Regulation of immune responses by tuft cells

Probiotics as a strategy for addressing helminth infections in low-income countries: Working smarter rather than richer

Helminth infections, which affect approximately 1.5 billion individuals worldwide (mainly children), are common in low- and middle-income tropical countries and can lead to various diseases. One crucial factor affecting the occurrence of these diseases is the reduced diversity of the gut microbiome due to antibiotic use. This reduced diversity compromises immune health in hosts and alters host gene expression through epigenetic mechanisms. Helminth infections may produce complex biochemical signatures that could serve as therapeutic targets. Such therapies include next-generation probiotics, live biotherapeutic products, and biochemical drug approaches. Probiotics can bind ferric hydroxide, reducing the iron that is available to opportunistic microorganisms. They also produce short-chain fatty acids associated with immune response modulation, oral tolerance facilitation, and inflammation reduction. In this review, we examine the potential link between these effects and epigenetic changes in immune response-related genes by analyzing methyltransferase-related genes within probiotic strains discussed in the literature. The identified genes were only correlated with methylation in bacterial genes. Various metabolic interactions among hosts, helminth parasites, and intestinal microbiomes can impact the immune system, potentially aiding or hindering worm expulsion through chemical signaling. Implementing a comprehensive strategy using probiotics may reduce the impact of drug-resistant helminth strains.

Mammalian SWI/SNF complex activity regulates POU2F3 and constitutes a targetable dependency in small cell lung cancer

Small cell lung cancers (SCLCs) are composed of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLCs, ∼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes as top dependencies specific to POU2F3-positive SCLC. Notably, chemical disruption of mSWI/SNF ATPase activity attenuates proliferation of all POU2F3-positive SCLCs, while disruption of non-canonical BAF (ncBAF) via BRD9 degradation is effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF targets to and maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, clinical-grade pharmacologic disruption of SMARCA4/2 ATPases and BRD9 decreases POU2F3-SCLC tumor growth and increases survival in vivo. These results demonstrate mSWI/SNF-mediated governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for POU2F3-positive SCLCs.

Airway basal stem cells are necessary for the maintenance of functional intraepithelial airway macrophages

Adult stem cells play a crucial role in tissue homeostasis and repair through multiple mechanisms. In addition to being able to replace aged or damaged cells, stem cells provide signals that contribute to the maintenance and function of neighboring cells. In the lung, airway basal stem cells also produce cytokines and chemokines in response to inhaled irritants, allergens, and pathogens, which affect specific immune cell populations and shape the nature of the immune response. However, direct cell-to-cell signaling through contact between airway basal stem cells and immune cells has not been demonstrated. Recently, a unique population of intraepithelial airway macrophages (IAMs) has been identified in the murine trachea. Here, we demonstrate that IAMs require Notch signaling from airway basal stem cells for maintenance of their differentiated state and function. Furthermore, we demonstrate that Notch signaling between airway basal stem cells and IAMs is required for antigen-induced allergic inflammation only in the trachea where the basal stem cells are located whereas allergic responses in distal lung tissues are preserved consistent with a local circuit linking stem cells to proximate immune cells. Finally, we demonstrate that IAM-like cells are present in human conducting airways and that these cells display Notch activation, mirroring their murine counterparts. Since diverse lung stem cells have recently been identified and localized to specific anatomic niches along the proximodistal axis of the respiratory tree, we hypothesize that the direct functional coupling of local stem cell-mediated regeneration and immune responses permits a compartmentalized inflammatory response.

Tuft cell-derived acetylcholine promotes epithelial chloride secretion and intestinal helminth clearance

Epithelial cells secrete chloride to regulate water release at mucosal barriers, supporting both homeostatic hydration and the "weep" response that is critical for type 2 immune defense against parasitic worms (helminths). Epithelial tuft cells in the small intestine sense helminths and release cytokines and lipids to activate type 2 immune cells, but whether they regulate epithelial secretion is unknown. Here, we found that tuft cell activation rapidly induced epithelial chloride secretion in the small intestine. This response required tuft cell sensory functions and tuft cell-derived acetylcholine (ACh), which acted directly on neighboring epithelial cells to stimulate chloride secretion, independent of neurons. Maximal tuft cell-induced chloride secretion coincided with immune restriction of helminths, and clearance was delayed in mice lacking tuft cell-derived ACh, despite normal type 2 inflammation. Thus, we have uncovered an epithelium-intrinsic response unit that uses ACh to couple tuft cell sensing to the secretory defenses of neighboring epithelial cells.

Molecular subtypes of neuroendocrine carcinomas: A cross-tissue classification framework based on five transcriptional regulators

Neuroendocrine carcinomas (NECs) are extremely lethal malignancies that can arise at almost any anatomic site. Characterization of NECs is hindered by their rarity and significant inter- and intra-tissue heterogeneity. Herein, through an integrative analysis of over 1,000 NECs originating from 31 various tissues, we reveal their tissue-independent convergence and further unveil molecular divergence driven by distinct transcriptional regulators. Pan-tissue NECs are therefore categorized into five intrinsic subtypes defined by ASCL1, NEUROD1, HNF4A, POU2F3, and YAP1. A comprehensive portrait of these subtypes is depicted, highlighting subtype-specific transcriptional programs, genomic alterations, evolution trajectories, therapeutic vulnerabilities, and clinicopathological presentations. Notably, the newly discovered HNF4A-dominated subtype-H exhibits a gastrointestinal-like signature, wild-type RB1, unique neuroendocrine differentiation, poor chemotherapeutic response, and prevalent large-cell morphology. The proposal of uniform classification paradigm illuminates transcriptional basis of NEC heterogeneity and bridges the gap across different lineages and cytomorphological variants, in which context-dependent prevalence of subtypes underlies their phenotypic disparities.

Intestinal Taste Receptor Expression and Its Implications for Health: An Integrative Analysis in Female Rats after Chronic Insect Supplementation

Taste receptors are found in the gastrointestinal tract, where they are susceptible to dietary modulation, a key point that is crucial for diet-related responses. Insects are sustainable and good-quality protein sources. This study analyzed the impact of insect consumption on the modulation of taste receptor expression across various segments of the rat intestine under healthy or inflammatory conditions. Female Wistar rats were supplemented with Tenebrio molitor (T) or Alphitobius diaperinus (B), alongside a control group (C), over 21 days under healthy or LPS-induced inflammation. The present study reveals, for the first time, that insect consumption modulates taste receptor gene expression, mainly in the ascending colon. This modulation was not found under inflammation. Integrative analysis revealed colonic Tas1r1 as a key discriminator for insect consumption (C = 1.04 ± 0.32, T = 1.78 ± 0.72, B = 1.99 ± 0.82, p-value <0.05 and 0.01, respectively). Additionally, correlation analysis showed the interplay between intestinal taste receptors and metabolic and inflammatory responses. These findings underscore how insect consumption modulates taste receptors, influencing intestinal function and broader physiological mechanisms.

