Causal relationship between gut microbiota and Behçet's disease: a Mendelian randomization study.

Background: While observational epidemiological studies have suggested an association between gut microbiota and Behçet's disease (BD), the causal relationship between the two remains uncertain. Methods: Statistical data were obtained from gut microbiome Genome-Wide Association Studies (GWAS) published by the MiBioGen consortium, and genetic variation points were screened as instrumental variables (IV). Mendelian randomization (MR) study was performed using inverse variance weighted (IVW), weighted median, MR-Egger regression, simple mode, and weighted mode methods to evaluate the causal relationship between gut microbiota (18,340 individuals) and BD (317,252 individuals). IVW was the main method of analysis. The stability and reliability of the results were verified using the leave-one-out method, heterogeneity test, and horizontal genetic pleiotropy test. Finally, a reverse MR analysis was performed to explore reverse causality. Results: Inverse variance weighted (IVW) results showed that the genus Parasutterella (OR = 0.203, 95%CI 0.055-0.747, p = 0.016), Lachnospiraceae NC2004 group (OR = 0.101, 95%CI 0.015-0.666, p = 0.017), Turicibacter (OR = 0.043, 95%CI 0.007-0.273, p = 0.001), and Erysipelatoclostridium (OR = 0.194, 95%CI 0.040-0.926, p = 0.040) were protective factors against BD, while Intestinibacter (OR = 7.589, 95%CI 1.340-42.978, p = 0.022) might be a risk factor for BD. Conclusion: Our study revealed the causal relationship between gut microbiota and BD. The microbiota that related to BD may become new biomarkers; provide new potential indicators and targets for the prevention and treatment of BD.

The protease inhibitor E64d might attenuate the development of experimental anti-glomerular basement membrane disease through regulating the activation of Th1 cells.

BACKGROUND: Cathepsins have been recently identified as a regulator in the activation of Th1 and Th17 cells, which play an important role in the pathogenesis of anti-glomerular basement membrane (GBM) disease. Whether cathepsins contribute to the development of anti-GBM disease through regulating the activation of CD4+ T cell is still unclear. METHODS: Rats with experimental anti-GBM disease was established by immunization with the nephritogenic T cell epitope α3127-148. E64d, a cysteine cathepsin inhibitor, was administered in vitro and vivo to evaluate the effect of cathepsins on regulating the activation of antigen specific T cells and the development of anti-GBM disease. RESULTS: In rats with experimental anti-GBM diseases, E64d treatment not only reduced the levels of proteinuria, serum creatinine and anti-GBM antibody, but also ameliorated the kidney injury with less glomerular IgG deposition, a lower percentage of crescents and less infiltration of CD4+ T cells, CD8+ T cells and macrophages, as well as a lower percentage of splenic Th1 cells. In vitro, E64d treatment could significantly reduce the production of IFN-γ in the supernatant which might be produced by the activation of Th1 cells after being recalled with the autoantigen α3127-148. We also found the CD4+ T cells of rats with anti-GBM disease had an increased expression of cathepsin L (Cts-L), and the percentage of CD4+ T cells with extracellular expression of Cts-L was obviously higher, indicating it as a potential key regulator. CONCLUSIONS: E64d might attenuate the development of anti-GBM disease by participating in the activation of Th1 cells, indicating it as a potential drug for anti-GBM disease in the future.

Significance of thyroid dysfunction in the patients with primary membranous nephropathy.

BACKGROUND: Thyroid dysfunction is common in patients with nephrotic syndrome, especially patients with primary membranous nephropathy (pMN). In view of both MN and thyroid dysfunction are associated with autoimmunity, the current study aimed to elucidate the significance of thyroid dysfunction in patients with pMN. METHODS: Four hundred and twenty patients with biopsy-proven pMN from 2018-2021 were retrospectively enrolled. Clinical and pathological parameters, and treatment response of patients with and without thyroid dysfunction were analyzed. RESULTS: Ninety-one (21.7%) patients with pMN suffered from thyroid dysfunction, among which subclinical hypothyroidism (52.7%) was the main disorder. Compared to patients with normal thyroid function, patients with thyroid dysfunction presented with a higher level of proteinuria, a lower level of serum albumin, a higher level of serum creatinine and more severe tubulointerstitial injury at the time of biopsy. But the positive rate and level of circulating anti-phospholipase A2 receptor (PLA2R) antibody were comparable between these two groups. Though following the similar treatment, the percentage of no response to treatment were significantly higher in the patients with thyroid dysfunction (38.6 vs. 20.0%, P = 0.003). Similar to the urinary protein and the positivity of anti-PLA2R antibody, multivariate COX analysis showed thyroid dysfunction was also identified as an independent risk factor for the failure to remission (HR = 1.91, 95%CI, 1.07-3.40, P = 0.029). CONCLUSION: In conclusion, thyroid dysfunction is common in the patients with pMN and might predict a severe clinical manifestation and a poor clinical outcome, which indicated that the thyroid dysfunction might be involved in the disease progression of pMN.

