Biology subjects

Arike, L.

Publications and source records attributed to Arike, L..

6 recordsLinked to original sources

bioRxiv2025

Proteomic analysis of bronchoalveolar lavage fluid after lung transplantation associates stable allograft function with less lung damage at 12 months

IntroductionFreedom from chronic lung allograft dysfunction (CLAD) is a key objective after lung transplantation, yet predicting its onset remains challenging. This study investigated whether early proteomic changes in bronchoalveolar lavage fluid (BALF) can differentiate between patients maintaining stable graft function at 36 months and those developing CLAD within the first year. Additionally, findings were compared to proteomic data from non-transplanted individuals. MethodsBALF samples were collected at one and twelve months post-transplant from 43 lung transplant recipients together with clinical parameters. Proteomic analysis was performed using mass spectrometry with label-free quantification for global protein profiling and heavy-labelled peptides for absolute quantification of mucins and related proteins. Differentially expressed proteins were identified and analyzed through pathway enrichment to explore biological mechanisms associated with CLAD. ResultsNo significant proteomic differences were detected at one month. By twelve months, 63 proteins were differentially expressed between patients who developed early CLAD and those with stable function. Mucin levels declined in stable patients but remained elevated in both groups compared to healthy controls. Cartilage acidic protein 1 was significantly higher in stable patients at twelve months and correlated with better pulmonary function. Pathway analysis linked several altered proteins in CLAD patients to networks associated with lung injury and remodelling. ConclusionProtein profiles in BALF that resemble those of healthy lungs are associated with sustained graft function, while persistent expression of lung injury markers is associated with early CLAD. This suggests an adaptive process is needed for long-term post-transplant success.

molecular biology↗

bioRxiv2025

Degradation of the intestinal mucus layer by the ETEC protease EatA is species specific determined by the structure of the MUC2 mucin

Enterotoxigenic Escherichia coli (ETEC) infections are a leading cause of diarrheal illness, responsible for an estimated 100,000 deaths annually. ETEC pathogenesis is driven by various virulence factors, including toxins, adhesins, and noncanonical factors such as the protease EatA. The first line of host defense against intestinal pathogenic bacterial infections is the protective intestinal mucus layer. Here, we demonstrate the mechanism by which EatA facilitates access to the epithelial cell surface by degrading the core mucus component MUC2, thereby aiding to the infection. We identify the specific cleavage site region localized at the C-terminal of MUC2. EatAs protease activity depends on the interaction between two distinct domains, which are uniquely spaced in human MUC2, contributing to species specificity. This was confirmed using a novel chimeric mouse model solely expressing human MUC2, which allowed us to study the role of the mucus layer in the infection of human intestinal pathogens. These findings highlight how ETEC has adapted to specifically degrade the mucus layer of its human host.

molecular biology↗

bioRxiv2024

Neonatal microbiota colonization drives maturation of primary and secondary goblet cell mediated protection in the pre-weaning colon

In the distal colon, mucus secreting goblet cells primarily confer protection from luminal microorganisms via generation of a sterile inner mucus layer barrier structure. Bacteria-sensing sentinel goblet cells provide a secondary defensive mechanism that orchestrates mucus secretion in response to microbes that breach the mucus barrier. Previous reports have identified mucus barrier deficiencies in adult germ-free mice, thus implicating a fundamental role for the microbiota in programming mucus barrier generation. In this study, we have investigated the natural neonatal development of the mucus barrier and sentinel goblet cell-dependent secretory responses upon postnatal colonization. Combined in vivo and ex vivo analyses of pre- and post-weaning colonic mucus barrier and sentinel goblet cell maturation demonstrated a sequential microbiota-dependent development of these primary and secondary goblet cell-intrinsic protective functions, with dynamic changes in mucus processing dependent on innate immune signalling via MyD88, and development of functional sentinel goblet cells dependent on the NADPH/Dual oxidase family member Duox2. Our findings therefore identify new mechanisms of microbiota-goblet cell regulatory interaction and highlight the critical importance of the pre-weaning period for the normal development of colonic barrier function.