Orco-dependent survival of odorant receptor neurons in ants

Olfaction is essential for complex social behavior in insects. To discriminate complex social cues, ants evolved an expanded number of odorant receptor (Or) genes. Mutations in the obligate odorant co-receptor gene orco lead to the loss of ~80% of the antennal lobe glomeruli in the jumping ant Harpegnathos saltator. However, the cellular mechanism remains unclear. Here, we demonstrate massive apoptosis of odorant receptor neurons (ORNs) in the mid to late stages of pupal development, possibly due to ER stress in the absence of Orco. Further bulk and single-nucleus transcriptome analysis shows that, although most orco-expressing ORNs die in orco mutants, a small proportion of them survive: They express ionotropic receptor (Ir) genes that form IR complexes. In addition, we found that some Or genes are expressed in mechanosensory neurons and nonneuronal cells, possibly due to leaky regulation from nearby non-Or genes. Our findings provide a comprehensive overview of ORN development and Or expression in H. saltator.

Colonic Tuft Cells: The Less-Recognized Therapeutic Targets in Inflammatory Bowel Disease and Colorectal Cancer

Tuft cells are more than guardian chemosensory elements of the digestive tract. They produce a variety of immunological effector molecules in response to stimulation; moreover, they are essential for defense against protozoa and nematodes. Beyond the description of their characteristics, this review aims to elucidate the potential pathogenic and therapeutic roles of colonic tuft cells in inflammatory bowel disease and colorectal cancer, focusing on their primarily immunomodulatory action. Regarding inflammatory bowel disease, tuft cells are implicated in both maintaining the integrity of the intestinal epithelial barrier and in tissue repair and regeneration processes. In addition to maintaining intestinal homeostasis, they display complex immune-regulatory functions. During the development of colorectal cancer, tuft cells can promote the epithelial-to-mesenchymal transition, alter the gastrointestinal microenvironment, and modulate both the anti-tumor immune response and the tumor microenvironment. A wide variety of their biological functions can be targeted for anti-inflammatory or anti-tumor therapies; however, the adverse side effects of immunomodulatory actions must be strictly considered.

The taste for health: the role of taste receptors and their ligands in the complex food/health relationship

Taste, food, and health are terms that have since always accompanied the act of eating, but the association was simple: taste serves to classify a food as good or bad and therefore influences food choices, which determine the nutritional status and therefore health. The identification of taste receptors, particularly, the G protein-coupled receptors that mediate sweet, umami, and bitter tastes, in the gastrointestinal tract has assigned them much more relevant tasks, from nutrient sensing and hormone release to microbiota composition and immune response and finally to a rationale for the gut-brain axis. Particularly interesting are bitter taste receptors since most of the times they do not mediate macronutrients (energy). The relevant roles of bitter taste receptors in the gut indicate that they could become new drug targets and their ligands new medications or components in nutraceutical formulations. Traditional knowledge from different cultures reported that bitterness intensity was an indicator for distinguishing plants used as food from those used as medicine, and many non-cultivated plants were used to control glucose level and treat diabetes, modulate hunger, and heal gastrointestinal disorders caused by pathogens and parasites. This concept represents a means for the scientific integration of ancient wisdom with advanced medicine, constituting a possible boost for more sustainable food and functional food innovation and design.

Gut microbiota as a key regulator of intestinal mucosal immunity

Gut microbiota is a complex microbial community with the ability of maintaining intestinal health. Intestinal homeostasis largely depends on the mucosal immune system to defense external pathogens and promote tissue repair. In recent years, growing evidence revealed the importance of gut microbiota in shaping intestinal mucosal immunity. Therefore, according to the existing findings, this review first provided an overview of intestinal mucosal immune system before summarizing the regulatory roles of gut microbiota in intestinal innate and adaptive immunity. Specifically, this review delved into the gut microbial interactions with the cells such as intestinal epithelial cells (IECs), macrophages, dendritic cells (DCs), neutrophils, and innate lymphoid cells (ILCs) in innate immunity, and T and B lymphocytes in adaptive immunity. Furthermore, this review discussed the main effects of gut microbiota dysbiosis in intestinal diseases and offered future research prospects. The review highlighted the key regulatory roles of gut microbiota in intestinal mucosal immunity via various host-microbe interactions, providing valuable references for the development of microbial therapy in intestinal diseases.

Intraepithelial mast cells drive gasdermin C-mediated type 2 immunity

A specialized population of mast cells residing within epithelial layers, currently known as intraepithelial mast cells (IEMCs), was originally observed over a century ago, yet their physiological functions have remained enigmatic. In this study, we unveil an unexpected and crucial role of IEMCs in driving gasdermin C-mediated type 2 immunity. During helminth infection, αEβ7 integrin-positive IEMCs engaged in extensive intercellular crosstalk with neighboring intestinal epithelial cells (IECs). Through the action of IEMC-derived proteases, gasdermin C proteins intrinsic to the epithelial cells underwent cleavage, leading to the release of a critical type 2 cytokine, interleukin-33 (IL-33). Notably, mast cell deficiency abolished the gasdermin C-mediated immune cascade initiated by epithelium. These findings shed light on the functions of IEMCs, uncover a previously unrecognized phase of type 2 immunity involving mast cell-epithelial cell crosstalk, and advance our understanding of the cellular mechanisms underlying gasdermin C activation.

Nasal solitary chemosensory cells govern daily rhythm in mouse model of allergic rhinitis

BACKGROUND

While the daily rhythm of allergic rhinitis (AR) has long been recognized, the molecular mechanism underlying this phenomenon remains enigmatic.

OBJECTIVE

We aimed to investigate the role of circadian clock in AR development and to clarify the mechanism by which the daily rhythm of AR is generated.

METHODS

AR was induced in mice with ovalbumin. Toluidine blue staining, liquid chromatography-tandem mass spectrometry analysis, real-time quantitative PCR, and immunoblotting were performed with AR and control mice.

RESULTS

Ovalbumin-induced AR is diurnally rhythmic and associated with clock gene disruption in nasal mucosa. In particular, Rev-erbα is generally downregulated and its rhythm retained, but with a near-12-hour phase shift. Furthermore, global knockout of core clock gene Bmal1 or Rev-erbα increases the susceptibility of mice to AR and blunts AR rhythmicity. Importantly, nasal solitary chemosensory cells (SCCs) are rhythmically activated, and inhibition of the SCC pathway leads to attenuated AR and a loss of its rhythm. Moreover, rhythmic activation of SCCs is accounted for by diurnal expression of ChAT (an enzyme responsible for the synthesis of acetylcholine) and temporal generation of the neurotransmitter acetylcholine. Mechanistically, Rev-erbα trans-represses Chat through direct binding to a specific response element, generating a diurnal oscillation in this target gene.

CONCLUSION

SCCs, under the control of Rev-erbα, are a driver of AR rhythmicity; targeting SCCs should be considered as a new avenue for AR management.

