Their reported values for other proteins (i.e., ALBU - 25.4%, KNG1 - 4.3%, and APOD - 2.7%) agreed well with our observations, especially when we adjusted the UROM concentration within our set to match the 1.3 %SC concentration they reported. Other proteins with appropriate comparison data include IGHA1, where our data were consistent with normal baseline measures reported,[33, 34] and A1AT, where similar concentrations were reported in hypertensive individuals with normal kidney function. [35] Other studies have manipulated samples to enhance lower abundance proteins, by first depleting their samples of high abundance proteins, such as ALBU, UROM and immunoglobulins, which makes comparison with our data problematic.…”

CD147 renal expression as a biomarker for progressive IgAN

“…For the tubulointerstitial lesions, tubular atrophy, interstitial fibrosis, and interstitial inflammatory cell infiltration of each section were scored as follows: 0 if absent, 1 for mild (involving \25 % of the interstitium and tubules), 2 for moderate (involving 25-50 % of the interstitium and tubules), and 3 for severe (involving [50 % of the interstitium and tubules). The sum of these scores resulted in a final score for the tubulointerstitial lesion of 0-9 [14]. All of the patients were divided into four groups: no disease (0), mild disease (B2), moderate disease (3)(4)(5) or severe disease (C6).…”

Serum and Urinary Biomarkers Determination and Their Significance in Diagnosis of Kidney Diseases

“…The fractional excretion of IgG has been shown to predict the progression of primary FSGS and the response of this disease to treatment (50). Similarly, urine levels of IgA can be an indicator of the severity of renal damage in IgA nephropathy and are known to correlate with proteinuria, serum creatinine and glomerulosclerosis in this disease (51). In comparison, urine levels of IgM are a strong predictor of disease progression for patients with anti-nuclear cytoplasmic antibody (ANCA)-associated vasculitis (52).…”