The potential pathogenic roles of S100A8/A9 and S100A12 in patients with MPO-ANCA-positive vasculitis.

BACKGROUND: The significance of S100A8/A9 and S100A12 in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has not been clarified. This study was dedicated to exploring the potential pathogenic roles of S100A8/A9 and S100A12 in patients with myeloperoxidase (MPO)-ANCA-positive vasculitis. METHODS: Serum and urine concentrations of S100A8/A9 and S100A12 of forty-two AAV patients were evaluated. The influence of S100A8/A9 and S100A12 on the chemotaxis, the apoptosis, the release of IL-1ß, the complement activation, the respiratory burst, as well as the neutrophil extracellular traps (NETs) formation of MPO-ANCA-activated neutrophils was investigated. RESULTS: The serum and urine S100A8/A9 and S100A12 of active MPO-AAV significantly increased (compared with inactive AAV and healthy controls, p < 0.001) and were correlated with the severity of the disease. In vitro study showed that S100A8/A9 and S100A12 activated the p38 MAPK/NF-κB p65 pathway, increased the chemotaxis index (CI) and the release of IL-1ß, extended the life span, and enhanced the complement activation ability of MPO-ANCA-activated neutrophils. The Blockade of TLR4 and RAGE inhibited the effects of S100A8/A9 and S100A12. All above-mentioned effects of S100A8/A9 and S100A12 were ROS-independent because neither S100A8/A9 nor S100A12 enhanced the ROS formation and NETs formation of MPO-ANCA-activated neutrophils. CONCLUSION: S100A8/A9 and S100A12 serve as markers for assessing the disease severity, and they may also play a role in MPO-AAV pathogenesis.

Circulating nicotinamide adenine dinucleotide-ubiquinone oxidoreductase chain 6 is associated with disease activity of anti-neutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: Increased serum and urinary mitochondrial DNA have been demonstrated in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Here we investigated the significance of serum nicotinamide adenine dinucleotide-ubiquinone oxidoreductase chain 6 (ND6), which is encoded by mtDNA and can attract neutrophils, in AAV. METHODS: Thirty-seven AAV patients (32 patients with positive myeloperoxidase-ANCA and 5 patients with proteinase 3-ANCA) were enrolled. Relationship between serum ND6 and clinico-laboratory characteristics were analyzed. RESULTS: The ND6 level of patients was higher than normal people (46.56 ± 23.67 pg/mL vs. 4.95 ± 2.45 pg/mL, P < 0.001) The ND6 levels of patients who needed hemodialysis at disease onset and who had pulmonary hemorrhage (PH) were higher than that of the corresponding controls (P = 0.004 and 0.044 respectively). The ND6 level negatively correlated with the percentages of normal glomeruli in kidney biopsy. The AUC of ROC curve to diagnose hemodialysis and PH was 0.804 and 0.750 respectively. ND6 level positively correlated with Birmingham Vasculitis Activity Score in active disease, and returned to normal after remission. Patients with higher serum ND6 had higher mortality (P = 0.023). CONCLUSIONS: Serum ND6 increases in active AAV, and its level correlates with the severity of disease. High ND6 level is associated with severe organ injury and predicts poor prognosis of AAV.

High serum hepcidin is associated with the occurrence of anemia in anti-myeloperoxidase antibody-associated vasculitis with normal kidney function: a cross-sectional study.

The etiology of anemia in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has not been elucidated. In this cross-sectional study, we tried to investigate the relationship between serum hepcidin and anemia in myeloperoxidase (MPO)-ANCA-AAV. Data of 64 newly diagnosed AAV patients who did not have kidney dysfunction or hemorrhage were analyzed. Serum hepcidin was measured with enzyme linked immunosorbent assay. Twenty-three of 64 patients had anemia. Compared with patients without anemia, patients with anemia had higher Birmingham vasculitis activity score [10 (3, 23) vs. 5 (3, 17), p = 0.020], lower levels of serum iron (5.83 ± 1.63 vs. 9.76 ± 1.54, p < 0.001) and higher levels of ferrtin [358.00 (59.85, 1314.10) vs. 151.05 (43.00, 645.30), p = 0.006]. All 64 patients had increased levels of serum hepcidin compared with normal controls, while patients with anemia had higher serum hepcidin than patients without anemia (85.30 ± 16.92 ng/mL vs. 53.48 ± 13.32 ng/mL, p < 0.001). In the multivariable analysis, the level of hemoglobin correlated with the levels of serum iron (r = 0.344, p = 0.026) and hepcidin (r = - 0.353, p = 0.022). Low level of serum iron was related to high level of serum hepcidin (r = - 0.472, p = 0.001). Immunosuppressive treatment induced rapid decrease of hepcidin and increase of serum iron on the 1st month, while the recovery of hemoglobin was relatively slow. This study indicated that in MPO-AAV without kidney dysfunction or hemorrhage, the existence of anemia is associated with high level of hepcidin which induces low serum iron and the abnormality of iron utilization.