Physiologic disruption and metabolic reprogramming in infection and sepsis

Effective responses against severe systemic infection require coordination between two complementary defense strategies that minimize the negative impact of infection on the host: resistance, aimed at pathogen elimination, and disease tolerance, which limits tissue damage and preserves organ function. Resistance and disease tolerance mostly rely on divergent metabolic programs that may not operate simultaneously in time and space. Due to evolutionary reasons, the host initially prioritizes the elimination of the pathogen, leading to dominant resistance mechanisms at the potential expense of disease tolerance, which can contribute to organ failure. Here, we summarize our current understanding of the role of physiological perturbations resulting from infection in immune response dynamics and the metabolic program requirements associated with resistance and disease tolerance mechanisms. We then discuss how insight into the interplay of these mechanisms could inform future research aimed at improving sepsis outcomes and the potential for therapeutic interventions.

Gastrointestinal and brain barriers: unlocking gates of communication across the microbiota-gut-brain axis

Crosstalk between gut and brain has long been appreciated in health and disease, and the gut microbiota is a key player in communication between these two distant organs. Yet, the mechanisms through which the microbiota influences development and function of the gut-brain axis remain largely unknown. Barriers present in the gut and brain are specialized cellular interfaces that maintain strict homeostasis of different compartments across this axis. These barriers include the gut epithelial barrier, the blood-brain barrier and the blood-cerebrospinal fluid barrier. Barriers are ideally positioned to receive and communicate gut microbial signals constituting a gateway for gut-microbiota-brain communication. In this Review, we focus on how modulation of these barriers by the gut microbiota can constitute an important channel of communication across the gut-brain axis. Moreover, barrier malfunction upon alterations in gut microbial composition could form the basis of various conditions, including often comorbid neurological and gastrointestinal disorders. Thus, we should focus on unravelling the molecular and cellular basis of this communication and move from simplistic framing as 'leaky gut'. A mechanistic understanding of gut microbiota modulation of barriers, especially during critical windows of development, could be key to understanding the aetiology of gastrointestinal and neurological disorders.

Salicin alleviates periodontitis via Tas2r143/gustducin signaling in fibroblasts

Introduction

Cells expressing taste signaling elements in non-gustatory tissues have been described as solitary chemosensory cells (SCCs) or tuft cells. These "taste-like" cells play a critical role in the maintenance of tissue homeostasis. Although the expression of SCC markers and taste signaling constituents has been identified in mouse gingivae, their role in periodontal homeostasis is still unclear.

Methods

Public RNA sequencing datasets were re-analyzed and further validated with RT-PCR/qRT-PCR and immunofluorescent staining to explore the expression of TAS2Rs and downstream signaling constituents in mouse gingival fibroblasts (MGFs). The specific action of salicin on MGFs via Tas2r143 was validated with RNA silence, heterologous expression of taste receptor/Gα-gustducin and calcium imaging. The anti-inflammatory effects of salicin against LPS-induced MGFs were investigated in cell cultures, and were further validated with a ligature-induced periodontitis mouse model using Ga-gustducin-null (Gnat3-/-) mice.

Results

The expression of Tas2r143, Gnat3, Plcb2, and TrpM5 was detected in MGFs. Moreover, salicin could activate Tas2r143, elicited taste signaling and thus inhibited LPS-induced chemokines expression (CXCL1, CXCL2, and CXCL5) in MGFs. Consistently, salicin-treatment inhibited periodontal bone loss, inflammatory/chemotactic factors expression, and neutrophil infiltration in periodontitis mice, while these effects were abolished in Gnat3-/- mice.

Discussion

Gingival fibroblasts play a critical role in the maintenance of periodontal homeostasis via "SCC-like" activity. Salicin can activate Tas2r143-mediated bitter taste signaling and thus alleviate periodontitis in mouse, indicating a promising approach to the resolution of periodontal inflammation via stimulating the "SCC-like" function of gingival fibroblasts.

IκBζ is a dual-use coactivator of NF-κB and POU transcription factors

OCA-B, OCA-T1, and OCA-T2 belong to a family of coactivators that bind to POU transcription factors (TFs) to regulate gene expression in immune cells. Here, we identify IκBζ (encoded by the NFKBIZ gene) as an additional coactivator of POU TFs. Although originally discovered as an inducible regulator of NF-κB, we show here that IκBζ shares a microhomology with OCA proteins and uses this segment to bind to POU TFs and octamer-motif-containing DNA. Our functional experiments suggest that IκBζ requires its interaction with POU TFs to coactivate immune-related genes. This finding is reinforced by epigenomic analysis of MYD88L265P-mutant lymphoma cells, which revealed colocalization of IκBζ with the POU TF OCT2 and NF-κB:p50 at hundreds of DNA elements harboring octamer and κB motifs. These results suggest that IκBζ is a transcriptional coactivator that can amplify and integrate the output of NF-κB and POU TFs at inducible genes in immune cells.

An organism-wide atlas of hormonal signaling based on the mouse lemur single-cell transcriptome

Hormones mediate long-range cell communication and play vital roles in physiology, metabolism, and health. Traditionally, endocrinologists have focused on one hormone or organ system at a time. Yet, hormone signaling by its very nature connects cells of different organs and involves crosstalk of different hormones. Here, we leverage the organism-wide single cell transcriptional atlas of a non-human primate, the mouse lemur (Microcebus murinus), to systematically map source and target cells for 84 classes of hormones. This work uncovers previously-uncharacterized sites of hormone regulation, and shows that the hormonal signaling network is densely connected, decentralized, and rich in feedback loops. Evolutionary comparisons of hormonal genes and their expression patterns show that mouse lemur better models human hormonal signaling than mouse, at both the genomic and transcriptomic levels, and reveal primate-specific rewiring of hormone-producing/target cells. This work complements the scale and resolution of classical endocrine studies and sheds light on primate hormone regulation.

Tuft cell IL-17RB restrains IL-25 bioavailability and reveals context-dependent ILC2 hypoproliferation

The tuft cell-ILC2 circuit orchestrates rapid type 2 responses upon detecting microbe-derived succinate and luminal helminths. Our findings delineate key mechanistic steps, involving IP3R2 engagement and Ca 2+ flux, governing IL-25 production by tuft cells triggered by succinate detection. While IL-17RB plays a pivotal intrinsic role in ILC2 activation, it exerts a regulatory function in tuft cells. Tuft cells exhibit constitutive Il25 expression, placing them in an anticipatory state that facilitates rapid production of IL-25 protein for ILC2 activation. Tuft cell IL-17RB is crucial for restraining IL-25 bioavailability, preventing excessive tonic ILC2 stimulation due to basal Il25 expression. Suboptimal ILC2 stimulation by IL-25 resulting from tuft cell Il17rb -deficiency or prolonged succinate exposure induces a state of hypoproliferation in ILC2s, also observed in chronic helminth infection. Our study offers critical insights into the regulatory dynamics of IL-25 in this circuit, highlighting the delicate tuning required for responses to diverse luminal states.

