Biology subjects

von Vietinghoff, S.

Publications and source records attributed to von Vietinghoff, S..

5 recordsLinked to original sources

bioRxiv2026

Complement receptor-mediated uptake into renal mononuclear phagocytes promotes intracellular UPEC persistence and limits β-lactam efficacy in pyelonephritis

IntroductionAcute pyelonephritis remains a major clinical problem. Relapses occur despite apparently appropriate antibiotic therapy, suggesting that uropathogenic Escherichia coli (UPEC) persist in intrarenal niches. Intracellular bacterial reservoirs are a plausible explanation, but the relevant host cells, entry mechanisms and therapeutic implications in the kidney remain undefined. In principle, such reservoirs should favor choosing intracellularly active antibiotics, but increasing resistance to many of these agents leaves {beta}-lactams widely used in clinical practice, despite their predominantly extracellular activity. MethodsWe analyzed murine pyelonephritis to identify the cellular reservoir of persistent UPEC. We generated mice genetically deficient for complement receptors CR3 and CR4 and tested their role in bacterial entry and persistence in vivo. Pharmacological complement receptor inhibition was applied to assess whether blocking bacterial re-entry into host cells improves antibiotic efficacy. ResultsRenal MNP were identified as the major intracellular reservoir for UPEC in mice. Complement opsonization enabled bacterial entry into these cells through CR3 and CR4, allowing UPEC to evade neutrophil-mediated killing and extracellularly active antibiotics. Genetic deletion of CR3 and CR4 abolished intracellular bacterial persistence and reduced renal bacterial burden. Because MNP undergo physiological turnover, intracellular UPEC must periodically exit host cells and infect new ones. Pharmacological inhibition of complement receptors prevented such bacterial re-entry and enhanced the efficacy of {beta}-lactam antibiotics which cannot penetrate cell membranes. ConclusionsComplement receptor-mediated entry into renal MNP establishes an intracellular UPEC reservoir that promotes persistence during experimental pyelonephritis. Blocking these receptors prevents renewal of the intracellular niche and improves {beta}-lactam efficacy in mice.

microbiology↗

bioRxiv2026

Integrated kidney and urine proteomics define encrypted antimicrobial peptides as effectors of host defence in human pyelonephritis

Antimicrobial peptides (AMPs) are key effectors of host defence, however, their functional deployment across renal tissue and urine in pyelonephritis (PN) remains incompletely understood. Here, we integrate kidney and urine proteomics with urinary peptidomics and computational prediction to define AMP organisation and function. Proteomic analysis indicated coordinated induction of multiple AMPs in infected kidneys. These patterns were recapitulated in the urinary proteome, where AMP abundance correlated with leukocyte counts. Multiplex immunofluorescence microscopy localised these AMPs to myeloid cells, identifying them as central effector sources. Importantly, analysis of the urine peptidome revealed multiple encrypted AMPs (EPs), which arise from proteolytic processing of precursor proteins. To systematically assess their relevance for host defence, we applied an ensemble of machine learning-based predictors to prioritise candidates with activity in the urinary environment. This approach identified several potential EPs, among which the S100A12-derived peptide Calcitermin was confirmed in patient urine. Furthermore, it exerts antibacterial activity against uropathogenic E. coli (UPEC) and modulates myeloid cell responses. Together, these findings define a coordinated and compartmentalised AMP defence programme in human PN that extends beyond increased peptide expression, highlighting EPs as functionally relevant effectors with therapeutic potential.

immunology↗

bioRxiv2026

Lactate-dependent metabolic rewiring is associated with CD163+ macrophage polarization in human pyelonephritis