Severe acute interstitial nephritis induced by valsartan: A case report.

RATIONALE: Angiotensin receptor blocker (ARB) can increase serum creatinine or potassium levels in patients with renal insufficiency, renal artery stenosis, heart failure or hypovolemia, but hardly cause severe kidney injury in patients without any risk factors. A case of severe acute interstitial nephritis (AIN) induced by valsartan was reported here. PATIENT CONCERNS: A 62-year-old female with nausea for 1 month and acute deterioration of kidney function for 2 weeks was admitted. She had a history of hypertension for 5 months and had taken valsartan 40 mg daily for 4 months. Although the valsartan had been stopped for 2 weeks, the serum creatinine continuously increased after admission. Kidney biopsy demonstrated the eosinophils infiltration in interstitium. DIAGNOSES: AIN induced by valsartan. INTERVENTIONS: The patient was treated with glucocorticoid. OUTCOMES: The serum creatinine decreased gradually and got back to normal level 5 months later. Then therapy of glucocorticoid was stopped. Renal artery stenosis was excluded by computed tomography angiography (CTA). LESSONS: Although valsartan-induced allergy has been reported previously, AIN was firstly recognized as a severe complication of this drug. We suggest when there is a ARB-associated continuous deterioration of kidney function for patients without renal insufficiency, renal artery stenosis, heart failure or hypovolemia, AIN should be thought of and therapy with glucocorticoid should be considered if necessary.

Myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitis developed from ANCA negative renal limited vasculitis: A case report.

RATIONALE: The relationship between antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) and ANCA-negative vasculitis has not been elucidated. PATIENT CONCERNS: A 64-year-old female with edema and proteinuria was admitted. A kidney biopsy indicated focal proliferative nephritis with crescents in 25% of glomeruli. Serum ANCA was negative. Eighteen months later, systemic symptoms emerged and acute kidney injury occurred. Serum ANCA against myeloperoxidase (MPO) turned positive. Repeated kidney biopsy showed more severe lesion than last time. Immunoglobulin (Ig)G was purified from serum obtained before the first kidney biopsy. Weak ANCA which could not be detected in serum was found in IgG. DIAGNOSES: MPO-ANCA-associated AAV developed from ANCA-negative renal-limited AAV. INTERVENTIONS: The patient was treated with glucocorticoid. OUTCOMES: The serum creatinine decreased to 2.17 mg/dL a week later. MPO-ANCA turned negative when re-examined 3 weeks later. No relapse has been observed during follow-up for 6 months. LESSONS: This is the first reported case about the spontaneous transformation from ANCA-negative renal-limited AAV to ANCA-positive systemic vasculitis. There might be a slow process of epitope spreading in the pathogenesis of disease. Physicians should try their best to detect the ANCA in the diagnose and treatment of ANCA-negative AAV.

Renal tubular damage may contribute more to acute hyperglycemia induced kidney injury in non-diabetic conscious rats.

AIMS: Growing evidences suggest that acute hyperglycemia is strongly related to kidney injury. Our study aimed to investigate the effects of acute hyperglycemia on kidney glomerular and tubular impairment in non-diabetic conscious rats. METHODS: Non-diabetic conscious rats were randomly subjected to 6h of saline (control group) or high glucose (acute hyperglycemia group) infusion. Blood glucose was maintained at 16.0-18.0 mmol/L in acute hyperglycemia group. Renal structure and function alterations, systemic/renal inflammation and oxidative stress markers were assessed, and apoptosis markers of renal inherent cells were evaluated. RESULTS: Acute hyperglycemia caused significant injury to structure of glomerular filtration barrier, tubular epithelial cells and peritubular vascular endothelial cells. It increased urinary microalbumin (68.01 ± 27.09 µg/24h vs 33.81 ± 13.81 µg/24h , P=0.014), ß2-microglobulin, Cystatin C, urinary and serous neutrophil gelatinase-associated lipocalin levels (P < 0.05). Acute hyperglycemia decreased megalin and cubilin expression, activated systemic and renal oxidative stress as well as inflammation and promoted renal inherent cell apoptosis. CONCLUSIONS: Acute hyperglycemia causes significant injury to kidney function and structure. Compared with damages of glomerular filtration barrier, renal tubular injury may contribute more to acute hyperglycemia induced proteinuria. Activation of inflammation especially renal inflammation, oxidative stress and enhanced apoptosis may be the underlying mechanisms.

