Biology subjects

Ngai, L.

Publications and source records attributed to Ngai, L..

4 recordsLinked to original sources

bioRxiv2022

The protozoan commensal Tritrichomonas musculis is a natural adjuvant for mucosal IgA.

Immunoglobulin(Ig) A antibodies are the most abundant antibodies supporting mucosal immune homeostasis and host-microbiota interactions. Driven by gut commensal microbes, IgA-secreting plasma cells (PC) differentiate through T cell-dependent (Td) or T cell independent (Ti) mechanisms. While commensal bacteria within the microbiota are known for their ability to promote IgA, the role of non-bacterial commensal microbes on the induction of IgA remains elusive. Here, we demonstrate that permanent colonization with the protozoan commensal Tritrichomonas musculis (T.mu) promotes T-cell dependent, IgA class-switch recombination and intestinal accumulation of IgA-secreting PC. T.mu colonization specifically drives the expansion of T follicular helper cells and a unique ICOS+ non-Tfh cell population, accompanied by an increase in germinal center B cells. Blockade of ICOS:ICOSL co-stimulation or MHCII-expression on B cells are central for the induction of IgA following colonization by T.mu, implicating a previously underappreciated mode of IgA induction following protozoan commensal colonization. Finally, the commensal T.mu further improves the induction of IgA-secreting plasma cells and their peripheral dissemination, even against non-protozoan, orally ingested antigens, identifying T.mu as natural adjuvant for IgA. Collectively, these findings propose a previously unknown, protozoa-driven mode of IgA induction that supports intestinal immune homeostasis even against non-microbial antigens.

immunology↗

bioRxiv2022

A gut commensal protozoa remotely shapes a lung niche for asthma-promoting eosinophils.

The gut microbiome influences chronic inflammation of the airways via the gut-lung axis. However, causal connections between microbes and their host, including the underlying mechanisms for this phenomenon remain largely unknown. Here, we show that colonization with the gut commensal protozoa, Tritrichomonas musculis (T.mu), remotely shapes the lung immune landscape and exacerbates allergic airway inflammation. We demonstrate that colonization with T.mu mediates the T and B cell-dependent accumulation and activation of inflammatory group 2 innate lymphoid cells in the lungs to constitute a tripartite immune network that serves as a niche for lung eosinophils. Animals colonized with T.mu show severely exacerbated allergic inflammation in the airways and reveal a new protozoan-driven gut-lung axis that remotely shapes the lung immune network to potentiate chronic pulmonary inflammation. One-Sentence SummaryA gut microbe exacerbates asthma severity by promoting lung eosinophilia through a tripartite lymphocyte immune network.

immunology↗

bioRxiv2022

Microbial Energy Metabolism Fuels a CSF2-dependent Intestinal Macrophage Niche within Tertiary Lymphoid Organs

Maintaining intestinal macrophage (MP) heterogeneity is critical to ensure tissue homeostasis and host defense. The gut microbiota and host factors are thought to synergistically shape colonic MP development, although there remains a fundamental gap in our understanding of the details of such collaboration. Here, we report tertiary lymphoid organs (TLOs), enriched in group 3 innate lymphoid cells (ILC3s), as a microbiota-operated intestinal niche for the development of monocyte-derived MPs. ILC3-derived colony stimulating factor 2 (CSF2) serves as a developmental and functional determinant for MPs and required microbe-derived extracellular adenosine 5-triphosphate (ATP) as a trigger. Microbial communities rich in extracellular ATP promoted MP turnover via ILC3 activity in an NLRP3-dependent fashion. Single cell RNA-sequencing of MPs revealed unique TLO-associated, CSF2-dependent MP populations critical for anti-microbial defense against enteric infection. Collectively, these findings describe a fundamental framework that constitutes an intestinal MP niche fueled by microbial energy metabolism.

immunology↗

bioRxiv2021

NLRP1B and NLRP3 control the host response following colonization by the commensal protist Tritrichomonas musculis.

Commensal intestinal protozoa, unlike their pathogenic relatives, are neglected members of the mammalian microbiome. These microbes have a significant impact on the hosts intestinal immune homeostasis, typically by elevating anti-microbial host defense. Tritrichomonas musculis (T. mu), a protozoan gut commensal, strengthens the intestinal host defense against enteric Salmonella infections through Asc- and Il1r1-dependent Th1 and Th17 cell activation. However, the underlying inflammasomes mediating this effect remain unknown. Here, we report that colonization with T. mu results in an increase in luminal extracellular ATP, elevated levels of IL-1{beta}, and increased numbers of IL-18 receptor-expressing Th1 and Th17 cells in the colon. Mice deficient in either Nlrp1b or Nlrp3 failed to display these protozoan-driven immune changes and lost resistance to enteric Salmonella infections even in the presence of T. mu. These findings demonstrate that T. mu-mediated host protection requires sensors of extra and intracellular ATP to confer resistance to enteric Salmonella infections. KEY POINTSO_LIIntestinal colonization with the commensal Tritrichomonas musculis elevates luminal ATP levels C_LIO_LINLRP1B and NLRP3 activation is required for Tritrichomonas musculis-driven Th cell response. C_LI

immunology↗