Chemosensory Cells Research Articles

Lipids regulate peripheral serotonin release via gut CD1d

The crosstalk between the immune and neuroendocrine systems is critical for intestinal homeostasis and gut-brain communications. However, it remains unclear how immune cells participate in gut sensation of hormones and neurotransmitters release in response to environmental cues, such as self-lipids and microbial lipids. We show here that lipid-mediated engagement of invariant natural killer T (iNKT) cells with enterochromaffin (EC) cells, a subset of intestinal epithelial cells, promoted peripheral serotonin (5-HT) release via a CD1d-dependent manner, regulating gut motility and hemostasis. We also demonstrated that inhibitory sphingolipids from symbiotic microbe Bacteroides fragilis represses 5-HT release. Mechanistically, CD1d ligation on EC cells transduced a signal and restrained potassium conductance through activation of protein tyrosine kinase Pyk2, leading to calcium influx and 5-HT secretion. Together, our data reveal that by engaging with iNKT cells, gut chemosensory cells selectively perceive lipid antigens via CD1d to control 5-HT release, modulating intestinal and systemic homeostasis.

Activating transcription factor 5 (ATF5) controls intestinal tuft and goblet cell expansion upon succinate-induced type 2 immune responses in mice.

Intestinal tuft cells, a chemosensory cell type in mucosal epithelia that secrete interleukin (IL)-25, play a pivotal role in type 2 immune responses triggered by parasitic infections. Tuft cell-derived IL-25 activates type 2 innate lymphoid cells (ILC2) to secrete IL-13, which, in turn, acts on intestinal stem or transient amplifying cells to expand tuft cells themselves and mucus-secreting goblet cells. However, the molecular mechanisms of tuft cell differentiation under type 2 immune responses remain unclear. The present study investigated the effects of the deletion of activating transcription factor 5 (ATF5) on the type 2 immune response triggered by succinate (a metabolite of parasites) in mice. ATF5 mRNAs were expressed in the small intestine, and the loss of the ATF5 gene did not affect the gross morphology of the tissue or the basal differentiation of epithelial cell subtypes. Succinate induced marked increases in tuft and goblet cell numbers in the ATF5-deficient ileum. Tuft cells in the ATF5-deficient ileum are assumed to be a subtype of intestinal tuft cells (Tuft-2 cells) marked by the transcription factor Spib. Exogenous IL-25 induced similar increases in tuft and goblet cell numbers in wild-type and ATF5-deficient ilea. IL-13 at a submaximal dose enhanced tuft cell differentiation more in ATF5-deficient than in wild-type intestinal organoids. These results indicate that the loss of ATF5 enhanced the tuft cell-ILC2 type 2 immune response circuit by promoting tuft cell differentiation in the small intestine, suggesting its novel regulatory role in immune responses against parasitic infections.

Tuft cells mediate commensal remodeling of the small intestinal antimicrobial landscape

Succinate produced by the commensal protist Tritrichomonas musculis (T. mu) stimulates chemosensory tuft cells, resulting in intestinal type 2 immunity. Tuft cells express the succinate receptor SUCNR1, yet this receptor does not mediate antihelminth immunity nor alter protist colonization. Here, we report that microbial-derived succinate increases Paneth cell numbers and profoundly alters the antimicrobial peptide (AMP) landscape in the small intestine. Succinate was sufficient to drive this epithelial remodeling, but not in mice lacking tuft cell chemosensory components required to detect this metabolite. Tuft cells respond to succinate by stimulating type 2 immunity, leading to interleukin-13-mediated epithelial and AMP expression changes. Moreover, type 2 immunity decreases the total number of mucosa-associated bacteria and alters the small intestinal microbiota composition. Finally, tuft cells can detect short-term bacterial dysbiosis that leads to a spike in luminal succinate levels and modulate AMP production in response. These findings demonstrate that a single metabolite produced by commensals can markedly shift the intestinal AMP profile and suggest that tuft cells utilize SUCNR1 and succinate sensing to modulate bacterial homeostasis.

