Distal renal tubular acidosis (dRTA) is a rare but recognized renal complication of Sjögren's syndrome (SS), often resulting from autoimmune-mediated damage to acid-base transporters in the distal nephron. It commonly presents with electrolyte abnormalities including hypokalemia and metabolic acidosis. A 47-year-old woman with chronic kidney disease presented with recurrent hypokalemia, mild proteinuria, and sicca symptoms. Workup revealed non-anion gap metabolic acidosis, a positive urine anion gap, and renal potassium wasting consistent with dRTA. Autoimmune testing showed a high-titer ANA (1:1280) and elevated SSA (>8.0), confirming SS. Renal biopsy revealed mild interstitial fibrosis and glomerulosclerosis without evidence of tubulointerstitial nephritis or immune complex deposition. This finding supports prior evidence that SS-associated dRTA may occur secondary to functional tubular defects involving distal nephron transporters, even in the absence of overt inflammatory histologic changes. Acid-base disturbances improved with potassium and bicarbonate supplementation. This case highlights that significant tubular dysfunction in SS may occur despite minimal or absent histologic evidence of tubulointerstitial nephritis. dRTA in SS may result from autoimmune targeting of distal nephron transporters such as H⁺-ATPase and anion exchanger 1. Early recognition and supportive treatment are essential to prevent complications including nephrolithiasis, progressive kidney dysfunction, and life-threatening hypokalemia. SS should be considered in patients presenting with unexplained dRTA, and timely correction of electrolyte abnormalities is critical to optimizing outcomes.

Immunoglobulin G4-related disease (IgG4-RD) is a rare chronic immune-mediated multisystem disease with renal manifestations of tubulointerstitial nephritis (IgG4-TIN) and membranous nephropathy (IgG4-MN). IgG4-RD and its sequelae are treated with immunosuppressive therapy, including steroids and rituximab (RTX), which have demonstrated high efficacy in achieving disease remission. We describe a patient who was diagnosed with pancreatitis secondary to IgG4-RD through laboratory and imaging studies. Despite being on RTX, he developed acute kidney injury (AKI) and was diagnosed with IgG4-TIN via kidney biopsy. He was treated with prednisone and RTX, and his symptoms and renal function improved. Despite RTX reaching peak efficacy 6 months after administration, our patient had a breakthrough IgG4-TIN during this period. This case highlights the importance of maintaining a high index of suspicion for renal involvement (IgG4-TIN or IgG4-MN) in patients with AKI superimposed on IgG4-RD, and that maintenance therapy with RTX retreatment was associated with longer relapse-free survival at 12 months of follow-up. Our patient had no severe infections or hypogammaglobulinemia (≤5 g/l) with RTX, confirming RTX's safety and efficacy in maintenance remission therapy for recurrent IgG4-TIN.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immune-mediated fibro-inflammatory disorder with the potential to affect multiple organs, with the kidney being the most commonly involved organ, typically presenting as IgG4-related tubulointerstitial nephritis (IgG4-TIN). Anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (ANCA-GN), in contrast, is a pauci-immune necrotizing crescentic glomerulonephritis characterized by acute renal dysfunction and systemic inflammation. While early reports have interpreted IgG4-positive plasma cell infiltration in ANCA-associated vasculitis as evidence of overlap with IgG4-TIN, histologic resemblance in varying disease contexts can make differentiation challenging. In this context, we present the case of an 81-year-old woman diagnosed with both ANCA-GN and IgG4-TIN, informed by a comprehensive review of all previously reported cases. Renal biopsy confirmed this rare overlap, revealing pauci-immune crescentic glomerulonephritis alongside dense IgG4-positive plasma cell infiltration and storiform fibrosis. This case illustrates the diagnostic complexity posed by IgG4-rich inflammatory infiltrates in ANCA-associated disease and underscores the importance of careful clinicopathologic correlation to guide accurate diagnosis, appropriate immunosuppressive therapy, and improved understanding of potentially overlapping autoimmune mechanisms.

We report a case of vedolizumab (VDZ)-associated acute interstitial nephritis (AIN) in a 44-year-old man with refractory ulcerative colitis. The case highlights the need for nephrotoxicity monitoring in patients receiving VDZ for inflammatory bowel disease, as well as the inherent difficulties in recognizing AIN in this clinical setting. 4 months after starting VDZ therapy, the patient was admitted with dyspnoea and chest pain. Although investigations for suspected pulmonary embolism were negative, evidence of acute kidney injury was found and a kidney biopsy showed AIN. Identification of the causative role of VDZ was confounded by the fact that the patient was also being treated with omeprazole, which was considered to be the likely cause of AIN. However, rechallenge with VDZ in the absence of omeprazole again led to worsening kidney function that improved when the VDZ was stopped. The presumed recurrence of VDZ-associated AIN occurred during a tapering course of oral prednisolone. This case adds to the literature by reporting detailed tracking of a dechallenge-rechallenge sequence that provides convincing evidence of VDZ-induced AIN. These findings underscore the need for renal surveillance during VDZ therapy to prevent potential progression to chronic kidney disease.

