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JCI Insight Oct 2023Transglutaminase 2 (TGase2) has been shown to contribute to the mesangial IgA1 deposition in a humanized mouse model of IgA nephropathy (IgAN), but the mechanism is not...
Transglutaminase 2 (TGase2) has been shown to contribute to the mesangial IgA1 deposition in a humanized mouse model of IgA nephropathy (IgAN), but the mechanism is not fully understood. In this study, we found that inhibition of TGase2 activity could dramatically decrease the amount of polymeric IgA1 (pIgA1) isolated from patients with IgAN that interacts with human mesangial cells (HMC). TGase2 was expressed both in the cytosol and on the membrane of HMC. Upon treatment with pIgA1, there were more TGase2 recruited to the membrane. Using a cell model of mesangial deposition of pIgA1, we identified 253 potential TGase2-associated proteins in the cytosolic fraction and observed a higher concentration of cellular vesicles and increased expression of Ras homolog family member A (RhoA) in HMC after pIgA1 stimulation. Both the amount of pIgA1 deposited on HMC and membrane TGase2 level were decreased by inhibition of the vesicle trafficking pathway. Mechanistically, TGase2 was found to be coprecipitated with RhoA in the cellular vesicles. Membrane TGase2 expression was greatly increased by overexpression of RhoA, while it was reduced by knockdown of RhoA. Our in vitro approach demonstrated that TGase2 was transported from the cytosol to the membrane through a RhoA-mediated vesicle-trafficking pathway that can facilitate pIgA1 interaction with mesangium in IgAN.
Topics: Animals; Mice; Humans; Glomerulonephritis, IGA; Immunoglobulin A; Protein Glutamine gamma Glutamyltransferase 2; rhoA GTP-Binding Protein; Glomerular Mesangium; Polymers
PubMed: 37811653
DOI: 10.1172/jci.insight.160374 -
Wiener Klinische Wochenschrift Aug 2023Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis. It leads to end-stage kidney disease in about a third of the patients within 10 to...
Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis. It leads to end-stage kidney disease in about a third of the patients within 10 to 20 years. The pathogenesis of IgAN is incompletely understood. It is believed that a dysregulation of the mucosal immune system leads to undergalactosylation of IgA, followed by formation of IgG autoantibodies against undergalactosylated IgA, circulation of these IgG-IgA immune complexes, deposition of the immune complexes in the mesangium, ultimately resulting in glomerular inflammation. IgAN can occasionally be triggered by other diseases, these secondary causes of IgAN should be identified or ruled out (chronic inflammatory bowel disease, infections, tumors, rheumatic diseases). Characteristic findings of IgAN of variable extent are a nephritic urinary sediment (erythrocytes, acanthocytes, erythrocyte casts), proteinuria, impaired renal function, arterial hypertension, or intermittent painless macrohematuria, especially during infections of the upper respiratory tract. However, the diagnosis of IgAN can only be made by a kidney biopsy. A histological classification (MEST‑C score) should always be reported to be able to estimate the prognosis. The most important therapeutic measure is an optimization of the supportive therapy, which includes, among other things, a consistent control of the blood pressure, an inhibition of the RAS, and the administration of an SGLT2 inhibitor. A systemic immunosuppressive therapy with corticosteroids is discussed controversially, should be used restrictively and only administered after an individual benefit-risk assessment under certain conditions that speak for a progressive IgAN. New promising therapeutics are enteral Budesonide or the dual angiotensin-II-receptor- and endothelin-receptor-antagonist Sparsentan. Rapidly progressive IgAN should be treated with corticosteroids and cyclophosphamide like ANCA-associated vasculitis.
Topics: Humans; Glomerulonephritis, IGA; Antigen-Antibody Complex; Autoantibodies; Immunoglobulin A; Immunoglobulin G
PubMed: 37728647
DOI: 10.1007/s00508-023-02257-6 -
Internal Medicine (Tokyo, Japan) May 2024An elderly woman showed positive conversion of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCAs) following the diagnosis of interstitial lung disease...
An elderly woman showed positive conversion of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCAs) following the diagnosis of interstitial lung disease (ILD) and glomerular hematuria and subsequently experienced slowly progressive glomerulonephritis. A kidney biopsy revealed chronic damage and necrotizing crescentic glomerulonephritis with mesangial MPO deposits. After corticosteroid treatment, the patient's urinalysis results and MPO-ANCA titers almost normalized and her renal function stabilized. This case is similar to recently reported cases of slowly progressive ANCA-associated glomerulonephritis. ILD likely triggered the production of MPO-ANCAs, and the accumulation of MPO deposits in the glomeruli may have contributed to the progression of her renal disease.
