Studies in anti-neutrophil cytoplasm antibody (ANCA)–associated vasculitis (AAV) have revealed promising biomarkers. The aim of our study was to validate the most encouraging markers of granulomatosis with polyangiitis and microscopic polyangiitis identified by literature search and to create biomarker panels. A systematic literature review was performed and we identified 161 marker molecules that were ranked by their quantitative differential expression between active and inactive disease. Enzyme-linked immunosorbent assays were used to validate the results in a cross-sectional cohort of patients with renal involvement. Active vasculitis as assessed by the Birmingham Vasculitis Score version 3 (BVAS v3) was defined as BVAS v3 ≥1 and inactive disease as BVAS v3 = 0. Statistical analysis was performed with SPSS version 21 and the Salford Predictive Modeler 7.0 was used to generate a predictive biomarker panel. The review indicated abundant expression of sC5bC9, C3a, C5a and monocyte chemotactic protein (MCP)-1 in urine, whereas granulocyte macrophage colony-stimulating factor, C-reactive protein (CRP), soluble fms-like tyrosine kinase-1, interleukin-17A (IL-17A), C5a, hyaluronan, C3a and interleukin-18 binding protein (IL-18BP) were identified to be highly diverse in active and inactive disease in blood samples. Our cross-sectional analysis revealed significant up-regulation of CRP, C5a, C3a, IL-18BP in blood and C5a and MCP-1 in urine samples during active AAV (all P < 0.05). Creation of a biomarker panel comprising CRP and urinary MCP-1 yielded a sensitivity and specificity of 76% (area under the curve 0.89). We identified promising biomarkers in a literature-based review that were in part corroborated as has been shown for CRP, C3a, C5a, IL-18BP in blood and MCP-1 and C5a in urine samples. Moreover, we propose a biomarker panel comprising CRP and urinary MCP-1 in patients with AAV and renal involvement. Further investigations to confirm our preliminary results are clearly warranted, including the reliability to predict disease relapses.

Mechanisms underlying the onset and progression of nephropathy in diabetic patients are not fully elucidated. Deregulation of proteolytic systems is a known path leading to disease manifestation, therefore we hypothesized that proteases aberrantly expressed in diabetic nephropathy (DN) may be involved in the generation of DN-associated peptides in urine. We compared urinary peptide profiles of DN patients (macroalbuminuric, n = 121) to diabetic patients with no evidence of DN (normoalbuminuric, n = 118). 302 sequenced, differentially expressed peptides (adjusted p-value < 0.05) were analysed with the Proteasix tool predicting proteases potentially involved in their generation. Activity change was estimated based on the change in abundance of the investigated peptides. Predictions were correlated with transcriptomics (Nephroseq) and relevant protein expression data from the literature. This analysis yielded seventeen proteases, including multiple forms of MMPs, cathepsin D and K, kallikrein 4 and proprotein convertases. The activity of MMP-2 and MMP-9, predicted to be decreased in DN, was investigated using zymography in a DN mouse model confirming the predictions. Collectively, this proof-of-concept study links urine peptidomics to molecular changes at the tissue level, building hypotheses for further investigation in DN and providing a workflow with potential applications to other diseases.

SGLT2 inhibitor-related nephroprotection is—at least partially—mediated by anti-inflammatory drug effects, as previously demonstrated in diabetic animal and human studies, as well as hyperglycemic cell culture models. We recently presented first evidence for anti-inflammatory potential of empagliflozin (Empa) under normoglycemic conditions in human proximal tubular cells (HPTC) by demonstrating Empa-mediated inhibition of IL-1β-induced MCP-1/CCL2 and ET-1 expression on the mRNA and protein level. We now add corroborating evidence on a genome-wide level by demonstrating that Empa attenuates the expression of several inflammatory response genes in IL-1β-induced (10 ng/mL) normoglycemic HPTCs. Using microarray-hybridization analysis, 19 inflammatory response genes out of >30.000 human genes presented a consistent expression pattern, that is, inhibition of IL-1β (10 ng/mL)-stimulated gene expression by Empa (500 nM), in both HK-2 and RPTEC/TERT1 cells. Pathway enrichment analysis demonstrated statistically significant clustering of annotated pathways (enrichment score 3.64). Our transcriptomic approach reveals novel genes such as CXCL8/IL8, LOX, NOV, PTX3, and SGK1 that might be causally involved in glycemia-independent nephroprotection by SGLT2i.

Background: Ear, nose and throat involvement in granulomatosis with polyangiitis (GPA) is frequently the initial disease manifestation. Previous investigations have observed a higher prevalence ofStaphylococcus aureusin patients with GPA, and chronic nasal carriage has been linked with an increased risk of disease relapse. In this cross-sectional study, we investigated changes in the nasal microbiota including a detailed analysis ofStaphylococcusspp. by shotgun metagenomics in patients with active and inactive granulomatosis with polyangiitis (GPA). Shotgun metagenomic sequence data were also used to identify protein-encoding genes within the SEED database, and the abundance of proteins then correlated with the presence of bacterial species on an annotated heatmap.Results: The presence ofS. aureusin the nose as assessed by culture was more frequently detected in patients with active GPA (66.7%) compared with inactive GPA (34.1%). Beta diversity analysis of nasal microbiota by bacterial 16S rRNA profiling revealed a different composition between GPA patients and healthy controls (P = 0.039). Beta diversity analysis of shotgun metagenomic sequence data forStaphylococcusspp. revealed a different composition between active GPA patients and healthy controls and disease controls (P = 0.0007 andP = 0.0023, respectively), and between healthy controls and inactive GPA patients and household controls (P = 0.0168 andP = 0.0168, respectively). Patients with active GPA had a higher abundance ofS. aureus, mirroring the culture data, while healthy controls had a higher abundance ofS. epidermidis.Staphylococcus pseudintermedius, generally assumed to be a pathogen of cats and dogs, showed an abundance of 13% among theStaphylococcusspp. in our cohort. During long-term follow-up of patients with inactive GPA at baseline, a higherS. aureusabundance was not associated with an increased relapse risk. Functional analyses identified ten SEED protein subsystems that differed between the groups. Most significant associations were related to chorismate synthesis and involved in the vitamin B₁₂pathway.Conclusion: Our data revealed a distinct dysbiosis of the nasal microbiota in GPA patients compared with disease and healthy controls. Metagenomic sequencing demonstrated that this dysbiosis in active GPA patients is manifested by increased abundance ofS. aureusand a depletion ofS. epidermidis, further demonstrating the antagonist relationships between these species. SEED functional protein subsystem analysis identified an association between the unique bacterial nasal microbiota clusters seen mainly in GPA patients and an elevated abundance of genes associated with chorismate synthesis and vitamin B₁₂pathways. Further studies are required to further elucidate the relationship between the biosynthesis genes and the associated bacterial species.