Salmonella spp. is a major zoonotic pathogen. Although reptiles are mostly considered subclinical carriers, clinical disease may develop following immunosuppression. Clinical salmonellosis in reptiles has been extensively reported; however, the condition has been rarely described in bearded dragons (Pogona vitticeps). We retrospectively analyzed six cases of salmonellosis in bearded dragons and characterized the pathological, immunohistochemical, and bacteriological findings. Clinical signs and gross findings were mostly non-specific. Histological findings mainly consisted of fibrinonecrotizing enterocolitis (83.3%); necrotizing or granulomatous hepatitis (66.7%); pneumonia including bronchopneumonia or interstitial pneumonia in one case each (33.3%); tubulointerstitial nephritis with tubular necrosis (16.7%); and coelomitis (16.7%). Salmonella enterica subsp. houtenae was cultured in three cases (33.3%), whereas S. enterica subsp. enterica serovar Rissen, S. enterica subsp. enterica serovar Cotham, and S. enterica subsp. diarizonae were cultured in one case each. Intralesional bacteria were detected via immunohistochemistry in kidneys and colon in two cases (33.3%). The predominance of lesions in the intestines and liver likely reflects initial intestinal colonization followed by hematogenous dissemination to the liver. Hepatic lesions are thought to represent different stages along a continuum, progressing from acute necrosis to discrete granuloma formation. Renal and respiratory involvement was infrequent, as reported in other reptile species. Some of the isolated Salmonella subspecies (S. diarizonae and S. houtenae) are well-recognized causes of clinical disease in other reptile species but not previously identified in bearded dragons. This study provides a comprehensive pathological, immunohistochemical, and bacteriological characterization of salmonellosis in bearded dragons, thus raising awareness and assisting in the identification of this condition.

Polygonum capitatum (PC) is an ethnomedicine with reported antibacterial and anti-inflammatory activities and has been clinically used in urinary tract infection (UTI)-related disorders. However, its in vivo exposure characteristics and metabolically associated therapeutic mechanisms in acute pyelonephritis (AP) remain insufficiently understood. To address this issue, this study aimed to evaluate the therapeutic effects of PC in an Escherichia coli (E. coli)-induced rat model of AP and to explore constituents and metabolic pathways associated with its activity. Different PC extracts were screened for antibacterial and anti-inflammatory activities, and the 70% ethanol extract was selected for further study. Seven major compounds were quantified by HPLC. In AP rats, the pharmacokinetic profiles of these compounds in plasma and the renal cortex were analyzed by microdialysis-coupled HPLC-MS/MS. Pharmacodynamic evaluation included urinary bacterial load, urinalysis, renal function, inflammatory cytokines, and renal histopathology. Exploratory PK-PD analysis, untargeted renal metabolomics, and targeted metabolomics of the tryptophan-kynurenine (Trp-Kyn) pathway were also performed. The 70% ethanol extract of PC exhibited the strongest antibacterial and anti-inflammatory activities. The total content of seven active compounds was 3.85%, with gallic acid being the predominant compound (3.42%). Pharmacokinetic analysis revealed that gallic acid, protocatechuic acid, methyl gallate, and quercitrin achieved relatively high systemic exposure and renal distribution. In AP rats, the pharmacokinetic profiles of several compounds were altered, with increased plasma exposure of protocatechuic acid, vanillic acid, ethyl gallate, and syringic acid, while protocatechuic acid also showed higher exposure in the renal cortex. PC treatment reduced urinary bacterial load, improved renal function and urinalysis parameters, alleviated histopathological injury, and decreased inflammatory mediator levels, particularly in renal tissue. Exploratory PK-PD correlations were observed between several compounds and selected pharmacodynamic indicators. Metabolomic analysis suggested disturbances in glycerophospholipid metabolism and the Trp-Kyn pathway in AP rats, some of which were partially reversed after PC treatment. PC showed antibacterial and anti-inflammatory effects in AP rats. Gallic acid, protocatechuic acid, methyl gallate, and quercitrin may be candidate constituents associated with the therapeutic effects of PC, while modulation of glycerophospholipid metabolism and the Trp-Kyn pathway may be involved in its action against AP. These findings provide preclinical pharmacological evidence supporting the therapeutic potential of PC in AP.

The European League Against Rheumatism recommends first-line induction therapy with rituximab or cyclophosphamide for patients with new-onset or relapsing antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with organ- or life-threatening disease. This report presents 2 patients with AAV: one with active AAV with severe renal injury and another with refractory active AAV with peripheral neuropathy. Both patients had interstitial pneumonia at admission. Ultimately, both patients achieved clinical remission after induction therapy with telitacicept.

We describe the case of a man in his 60s with metastatic melanoma on encorafenib/binimetinib and nivolumab/relatlimab, with a history of immune checkpoint inhibitor (ICI)-induced acute interstitial nephritis, who presented with acute-onset nausea, vomiting and profuse watery diarrhoea. Investigations excluded infectious causes, and flexible sigmoidoscopy with biopsy demonstrated lymphocytic colitis. His symptoms persisted despite discontinuation of Braftovi-Mektovi (BRAF-MEK) therapy and required escalation of corticosteroid therapy and budesonide initiation. This case highlights the diagnostic challenges of differentiating ICI-mediated colitis from adverse events of targeted therapy and underscores the importance of endoscopic and histological confirmation in guiding treatment.