Batf3-cDC1 control Th1 and fungicidal responses during cryptococcal meningitis: is this enough to control meningitis?

Dendritic cells are crucial for bridging innate and adaptive immunity. Cryptococcosis, caused by Cryptococcus neoformans and Cryptococcus gattii, is responsible for >15% of AIDS-related deaths. A recent study by Xu et al. showed that Batf3-dependent conventional type 1 dendritic (cDC1) cells are key players in generating IFNγ+ CD4+ T cell and fungicidal lung and brain tissue-resident responses during murine cryptococcosis, contributing to fungal clearance in the lungs and brain of mice (J. Xu, R. Hissong, R. Bareis, A. Creech, et al., mBio 15:e02853-23, 2024, https://doi.org/10.1128/mbio.02853-23). However, despite their critical role, the depletion of Batf3-dependent cDC1 cells did not significantly alter overall mouse survival or disease progression, highlighting the complex immune regulation required to survive cryptococcal infection and the need for further research in medical mycology.

Classical dendritic cells contribute to hypoxia-induced pulmonary hypertension.

Pulmonary hypertension (PH) is a chronic and progressive disease with significant morbidity and mortality. It is characterized by remodeled pulmonary vessels associated with perivascular and intravascular accumulation of inflammatory cells. Although there is compelling evidence that bone marrow-derived cells, such as macrophages and T cells, cluster in the vicinity of pulmonary vascular lesions in humans and contribute to PH development in different animal models, the role of dendritic cells in PH is less clear. Dendritic cells' involvement in PH is likely since they are responsible for coordinating innate and adaptive immune responses. We hypothesized that dendritic cells drive hypoxic PH. We demonstrate that a classical dendritic cell (cDC) subset (cDC2) is increased and activated in wild-type mouse lungs after hypoxia exposure. We observe significant protection after the depletion of cDCs in ZBTB46 DTR chimera mice before hypoxia exposure and after established hypoxic PH. In addition, we find that cDC depletion is associated with a reduced number of two macrophage subsets in the lung (FolR2+ MHCII+ CCR2+ and FolR2+ MHCII+ CCR2-). We found that depleting cDC2s, but not cDC1s, was protective against hypoxic PH. Finally, proof-of-concept studies in human lungs show increased perivascular cDC2s in patients with Idiopathic Pulmonary Arterial Hypertension (IPAH). Our data points to an essential role of cDCs, particularly cDC2s, in the pathophysiology of experimental PH.

EP2/EP4 targeting prevents tumor-derived PGE2-mediated immunosuppression in cDC2s.

Tumor-derived prostaglandin E2 (PGE2) impairs anti-tumor immunity by priming suppressive functions on various immune cell types, including dendritic cells (DCs). In this way, tumors mediate DC dysfunction and hamper their anti-tumoral activity. PGE2 is known to modulate DC function via signaling through the E-prostanoid receptor type (EP) 2 and EP4. Preclinical studies have demonstrated the therapeutic value of targeting EP2/4 receptor signaling in DCs. Ongoing phase I clinical trials with EP antagonists have shown immunomodulation in cancer patients. However, the systemic drug administration leads to off-target events and subsequent side-effects. To limit the off-target effects of EP targeting, EP2 and EP4 antagonists were encapsulated in polymeric nanoparticles (NPs). In this study we evaluated the efficacy of EP2/4 specific antagonists encapsulated in NPs to protect cDC2s from suppressive effects of tumor-derived PGE2 in different tumor models. We show that tumor-derived PGE2 signals via EP2/4 to mediate the acquisition of a suppressive phenotype of cDC2s. EP2/4 antagonists encapsulated NPs impaired the conversion of cDC2s towards a suppressive state and inhibited the occurrence of suppressive features such as IL-10 production or the ability to expand Tregs. Importantly, the NPs abolished the transition towards this suppressive state in different tumor models: Melanoma-conditioned media, ascites fluid derived from ovarian cancer patients (2D), and upon coculture with colorectal cancer patient-derived organoids (3D). We propose that targeting the PGE2-EP2/4 axis using NPs can achieve immunomodulation in the immune system of cancer patients, alleviate tumor-derived suppression, and thus facilitate the development of potent anti-tumor immunity in cancer patients.