Topics: Humans; Female; Lung Diseases, Interstitial; Antibodies, Antineutrophil Cytoplasmic; Glomerulonephritis; Peroxidase; Disease Progression; Aged; Glomerular Mesangium
PubMed: 37722892
DOI: 10.2169/internalmedicine.2512-23 -
Clinical Nephrology. Case Studies 2023Kidneys are commonly involved in systemic amyloidosis. Systemic AA amyloidosis is known to be associated with states of chronic inflammation such as autoimmune...
Kidneys are commonly involved in systemic amyloidosis. Systemic AA amyloidosis is known to be associated with states of chronic inflammation such as autoimmune conditions, chronic infections, and malignancies. Obesity is increasingly recognized to be a risk factor for low-grade, chronic inflammation. We report a 48-year-old female with morbid obesity who presented with unexplained persistent mild kidney dysfunction and low-grade proteinuria. Attempt at evaluating the cause of kidney dysfunction included performing kidney biopsy despite technical challenges. Kidney biopsy showed AA amyloidosis with predominant vascular deposition, explaining the absence of nephrotic-range proteinuria. Evaluation for secondary causes of systemic AA amyloidosis was negative. While our patient was treated with sleeve gastrectomy for morbid obesity with reasonable response, it is likely that ongoing chronic inflammation, reflected by her laboratory markers, resulted in AA amyloidosis. Treatment with anakinra, an interleukin-1 antagonist, led to improvement in the laboratory markers in the next 6 months, and her kidney function remained stable. This report highlights an important cause of kidney dysfunction in morbid obesity, an atypical presentation of AA amyloidosis, and emphasizes the value of kidney biopsy in such patients.
PubMed: 37533546
DOI: 10.5414/CNCS111133 -
Clinical Kidney Journal Jul 2023Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and it is characterized by mesangial IgA deposition. Asymptomatic... (Review)
Review
Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and it is characterized by mesangial IgA deposition. Asymptomatic hematuria with various degrees of proteinuria is the most common clinical presentation and up to 20%-40% of patients develop end-stage kidney disease within 20 years after disease onset. The pathogenesis of IgAN involves four sequential processes known as the "four-hit hypothesis" which starts with the production of a galactose-deficient IgA1 (gd-IgA1), followed by the formation of anti-gd-IgA1 IgG or IgA1 autoantibodies and immune complexes that ultimately deposit in the glomerular mesangium, leading to inflammation and injury. Although several key questions about the production of gd-IgA1 and the formation of anti-gd-IgA1 antibodies remain unanswered, a growing body of evidence is shedding light on the innate and adaptive immune mechanisms involved in this complex pathogenic process. Herein, we will focus on these mechanisms that, along with genetic and environmental factors, are thought to play a key role in disease pathogenesis.
PubMed: 37398689
DOI: 10.1093/ckj/sfad025 -
Clinical Nephrology. Case Studies 2023We performed a kidney biopsy in a 36-year-old man to evaluate microscopic hematuria and proteinuria. Light microscopy showed increased mesangial matrix and partial...
We performed a kidney biopsy in a 36-year-old man to evaluate microscopic hematuria and proteinuria. Light microscopy showed increased mesangial matrix and partial swelling of the glomerular basement membrane (GBM), and immunofluorescence showed positive staining only for C3. Immunoelectron microscopy showed that gold particle-labeled C3 was localized in the electron-dense and moderately electron-dense deposits shown by electron microscopy in the mesangium, the thickened GBM near the paramesangium, and the thickened distal portion of the GBM but was not localized in the non-thickened GBM. Gold-labeled immunoglobulin G, κ, and λ were not seen. C3 glomerulonephritis was more evident in gold-labeled electron microscopy, which further clarified the localization of C3 deposition.
PubMed: 37363300
DOI: 10.5414/CNCS111091 -
Nephron 2023In kidney transplant recipients (KTRs) whose primary disease is IgA nephropathy (IgAN), IgAN recurrence occurs in approximately half of patients by 5 years...
Clinical and Pathological Significance of Mesangial C1q Deposition in Kidney Transplant Recipients with Recurrent IgA Nephropathy and Patients with Native IgA Nephropathy.