Immunohistochemical analysis of glutamatergic and serotonergic signaling pathways in chemosensory cell clusters in the pharynx and larynx of rats

The present study examined cellular components and the localization of vesicular glutamate transporter (VGLUT) 1 and 2 and serotonin (5-HT) in chemosensory cell clusters in the rat pharynx and larynx. Triple immunolabeling for guanine nucleotide-binding protein G (t), subunit ⍺3 (GNAT3) and nucleoside triphosphate diphosphohydrolase 2 (NTPDase2) with synaptotagmin-1 (Syt1) revealed NTPDase2-immunoreactive type I-like cells in addition to GNAT3-immunoreactive type II-like and Syt1-immunoreactive type III-like cells in pharyngolaryngeal chemosensory cell clusters. Therefore, these clusters appear to comprise similar cell types to those in the lingual taste buds with slight morphological modifications. An immunofluorescence analysis of VGLUT1 or VGLUT2 and GNAT3 with P2X3 purinoceptors revealed that VGLUTs co-localized to P2X3‐immunoreactive spherical nerve terminals closely associated with GNAT3-immunoreactive type II-like cells. Moreover, triple immunolabeling for Syt1/synaptosomal-associated protein, 25 kDa (SNAP25) and P2X3 with VGLUT1 or VGLUT2 revealed punctate immunoreactive products for VGLUT1 and VGLUT2 within P2X3‐immunoreactive flat axon terminals wrapped around Syt1/SNAP25-immunoreactive type III-like cells. The afferent nerve fibers innervating cell clusters may contain glutamate and release it by exocytosis. On the other hand, immunoreactive products for 5-HT and dopa decarboxylase were detected in Syt1-immunoreactive cells, indicating the release of 5-HT by these cells. The present results suggest that chemosensory cell clusters in the pharynx and larynx may be modulated by intrinsic glutamate and 5-HT.

Lipid sensing by gut CD1d calibrates peripheral serotonin release

Abstract The crosstalk between the immune and the neuroendocrine system is critical for intestinal homeostasis and gut-brain communications. However, it remains unclear how immune cells participate in gut sensation of hormones release in response to environmental cues, such as self and microbial lipids. We show here that lipid-mediated engagement of invariant natural killer T (iNKT) cells with enterochromaffin (EC) cells, a subset of intestinal epithelial cells, promotes peripheral serotonin (5-HT) release via a CD1d-dependent manner, regulating gut motility and hemostasis. CD1d ligation on EC cells transduces a reverse signal and restrains potassium conductance, leading to calcium influx and 5-HT secretion. Together, we show that by coupling with iNKT cells, gut chemosensory cells perceive lipid antigens via CD1d to calibrate 5-HT release, modulating intestinal and systemic physiology.

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.

COLITIS-ASSOCIATED COLON CANCER: EXPLORING THE DCLK1-S-MMP13-P53 AXIS

Chronic intestinal inflammation in patients with inflammatory bowel diseases (IBD) significantly increases the risk of colorectal cancer (CRC). Tuft cells in the intestine marked by doublecortin-like kinase-1 (DCLK1), are long-lived chemosensory cells with newly identified roles in colitis as epithelial ablation of DCLK1 worsens disease outcome. DCLK1 exists in long and short isoforms (DCLK1-L and DCLK1-S). Hypermethylation of DCLK1 alpha promoter encoding DCLK1-L particularly in CRC, allows switching to the DCLK1-S isoform that confers a more invasive tumor phenotype. In an infectious colitis model, we recently discovered that DCLK1-S is predominantly expressed in Ly6G+;MHCII- neutrophils that coincides with elevated levels of CXCL1/KC and MMP13 expression in the colon. In an unbiased molecular docking study, DCLK1’s kinase domain was found to interact with the catalytic domain of MMP13. MMP13 plays a crucial role in the modulation of extracellular matrix (ECM) degradation and cell-matrix interactions and wild type and mutant p53 differentially regulate MMP13 gene expression. Mutations in TP53 (tumor suppressor p53) are crucial for neoplasia initiation in IBD patients and are observed in 50-85% of colitis-associated colon cancers (CACCs). We further observed that p53 mutation status dictates DCLK1-S expression in colon cancer cells and in mice mutant for p53, expression of DCLK1-S and MMP13 correlated with neutrophilic inflammation and crypt hyperplasia. We will expand on these novel discoveries by employing high fidelity proteomic and phosphoproteomic studies and decipher how DCLK1-S-MMP13-p53 axes stimulate fibrosis, tumorigenesis, and tumor progression. These studies are expected to lead to therapeutic avenues to target CACCs.