TRPM channels in health and disease

Different cell channels and transporters tightly regulate cytoplasmic levels and the intraorganelle distribution of cations. Perturbations in these processes lead to human diseases that are frequently associated with kidney impairment. The family of melastatin-related transient receptor potential (TRPM) channels, which has eight members in mammals (TRPM1-TRPM8), includes ion channels that are highly permeable to divalent cations, such as Ca2+, Mg2+ and Zn2+ (TRPM1, TRPM3, TRPM6 and TRPM7), non-selective cation channels (TRPM2 and TRPM8) and monovalent cation-selective channels (TRPM4 and TRPM5). Three family members contain an enzymatic protein moiety: TRPM6 and TRPM7 are fused to α-kinase domains, whereas TRPM2 is linked to an ADP-ribose-binding NUDT9 homology domain. TRPM channels also function as crucial cellular sensors involved in many physiological processes, including mineral homeostasis, blood pressure, cardiac rhythm and immunity, as well as photoreception, taste reception and thermoreception. TRPM channels are abundantly expressed in the kidney. Mutations in TRPM genes cause several inherited human diseases, and preclinical studies in animal models of human disease have highlighted TRPM channels as promising new therapeutic targets. Here, we provide an overview of this rapidly evolving research area and delineate the emerging role of TRPM channels in kidney pathophysiology.

Microbiota-derived butyrate restricts tuft cell differentiation via histone deacetylase 3 to modulate intestinal type 2 immunity

Tuft cells in mucosal tissues are key regulators of type 2 immunity. Here, we examined the impact of the microbiota on tuft cell biology in the intestine. Succinate induction of tuft cells and type 2 innate lymphoid cells was elevated with loss of gut microbiota. Colonization with butyrate-producing bacteria or treatment with butyrate suppressed this effect and reduced intestinal histone deacetylase activity. Epithelial-intrinsic deletion of the epigenetic-modifying enzyme histone deacetylase 3 (HDAC3) inhibited tuft cell expansion in vivo and impaired type 2 immune responses during helminth infection. Butyrate restricted stem cell differentiation into tuft cells, and inhibition of HDAC3 in adult mice and human intestinal organoids blocked tuft cell expansion. Collectively, these data define a HDAC3 mechanism in stem cells for tuft cell differentiation that is dampened by a commensal metabolite, revealing a pathway whereby the microbiota calibrate intestinal type 2 immunity.

Host-microbial crosstalk relies on "tuft" love

How commensals influence intestinal immunity is incompletely understood. In this issue of Immunity, Eshleman et al. demonstrate that microbiota-derived butyrate restrains tuft cell development via HDAC3 modulation in intestinal epithelial cells, showing how microbial metabolites impact intestinal type 2 immunity.

Intestinal Tuft Cells: Morphology, Function, and Implications for Human Health

Tuft cells are a rare and morphologically distinct chemosensory cell type found throughout many organs, including the gastrointestinal tract. These cells were identified by their unique morphologies distinguished by large apical protrusions. Ultrastructural data have begun to describe the molecular underpinnings of their cytoskeletal features, and tuft cell-enriched cytoskeletal proteins have been identified, although the connection of tuft cell morphology to tuft cell functionality has not yet been established. Furthermore, tuft cells display variations in function and identity between and within tissues, leading to the delineation of distinct tuft cell populations. As a chemosensory cell type, they display receptors that are responsive to ligands specific for their environment. While many studies have demonstrated the tuft cell response to protists and helminths in the intestine, recent research has highlighted other roles of tuft cells as well as implicated tuft cells in other disease processes including inflammation, cancer, and viral infections. Here, we review the literature on the cytoskeletal structure of tuft cells. Additionally, we focus on new research discussing tuft cell lineage, ligand-receptor interactions, tuft cell tropism, and the role of tuft cells in intestinal disease. Finally, we discuss the implication of tuft cell-targeted therapies in human health and how the morphology of tuft cells may contribute to their functionality.

PCGF6 controls murine Tuft cell differentiation via H3K9me2 modification independently of Polycomb repression

Cell fate is determined by specific transcription programs that are essential for tissue homeostasis and regeneration. The E3-ligases RING1A and B represent the core activity of the Polycomb repressive complex 1 (PRC1) that deposits repressive histone H2AK119 mono-ubiquitination (H2AK119ub1), which is essential for mouse intestinal homeostasis by preserving stem cell functions. However, the specific role of different PRC1 forms, which are defined by the six distinct PCGF1-6 paralogs, remains largely unexplored in vivo. We report that PCGF6 regulates mouse intestinal Tuft cell differentiation independently of H2AK119ub1 deposition. We show that PCGF6 chromatin occupancy expands outside Polycomb repressive domains, associating with unique promoter and distal regulatory elements. This occurs in the absence of RING1A/B and involves MGA-mediated E-BOX recognition and specific H3K9me2 promoter deposition. PCGF6 inactivation induces an epithelial autonomous accumulation of Tuft cells that was not phenocopied by RING1A/B loss. This involves direct PCGF6 association with a Tuft cell differentiation program that identified Polycomb-independent properties of PCGF6 in adult tissues homeostasis.

Folate supports IL-25-induced tuft cell expansion following enteroviral infections

Intestinal tuft cells, a kind of epithelial immune cells, rapidly expand in response to pathogenic infections, which is associated with infection-induced interleukin 25 (IL-25) upregulation. However, the metabolic mechanism of IL-25-induced tuft cell expansion is largely unknown. Folate metabolism provides essential purine and methyl substrates for cell proliferation and differentiation. Thus, we aim to investigate the roles of folate metabolism playing in IL-25-induced tuft cell expansion by enteroviral infection and recombinant murine IL-25 (rmIL-25) protein-stimulated mouse models. At present, enteroviruses, such as EV71, CVA16, CVB3, and CVB4, upregulated IL-25 expression and induced tuft cell expansion in the intestinal tissues of mice. However, EV71 did not induce intestinal tuft cell expansion in IL-25-/- mice. Interestingly, compared to the mock group, folate was enriched in the intestinal tissues of both the EV71-infected group and the rmIL-25 protein-stimulated group. Moreover, folate metabolism supported IL-25-induced tuft cell expansion since both folate-depletion and anti-folate MTX-treated mice had a disrupted tuft cell expansion in response to rmIL-25 protein stimulation. In summary, our data suggested that folate metabolism supported intestinal tuft cell expansion in response to enterovirus-induced IL-25 expression, which provided a new insight into the mechanisms of tuft cell expansion from the perspective of folate metabolism.

