Biology subjects

Chan, B. H.

Publications and source records attributed to Chan, B. H..

4 recordsLinked to original sources

bioRxiv2021

Genotype and Th2 cells control monocyte to tissue resident macrophage differentiation during nematode infection of the pleural cavity

The recent revolution in tissue-resident macrophage biology has resulted largely from murine studies performed in the C57BL/6 strain. Here, we provide a comprehensive analysis of immune cells in the pleural cavity using both C57BL/6 and BALB/c mice. Unlike C57BL/6 mice, naive tissue-resident Large Cavity Macrophages (LCM) of BALB/c mice failed to fully implement the tissue residency program. Following infection with a pleural-dwelling nematode these pre-existing differences were accentuated with LCM expansion occurring in C57BL/6 but not BALB/c mice. While infection drove monocyte recruitment in both strains, only in C57BL/6 mice were monocytes able to efficiently integrate into the resident pool. Monocyte to macrophage conversion required both T cells and IL-4R signalling. Host genetics are therefore a key influence on tissue resident macrophage biology, and during nematode infection Th2 cells control the differentiation pathway of tissue resident macrophages. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/472661v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@bba5e1org.highwire.dtl.DTLVardef@1876aa4org.highwire.dtl.DTLVardef@16a6b1corg.highwire.dtl.DTLVardef@19e18b6_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

IL-13 deficiency exacerbates lung damage and impairs epithelial-derived type 2 molecules during nematode infection

IL-13 plays a key role during protective type 2 immune responses at mucosal sites, such as during infection with nematodes. However, dysregulation of IL-13 can also contribute to the pathogenesis of atopic and fibrotic diseases such as allergic asthma. Matrix remodelling is an important component of repair processes in the lung but also a hallmark of chronic conditions involving fibrosis. Hence, understanding the role of IL-13 in tissue remodelling has important clinical implications. Since IL-13 shares receptors and signalling pathways with IL-4, disentangling the relative contributions of these type 2 cytokines has been challenging. Additionally, little is known about the singular role of IL-13 following acute tissue injury. In this study, we used Nippostrongylus brasiliensis infection as a model of acute lung tissue damage comparing responses between WT and IL-13-deficient mice, in which IL-4 signalling is intact. Importantly, we found that IL-13 played a critical role in limiting tissue injury and haemorrhaging in the lung following infection. Through proteomic and transcriptomic profiling, we identified IL-13-dependent changes in matrix and associated regulators. We further showed that IL-13 is required for the induction of epithelial-derived type 2 effector molecules such as RELM- and surfactant protein D. Pathway analyses predicted that IL-13 was heavily involved in the induction of cellular stress responses and regulation of lung epithelial cell differentiation by suppression of Foxa2 pathways. Thus, we propose that IL-13 has tissue-protective functions during lung injury and regulates epithelial cell responses during type 2 immunity in this acute setting.

immunology↗

bioRxiv2019

IL-17A both initiates (via IFNγ suppression) and limits the pulmonary type 2 immune response to nematode infection

Nippostrongylus brasiliensis is a well-defined model of type-2 immunity but the early lung-migrating phase is dominated by innate IL-17A production and neutrophilia. Using N. brasiliensis infection we confirm previous observations that Il17a-KO mice exhibit an impaired type-2 immune response. Neutrophil depletion and reconstitution studies demonstrated that neutrophils contribute to the subsequent eosinophilia but are not responsible for the ability of IL-17A to promote type-2 cytokine responses. Transcriptional profiling of the lung on day 2 of N. brasiliensis infection revealed an increased Ifn{gamma} signature in the Il17a-KO mice confirmed by enhanced IFN{gamma} protein production. Depletion of early IFN{gamma} rescued type-2 immune responses in the Il17a-KO mice demonstrating that IL-17A-mediated suppression of IFN{gamma} promotes type-2 immunity. Notably, when IL-17A was blocked later in infection, the type-2 response increased. IL-17A regulation of type-2 immunity was lung-specific and infection with Trichuris muris, revealed that IL-17A promotes a type-2 immune response in the lung even when a parasite lifecycle is restricted to the intestine. Together our data reveal IL-17A as a major regulator of pulmonary type-2 immunity which supports the development of a protective type-2 immune response but subsequently limits the magnitude of that response.

immunology↗

bioRxiv2019

Inflammasome-independent role for NLRP3 in controlling innate anti-helminth immunity and tissue repair in the lung

Alternatively activated macrophages are essential effector cells during type 2 immunity and tissue repair following helminth infections. We previously showed that Ym1, an alternative activation marker, can drive innate IL-1R-dependent neutrophil recruitment during infection with the lung-migrating nematode, Nippostrongylus brasiliensis suggesting a potential role for the inflammasome in the IL-1-mediated innate response to infection. While inflammasome proteins such as NLRP3 have important pro-inflammatory functions in macrophages, their role during type 2 responses and repair are less defined. We therefore infected Nlrp3-/- mice with N. brasiliensis. Unexpectedly, compared to WT mice, infected Nlrp3-/- mice had increased neutrophilia and eosinophilia, correlating with enhanced worm killing but at the expense of increased tissue damage and delayed lung repair. Transcriptional profiling showed that infected Nlrp3-/- mice exhibited elevated type 2 gene expression compared to WT mice. Notably, inflammasome activation was not evident early post-infection with N. brasiliensis and in contrast to Nlrp3-/- mice, anti-helminth responses were unaffected in caspase-1/11 deficient or WT mice treated with the NLRP3-specific inhibitor MCC950. Together these data suggest that NLRP3 can constrain lung neutrophilia and helminth killing and negatively regulate type 2 immune responses in an inflammasome-independent manner.

immunology↗