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.

The Nasal Solitary Chemosensory Cell Signaling Pathway Triggers Mouse Avoidance Behavior to Inhaled Nebulized Irritants.

The nasal epithelium houses a population of solitary chemosensory cells (SCCs). SCCs express bitter taste receptors and taste transduction signaling components and are innervated by peptidergic trigeminal polymodal nociceptive nerve fibers. Thus, nasal SCCs respond to bitter compounds, including bacterial metabolites, and these reactions evoke protective respiratory reflexes and innate immune and inflammatory responses. We tested whether SCCs are implicated in aversive behavior to specific inhaled nebulized irritants using a custom-built dual-chamber forced-choice device. The behavior of mice was recorded and analyzed for the time spent in each chamber. Wild-type (WT) mice exhibited an aversion to 10 mm denatonium benzoate (Den) or cycloheximide and spent more time in the control (saline) chamber. The SCC-pathway knock-out (KO) mice did not exhibit such an aversion response. The bitter avoidance behavior of WT mice was positively correlated with the concentration increase of Den and the number of exposures. Bitter-ageusic P2X2/3 double KO mice similarly showed an avoidance response to nebulized Den, excluding the taste system's involvement and pointing to an SCC-mediated major contributor to the aversive response. Interestingly, SCC-pathway KO mice showed an attraction to higher Den concentrations; however, chemical ablation of the olfactory epithelium eliminated this attraction attributed to the smell of Den. These results demonstrate that activation of SCCs leads to a rapid aversive response to certain classes of irritants with olfaction, but not gustation, contributing to the avoidance behavior during subsequent irritant exposures. This SCC-mediated avoidance behavior represents an important defense mechanism against the inhalation of noxious chemicals.

Human T2R38 Bitter Taste Receptor Expression and COVID-19: From Immunity to Prognosis

Bitter taste-sensing type 2 receptor (T2Rs or TAS2Rs) found on ciliated epithelial cells and solitary chemosensory cells have a role in respiratory tract immunity. T2Rs have shown protection against SARS-CoV-2 by enhancing the innate immune response. The purpose of this review is to outline the current sphere of knowledge regarding this association. A narrative review of the literature was done by searching (T2R38 OR bitter taste receptor) AND (COVID-19 OR SARS-CoV-2) keywords in PubMed and google scholar. T2R38, an isoform of T2Rs encoded by the TAS2R38 gene, may have a potential association between phenotypic expression of T2R38 and prognosis of COVID-19. Current studies suggest that due to different genotypes and widespread distributions of T2Rs within the respiratory tract and their role in innate immunity, treatment protocols for COVID-19 and other respiratory diseases may change accordingly. Based on the phenotypic expression of T2R38, it varies in innate immunity and host response to respiratory infection, systemic symptoms and hospitalization. This review reveals that patients' innate immune response to SARS-COV-2 could be influenced by T2R38 receptor allelic variations.

Cerebrospinal fluid-contacting neuron tracing reveals structural and functional connectivity for locomotion in the mouse spinal cord.

Cerebrospinal fluid-contacting neurons (CSF-cNs) are enigmatic mechano- or chemosensory cells lying along the central canal of the spinal cord. Recent studies in zebrafish larvae and lampreys have shown that CSF-cNs control postures and movements via spinal connections. However, the structures, connectivity, and functions in mammals remain largely unknown. Here we developed a method to genetically target mouse CSF-cNs that highlighted structural connections and functions. We first found that intracerebroventricular injection of adeno-associated virus with a neuron-specific promoter and Pkd2l1-Cre mice specifically labeled CSF-cNs. Single-cell labeling of 71 CSF-cNs revealed rostral axon extensions of over 1800 μm in unmyelinated bundles in the ventral funiculus and terminated on CSF-cNs to form a recurrent circuitry, which was further determined by serial electron microscopy and electrophysiology. CSF-cNs were also found to connect with axial motor neurons and premotor interneurons around the central canal and within the axon bundles. Chemogenetic CSF-cNs inactivation reduced speed and step frequency during treadmill locomotion. Our data revealed the basic structures and connections of mouse CSF-cNs to control spinal motor circuits for proper locomotion. The versatile methods developed in this study will contribute to further understanding of CSF-cN functions in mammals.