Clara cell 10 (CC10) protein attenuates allergic airway inflammation by modulating lung dendritic cell functions.

Allergic asthma is a complex inflammatory disorder predominantly orchestrated by T helper 2 (Th2) lymphocytes. The anti-inflammatory protein Clara Cell 10-kDa (CC10), also known as secretoglobin family 1A member 1 (SCGB1A1), shows promise in modulating respiratory diseases. However, its precise role in asthma remains unclear. This study examines the potential of CC10 to suppress allergic asthma inflammation, specifically assessing its regulatory effects on Th2 cell responses and dendritic cells (DCs). Lower CC10 levels in asthma were observed and correlated with increased IgE and lymphocytes. Cc10-/- mice exhibited exacerbated allergic airway inflammation marked by increased inflammatory cell infiltration, Th2 cytokines, serum antigen-specific IgE levels, and airway hyperresponsiveness (AHR) in house dust mite (HDM)-induced models. Conversely, recombinant CC10 significantly attenuated these inflammatory responses. Intriguingly, CC10 did not directly inhibit Th cell activation but significantly downregulated the population of CD11b+CD103- DCs subsets in lungs of asthmatic mice and modulated the immune activation functions of DCs through NF-κB signaling pathway. The mixed lymphocyte response assay revealed that DCs mediated the suppressive effect of CC10 on Th2 cell responses. Collectively, CC10 profoundly mitigates Th2-type allergic inflammation in asthma by modulating lung DC phenotype and functions, highlighting its therapeutic potential for inflammatory airway conditions and other related immunological disorders.

Amniotic fluid stem cell-derived extracellular vesicles educate type 2 conventional dendritic cells to rescue autoimmune disorders in a multiple sclerosis mouse model.

Dendritic cells (DCs) are essential orchestrators of immune responses and represent potential targets for immunomodulation in autoimmune diseases. Human amniotic fluid secretome is abundant in immunoregulatory factors, with extracellular vesicles (EVs) being a significant component. However, the impact of these EVs on dendritic cells subsets remain unexplored. In this study, we investigated the interaction between highly purified dendritic cell subsets and EVs derived from amniotic fluid stem cell lines (HAFSC-EVs). Our results suggest that HAFSC-EVs are preferentially taken up by conventional dendritic cell type 2 (cDC2) through CD29 receptor-mediated internalization, resulting in a tolerogenic DC phenotype characterized by reduced expression and production of pro-inflammatory mediators. Furthermore, treatment of cDC2 cells with HAFSC-EVs in coculture systems resulted in a higher proportion of T cells expressing the regulatory T cell marker Foxp3 compared to vehicle-treated control cells. Moreover, transfer of HAFSC-EV-treated cDC2s into an EAE mouse model resulted in the suppression of autoimmune responses and clinical improvement. These results suggest that HAFSC-EVs may serve as a promising tool for reprogramming inflammatory cDC2s towards a tolerogenic phenotype and for controlling autoimmune responses in the central nervous system, representing a potential platform for the study of the effects of EVs in DC subsets.

The histone deacetylase HDAC1 controls dendritic cell development and anti-tumor immunity.

Dendritic cell (DC) progenitors adapt their transcriptional program during development, generating different subsets. How chromatin modifications modulate these processes is unclear. Here, we investigate the impact of histone deacetylation on DCs by genetically deleting histone deacetylase 1 (HDAC1) or HDAC2 in hematopoietic progenitors and CD11c-expressing cells. While HDAC2 is not critical for DC development, HDAC1 deletion impairs pro-pDC and mature pDC generation and affects ESAM+cDC2 differentiation from tDCs and pre-cDC2s, whereas cDC1s are unchanged. HDAC1 knockdown in human hematopoietic cells also impairs cDC2 development, highlighting its crucial role across species. Multi-omics analyses reveal that HDAC1 controls expression, chromatin accessibility, and histone acetylation of the transcription factors IRF4, IRF8, and SPIB required for efficient development of cDC2 subsets. Without HDAC1, DCs switch immunologically, enhancing tumor surveillance through increased cDC1 maturation and interleukin-12 production, driving T helper 1-mediated immunity and CD8+ T cell recruitment. Our study reveals the importance of histone acetylation in DC development and anti-tumor immunity, suggesting DC-targeted therapeutic strategies for immuno-oncology.