Mammalian SWI/SNF complex activity regulates POU2F3 and constitutes a targetable dependency in small cell lung cancer

Small cell lung cancers (SCLC) are comprised of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLC, ∼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes, including non-canonical BAF (ncBAF) complexes, as top dependencies specific to POU2F3-positive SCLC. Notably, clinical-grade pharmacologic mSWI/SNF inhibition attenuates proliferation of all POU2F3-positive SCLCs, while disruption of ncBAF via BRD9 degradation is uniquely effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, chemical targeting of SMARCA4/2 mSWI/SNF ATPases and BRD9 decrease POU2F3-SCLC tumor growth and increase survival in vivo . Taken together, these results characterize mSWI/SNF-mediated global governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for SCLC.

The importance of the gut microbiome and its signals for a healthy nervous system and the multifaceted mechanisms of neuropsychiatric disorders

Increasing evidence links the gut microbiome and the nervous system in health and disease. This narrative review discusses current views on the interaction between the gut microbiota, the intestinal epithelium, and the brain, and provides an overview of the communication routes and signals of the bidirectional interactions between gut microbiota and the brain, including circulatory, immunological, neuroanatomical, and neuroendocrine pathways. Similarities and differences in healthy gut microbiota in humans and mice exist that are relevant for the translational gap between non-human model systems and patients. There is an increasing spectrum of metabolites and neurotransmitters that are released and/or modulated by the gut microbiota in both homeostatic and pathological conditions. Dysbiotic disruptions occur as consequences of critical illnesses such as cancer, cardiovascular and chronic kidney disease but also neurological, mental, and pain disorders, as well as ischemic and traumatic brain injury. Changes in the gut microbiota (dysbiosis) and a concomitant imbalance in the release of mediators may be cause or consequence of diseases of the central nervous system and are increasingly emerging as critical links to the disruption of healthy physiological function, alterations in nutrition intake, exposure to hypoxic conditions and others, observed in brain disorders. Despite the generally accepted importance of the gut microbiome, the bidirectional communication routes between brain and gut are not fully understood. Elucidating these routes and signaling pathways in more detail offers novel mechanistic insight into the pathophysiology and multifaceted aspects of brain disorders.

Mechanisms of intestinal dysbiosis: new insights into tuft cell functions

Symbiosis between the host and intestinal microbial communities is essential for human health. Disruption in this symbiosis is linked to gastrointestinal diseases, including inflammatory bowel diseases, as well as extra-gastrointestinal diseases. Unbalanced gut microbiome or gut dysbiosis contributes in multiple ways to disease frequency, severity and progression. Microbiome taxonomic profiling and metabolomics approaches greatly improved our understanding of gut dysbiosis features; however, the precise mechanisms involved in gut dysbiosis establishment still need to be clarified. The aim of this review is to present new actors and mechanisms underlying gut dysbiosis formation following parasitic infection or in a context of altered Paneth cells, revealing the existence of a critical crosstalk between Paneth and tuft cells to control microbiome composition.

Spatiotemporal observations of host-pathogen interactions in mucosa during SARS-CoV-2 infection indicate a protective role of ILC2s

IMPORTANCE

Our study revealed the spatial interaction between humanized ACE2 and pseudovirus expressing Spike, emphasizing the role of type 2 innate lymphoid cells during the initial phase of viral infection. These findings provide a foundation for the development of mucosal vaccines and other treatment approaches for both pre- and post-infection management of coronavirus disease 2019.

Both Horatio and Polonius: Innate Lymphoid Cells in Tissue Homeostasis and Repair

Innate lymphoid cells (ILCs) have emerged as critical tissue-resident lymphocytes that coordinate responses to environmental stress and injury. Traditionally, their function was thought to mirror adaptive lymphocytes that respond to specific pathogens. However, recent work has uncovered a more central role for ILCs in maintaining homeostasis even in the absence of infection. ILCs are now better conceptualized as an environmental rheostat that helps maintain the local tissue setpoint during environmental challenge by integrating sensory stimuli to direct homeostatic barrier and repair programs. In this article, we trace the developmental origins of ILCs, relate how ILCs sense danger signals, and describe their subsequent engagement of appropriate repair responses using a general paradigm of ILCs functioning as central controllers in tissue circuits. We propose that these interactions form the basis for how ILC subsets maintain organ function and organismal homeostasis, with important implications for human health.

A tuft cell - ILC2 signaling circuit provides therapeutic targets to inhibit gastric metaplasia and tumor development

Although gastric cancer is a leading cause of cancer-related deaths, systemic treatment strategies remain scarce. Here, we report the pro-tumorigenic properties of the crosstalk between intestinal tuft cells and type 2 innate lymphoid cells (ILC2) that is evolutionarily optimized for epithelial remodeling in response to helminth infection. We demonstrate that tuft cell-derived interleukin 25 (IL25) drives ILC2 activation, inducing the release of IL13 and promoting epithelial tuft cell hyperplasia. While the resulting tuft cell - ILC2 feed-forward circuit promotes gastric metaplasia and tumor formation, genetic depletion of tuft cells or ILC2s, or therapeutic targeting of IL13 or IL25 alleviates these pathologies in mice. In gastric cancer patients, tuft cell and ILC2 gene signatures predict worsening survival in intestinal-type gastric cancer where ~40% of the corresponding cancers show enriched co-existence of tuft cells and ILC2s. Our findings suggest a role for ILC2 and tuft cells, along with their associated cytokine IL13 and IL25 as gatekeepers and enablers of metaplastic transformation and gastric tumorigenesis, thereby providing an opportunity to therapeutically inhibit early-stage gastric cancer through repurposing antibody-mediated therapies.

Tuft cells utilize taste signaling molecules to respond to the pathobiont microbe Ruminococcus gnavus in the proximal colon

Tuft cells are a type of rare epithelial cells that have been recently found to utilize taste signal transduction pathways to detect and respond to various noxious stimuli and pathogens, including allergens, bacteria, protists and parasitic helminths. It is, however, not fully understood how many different types of pathogens they can sense or what exact molecular mechanisms they employ to initiate targeted responses. In this study, we found that an anaerobic pathobiont microbe, Ruminococcus gnavus (R. gnavus), can induce tuft cell proliferation in the proximal colon whereas the microbe's lysate can stimulate these proximal colonic tuft cells to release interleukin-25 (IL-25). Nullification of the Gng13 and Trpm5 genes that encode the G protein subunit Gγ13 and transient receptor potential ion channel Trpm5, respectively, or application of the Tas2r inhibitor allyl isothiocyanate (AITC), G protein Gβγ subunit inhibitor Gallein or the phospholipase Cβ2 (PLCβ2) inhibitor U73122 reduces R. gnavus-elicited tuft cell proliferation or IL-25 release or both. Furthermore, Gng13 conditional knockout or Trpm5 knockout diminishes the expression of gasdermins C2, C3 and C4, and concomitantly increases the activated forms of caspases 3, 8 and 9 as well as the number of TUNEL-positive apoptotic cells in the proximal colon. Together, our data suggest that taste signal transduction pathways are not only involved in the detection of R. gnavus infection, but also contribute to helping maintain gasdermin expression and prevent apoptotic cell death in the proximal colon, and these findings provide another strategy to combat R. gnavus infection and sheds light on new roles of taste signaling proteins along with gasdermins in protecting the integrity of the proximal colonic epithelium.

