Search

Objective: The PD-1 axis promotes protection against autoimmunity. Immune checkpoint (IC) molecules performance in anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) remains unknown. This study aims to assess the IC pathway's role in the AAV's pathophysiology., Methods: We recruited 88 AAV from our centre as a discovery cohort (acute=42, remission=46) and 30 patients from another institution for external validation (acute=16, remission=14).Serum, urine and peripheral blood mononuclear cells (PBMCs) were collected. In vitro IC molecules production by lymphocytes was studied with and without MPO/PR3 antigen stimulus. Cell culture supernatant (SN) was obtained by centrifugation. PD-1, PD-L1 and PD-L2 concentrations were assessed in serum (s), urine (u) and SN of AAV and healthy controls (HC) using a multiplex assay. PD-1 and PD-L1's expression was analysed in six diagnostic kidney biopsies., Results: uPD-1 and uPD-L2's concentration was lower in AAV than HC (p<0.0001, p=0.0075). Acute patients exhibited lower uPD-L2 levels compared with those in remission (p=0.036). Similarly, PBMCs showed reduced PD-1 production than HC (stimulated group p=0.04, unstimulated p=0.0074). Furthermore, patients with inflammatory renal lesions had fewer PD-1-positive interstitial cells/staining intensity compared with those with sclerotic lesions. Contradictorily, sPD-1 and sPD-L1's concentration was higher in AAV than HC (p=0.007, p<0.0001) with acute patients exhibiting elevated sPD-1 levels compared with those in remission (p=0.0051). Serum and urine findings were confirmed in the validation cohort., Conclusions: Results in urine, SN and histology suggest IC pathway abolition during acute disease restored in remission and contribute to understand PD-1 axis's role in AAV proposing it as a new biomarker of disease activity., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The document provides a comprehensive overview of the diagnosis, monitoring, and treatment of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) with renal involvement, focusing on granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). It outlines the definitions, clinical presentation, histopathological classification, monitoring strategies, induction and maintenance treatments, as well as special considerations for relapsing, refractory, and frail patients with renal AAV. The document was prepared by the Catalan Group for the Study of Glomerular Diseases (GLOMCAT), which comprises nephrologists with extensive experience in the diagnosis and treatment of AAV patients. Several virtual and face-to-face meetings were held for coordination, section assignments, and content discussion. An exhaustive and systematic search of the literature was carried out, which included, among others, the following databases: PubMed, EMBASE, Cochrane Library, Google Scholar, and ClinicalTrials.gov, as well as the abstract books of national and international congresses. Overall, the document provides a comprehensive guide for clinicians managing patients with renal AAV, offering evidence-based recommendations for diagnosis, monitoring, and treatment across various clinical scenarios.

Background: Acute interstitial nephritis (AIN) related to immune checkpoint inhibitors (ICI-AIN) has a not completely understood pathophysiology. Our objectives were to analyze possible biomarkers for the differentiation between acute tubular necrosis (ATN) and AIN, especially in cancer patients, and to study the participation of the immune checkpoint pathway in ICI-AIN., Methods: We performed an observational study. We recruited patients with incident diagnosis of ICI-AIN ( n  = 19). We measured soluble PD-1 (sPD-1), sPD-L1, and sPD-L2 in serum and urine at diagnosis and compared to it patients with non-ICI-related AIN (non-ICI-AIN) ( n  = 18) and ATN ( n  = 21). The findings were validated in an independent cohort from another institution ( n  = 30). Also, we performed PD-L1 and PD-L2 immunostaining of kidney biopsies from patients with ICI-AIN and compared to patients with non-ICI-AIN., Results: Urinary sPD-1 (usPD-1) was higher in patients with AIN compared to ATN ( P  = .03). Patients with AIN also showed higher serum sPD-1 (ssPD-1) than patients with ATN ( P  = .021). In cancer patients, usPD-1 <129.3 pg/ml had a 71.43% sensitivity and 94.44% specificity to differentiate ATN from ICI-AIN, with a likelihood ratio of 12.86. In the external validation cohort, the same cutoff showed a sensitivity of 80%. In kidney biopsies, patients with ICI-AIN showed higher density of PD-L1 positive tubules than patients with non-ICI-AIN ( P  = .02). The proportion of patients having >2.64/mm 2 PD-L2 positive tubules was higher among patients with ICI-AIN compared to non-ICI-AIN ( P  = .034). There was a positive correlation ( P  = .009, r  = 0.72) between usPD-1 and the number of PD-L1 positive tubules., Conclusions: UsPD-1 and ssPD-1 are higher in AIN than ATN. Moreover, there was a strong correlation between usPD-1 and renal tubular PD-L1 expression. Our findings suggest a role of usPD-1 as non-invasive biomarker to differentiate ICI-AIN from ATN, especially in cancer patients, which has been confirmed in an external validation cohort., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