Chronic pyelonephritis is characterized by persistent bacterial infection of the kidney and a dysregulated immune response that promotes disease progression. Macrophages are central regulators of antibacterial immunity in the urinary tract. However, the mechanisms underlying their functional reprogramming in chronic infection remain poorly understood. Here, we identify lactate as a key metabolic determinant of macrophage polarization in human pyelonephritis. Proteomic analysis of human kidney tissue revealed extensive metabolic remodelling, including upregulation of enzymes involved in glycolysis. Consistent with this, lactate levels were significantly elevated in urine and plasma of pyelonephritis patients. Concomitantly, we observed a pronounced accumulation of CD163 macrophages in infected kidneys, representing a distinct macrophage subset with immunomodulatory function. Correlation-based network analysis revealed a strong association between CD163 and lactate dehydrogenase A, supporting a functional association between lactate metabolism and macrophage polarization. Mechanistically, exposure of murine bone marrow-derived macrophages to lactate induced intracellular protein lactylation and promoted polarization toward a CD163 phenotype, defining a metabolically imprinted macrophage state distinct from classical activation paradigms. Proteomic profiling demonstrated extensive remodelling of macrophage protein expression in response to lactate with significant alteration of mediators of phagocytosis, Toll-like receptor signalling, and interferon response. Together, these findings identify lactate as a potent metabolic driver of macrophage reprogramming and establish a foundation for investigating lactylation-dependent immune dysfunction in chronic pyelonephritis.

immunology↗

bioRxiv2023

Proteomic adaptations in the kidney reveal orchestration of local and secreted antimicrobial peptides in human pyelonephritis

Pyelonephritis (PN) is a frequent bacterial infection of the kidney and is often associated with severe diseases, organ loss and sepsis. Antibiotics are the cornerstone of therapy, however, increasing antibiotic resistance threatens therapy success and necessitates novel treatment strategies. Various proteins, such as antimicrobial peptides (AMPs), are key molecules of the innate immune response and insights into their regulation may help overcome multi-drug resistance and severe diseases. Using label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS), several cellular, biological, and metabolic processes important for the antimicrobial response were identified, including a significant increase in previously undescribed proteins in human PN with antimicrobial function. Among others, we observed elevation of AMPs, such as calprotectin, azurocidin-1, and cathepsin G in the kidney, which we validated in the urine. Additionally, we observed a negative correlation of azurocidin-1 with plasma levels of C-reactive protein suggesting that the presence in the kidney may protect from severe diseases and systemic inflammation. This study represents the first renal proteomic dataset of human PN, enabling novel insights into the expression of AMPs in the context of PN. Lay SummaryGrowing antimicrobial resistance necessitates a better understanding of the expression of proteins that are critical for the immune response. Using mass spectrometry we identified AMPs in the kidney and urine of PN patients. Elevated levels of the AMP azurocidin-1 was associated with reduced systemic inflammation, indicated by lower C-reactive protein. Overall, this study identified expression of previously undescribed AMPs in the context of human PN. These proteins may play a pivotal role in protection from severe diseases and systemic inflammation.

immunology↗

bioRxiv2020

SGLT2 inhibition by intraperitoneal dapagliflozin mitigates peritoneal fibrosis and ultrafiltration failure in a mouse model of chronic peritoneal exposure to high-glucose dialysate

Peritoneal dialysis (PD) is limited by glucose-mediated peritoneal membrane (PM) fibrosis, angiogenesis and ultrafiltration failure. Influencing PM integrity by pharmacologically targeting sodium-dependent glucose transporter (SGLT)-mediated glucose uptake has not been studied. In this study wildtype C57Bl/6N mice were treated with high-glucose dialysate via an intraperitoneal catheter, with or without addition of selective SGLT2 inhibitor dapagliflozin. PM structural changes, ultrafiltration capacity and PET status for glucose, urea and creatinine were analyzed. Expression of SGLT and GLUT was analyzed by real-time PCR, immunofluorescence and immunohistochemistry. Peritoneal effluents were analyzed for cellular and cytokine composition. We found that peritoneal SGLT2 was expressed in mesothelial cells and in skeletal muscle. Dapagliflozin significantly reduced effluent TGF-{beta} concentrations, peritoneal thickening and fibrosis as well as microvessel density, resulting in improved ultrafiltration, despite the fact that it did not affect development of high glucose transporter status. In vitro, dapagliflozin reduced monocyte chemoattractant protein-1 release under high glucose conditions in human and murine peritoneal mesothelial cells. Pro-inflammatory cytokine release in macrophages was reduced only when cultured in high glucose conditions with an additional inflammatory stimulus. In summary, dapagliflozin improved structural and functional peritoneal health in the context of high glucose PD.

molecular biology↗