Biology subjects

Kienzl, M.

Publications and source records attributed to Kienzl, M..

3 recordsLinked to original sources

bioRxiv2026

Enhanced environmental complexity worsens experimental colitis and dysregulates microbiota-gut-brain axis signalling in female mice

Ulcerative colitis (UC) is a chronic inflammatory disease characterized by colonic inflammation and bloody diarrhoea. Accumulating evidence suggests that UC not only affects the intestinal tract, but also distant organs including the brain. Environmental factors are key determinants of the disease course, yet the impact and potential disease modifying effects of living environment complexity on microbiota-gut-brain axis signalling during colitis remain unclear. To address this gap, we investigated how enhanced environmental complexity (EC) affects the disease course and gut-brain axis signalling during experimental colitis in mice. Our results show that EC exacerbates dextran sulphate sodium (DSS)-induced colitis in female mice, but not in male mice, as evidenced by greater weight loss and higher disease activity. Immune cell profiling across the gut-brain axis reveals strong effects of DSS treatment on colonic, circulating and brain immune cell populations and a restriction of central nervous system (CNS) T cell infiltration due to EC. In addition, female EC/DSS mice have higher circulating corticosterone levels than controls indicating chronic stress. Metabolomics across the gut-brain axis revealed that EC exacerbates colitis-induced metabolite perturbations in plasma, brain tissue, brain interstitial and cerebrospinal fluid. Notably, microbiota-derived metabolites, including deoxycholic acid and trimethylamine-N-oxide (TMAO), are increased in EC/DSS mice, concordant with EC-associated microbiome changes and anxiety-like behaviour. Overall, this study indicates that EC worsens experimental colitis in female mice and directs microbiota-gut-brain axis signalling during colitis towards a less favourable state. From a translational perspective, this study highlights the importance of environmental factors for a sex-specific disease course of UC and associated neurobehavioral comorbidities. HighlightsO_LIEnhanced environmental complexity (EC) exacerbates experimental colitis C_LIO_LIColitis and EC have compartment-specific effects on immune cells C_LIO_LIEC augments colitis-induced metabolic shifts in plasma, brain and CSF C_LIO_LIMicrobiota-derived metabolites are important players for the effects of EC C_LI

neuroscience↗

bioRxiv2026

EZH2 inactivation drives MAPK-dependent vulnerability to MEK inhibition in RAS-mutant CMML

Chronic myelomonocytic leukemia (CMML) is a heterogeneous hematologic malignancy with limited therapeutic options. Although RAS and RAS-modifying mutations (RASmut) are common and associated with poor prognosis, targeting RAS signaling has shown limited clinical success. Here, we define co-occurrence of RASmut and EZH2 inactivation (EZH2inact) as a distinct molecular subgroup of CMML characterized by aggressive disease biology. Mechanistically, RASmutEZH2inact drives selective MAPK/ERK hyperactivation in mature myeloid cells and hematopoietic stem and progenitor compartments. Transcriptomic analysis of a large independent myeloid neoplasm cohort (Beat-AML) further supports this finding, demonstrating selective activation of gene signatures of MAPK/ERK activation in RASmutEZH2inact cases. Functionally, this signaling activation promotes proliferation and myelomonocytic differentiation in human and murine models. Therapeutically, this MAPK/ERK upregulation confers increased sensitivity to MEK inhibition (MEKi). In a murine RasmutEzh2inact-driven CMML model, MEKi suppresses MAPK/ERK activity and reduces leukemic burden by impairing proliferation and myelomonocytic differentiation without inducing cell death. In primary human CMML samples ex vivo, MEKi shows stronger anti-proliferative effects in RASmutEZH2inact specimens compared with RASmut samples. Drug-sensitivity data from the Beat-AML cohort further supported this. Ultimately, these findings were confirmed in a patient-derived xenograft model, where MEKi reduced the leukemic burden by selectively inhibiting the proliferation of transplanted human RASmutEZH2inact leukemic cells. In summary, our data define RASmutEZH2inact CMML as a clinically relevant subgroup with selective MAPK/ERK hyperactivation and increased sensitivity to MEKi. They provide a mechanistic explanation for the limited efficacy of MEK inhibitors in unselected CMML and support molecularly guided use of MEK-targeted therapy in this patient population.

molecular biology↗

bioRxiv2023

Myeloperoxidase promotes a tumorigenic microenvironment in non-small cell lungcancer

Myeloperoxidase (MPO) is a heme peroxidase that is mainly expressed and secreted by neutrophils. MPOs role in inflammatory diseases has been highlighted in recent years, but its role in tumor development remains unclear. Therefore, we investigated the role of MPO in non-small cell lung cancer (NSCLC). In silico analysis revealed a survival benefit in patients with NSCLC and low MPO expression. Furthermore, a syngeneic tumor model using MPO knockout (KO) mice revealed that mice lacking MPO had lower tumor growth than controls. The reduction in tumor size was accompanied by an increase in lymphoid populations, including natural killer cells and CD8+ T cells, suggesting a shift to a more anti-tumorigenic immune environment in MPO-KO mouse tumors. The T cell induced interferon-gamma (IFN-{gamma}) expression was increased in MPO-KO tumors, indicating increased tumoricidal activity. CD8 depletion abolished the previously observed reduction in tumor size in MPO-KO mice, indicating that CD8+ T cells play an important role. In vitro, T cells treated with MPO showed reduced proliferation and IFN-{gamma} expression. Furthermore, MPO could be internalized into T cells. Heparin pretreatment of T cells blocked MPO binding and internalization into T cells and reversed MPO-induced proliferation reduction. Interestingly, MPO+ lymphocytes were found in tumor samples from patients with NSCLC. Our findings suggest that MPO plays an immunosuppressive role in NSCLC. One Sentence SummaryHigh myeloperoxidase (MPO) expression in non-small cell lung cancer patients is a predictor for adverse outcome and mice lacking MPO showed enhanced anti-tumorigenic leukocyte infiltration, suggesting a pro-tumorigenic role of MPO.

cancer biology↗