The inflammasome regulates the innate inflammatory response and is involved in autoimmune diseases. In this study, we explored the levels of IL-18 and IL-1β in serum and urine and the influence of various single-nucleotide polymorphisms (SNPs) on kidney lesions at diagnosis in patients with ANCA-associated vasculitis (AAV) and their clinical outcomes. Ninety-two patients with renal AAV were recruited, and blood and urine were collected at diagnosis. Serum and urine cytokine levels were measured by ELISA. DNA was extracted and genotyped using TaqMan assays for SNPs in several inflammasome genes. Lower serum IL-18 ( p = 0.049) and the IL-18 rs187238 G-carrier genotype ( p = 0.042) were associated with severe fibrosis. The IL-18 rs1946518 TT genotype was associated with an increased risk of relapse ( p = 0.05), whereas GG was related to better renal outcomes ( p = 0.031). The rs187238 GG genotype was identified as a risk factor for mortality within the first year after AAV diagnosis, independent of the requirement for dialysis or lung involvement ( p = 0.013). We suggest that decreased cytokine levels could be a surrogate marker of scarring and chronicity of the renal lesions, together with the rs187238 GG genotype. If our results are validated, the rs1946518 TT genotype predicts the risk of relapse and renal outcomes during follow-up.

Introduction: Immune checkpoint inhibitors (ICIs) induce acute interstitial nephritis (AIN) in 2-5% of patients, with a clearly higher incidence when they are combined with platinum derivatives. Unfortunately, suitable disease models and non-invasive biomarkers are lacking. To fill this gap in our understanding, we investigated the renal effects of cisplatin and anti-PD-L1 antibodies in mice, assessing PD-1 renal expression and cytokine levels in mice with AIN, and then we compared these findings with those in AIN-diagnosed cancer patients., Methods: Twenty C57BL6J mice received 200 µg of anti-PD-L1 antibody and 5 mg/kg cisplatin intraperitoneally and were compared with those receiving cisplatin (n = 6), anti-PD-L1 (n = 7), or saline (n = 6). After 7 days, the mice were euthanized. Serum and urinary concentrations of TNFα, CXCL10, IL-6, and MCP-1 were measured by Luminex. The kidney sections were stained to determine PD-1 tissue expression. Thirty-nine cancer patients with AKI were enrolled (AIN n = 33, acute tubular necrosis (ATN) n = 6), urine MCP-1 (uMCP-1) was measured, and kidney sections were stained to assess PD-1 expression., Results: Cisplatin and anti PD-L1 treatment led to 40% AIN development (p = 0.03) in mice, accompanied by elevated serum creatinine and uMCP1. AIN-diagnosed cancer patients also had higher uMCP1 levels than ATN-diagnosed patients, confirming our previous findings. Mice with AIN exhibited interstitial PD-1 staining and stronger glomerular PD-1 expression, especially with combination treatment. Conversely, human AIN patients only showed interstitial PD-1 positivity., Conclusions: Only mice receiving cisplatin and anti-PDL1 concomitantly developed AIN, accompanied with a more severe kidney injury. AIN induced by this drug combination was linked to elevated uMCP1, consistently with human AIN, suggesting that uMCP1 can be potentially used as an AIN biomarker., (© 2024. The Author(s).)