Ⅰ型纤溶酶原激活物抑制物在IgA肾病肾小管间质损伤中的作用研究

目的 探讨Ⅰ型纤溶酶原激活物抑制物（ＰＡＩ－１）在ＩｇＡ肾病肾小管间质损害中的作用。方法 采用原位杂交和免疫组织化学技术,分别在基因和蛋白质水平检测３８例ＩｇＡ肾病患者肾小管间质中的ＰＡＩ－１表达,同时观察α－平滑肌肌动蛋白和增殖细胞核抗原（ＰＣＮＡ）的表达变化。     

Nestin is a novel marker for renal tubulointerstitial injury in immunoglobulin A nephropathy

Aim: Nestin, an intermediate filament originally identified as a marker of neural progenitor cells, is transiently expressed in endothelial cells and tubuloepithelial cells during kidney development. However, in adult kidneys, podocytes are the only cells that express nestin. In this study, we examined tubulointerstitial nestin expression in human glomerulonephritis. Methods: Renal biopsy specimens obtained from 41 adult patients with immunoglobulin (Ig)A nephropathy were studied. Nestin expression was determined by immunohistochemical staining and estimated by digital image analysis. To identify the phenotype of nestin‐positive cells, a double immunofluorescent study was performed for nestin and CD34 (a marker for endothelial cells) or α‐smooth muscle actin (α‐SMA, a marker for myofibroblasts). Results: In normal kidney, nestin expression was restricted to the podocytes and was not detected in tubular cells and tubulointerstitial cells. In contrast, increased nestin expression was observed at tubulointerstitial areas of IgA nephropathy. The degree of tubulointerstitial nestin expression was positively correlated with tubulointerstitial fibrosis (r = 0.546, P < 0.001). The double immunofluorescent study showed that most nestin‐positive cells in the interstitium were co‐stained with CD34 or α‐SMA, suggesting that peritubular endothelial cells and tubulointerstitial myofibroblasts express nestin during the progression of tubulointerstitial injury. In addition, strong nestin expression was associated with deterioration of renal function. Conclusion: Nestin expression is associated with tubulointerstitial injury and predicts renal prognosis in IgA nephropathy. Nestin could be a new marker for peritubular endothelial cell injury and tubulointerstitial fibrosis.     

Evolution of renal injury in a chronic model of IgA immune-complex-associated nephropathy

BACKGROUND.: IgA nephropathy (IgAN) is characterized by intense and diffuseIgA mesangial deposits, a variety of histopathological changesand unpredictable clinical course. To elucidate the cause ofthe discrepancy between the unvariable IgA deposition and thehistological picture, we examined the short- and long-term influenceof glomerular IgA immune complexes (IgA-IC) on the progressionof renal lesions in experimental IgAN. METHODS.: IgA-IC renal deposits were induced by sequential administrationof IgA anti-phosphorylcholine and pneumococcal C polysaccharide.Mice treated every other day by three injections (groups A)or nine injections (groups B) were sacrificed 24 h and 1, 4,or 8 weeks (groups 1–4) after cessation of treatment. RESULTS.: Group A1 showed segmental glomerular necrosis and thrombosis.Lesions then converted to segmental mesangial proliferation(A2), more pronounced in A3 and minimal in A4. Group B1 showedsevere proliferative glomerulonephritis and segmental necrosis.The pattern altered to mesangial expansion with glomerular/interstitialinfiltration in B2, milder features in B3 and residual mesangialproliferation in B4. Proteinuria increased progressively duringtreatment reaching its maximum in group B1, but it returnedto near normal levels in group B4. The development of proteinuriaparalleled glomerular/interstitial T cell infiltration. CONCLUSIONS.: These findings demonstrate that renal histopathological alterationsobserved in experimental IgA nephropathy are sustainable onlyby continuous deposition of nephritogenic IgA-IC.     

TNF-α-mediated podocyte injury via the apoptotic death receptor pathway in a mouse model of IgA nephropathy

BackgroundIgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and it is characterized by mesangial IgA deposits. Proteinuria is a common clinical feature of IgAN, which has a critical connection to podocyte injury and has been used as a clinical prognostic factor for IgAN. Evidence has shown that TNF-α released from mesangial cells may lead to podocyte apoptosis.MethodsForty male BALB/c mouse were randomly divided into the control group and IgAN group. A mice model of IgAN was developed by oral administration of bovine serum albumin (BSA) combined with Staphylococcus Enterotoxin B (SEB) tail vein injection. Urinary protein concentrations, renal function, renal morphological, IgA deposition, apoptosis situation, and the mRNA and protein expression of nephrin, podocin, TNF-α, TNFR1, caspase-8 and caspase-3, were detected after 12 weeks.ResultsBSA and SEB can successfully establish an IgAN mouse model, and the main pathological changes are the IgA immune complex deposition in the mesangial area. The gene and protein expression levels of nephrin and podocin were found to be downregulated, and death receptor pathway-related indicators were upregulated, and they were involved in TNF-α-activated podocyte injury and apoptosis in IgAN mice.ConclusionTNF-α may play an important role in the pathogenesis of podocyte apoptosis in IgAN, and its effects may be mediated through the apoptotic death receptor pathway.     