Progenitors of distinct lineages shape the diversity of mature type 2 conventional dendritic cells.

Conventional dendritic cells (cDC) are antigen-presenting cells comprising cDC1 and cDC2, responsible for priming naive CD8+ and CD4+ T cells, respectively. Recent studies have unveiled cDC2 heterogeneity and identified various cDC2 progenitors beyond the common DC progenitor (CDP), hinting at distinct cDC2 lineages. By generating Cd300ciCre-hCD2R26tdTomato reporter mice, we identified a bone marrow pro-cDC2 progenitor exclusively generating cDC2 in vitro and in vivo. Single-cell analyses and multiparametric flow cytometry demonstrated that pro-cDC2 encompasses myeloid-derived pre-cDC2 and lymphoid-derived plasmacytoid DC (pDC)-like precursors differentiating into a transcriptionally convergent cDC2 phenotype. Cd300c-traced cDC2 had distinct transcriptomic profiles, phenotypes, and tissue distributions compared with Ms4a3CreR26tdTomato lineage-traced DC3, a monocyte-DC progenitor (MDP)-derived subset that bypasses CDP. Mice with reduced Cd300c-traced cDC2 showed impaired humoral responses to T cell-dependent antigens. We conclude that progenitors of distinct lineages shape the diversity of mature cDC2 across tissues. Thus, ontogenesis may impact tissue immune responses.

Targeting the Cdc2-like kinase 2 for overcoming platinum resistance in ovarian cancer.

Platinum resistance represents a major barrier to the survival of patients with ovarian cancer (OC). Cdc2-like kinase 2 (CLK2) is a major protein kinase associated with oncogenic phenotype and development in some solid tumors. However, the exact role and underlying mechanism of CLK2 in the progression of OC is currently unknown. Using microarray gene expression profiling and immunostaining on OC tissues, we found that CLK2 was upregulated in OC tissues and was associated with a short platinum-free interval in patients. Functional assays showed that CLK2 protected OC cells from platinum-induced apoptosis and allowed tumor xenografts to be more resistant to platinum. Mechanistically, CLK2 phosphorylated breast cancer gene 1 (BRCA1) at serine 1423 (Ser1423) to enhance DNA damage repair, resulting in platinum resistance in OC cells. Meanwhile, in OC cells treated with platinum, p38 stabilized CLK2 protein through phosphorylating at threonine 343 of CLK2. Consequently, the combination of CLK2 and poly ADP-ribose polymerase inhibitors achieved synergistic lethal effect to overcome platinum resistance in patient-derived xenografts, especially those with wild-type BRCA1. These findings provide evidence for a potential strategy to overcome platinum resistance in OC patients by targeting CLK2.

919 granules improve postpartum depression through the regulation of abnormal peripheral blood IL-1ß.

Postpartum depression (PPD) has a significant impact on the physical and mental health of mothers, potentially leading to symptoms such as low mood, fatigue, and decreased appetite. It may also affect the healthy growth of the infant. The onset of PPD is closely related to abnormalities in inflammation and the immune system. PPD patients exhibit abnormalities in the proportion of peripheral blood immune cells, along with an increase in pro-inflammatory cytokines. Excessive pro-inflammatory cytokines in peripheral blood can disrupt the blood-brain barrier (BBB) by activating astrocytes and reducing transendothelial electrical resistance (TEER), allowing peripheral immune cells or cytokines to enter the brain and trigger inflammation, ultimately leading to the onset of depression. In addition, PPD lacks safe and effective treatment medications. In this study, we collected peripheral blood from both healthy postpartum women and those with PPD, conducted single cell RNA sequencing (scRNA-seq), and used an in-house analytical tool scSTAR to reveal that PPD patients exhibit elevated proportions of peripheral blood cDC2 and Proliferation B cells, which are significantly correlated with IL-1ß. Additionally, animal experiments were designed to validate that 919 granules can improve PPD by modulating the levels of peripheral blood IL-1ß, providing a potential therapeutic mechanism for PPD treatment.

Theoretical Prediction and Experimental Synthesis of Zr3AC2 (A = Cd, Sb) Phases.