IgG4-related membranous nephropathy with high blood and low urine IgG4/IgG ratio: a case report and review of the literature.

Membranous nephropathy (MN) is a rare manifestation of IgG4-related disease. Interestingly, the significance of IgG4 has also been documented in idiopathic MN (IMN). Previous studies reported that urine IgG4/IgG ratios were significantly higher in IMN compared with other kinds of nephropathy, indicating that impairment of charge selectivity barrier seemed to be an obvious characteristic of IMN. Although high blood concentration of IgG4 is very common in IgG4-related MN, no study about the urine IgG4 has been described before. Here, we present a 55-year-old male with IgG4-related MN. Complete remission of proteinuria was promptly achieved by glucocorticoid treatment without immunosuppressant. Consistent with previous reports, the serum antibody against M-type phospholipase A2 receptor was negative. Surprisingly, although the blood concentration of IgG4/IgG reached as high as 36 %, the urine concentration of IgG4/IgG was only 5 %. The calculated ratio of the renal clearance of IgG4 to IgG of this patient (0.15) was obviously lower than that of five patients with IMN (0.53∼0.81). We speculated that this phenomenon might be a clue of the different pathogenesis between IgG4-related MN and IMN.

Serum osteoprotegerin measurement for early diagnosis of chronic kidney disease-mineral and bone disorder.

AIM: Chronic kidney disease-mineral and bone disorder (CKD-MBD) has been proposed to be the replacement of renal osteodystrophy by the Organization of Kidney Disease: Improving Global Outcomes since 2005 because the mineral disorder is not confined to the skeleton in CKD. Accordingly, laboratory and imaging tests have been emphasized for the clinical assessment of patients with CKD besides renal biopsy. The objective of the current study was to investigate whether osteoprotegerin (OPG) could be made a useful biomarker for early diagnosis of CKD-MBD. METHODS: Sixty pre-dialysis patients with CKD 1-5 were enrolled in this study. The serum calcium, phosphorus, blood urea nitrogen, creatinine, alkaline phosphatase, Osteocalcin, Calcitonin, intact parathyroid hormone and OPG were measured. Bone mineral densities of the lumbar spine (L2-L4), femoral neck, Ward's triangle and trochanter were measured by dual-energy X-ray absorptiometry. RESULTS: Among all measured serum bone metabolism indexes, the changing of serum OPG level happened at the earliest time (CKD 3) and its correlation coefficient with estimated glomerular filtration rate (eGFR) was also the highest (r = -0.601, P = 0.001). In the multivariable analysis that included sex, age and eGFR as controlling factors, the serum OPG correlated with the bone mineral density (BMD) of Ward's triangle (r = -0.390, P = 0.041). CONCLUSION: Serum OPG may be a useful biomarker for early diagnosis of CKD-MBD.

[The histological changes in radial artery in uremia and their effects on arterial stiffness].

OBJECTIVE: To examine the changes of histological parameters of radial artery in uremia, and to explore their effects on arterial stiffness. METHODS: Sixty uremic patients underwent arteriovenous fistula surgery for hemodialysis and 20 healthy subjects received healthy examination were collected as uremia group and control group, respectively. Segments of radial arteries were obtained from all of uremic subjects and were evaluated by HE, Masson, van Kossa staining and electron microscopy. The expressions of osteopontin (OPN), α-SMA and elastin in arterial wall were detected by immunostaining, and apoptotic cells were determined by TUNEL assay. All of the subjects in the two groups received brachial ankle pulse wave velocity (baPWV) examination and the results were compared. The associations among histological parameters and baPWV were analyzed. RESULTS: More than one half (34/60) of artery samples presented uniformly thickening intima, in which most of cells expressed α-SMA and a few cells underwent apoptosis. The subendothelial matrix was abundant in collagen fibers, and no calcium deposition was found. The media thickened obviously, with increased collagen fibers, reduced elastin, unchanged α-SMA expression, and a few apoptotic smooth muscle cells. Two thirds uremic arteries expressed OPN, of which only one half had significant calcium deposition. The adventitia thickened and no calcium deposition was found. The baPWV level in uremic subjects was (18.5±3.2) m/s, far greater than that in control subjects (P<0.001). Statistical analysis showed that baPWV value was correlated with media thickness, calcification degree, and collagen content positively, and with elastin expression negatively. For diabetic uremic subjects, the OR values of vascular calcium deposition and remarkably-elevated baPWV value were 3.1, 2.3, respectively. CONCLUSIONS: Radial arterial intima often presents hyperplasia which is not related with baPWV increment in uremia. Arterial media calcification and collagen content incremental are the most two protuberant characteristics in uremia, especially in ones accompanied with diabetes. Medical calcification, collagen accumulation, and elastin reduction may contribute to the increased arterial stiffness in uremia.