The treatment of tacrolimus in primary IgA nephropathy with mild or moderate renal injury: a randomized controlled study

Objective To investigate the efficacy and safety of immunosuppressive therapy (Tacrolimus or CTX) in primary IgA nephropathy (IgAN) with mild or moderate renal dysfunction. Methods Thirty-six primary IgAN patients diagnosed by renal biopsy, with mild or moderate renal dysfunction[30 ml•min-1•(1.73m2)-1≤eGFR＜90 ml•min-1•(1.73m2)-1, proteinuria＞1.0 g/24 h] were recruited in this randomized controlled trial. All the patients were assigned into steroid therapy alone, steroid combined with CTX (CTX group) and steroid combined with tacrolimus (tacrolimus group). Results The 24-hour proteinuria at baseline were (1.91±0.81) g/24 h, (2.42±1.46) g/24 h, (2.57±1.87) g/24 h in steroid group, CTX group and tacrolimus group respectively. Compared with baseline, it was significantly decreased in steroid group at 3 months [(0.90±0.75) g/24 h, P＜0.05], 6 months [(0.76±0.73) g/24 h, P＜0.05] and 12 months [(0.35±0.35) g/24 h, P＜0.05], in CTX group at 3 months [(1.40±1.24) g/24 h, P＜0.05], 6 months [(0.87±0.83) g/24 h, P＜0.05] and 12 months [(0.68±0.70) g/24 h, P＜0.05], and in FK506 group at 3 months [(1.10±1.33) g/24 h, P＜0.05], 6 months [(0.78±0.69) g/24 h, P＜0.05] and 12 months [(0.69±0.82) g/24 h, P＜0.05]. At 6 months, serum creatinine were decreased in steroid alone [(111.72±31.23) μmol/L vs (121.17±36.51) μmol/L, P＜0.05] and in CTX group [(111.33±22.76) μmol/L vs (124.33±35.51) μmol/L, P＜0.05], while no significant difference was detected in tacrolimus group. At 12 months, there was no significant difference in terms of serum creatinine in all three groups. Besides, there was no significant difference in terms of eGFR (CKD-EPI) in all three groups. One case presented hyperglycemia and one case had liver dysfunction during the treatment in steroid group. Two cases had hyperglycemia, one case had impaired glucose tolerance and one case had liver dysfunction in the tacrolimus group. Conclusions Steroid along, steroid combined with tacrolimus or combined with CTX are efficient in reducing urine protein in the treatment of primary IgAN with mild or moderate renal dysfunction without inducing increased serum creatinine. Given the occurrence of hyperglycemia during the treatment with steroid combined with tacrolimus, it is important to monitor tacrolimus concentration during the treatment.     

Tonsillar IgA1 as a possible source of hypoglycosylated IgA1 in the serum of IgA nephropathy patients.

BACKGROUND: There are many reports of incompletely glycosylated O-linked oligosaccharides on the IgA1 hinge region in certain IgA nephropathy patients. In addition, other reports have noted a relationship between tonsillectomy and IgA nephropathy. METHODS: Immunoglobulins from extracts of tonsillectomized tissue and other sources were analysed by isoelectric focusing (IEF) and by enzyme-linked immunosorbent assay (ELISA). RESULTS: The IEF profile of tonsillar IgA differed from that of serum IgA and it was enriched in cationic IgA. However, extracts from tonsillitis controls and IgA nephropathy patients exhibited profiles that were very similar. Enzymatic removal of sialic acid induced a shift of the peaks to the cathode side. The profiles of IgA from treated tonsillar extract and treated serum were closely overlapped. In addition, asialo Galbeta1,3GalNAc was clearly present in cationic IgA from tonsillar extract and in aberrant IgA1 from serum following enzymatic transfer of sialic acid to IgA1. Serum IgA also contained partly sialylated IgA1. Quantitative analysis of IgA and IgG in the extracts indicated that IgA was significantly higher, whereas IgG was significantly lower in IgA nephropathy patients. CONCLUSIONS: We found that the IgA1 produced in tonsillar tissue differed from serum IgA1. Furthermore, an overproduction of asialo IgA1 resulted from the disordered balance between IgA- and IgG-producing cells in the tonsils from the IgA nephropathy patient. Although it is unclear how such asialo IgA1 molecules are transferred from tonsil tissue to serum, a tonsillar source may produce a few micrograms of aberrant IgA1 that then appears in serum.     

HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

Abstract: Background: The HLA‐B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients. Methods: From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non‐glomerular diseases. Death‐censored graft loss according to the HLA‐B8, DR3 haplotype was calculated with Kaplan–Meier analysis and Cox‐regression model was used to correct for various risk factors. Results: The frequency of the HLA‐B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten‐year graft survival was identical in the control group with and without the HLA‐B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA‐B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA‐B8, DR3 haplotype and independent of well‐known risk factors. Conclusions: We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.     

Recurrence of IgA nephropathy after kidney transplantation in steroid continuation versus early steroid‐withdrawal regimens: a retrospective analysis of the UNOS/OPTN database

In the past 20 years, there has been an increase in use of steroid‐withdrawal regimens in kidney transplantation. However, steroid withdrawal may be associated with an increased risk of recurrent IgA nephropathy (IgAN). Using United Network of (Organ Sharing/Organ Procurement and Transplantation Network) UNOS/OPTN data, we analyzed adult patients with end‐stage renal disease (ESRD) due to IgAN who received their first kidney transplant between 2000 and 2014. For the primary outcome, we used a competing risk analysis to compare the cumulative incidence of graft loss due to IgAN recurrence between early steroid‐withdrawal (ESW) and steroid continuation groups. The secondary outcomes were patient survival and death‐censored graft survival (DCGS). A total of 9690 recipients were included (2831 in ESW group and 6859 in steroid continuation group). In total, 1238 recipients experienced graft loss, of which 191 (15.43%) were due to IgAN recurrence. In multivariable analysis, steroid use was associated with a decreased risk of recurrence (subdistribution hazard ratio 0.666, 95% CI 0.482–0.921; P = 0.014). Patient survival and DCGS were not different between the two groups. In the USA, ESW in transplant for ESRD due to IgAN is associated with a higher risk of graft loss due to disease recurrence. Future prospective studies are warranted to further address which patients with IgAN would benefit from steroid continuation.     

Polymeric IgA increases the synthesis of macrophage migration inhibitory factor by human mesangial cells in IgA nephropathy.

BACKGROUND: It has been suggested that polymeric IgA (pIgA) or IgA immune complexes play a significant pathogenic role in IgA nephropathy (IgAN). Macrophage migration inhibitory factor (MIF) shares many activities with other pro-inflammatory cytokines. In human glomerulonephritis, including IgAN, glomerular expression of MIF is found to correlate with progressive renal injury. We hypothesized that deposition of pIgA within the kidney may lead to enhanced synthesis of MIF by mesangial cells. METHODS: In this study we examined the effect of pIgA and monomeric IgA (mIgA) from randomly selected patients with IgAN in clinical quiescence on the gene expression and protein synthesis of MIF in cultured human mesangial cells (HMC). RESULTS: Both pIgA and mIgA from IgAN patients or matched healthy controls increased MIF gene expression and protein synthesis in a dose-dependent fashion. The magnitude of MIF protein induction by pIgA (100 microg/ml) was similar to that of tumour necrosis factor-alpha (TNF-alpha) at 10 pg/ml. In all subjects, the induction of MIF was higher for pIgA when compared with mIgA (P < 0.01). Furthermore, the up-regulation of MIF synthesis by either pIgA or mIgA was significantly higher in IgAN patients than in healthy controls (P < 0.05). Similarly, pIgA and mIgA were able to induce TNF-alpha gene expression and protein synthesis in mesangial cells. Incubation of mesangial cells with neutralizing antibody to TNF-alpha reduced the MIF synthesis induced by pIgA. CONCLUSION: We demonstrate that pIgA is capable of inducing MIF and TNF-alpha production in HMC, which may play a major pathogenic role in IgAN. Induction of MIF can be partially blocked by neutralizing antibody to TNF-alpha, suggesting the possibility that up-regulation of MIF synthesis in HMC is mediated via an amplifying proinflammatory loop involving TNF-alpha.     

