Biomedical subjects

Sibylle Pfammatter

Publications and source records attributed to Sibylle Pfammatter.

3 recordsLinked to original sources

PubMed2026

Utility of monocyte-derived cells to investigate immune-mediated drug-induced liver injury.

Immune-mediated drug-induced liver injury (DILI) is triggered or exacerbated by the immune system mounting an attack against the drug or its metabolites. The array of in vitro assays for evaluating drug immune liability is limited, highlighting a significant gap in effectively predicting and understanding immune-mediated hepatotoxicity. We aimed to investigate whether monocytes differentiated with the Metaheps (MH) protocol could provide insights into the molecular mechanisms of immune-mediated DILI. MH were generated from monocytes of healthy volunteers (HV) and DILI patients. MH phenotypic characterization was performed by proteomics and qPCR. MH sensitivity to drugs associated with immune-mediated DILI was assessed by lactate dehydrogenase (LDH) assay. Drug-induced LDH release by DILI-derived MH was compared to the upper limit of the 95% CI calculated from HV-derived MH cells treated with the same drug. The 95% CI determined in HV-derived MH was set as the sensitivity threshold for the specific drug. MH cells retain the expression of several immune-related proteins of the parental monocytes and activate a pro-inflammatory response upon exposure to lipopolysaccharide. For all MH (6 out of 6) generated from patients with penicillin-induced DILI, the LDH release upon re-challenge was above the threshold. The sensitivity of MH generated from seven patients with immune checkpoint inhibitor (ICI)-induced hepatotoxicity was ICI-dependent, responding to nivolumab and/or ipilimumab (4 out of 5), but not to pembrolizumab (0 out of 2). Additionally, DILI-derived MH were not sensitive to non-DILI drugs. In conclusion, monocyte-derived cells may serve as an additional tool for drug-specific mechanistic studies of immune-mediated DILI.

Humans↗

PubMed2026

Deep visual multi-omics profiling links morphology and molecular programs in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma exhibits striking intra-tumoral heterogeneity at morphological and genetic levels, complicating treatment and contributing to disease progression. CcRCCs with rhabdoid differentiation are highly aggressive tumors characterized by distinct histopathologies. However, the relationship between morphology, underlying molecular alterations, and tumor behavior remains largely unclear. Here, we present Deep Visual Multi-Omics, an approach integrating digital pathology, morphology-guided single-cell isolation, and ultra-sensitive multi-omics profiling to link cell morphologies to their molecular underpinnings. Across five tumors, we profiled ~40,000 AI-classified and expert-curated cells. We identified progressive molecular dysregulation across cells with increasing histopathological grade coexisting within heterogeneous tumors as well as distinct molecular alterations associated with aggressive rhabdoid ccRCC cells, including signatures consistent with enhanced FOXM1-driven proliferation, altered cell-matrix interactions, and a putative immunomodulatory phenotype. Notably, rhabdoid cells exhibited elevated expression of IFN-beta, PD-L1, CD38, ITGB2, and integrin signaling, suggesting that they themselves may act as a source of signals influencing the local immune microenvironment. Besides providing new insights into the biology of ccRCC and highlighting avenues for future translational studies, this illustrates the potential of Deep Visual Multi-omics to dissect cancer heterogeneity and characterize high-risk cell populations.

Humans↗

PubMed2023

Serine-threonine phosphoregulation by PknB and Stp contributes to quiescence and antibiotic tolerance in Staphylococcus aureus.

Staphylococcus aureus can cause infections that are often chronic and difficult to treat, even when the bacteria are not antibiotic resistant because most antibiotics act only on metabolically active cells. Subpopulations of persister cells are metabolically quiescent, a state associated with delayed growth, reduced protein synthesis, and increased tolerance to antibiotics. Serine-threonine kinases and phosphatases similar to those found in eukaryotes can fine-tune essential bacterial cellular processes, such as metabolism and stress signaling. We found that acid stress-mimicking conditions that S. aureus experiences in host tissues delayed growth, globally altered the serine and threonine phosphoproteome, and increased threonine phosphorylation of the activation loop of the serine-threonine protein kinase B (PknB). The deletion of stp, which encodes the only annotated functional serine-threonine phosphatase in S. aureus, increased the growth delay and phenotypic heterogeneity under different stress challenges, including growth in acidic conditions, the intracellular milieu of human cells, and abscesses in mice. This growth delay was associated with reduced protein translation and intracellular ATP concentrations and increased antibiotic tolerance. Using phosphopeptide enrichment and mass spectrometry-based proteomics, we identified targets of serine-threonine phosphorylation that may regulate bacterial growth and metabolism. Together, our findings highlight the importance of phosphoregulation in mediating bacterial quiescence and antibiotic tolerance and suggest that targeting PknB or Stp might offer a future therapeutic strategy to prevent persister formation during S. aureus infections.

Animals↗