INTRODUCTION
In kidney transplant recipients (KTRs) whose primary disease is IgA nephropathy (IgAN), IgAN recurrence occurs in approximately half of patients by 5 years postoperatively and is associated with graft survival. Although the alternative and lectin pathways are important in the primary pathogenesis of IgAN, the significance of mesangial C1q deposition, which triggers the classical pathway, is unknown. We investigated the clinicopathological significance of mesangial C1q deposition in both recurrent IgAN in KTRs and native IgAN.
METHODS
Between 2000 and 2021, we conducted a 1:2 matched case-control study of 18 KTRs diagnosed with recurrent IgAN, with a group of native IgAN patients as the control. We evaluated the rate and presence/absence of mesangial C1q deposition in terms of pathological findings and kidney outcomes in each group.
RESULTS
The rate of mesangial C1q deposition was significantly higher in the recurrent IgAN patients in KTRs than in native IgAN patients (11/18 [61.1%] vs. 5/36 [13.9%], p = 0.001). In the former group, the incidence of glomerular crescents was relatively higher in C1q-positive patients. There was no significant difference in the annual rate of estimated glomerular filtration rate decline between C1q-positive and C1q-negative patients in either group.
CONCLUSION
Mesangial C1q deposition was more frequent in KTRs with recurrent IgAN than in patients with native IgAN, but we found no difference in kidney outcomes with respect to mesangial C1q deposition. Further large-scale investigations of the importance of mesangial C1q deposition are needed in both KTRs with recurrent IgAN and patients with native IgAN.
Topics: Humans; Glomerulonephritis, IGA; Complement C1q; Kidney Transplantation; Case-Control Studies; Glomerular Mesangium
PubMed: 37339606
DOI: 10.1159/000530916 -
Zhongguo Ying Yong Sheng Li Xue Za Zhi... Nov 2022To investigate the interventional effects of a new SUR2B/Kir6.1-type K Channel opener iptakalim on injury renal cells (the renal glomerular endothelial, mesangial and...
To investigate the interventional effects of a new SUR2B/Kir6.1-type K Channel opener iptakalim on injury renal cells (the renal glomerular endothelial, mesangial and tubular epithelial cells) and its mechanisms. ①Experimental protocol: control: the cells were treated with with 0 mg/L uric acid for 24 h; model: the cells were treated with with 1 200 mg/L uric acid for 24 h; pretreatment with iptakalim: the cells were pretreated with 0.01,0.1,1,10,100 μmol/L iptakalim for 24 h prior to treatment with 1 200 mg/L uric acid for 24 h; pretreatment with glibenclamide: the cells were preincubated with/without 10 μmol/L glibenclamide for 1 h and then treated with 10 μmol/L iptakalim for 24 h followed by incubation with 1 200 mg/L uric acid for another 24 h. ②The cell viability was measured by MTT assay and flow cytometry; the protein expressions of Kir6.1 and SUR2B and nuclear translocation were detected by immunostaining; the protein expressions of Kir6.1 and SUR2B were determined by Western blot analysis; adhesion of mononuclear cells to endothelial cells were tested by fluorimetric assay; the content of MCP-1 was measured by enzyme linked-immunosorbent assay (ELISA). The renal glomerular endothelial, mesangial and tubular epithelial cells were exposed to 1 200 mg/L uric acid for 24 h. Compared with the control group, 1 200 mg/L uric acid decreased the cell survival rates significantly (<0.01, <0.01, <0.01). Compared with the model group, pretreatment with 0.1, 1, 10, 100 μmol/L iptakalim could remarkably alleviate cellular damages of glomerular endothelium, mesangium cells induced by uric acid (<0.05, <0.01, <0.01, <0.01). The K channel blocker could clearly reduce survival rates of the renal glomerular endothelial, mesangial cells(<0.01) and markedly reverse the inhibitory effects of iptakalim on cell death (<0.05, <0.01), no obvious difference in comparison with the model group (>0.05). Compared with the model group, pretreatment with 10, 100 μmol/L iptakalim could notably attenuate cellular damages of tubular epithelial cells induced by uric acid (<0.05, <0.05). The K channel blocker could obviously damage the tubular epithelial cells (<0.01), no obvious difference in comparison with the model group (>0.05). Compared with control group, exposure of renal tubular epithelial, mesangial and glomerular endothelial cells to 1 200 mg/L uric acid for 24 h caused a significant increase in the protein expressions of Kir6.1 and SUR2B(<0.05). Compared with the model group, the overexpressions of Kir6.1 and SUR2B were suppressed in presence of iptakalim at a concentration of 10 μmol/L (<0.05). These decreases in the expressions of Kir6.1 and SUR2B were prevented by the K channel blocker, no obvious difference in comparison with the model group (>0.05). Compare with the control group, monocytic adhesion to renal glomerular endothelial cells was notably promoted by 1 200 mg/L uric acid for 24 h (<0.01). Pretreatment with 10 μmol/L iptakalim for 24 h significantly reduced the monocytic adhesion in comparison with the model group (<0.05). It was showed that the inhibitory effects of iptakalim were antagonized by the K channel blocker, no obvious difference in comparison with the model group (>0.05). After stimulating glomerular endothelial cells with 1 200 mg/L uric acid for 24 hours, the secretion of MCP-1 was significantly increased compared to the control group (<0.05). Compare with the model group, preincubation with 10 μmol/L iptakalim significantly decreased MCP-1 production (<0.05). K channel blocker suppressed the downregulation of MCP-1 protein synthesis induced by iptakalim. After stimulation with uric acid, translocation of NF-κB from cytoplasms to nuclei of renal glomerular endothelial cells were observed, while that of NF-κB was suppressed in presence of iptakalim at the concentration of 10 μmol/L. This inhibition of NF-κB translocation was clearly prevented by K channel blocker. These results suggests that a new SUR2B/Kir6.1-type K channel opener iptakalim plays interventional roles in renal cells damages caused by uirc acid and its mechanism is involved in activating Kchannels .