Clinicopathological study of IgA nephropathy in adults: The influence of onset age on clinical and renal histological findings and on the effect of steroid therapy

Background. The prognosis of IgA nephropathy (IgAN) varies according to the patient's age. It usually affects children or young adults. However, the onset age for IgAN may be at middle-age or older. The influence of onset age on the clinical and renal histological findings of adult IgAN was investigated. Methods. We selected 39 IgAN patients in whom renal biopsy was performed within 2 years from the onset. The patients were divided into two groups according to onset age; early-onset group (under 35 years; group E) and late-onset group (over 35 years; group L). The clinical and histological findings and the response to steroid therapy were compared in the two groups. Results. (1) Clinically, the levels of proteinuria and hematuria in groups E and L were not different, but the creatinine clearance was lower in group L than in group E. Hypertension was frequent in group L (66.7%), but not in group E. (2) Histologically, the rate of glomerular obsolescence and the grades of interstitial fibrosis and arterio- and arteriolosclerosis were more advanced in group L than in group E. However, there were no differences in the grade of mesangial cell proliferation or mesangial matrix increase, nor were the rates of glomerular crescent and tuft adhesion formation different between the two groups. (3) The reduction of proteinuria and hematuria after 1-year steroid therapy was similar in the two groups. Conclusion. Onset age does not affect the severity of glomerular lesions and the effect of steroid therapy in the early phase of adult IgAN. However, advanced interstitial fibrosis and arterio- and arteriolosclerosis, which may be related to hypertension or the aging process, lead to impaired renal function in late-onset IgAN patients. Received: March 18, 1998 / Accepted: October 29, 1998     

Combination therapy with DHA and BMSCs suppressed podocyte injury and attenuated renal fibrosis by modulating the TGF-β1/Smad pathway in MN mice

Artemisinin has immunomodulatory, anti-inflammatory, and antifibrotic effects. Some studies have demonstrated that artemisinins have a protective effect on the kidney. DHA is a derivative of artemisinin and has effects similar to those of artemisinin. Human bone marrow-derived mesenchymal stem cells (BMSCs) accelerate renal repair following acute injury. In the study, we investigated the effects of combination therapy with DHA and BMSCs on membranous nephropathy (MN) mice. The 24-h urinary protein, serum total cholesterol (TC) and triglyceride (TG) levels, and renal histopathology, were measured to evaluate kidney damage. Anti-PLA2R, IgG, and complement 3 (C3) were detected by ELISA. The expression levels of the podocyte injury-related proteins were analyzed by immunohistochemistry. The protein expression levels of α-SMA, ED-1, TGF-β1, p-Smad2, and p-Smad3 were detected by western blot to analyze renal fibrosis and its regulatory mechanism. Results showed that combination therapy with DHA and BMSCs significantly ameliorated kidney damage in MN model mice by decreasing the levels of 24 h urinary protein, TC and TG. This combination therapy also improved renal histology and reduced the expression of IgG and C3 in the glomerulus. In addition, this combination therapy decreased the expression of podocin and nephrin and relieved renal fibrosis by downregulating α-SMA and ED-1. Furthermore, this combination therapy suppressed TGF-β1 expression and Smad2/3 phosphorylation. This result (i.e., this combination therapy inhibited the TGF-β1/Smad pathway) was also supported in vitro. Taken together, combination therapy with DHA and BMSCs ameliorated podocyte injury and renal fibrosis in MN mice by downregulating the TGFβ1/Smad pathway.     

Interventions for decreasing the risk of recurrent IgA nephropathy: A systematic review and meta-analysis

Recurrent IgA nephropathy (rIgAN) is an important cause of kidney allograft loss. Till now, no proven strategies have been confirmed to prevent/decrease the rIgAN. Here, a systematic review and meta-analysis were performed on the available interventions impacting rIgAN. PubMed, Embase, Web of sciences, ProQuest, and Cochrane library databases along with Google Scholar were searched for articles evaluating the rIgAN after kidney transplantation (up to 23 February 2023). The main inclusion criteria were kidney transplantation because of primary IgAN and articles studying the rate of the rIgAN based on different therapeutic interventions to find their effects on the disease recurrence. Based on our criteria, 11 papers were included in this systematic review, two of which pleased the criteria for the meta-analysis. Meta-analysis showed that the risk of the rIgAN in the steroid-free group was 3.33 times more than that of the steroid-receiving group (Pooled Hazard Ratio = 3.33, 95% CI 0.60 to18.33, Z-value = 1.38, p-value = 0.16). Steroid-free therapy increases the risk of rIgAN in kidney transplant recipients with primary IgAN. High-quality trials with large sample sizes studies are needed to confirm the impact of the steroids on decreasing the rate of the rIgAN.