Targeting helminths: The expanding world of type 2 immune effector mechanisms

In this new review, Rick Maizels and Bill Gause summarize how type 2 immune responses combat helminth parasites through novel mechanisms, coordinating multiple innate and adaptive cell and molecular players that can eliminate infection and repair-resultant tissue damage.

Chronic stress induces pulmonary epithelial cells to produce acetylcholine that remodels lung pre-metastatic niche of breast cancer by enhancing NETosis

BACKGROUND

Chronic stress promotes most hallmarks of cancer through impacting the malignant tissues, their microenvironment, immunity, lymphatic flow, etc. Existing studies mainly focused on the roles of stress-induced activation of systemic sympathetic nervous system and other stress-induced hormones, the organ specificity of chronic stress in shaping the pre-metastatic niche remains largely unknown. This study investigated the role of chronic stress in remodeling lung pre-metastatic niche of breast cancer.

METHODS

Breast cancer mouse models with chronic stress were constructed by restraint or unpredictable stress. Expressions of tyrosine hydroxylase, vesicular acetylcholine transporter (VAChT), EpCAM and NETosis were examined by immunofluorescence and confocal microscopy. mRNA and protein levels of choline acetyltransferase (ChAT), VAChT, and peptidylarginine deiminase 4 were detected by qRT-PCR and Western blotting, respectively. Immune cell subsets were analyzed by flow cytometry. Acetylcholine (ACh) and chemokines were detected by ELISA and multi chemokine array, respectively. ChAT in lung tissues from patients was examined by immunohistochemistry.

RESULTS

Breast cancer-bearing mice suffered chronic stress metastasized earlier and showed more severe lung metastasis than did mice in control group. VAChT, ChAT and ChAT+ epithelial cells were increased significantly in lung of model mice undergone chronic stress. ACh and chemokines especially CXCL2 in lung culture supernatants from model mice with chronic stress were profoundly increased. Chronic stress remodeled lung immune cell subsets with striking increase of neutrophils, enhanced NETosis in lung and promoted NETotic neutrophils to capture cancer cells. ACh treatment resulted in enhanced NETosis of neutrophils. The expression of ChAT in lung tissues from breast cancer patients with lung metastasis was significantly higher than that in patients with non-tumor pulmonary diseases.

CONCLUSIONS

Chronic stress promotes production of CXCL2 that recruits neutrophils into lung, and induces pulmonary epithelial cells to produce ACh that enhances NETosis of neutrophils. Our findings demonstrate for the first time that chronic stress induced epithelial cell derived ACh plays a key role in remodeling lung pre-metastatic niche of breast cancer.

IFNγ synergies with cold atmospheric plasma in triggering colorectal cancer cell ferroptosis via the IFNγ/IFNR2/APC/TCF4/GPX4 axis

Colorectal cancer accounts for the second most common cancer-related lethality. Intestinal stem cells are responsible for enteric homeostasis maintenance that, once being transformed, become colorectal cancer stem cells. Arresting cancer stemness represents an innovative strategy for colorectal cancer management. Using intestinal stem cell organoids as the primary model, we screened common inflammatory cytokines to identify key players targeting cancer stemness. We also explored the downstream signaling that drives the functionalities of the identified cytokine through both experimental investigations and computational predictions. As the results, we identified IFNγ as the key cytokine capable of arresting intestinal stem cells via the IFNγ/IFNGR2/APC/TCF4/GPX4 axis, proposed its role in killing colorectal cancer stem cells via triggering GPX4-dependent ferroptosis, and demonstrated its synergistic anti-cancer effect with cold atmospheric plasma in killing colorectal cancer cells that is worthy to be experimentally validated.

Novel mechanistic insights underlying fungal allergic inflammation

The worldwide prevalence of asthma and allergic disorders (allergic rhinitis, atopic dermatitis, food allergy) has been steadily rising in recent decades. It is now estimated that up to 20% of the global population is afflicted by an allergic disease, with increasing incidence rates in both high- and low-income countries. The World Allergy Organization estimates that the total economic burden of asthma and allergic rhinitis alone is approximately $21 billion per year. While allergic stimuli are a complex and heterogenous class of inputs including parasites, pollens, food antigens, drugs, and metals, it has become clear that fungi are major drivers of allergic disease, with estimates that fungal sensitization occurs in 20-30% of atopic individuals and up to 80% of asthma patients. Fungi are eukaryotic microorganisms that can be found throughout the world in high abundance in both indoor and outdoor environments. Understanding how and why fungi act as triggers of allergic type 2 inflammation will be crucial for combating this important health problem. In recent years, there have been significant advances in our understanding of fungi-induced type 2 immunity, however there is still much we don't understand, including why fungi have a tendency to induce allergic reactions in the first place. Here, we will discuss how fungi trigger type 2 immune responses and posit why this response has been evolutionarily selected for induction during fungal encounter.

Airway epithelial development and function: A key player in asthma pathogenesis?

Though asthma is a common and relatively easy to diagnose disease, attempts at primary or secondary prevention, and cure, have been disappointing. The widespread use of inhaled steroids has dramatically improved asthma control but has offered nothing in terms of altering long-term outcomes or reversing airway remodeling and impairment in lung function. The inability to cure asthma is unsurprising given our limited understanding of the factors that contribute to disease initiation and persistence. New data have focused on the airway epithelium as a potentially key factor orchestrating the different stages of asthma. In this review we summarize for the clinician the current evidence on the central role of the airway epithelium in asthma pathogenesis and the factors that may alter epithelial integrity and functionality.

Critical Signaling Transduction Pathways and Intestinal Barrier: Implications for Pathophysiology and Therapeutics

The intestinal barrier is a sum of the functions and structures consisting of the intestinal mucosal epithelium, mucus, intestinal flora, secretory immunoglobulins, and digestive juices. It is the first-line defense mechanism that resists nonspecific infections with powerful functions that include physical, endocrine, and immune defenses. Health and physiological homeostasis are greatly dependent on the sturdiness of the intestinal barrier shield, whose dysfunction can contribute to the progression of numerous types of intestinal diseases. Disorders of internal homeostasis may also induce barrier impairment and form vicious cycles during the response to diseases. Therefore, the identification of the underlying mechanisms involved in intestinal barrier function and the development of effective drugs targeting its damage have become popular research topics. Evidence has shown that multiple signaling pathways and corresponding critical molecules are extensively involved in the regulation of the barrier pathophysiological state. Ectopic expression or activation of signaling pathways plays an essential role in the process of shield destruction. Although some drugs, such as molecular or signaling inhibitors, are currently used for the treatment of intestinal diseases, their efficacy cannot meet current medical requirements. In this review, we summarize the current achievements in research on the relationships between the intestinal barrier and signaling pathways. The limitations and future perspectives are also discussed to provide new horizons for targeted therapies for restoring intestinal barrier function that have translational potential.