Topics: Endothelial Cells; Glyburide; NF-kappa B; Uric Acid; Adenosine Triphosphate
PubMed: 37308403
DOI: 10.12047/j.cjap.6356.2022.110 -
Scientific Reports May 2023To explore the feasibility of mesangium or membrane anatomy theory in thoracolaparoscopic radical esophagectomy for esophageal cancer, 98 patients with esophageal cancer...
To explore the feasibility of mesangium or membrane anatomy theory in thoracolaparoscopic radical esophagectomy for esophageal cancer, 98 patients with esophageal cancer were enrolled including 45 patients in the mesoesophageal esophagectomy group and 53 patients in the non-mesoesophageal esophagectomy group. Thoracolaparoscopic radical esophagecotmy was technically successful in all patients. Compared the non-mesoesophageal group, the mesoesophageal group had significantly (P < 0.05) shorter surgical duration (211.9 ± 42.0 min vs. 282.0 ± 44.5 min), less blood loss during the procedure (68.9 ± 45.9 ml vs. 167.0 ± 91.4 ml), more harvested lymph nodes (25.9 ± 6.3 vs. 21.8 ± 7.3), shorter hospital stay after surgery (10.5 ± 2.5 d vs. 12.5 ± 4.2 d), shorter fasting time or quicker postoperative feeding time (7.3 ± 1.2 d vs. 9.5 ± 3.9 d), and quicker removal of the thoracic drainage tube after surgery (7.7 ± 2.0 d vs. 9.2 ± 4.1 d). The overall incidence of postoperative complications was 46.7% (21/45) in the mesoesophageal group, which was significantly (P = 0.02) fewer than that (69.8% or 37/53) of the non-mesoesophageal group (P = 0.020). During follow-up 20.6 ± 4.3 or 20.8 ± 3.4 months after esophagectomy, liver metastasis occurred in 1 case and lung metastasis in 1 in the mesoesophageal group, whereas liver metastasis occurred in 2 cases, mediastinal metastasis in 2, and anastomotic recurrence in 1 in the non-mesoesophageal group. The mesoesophageal group had significantly better physical function (81.9 ± 7.3 vs. 78.3 ± 7.6), social function (65.1 ± 7.1 vs. 56.2 ± 18.2), global health status (65.3 ± 10.1 vs. 58.7 ± 12.4), and pain improvement (29.5 ± 9.5 vs. 35.6 ± 10.6). The overall survival rate was 82.2% (37/45) in the mesoesophageal group and 71.7% (38/53) in the non-mesoesophageal group (P = 0.26). The disease-free survival rate was 77.8% (35/45) for the mesoesophageal group and 62.3% (33/53) for the non-mesoesophageal group (P = 0.13). In conclusion:, the mesangium or membrane anatomy theory can be used safely and effectively to guide thoracolaparoscopic radical esophagectomy for esophageal cancer, with advantages of shorter surgical time, less bleeding, more lymph node harvest, fewer complications, and faster postoperative recovery.
Topics: Humans; Esophagectomy; Lymph Node Excision; Esophageal Neoplasms; Lymph Nodes; Postoperative Complications; Retrospective Studies
PubMed: 37253750
DOI: 10.1038/s41598-023-35513-w