Coronavirus infection in chemosensory cells.

Clinical manifestations of human coronavirus (HCoV)-related diseases are mostly related to the respiratory system, although secondary complications such as headache, anosmia, ageusia, and myalgia have been reported. HCoV infection and replication in chemosensory cells associated with ageusia and anosmia is poorly understood. Here, we characterized HCoV-OC43 and SARS-CoV-2 infection in two types of chemosensory cells, olfactory and taste cells, with their unique molecular and histological characteristics. We first assessed HCoV-OC43 infection in in vitro cultured human olfactory epithelial cells (hOECs) and fungiform taste papilla (HBO) cells. Interestingly, while both cell types were susceptible to HCoV-OC43 infection, viral replication rates were significantly reduced in HBO cells compared to hOECs. More interestingly, while culture media from hOECs was able to produce secondary infection in Vero cells, there was very limited secondary infection from HBO cells, suggesting that HBO cells may not be able to release infectious virus. On the other hand, unlike HCoV-OC43, SARS-CoV-2 showed comparable levels of viral infection rates in both hOECs and HBO cells. Furthermore, our RT-qPCR-based gene array studies revealed that several key genes involved in taste and olfactory functions were significantly altered by SARS-CoV-2 infection. These results may suggest a possible mechanism associated with chemosensory symptoms, such as anosmia and ageusia in patients infected with SARS-CoV-2.

COLITIS-ASSOCIATED COLON CANCER: EXPLORING THE DCLK1-S-MMP13-P53 AXIS

Abstract Chronic intestinal inflammation in patients with inflammatory bowel diseases (IBD) significantly increases the risk of colorectal cancer (CRC). Tuft cells in the intestine marked by doublecortin-like kinase-1 (DCLK1), are long-lived chemosensory cells with newly identified roles in colitis as epithelial ablation of DCLK1 worsens disease outcome. DCLK1 exists in long and short isoforms (DCLK1-L and DCLK1-S). Hypermethylation of DCLK1 alpha promoter encoding DCLK1-L particularly in CRC, allows switching to the DCLK1-S isoform that confers a more invasive tumor phenotype. In an infectious colitis model, we recently discovered that DCLK1-S is predominantly expressed in Ly6G+;MHCII- neutrophils that coincides with elevated levels of CXCL1/KC and MMP13 expression in the colon. In an unbiased molecular docking study, DCLK1’s kinase domain was found to interact with the catalytic domain of MMP13. MMP13 plays a crucial role in the modulation of extracellular matrix (ECM) degradation and cell-matrix interactions and wild type and mutant p53 differentially regulate MMP13 gene expression. Mutations in TP53 (tumor suppressor p53) are crucial for neoplasia initiation in IBD patients and are observed in 50-85% of colitis-associated colon cancers (CACCs). We further observed that p53 mutation status dictates DCLK1-S expression in colon cancer cells and in mice mutant for p53, expression of DCLK1-S and MMP13 correlated with neutrophilic inflammation and crypt hyperplasia. We will expand on these novel discoveries by employing high fidelity proteomic and phosphoproteomic studies and decipher how DCLK1-S-MMP13-p53 axes stimulate fibrosis, tumorigenesis, and tumor progression. These studies are expected to lead to therapeutic avenues to target CACCs.

Savory Signaling: T1R Umami Receptor Modulates Endoplasmic Reticulum Calcium Store Content and Release Dynamics in Airway Epithelial Cells.