immunology↗

bioRxiv2024

BPP43_05035 is a Brachyspira pilosicoli cell surface adhesin that weakens the integrity of the epithelial barrier during infection

The anaerobic spirochete Brachyspira causes intestinal spirochetosis, characterized by the intimate attachment of bacterial cells to the colonic mucosa, potentially leading to symptoms such as diarrhea, abdominal pain, and weight loss. Despite the clinical significance of Brachyspira infections, the mechanism behind the interaction between Brachyspira and the colonic epithelium is not known. In this study, we characterized the molecular mechanism of B. pilosicoli-epithelium interaction and its impact on the epithelial barrier during infection. Through a proteomics approach, we identified BPP43_05035 as a candidate B. pilosicoli adhesion protein that mediates bacterial attachment to cultured human colonic epithelial cells. The crystal structure of BPP43_05035 revealed a globular lipoprotein with a six-bladed beta-propeller domain. Blocking the native BPP43_05035 on B. pilosicoli, either with a specific antibody or via competitive inhibition, abrogated its binding to epithelial cells. Furthermore, the binding of BPP43_05035 to epithelial cells required surface-exposed host N-glycans. Proximity labeling and interaction assays revealed that BPP43_05035 bound to tight junctions, thereby increasing the permeability of the epithelial monolayer. Extending our investigation to human patients, we identified a downregulation of tight junction and brush border genes in B. pilosicoli-infected patients carrying detectible levels of epithelium-bound BPP43_05035. Collectively, our findings identify BPP43_05035 as a B. pilosicoli adhesin that weakens the colonic epithelial barrier during infection.

microbiology↗

bioRxiv2024

MUC17 is an essential small intestinal glycocalyx component that is disrupted in Crohn's disease

Crohns disease (CD) is the chronic inflammation of the ileum and colon triggered by bacteria, but insights into molecular perturbations at the bacteria-epithelium interface are limited. We report that membrane mucin MUC17 protects small intestinal enterocytes against commensal and pathogenic bacteria. In non-inflamed CD ileum, reduced MUC17 levels correlated with a compromised glycocalyx, allowing bacterial contact with enterocytes. Muc17 deletion in mice rendered the small intestine prone to atypical infection while maintaining resistance to colitis. The loss of Muc17 resulted in spontaneous deterioration of epithelial homeostasis and extra-intestinal translocation of bacteria. Finally, Muc17-deficient mice harbored specific small intestinal bacterial taxa observed in CD. Our findings highlight MUC17 as an essential line of defense in the small intestine with relevance for early epithelial defects in CD. One-sentence summaryMembrane mucin MUC17 protects enterocytes against bacterial attachment and constitutes an early defect in Crohns disease.

physiology↗

bioRxiv2017

COPD lungs show an attached stratified mucus layer resembling the protective colonic mucus

The respiratory tract is normally kept essentially free of bacteria by cilia-mediated mucus transport, but in chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) mucus accumulates due to goblet cell hyperplasia and mucin overexpression. To address mechanisms behind the mucus accumulation, the elastase-induced mouse model was utilized. The proteomes of bronchoalveolar lavage fluid from elastase-induced mice and COPD patients showed similarities to each other and to colonic mucus. Lung mucus showed a striated, laminated appearance in the elastase-induced mice, COPD and CF, resembling that observed for colonic mucus. Less mucus obstruction was observed in mice lacking the Muc5b mucin. The accumulated mucus plugs of the elastase-induced mice were possible to wash out, but a mucus layer covering the epithelium remained attached to the surface goblet cells also after hypertonic saline washings as widely used in CF therapy. The results suggest that the lung can convert its mucus system into an attached mucus layer that protects the epithelium, similarly to the colon.

physiology↗