Alcaraz, J. | Search bioRxiv

bioRxiv2025

Chronic intestinal immune activation reveals separable impacts of inflammation and barrier loss on hallmarks of ageing.

Inflammaging is considered a driver of age-associated pathology across tissues. Similarly, intestinal permeability is a feature of ageing and underlies a range of inflammatory and age-related diseases. Increased intestinal permeability has been described as both a cause and a consequence of inflammation. Both intestinal permeability and inflammation are closely associated with microbial dysbiosis, epithelial dysplasia and mortality but dissecting the complex interplay between these phenotypes remains challenging. Here we genetically induce intestinal immune activation in Drosophila and stratify animals by their intestinal barrier status using the Smurf assay. We demonstrate that intestinal immune activation and barrier failure have distinct impacts on the microbiota. Further, intestinal immune activation drives intestinal barrier failure and mortality even in the absence of the microbiota. Importantly, immune-induced intestinal barrier failure takes time to develop and is closely associated with the onset of mortality. Our work adds to building evidence that the impact of intestinal permeability on the microbiota and on animal health needs to be considered independently of its relationship with inflammation.

physiology↗

bioRxiv2025

RAS-PI3K Pathway in CAFs Shapes Physicochemical Properties of Tumor ECM and restrains Tumor progression

Cancer-associated fibroblasts display extensive functional plasticity, yet the signaling mechanisms that stabilize distinct CAF states remain poorly understood. Here, we identify stromal RAS-PI3K signaling as a key regulator of myofibroblastic CAF identity and matrix competence in lung cancer. Genetic disruption of the RAS-PI3K interaction in fibroblasts preserved upstream responsiveness to activating cues but impaired cytoskeletal remodeling, contractile execution and acquisition of a matrix-remodeling CAF program. As a result, RAS-PI3K-deficient CAFs generated extracellular matrices with defective collagen and fibronectin organization, reduced stiffness, altered microstructural properties and broad compositional remodeling of the matrisome, including changes in ECM glycoproteins and glycosylation-associated enzymes. These altered matrices failed to efficiently provide directional, adhesive and proliferative cues to tumor cells, attenuated EMT-associated programs and increased sensitivity to cisplatin plus pemetrexed. In vivo, fibroblast-specific RAS-PI3K disruption reduced tumor burden, decreased tumor cell proliferation, prolonged survival and improved chemotherapy response. Loss of RAS-PI3K signaling did not simply suppress CAF activation, but redirected CAFs toward a STAT3/NF-{kappa}B-linked immunomodulatory state associated with IL6, CXCL12 and PDGFR induction. Functionally, this altered stromal state promoted iNOS-associated macrophage features and was accompanied in vivo by reduced macrophage accumulation and increased CD8 T cell infiltration. These findings establish RAS-PI3K signaling as a stromal state-control mechanism that couples myofibroblastic matrix competence to tumor-supportive microenvironmental function while restraining alternative immunomodulatory CAF programs.

cancer biology↗