T1Rs are expressed in solitary chemosensory cells of the upper airway where they detect apical glucose levels and repress bitter taste receptor Ca2+ signaling pathways. Microbial growth leads to a decrease in apical glucose levels. T1Rs detect this change and liberate bitter taste receptor signaling, initiating an innate immune response to both kill and expel pathogens through releasing antimicrobial peptides and increasing nitric oxide production and ciliary beat frequency. However, chronic inflammation due to disease, smoking, or viral infections causes a remodeling of the epithelial airway. The resulting squamous metaplasia causes a loss of multi-ciliated cells and solitary chemosensory cells, replaced by basal epithelial cells. To understand how T1R function is altered during disease, we used basal epithelial cells as a model to study the function of T1R3 on Ca2+ signaling dynamics. We found that both T1R1 and T1R3 detect amino acids and signal via cAMP, increasing the responsiveness of the cells to Ca2+ signaling stimuli. Either knocking down T1R1/3 or treating wild-type cells with MEM amino acids caused a reduction in ER Ca2+ content through a non-cAMP signaled pathway. Treatment with amino acids led to a reduction in downstream denatonium-induced Ca2+-signaled caspase activity. Thus, amino acids may be used to reduce unwanted apoptosis signaling in treatments containing bitter compounds.

Microbial metabolite succinate activates solitary chemosensory cells in the human sinonasal epithelium.

Succinate, although most famous for its role in the Krebs cycle, can be released extracellularly as a signal of cellular distress, particularly in situations of metabolic stress and inflammation. Solitary chemosensory cells (SCCs) express SUCNR1, the succinate receptor, and modulate type 2 inflammatory responses in helminth and protozoal infections in the small intestine. SCCs are the dominant epithelial source of interleukin-25, as well as an important source of cysteinyl leukotrienes in the airway, and have been implicated as upstream agents in type 2 inflammation in chronic rhinosinusitis (CRS) and asthma. In this study, we used scRNAseq analysis, live cell imaging of intracellular calcium from primary sinonasal air-liquid interface (ALI) cultures from 1 donor, andmeasure antimicrobial peptide release from 5 donors to demonstrate preliminary evidence suggesting that succinate can act as a stimulant of SCCs in the human sinonasal epithelium. Results from scRNAseq analysis show that approximately 10% of the SCC/ionocyte cluster of cells expressed SUCNR1 as well as a small population of immune cells. Using live cell imaging of intracellular calcium, we also demonstrate that clusters of cells on primary sinonasal ALI cultures initiated calcium-mediated signaling in response to succinate stimulation. Furthermore, we present evidence that primary sinonasal ALI cultures treated with succinate had increased levels of apical beta-defensin 2, an antimicrobial peptide, compared to treatment with a control solution. Overall, these findings demonstrate the need for further investigation into the activation of the sinonasal epithelium by succinate in the pathogenesis of CRS.

Expression of taste sentinels, T1R, T2R, and PLCß2, on the passageway for olfactory signals in zebrafish.

The senses of taste and smell detect overlapping sets of chemical compounds in fish, e.g. amino acids are detected by both senses. However, so far taste and smell organs appeared morphologically to be very distinct, with a specialized olfactory epithelium for detection of odors and taste buds located in the oral cavity and lip for detection of tastants. Here we report dense clusters of cells expressing T1R and T2R receptors as well as their signal transduction molecule PLCß2 in nostrils of zebrafish, i.e. on the entrance funnel through which odor molecules must pass to be detected by olfactory sensory neurons. Quantitative evaluation shows the density of these chemosensory cells in the nostrils to be as high or higher than that in the established taste organs oral cavity and lower lip. Hydrodynamic flow is maximal at the nostril rim enabling high throughput chemosensation in this organ. Taken together, our results suggest a sentinel function for these chemosensory cells in the nostril.

Constitutive Expression of Hif2α Confers Acute O2 Sensitivity to Carotid Body Glomus Cells.

Acute oxygen (O2) sensing and adaptation to hypoxia are essential for physiological homeostasis. The prototypical acute O2 sensing organ is the carotid body, which contains chemosensory glomus cells expressing O2-sensitive K+ channels. Inhibition of these channels during hypoxia leads to cell depolarization, transmitter release, and activation of afferent sensory fibers terminating in the brain stem respiratory and autonomic centers. Focusing on recent data, here we discuss the special sensitivity of glomus cell mitochondria to changes in O2 tension due to Hif2α-dependent expression of several atypical mitochondrial electron transport chain subunits and enzymes. These are responsible for an accelerated oxidative metabolism and the strict dependence of mitochondrial complex IV activity on O2 availability. We report that ablation of Epas1 (the gene coding Hif2α) causes a selective downregulation of the atypical mitochondrial genes and a strong inhibition of glomus cell acute responsiveness to hypoxia. Our observations indicate that Hif2α expression is required for the characteristic metabolic profile of glomus cells and provide a mechanistic explanation for the acute O2 regulation of breathing.