Thymic tuft cells: potential "regulators" of non-mucosal tissue development and immune response

As the leading central immune organ, the thymus is where T cells differentiate and mature, and plays an essential regulatory role in the adaptive immune response. Tuft cells, as chemosensory cells, were first found in rat tracheal epithelial, later gradually confirmed to exist in various mucosal and non-mucosal tissues. Although tuft cells are epithelial-derived, because of their wide heterogeneity, they show functions similar to cholinergic and immune cells in addition to chemosensory ability. As newly discovered non-mucosal tuft cells, thymic tuft cells have been demonstrated to be involved in and play vital roles in immune responses such as antigen presentation, immune tolerance, and type 2 immunity. In addition to their unique functions in the thymus, thymic tuft cells have the characteristics of peripheral tuft cells, so they may also participate in the process of tumorigenesis and virus infection. Here, we review tuft cells' characteristics, distribution, and potential functions. More importantly, the potential role of thymic tuft cells in immune response, tumorigenesis, and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) infection was summarized and discussed.

Advances in tuft cells, a chemosensory cell in sequential diseases of the pancreas

Tuft cells are solitary chemosensory cells distributed mainly in hollow organs and detected in human and mouse pancreas precursor lesions of pancreatic cancer. Induced by inflammation and KRAS mutation, pancreatic acinar cell-derived tuft cells play a protective role in epithelium injury. The tumour suppression of tuft cells has been indicated in some studies. However, the function of tuft cells in pancreatic cancer remains unclear. In this review, we first introduce the definition of tuft cells and then review the relationship between tuft cells and pancreatic inflammation. In addition, we emphasized the role of tuft cells in the genesis and development of pancreatic cancers, especially the part of markers for tuft cell's doublecortin-like kinase 1 (DCLK1). Finally, we turn to the microscopic perspective and review the interactions between tuft cells and the microbiome in the pancreatic microenvironment. Overall, we describe the role of tuft cells in response to tissue damage and tumour progression in the pancreas. Nevertheless, the specific formation principle and the more detailed mechanism of action of tuft cells in the pancreas remain to be further explored.

The abundance and morphology of human large intestinal goblet and tuft cells during chronic schistosomiasis

Schistosomiasis affects nearly 240 million people in predominately low- and middle-income countries and ranks second in the number of cases and socio-economic burden among all parasitic diseases. Despite the enormous burden posed by schistosomes, our understanding of how schistosomiasis impacts infected human tissues remains limited. Intestinal schistosomiasis in animal models leads to goblet cell hyperplasia, likely increasing mucus production and reflecting an intestinal type 2 immune response. However, it is unknown whether these same changes occur in schistosome-infected humans. Using immunofluorescence and light microscopy, we compared the abundance and morphology of goblet cells in patients diagnosed with schistosomiasis to uninfected controls. The mucin-containing vesicles in goblet cells from schistosome-infected patients were significantly larger (hypertrophic) than uninfected individuals, although goblet cell hyperplasia was absent in chronic human schistosomiasis. In addition, we examined tuft cells in the large intestinal epithelium of control and schistosome-infected patients. Tuft cell numbers expand during helminth infection in mice, but these cells have not been characterized in human parasite infections. We found no evidence of tuft cell hyperplasia during human schistosome infection. Thus, our study provides novel insight into schistosome-associated changes to the intestinal epithelium in humans, suggesting an increase in mucus production by large intestinal goblet cells but relatively minor effects on tuft cell numbers.

Interkingdom Detection of Bacterial Quorum-Sensing Molecules by Mammalian Taste Receptors

Bitter and sweet taste G protein-coupled receptors (known as T2Rs and T1Rs, respectively) were originally identified in type II taste cells on the tongue, where they signal perception of bitter and sweet tastes, respectively. Over the past ~15 years, taste receptors have been identified in cells all over the body, demonstrating a more general chemosensory role beyond taste. Bitter and sweet taste receptors regulate gut epithelial function, pancreatic β cell secretion, thyroid hormone secretion, adipocyte function, and many other processes. Emerging data from a variety of tissues suggest that taste receptors are also used by mammalian cells to "eavesdrop" on bacterial communications. These receptors are activated by several quorum-sensing molecules, including acyl-homoserine lactones and quinolones from Gram-negative bacteria such as Pseudomonas aeruginosa, competence stimulating peptides from Streptococcus mutans, and D-amino acids from Staphylococcus aureus. Taste receptors are an arm of immune surveillance similar to Toll-like receptors and other pattern recognition receptors. Because they are activated by quorum-sensing molecules, taste receptors report information about microbial population density based on the chemical composition of the extracellular environment. This review summarizes current knowledge of bacterial activation of taste receptors and identifies important questions remaining in this field.

Tuft cells - the immunological interface and role in disease regulation

Tuft cells, also known as taste chemosensory cells, accumulate during parasite colonization or infection and have powerful immunomodulatory effects on substances that could be detrimental, as well as possible anti-inflammatory or antibacterial effects. Tuft cells are the primary source of interleukin (IL)-25. They trigger extra Innate lymphoid type-2 cells (ILC2) in the intestinal lamina propria to create cytokines (type 2); for instance, IL-13, which leads to an increase in IL-25. As tuft cells can produce biological effector molecules, such as IL-25 and eicosanoids involved in allergy (for example, cysteinyl leukotrienes and prostaglandin D₂) and the neurotransmitter acetylcholine. Following parasite infection, tuft cells require transient receptor potential cation channel subfamily M member 5 (TRPM5)-dependent chemosensation to produce responses. Secretory tuft cells provide a physical mucus barrier against the external environment and therefore have vital defensive roles against diseases by supporting tissue maintenance and repair. In addition to recent research on tuft cells, more studies are required to understand the distribution, cell turnover, molecular characteristics, responses in various species, involvement in immunological function across tissues, and most importantly, the mechanism involved in the control of various diseases.

Innate lymphoid cells and innate-like T cells in cancer - at the crossroads of innate and adaptive immunity

Immunotherapies targeting conventional T cells have revolutionized systemic treatment for many cancers, yet only a subset of patients benefit from these approaches. A better understanding of the complex immune microenvironment of tumours is needed to design the next generation of immunotherapeutics. Innate lymphoid cells (ILCs) and innate-like T cells (ILTCs) are abundant, tissue-resident lymphocytes that have recently been shown to have critical roles in many types of cancers. ILCs and ILTCs rapidly respond to changes in their surrounding environment and act as the first responders to bridge innate and adaptive immunity. This places ILCs and ILTCs as pivotal orchestrators of the final antitumour immune response. In this Review, we outline hallmarks of ILCs and ILTCs and discuss their emerging role in antitumour immunity, as well as the pathophysiological adaptations leading to their pro-tumorigenic function. We explore the pleiotropic, in parts redundant and sometimes opposing, mechanisms that underlie the delicate interplay between the different subsets of ILCs and ILTCs. Finally, we highlight their role in amplifying and complementing conventional T cell functions and summarize immunotherapeutic strategies for targeting ILCs and ILTCs in cancer.