The critical roles and therapeutic implications of tuft cells in cancer.

Tuft cells are solitary chemosensory epithelial cells with microvilli at the top, which are found in hollow organs such as the gastrointestinal tract, pancreas, and lungs. Recently, an increasing number of studies have revealed the chemotactic abilities and immune function of the tuft cells, and numerous efforts have been devoted to uncovering the role of tuft cells in tumors. Notably, accumulating evidence has shown that the specific genes (POU2F3, DCLK1) expressed in tuft cells are involved in vital processes related with carcinogenesis and cancer development. However, the interaction between the tuft cells and cancer remains to be further elucidated. Here, based on an introduction of biological functions and specific markers of the tuft cells, we have summarized the functional roles and potential therapeutic implications of tuft cells in cancers, including pancreatic cancer, lung cancer, gastric cancer, colon cancer, and liver cancer, which is in the hope of inspiring the future research in validating tuft cells as novel strategies for cancer therapies.

Glial regulators of ions and solutes required for specific chemosensory functions in Caenorhabditis elegans.

Glia and accessory cells regulate the microenvironment around neurons and primary sensory cells. However, the impact of specific glial regulators of ions and solutes on functionally diverse primary cells is poorly understood. Here, we systemically investigate the requirement of ion channels and transporters enriched in Caenorhabditis elegans Amsh glia for the function of chemosensory neurons. Although Amsh glia ablated worms show reduced function of ASH, AWC, AWA, and ASE neurons, we show that the loss of glial enriched ion channels and transporters impacts these neurons differently, with nociceptor ASH being the most affected. Furthermore, our analysis underscores the importance of K+, Cl-, and nucleoside homeostasis in the Amphid sensory organ and uncovers the contribution of glial genes implicated in neurological disorders. Our findings build a unique fingerprint of each glial enriched ion channel and transporter and may provide insights into the function of supporting cells of mammalian sensory organs.

Pulmonary cancers across different histotypes share hybrid tuft cell/ionocyte-like molecular features and potentially druggable vulnerabilities

Tuft cells are chemosensory epithelial cells in the respiratory tract and several other organs. Recent studies revealed tuft cell-like gene expression signatures in some pulmonary adenocarcinomas, squamous cell carcinomas (SQCC), small cell carcinomas (SCLC), and large cell neuroendocrine carcinomas (LCNEC). Identification of their similarities could inform shared druggable vulnerabilities. Clinicopathological features of tuft cell-like (tcl) subsets in various lung cancer histotypes were studied in two independent tumor cohorts using immunohistochemistry (n = 674 and 70). Findings were confirmed, and additional characteristics were explored using public datasets (RNA seq and immunohistochemical data) (n = 555). Drug susceptibilities of tuft cell-like SCLC cell lines were also investigated. By immunohistochemistry, 10–20% of SCLC and LCNEC, and approximately 2% of SQCC expressed POU2F3, the master regulator of tuft cells. These tuft cell-like tumors exhibited “lineage ambiguity” as they co-expressed NCAM1, a marker for neuroendocrine differentiation, and KRT5, a marker for squamous differentiation. In addition, tuft cell-like tumors co-expressed BCL2 and KIT, and tuft cell-like SCLC and LCNEC, but not SQCC, also highly expressed MYC. Data from public datasets confirmed these features and revealed that tuft cell-like SCLC and LCNEC co-clustered on hierarchical clustering. Furthermore, only tuft cell-like subsets among pulmonary cancers significantly expressed FOXI1, the master regulator of ionocytes, suggesting their bidirectional but immature differentiation status. Clinically, tuft cell-like SCLC and LCNEC had a similar prognosis. Experimentally, tuft cell-like SCLC cell lines were susceptible to PARP and BCL2 co-inhibition, indicating synergistic effects. Taken together, pulmonary tuft cell-like cancers maintain histotype-related clinicopathologic characteristics despite overlapping unique molecular features. From a therapeutic perspective, identification of tuft cell-like LCNECs might be crucial given their close kinship with tuft cell-like SCLC.