Metabolism in type 2 immune responses

The immune response is tailored to the environment in which it takes place. Immune cells sense and adapt to changes in their surroundings, and it is now appreciated that in addition to cytokines made by stromal and epithelial cells, metabolic cues provide key adaptation signals. Changes in immune cell activation states are linked to changes in cellular metabolism that support function. Furthermore, metabolites themselves can signal between as well as within cells. Here, we discuss recent progress in our understanding of how metabolic regulation relates to type 2 immunity firstly by considering specifics of metabolism within type 2 immune cells and secondly by stressing how type 2 immune cells are integrated more broadly into the metabolism of the organism as a whole.

Modes of type 2 immune response initiation

Type 2 immunity defends against macro-parasites and can cause allergic diseases. Our understanding of the mechanisms governing the initiation of type 2 immunity is limited, whereas we know more about type 1 immune responses. Type 2 immunity can be triggered by a wide array of inducers that do not share common features and via diverse pathways and mechanisms. To address the complexity of the type 2 initiation pathways, we suggest a framework that conceptualizes different modes of induction of type 2 immunity. We discuss categories of type 2 inducers and their immunogenicity, types of tissue perturbations that are caused by these inducers, sensing strategies for the initiation of Th2 immune responses, and categorization of the signals that are produced in response to type 2 challenges. We describe tissue-specific examples of functional disruption that could lead to type 2 inflammation and propose that different sensing strategies that operate at the tissue level converge on the initiation of type 2 immune responses.

The ins and outs of innate and adaptive type 2 immunity

Type 2 immunity is orchestrated by a canonical group of cytokines primarily produced by innate lymphoid cells, group 2, and their adaptive counterparts, CD4+ helper type 2 cells, and elaborated by myeloid cells and antibodies that accumulate in response. Here, we review the cytokine and cellular circuits that mediate type 2 immunity. Building from insights in cytokine evolution, we propose that innate type 2 immunity evolved to monitor the status of microbe-rich epithelial barriers (outside) and sterile parenchymal borders (inside) to meet the functional demands of local tissue, and, when necessary, to relay information to the adaptive immune system to reinforce demarcating borders to sustain these efforts. Allergic pathology likely results from deviations in local sustaining units caused by alterations imposed by environmental effects during postnatal developmental windows and exacerbated by mutations that increase vulnerabilities. This framework positions T2 immunity as central to sustaining tissue repair and regeneration and provides a context toward understanding allergic disease.

Molecular characterization of colorectal mucinous adenocarcinoma and adenocarcinoma, not otherwise specified, identified by multiomic data analysis

Adenocarcinoma not otherwise specified (AC) and mucinous adenocarcinoma (MC) have different biological behaviors and clinical features. We utilized our previous proteomic data and public transcriptome, single-cell transcriptome, and spatial transcriptome databases to profile the molecular atlas of the tumor microenvironments of MC, AC, and normal colon tissues. By exploring the general and specific molecular features of AC and MC, we found that AC was immune-active but exposed to a hypoxic microenvironment. MC cells could protect against DNA damage, and the microenvironment was unfavorable to leukocyte transendothelial migration. We identified several potential molecular and cellular targets of AC and MC for future research. We also highlighted that the major difference between AC and MC was not the variety of cell types and functions but possibly cell interactions. Stromal and epithelial cell interactions play important roles in both MC and AC, but different regulatory pathways were involved.

The gut microbiome and hypertension

A large body of evidence has emerged in the past decade supporting a role for the gut microbiome in the regulation of blood pressure. The field has moved from association to causation in the last 5 years, with studies that have used germ-free animals, antibiotic treatments and direct supplementation with microbial metabolites. The gut microbiome can regulate blood pressure through several mechanisms, including through gut dysbiosis-induced changes in microbiome-associated gene pathways in the host. Microbiota-derived metabolites are either beneficial (for example, short-chain fatty acids and indole-3-lactic acid) or detrimental (for example, trimethylamine N-oxide), and can activate several downstream signalling pathways via G protein-coupled receptors or through direct immune cell activation. Moreover, dysbiosis-associated breakdown of the gut epithelial barrier can elicit systemic inflammation and disrupt intestinal mechanotransduction. These alterations activate mechanisms that are traditionally associated with blood pressure regulation, such as the renin-angiotensin-aldosterone system, the autonomic nervous system, and the immune system. Several methodological and technological challenges remain in gut microbiome research, and the solutions involve minimizing confounding factors, establishing causality and acting globally to improve sample diversity. New clinical trials, precision microbiome medicine and computational methods such as Mendelian randomization have the potential to enable leveraging of the microbiome for translational applications to lower blood pressure.

Deoxycholic acid exacerbates intestinal inflammation by modulating interleukin-1β expression and tuft cell proportion in dextran sulfate sodium-induced murine colitis

Background

The etiology of inflammatory bowel disease (IBD) remains unclear. However, intestinal metabolism is known to be critical in the pathogenesis of IBD. Bile acid is one of the main intestinal metabolites, and its role in the pathogenesis of IBD is worthy of investigation. This study investigated the role of deoxycholic acid (DCA), a bile acid, in the pathogenesis of IBD.

Methods

Peripheral serum metabolomics, fecal metabolomics, and microbiome analyses were performed on patients with IBD and healthy controls. Flow cytometry, real-time quantitative polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, immunohistochemical staining, and immunofluorescence analysis were used to evaluate cytokines in the inflamed colonic mucosa and immune cells and tuft cells in the intestine of mice with dextran sulfate sodium (DSS)-induced colitis.

Results

In total, 156 patients with IBD and 58 healthy controls were enrolled. DCA levels in the serum and feces of patients with IBD were significantly decreased compared to the controls. This decrease was associated with a decrease in the abundance of intestinal flora, including Firmicutes, Clostridia, Ruminnococcaceae, and Lachnospiraceae. Additionally, interleukin (IL)-1β levels in the serum of patients with active Crohn's disease were significantly increased compared with the healthy controls. Moreover, in DCA-treated DSS-induced mice, the expression of IL-1β and the proportion of CD3⁺ and CD4⁺ T cells increased while the number of intestinal tuft cells decreased, compared with the DSS group.

Conclusion

In IBD patients, the decreased DCA levels in serum and fecal samples are associated with disturbances in gut microflora diversity and abundance. Possible mechanisms by which DCA affects immunity in DSS-induced murine colitis include increasing IL-1β secretion, reducing the number of tuft cells in the mucosa, and activating CD4⁺ and CD3⁺ T cells to exaggerate immune responses, consequently worsening intestinal inflammation.