MAX phases have great research value and application prospects, but it is challenging to synthesize the MAX phases containing Cd and Sb for the time being. In this paper, we confirmed the existence of the 312 MAX phases of Zr3CdC2 and Zr3SbC2, both from theoretical calculations and experimental synthesis. The Zr3AC2 (A = Cd, Sb) phase was predicted by the first-principles calculations, and the two MAX phases were confirmed to meet the requests of thermal, thermodynamic, and mechanical stabilities using formation energy, phonon dispersion, and the Born-Huang criteria. Their theoretical mechanical properties were also systematically investigated. It was found that the elastic moduli of Zr3CdC2 and Zr3SbC2 were 162.8 GPa and 164.3 GPa, respectively. Then, differences in the mechanical properties of Zr3AC2 (A = Cd, In, Sn, and Sb) were explained using bond layouts and charge transfers. The low theoretical Vickers hardness of the Zr3CdC2 (5.4 GPa) and Zr3SbC2 (4.3 GPa) phases exhibited excellent machinability. Subsequently, through spark plasma sintering, composites containing Zr3CdC2 and Zr3SbC2 phases were successfully synthesized at the temperatures of 850 °C and 1300 °C, respectively. The optimal molar ratio of Zr:Cd/Sb:C was determined as 3:1.5:1.5. SEM and the EDS results analysis confirmed the typical layered microstructure of Zr3CdC2 and Zr3SbC2 grains.

A Simple and Rapid Protocol for the Isolation of Murine Bone Marrow Suitable for the Differentiation of Dendritic Cells.

The generation of bone-marrow-derived dendritic cells is a widely used approach in immunological research to study antigen processing and presentation, as well as T-cell activation responses. However, the initial step of isolating the bone marrow can be time-consuming, especially when larger numbers of precursor cells are required. Here, we assessed whether an accelerated bone marrow isolation method using centrifugation is suitable for the differentiation of FMS-like tyrosine kinase 3 ligand-driven dendritic cells. Compared to the conventional flushing method, the centrifugation-based isolation method resulted in a similar bone marrow cell yield on Day 0, increased cell numbers by Day 8, similar proportions of dendritic cell subsets, and consequently a higher number of type 1 conventional dendritic cells (cDC1) from the culture. Although the primary purpose of this method of optimization was to improve experimental efficiency and increase the output of cDC1s, the protocol is also compatible with the differentiation of other dendritic cell subsets such as cDC2 and plasmacytoid dendritic cells, with an improved output cell count and a consistent phenotype.

cDC2 plasticity and acquisition of a DC3-like phenotype mediated by IL-6 and PGE2 in a patient-derived colorectal cancer organoids model.

Metastatic colorectal cancer (CRC) is highly resistant to therapy and prone to recur. The tumor-induced local and systemic immunosuppression allows cancer cells to evade immunosurveillance, facilitating their proliferation and dissemination. Dendritic cells (DCs) are required for the detection, processing, and presentation of tumor antigens, and subsequently for the activation of antigen-specific T cells to orchestrate an effective antitumor response. Notably, successful tumors have evolved mechanisms to disrupt and impair DC functions, underlining the key role of tumor-induced DC dysfunction in promoting tumor growth, metastasis initiation, and treatment resistance. Conventional DC type 2 (cDC2) are highly prevalent in tumors and have been shown to present high phenotypic and functional plasticity in response to tumor-released environmental cues. This plasticity reverberates on both the development of antitumor responses and on the efficacy of immunotherapies in cancer patients. Uncovering the processes, mechanisms, and mediators by which CRC shapes and disrupts cDC2 functions is crucial to restoring their full antitumor potential. In this study, we use our recently developed 3D DC-tumor co-culture system to investigate how patient-derived primary and metastatic CRC organoids modulate cDC2 phenotype and function. We first demonstrate that our collagen-based system displays extensive interaction between cDC2 and tumor organoids. Interestingly, we show that tumor-corrupted cDC2 shift toward a CD14+ population with defective expression of maturation markers, an intermediate phenotype positioned between cDC2 and monocytes, and impaired T-cell activating abilities. This phenotype aligns with the newly defined DC3 (CD14+ CD1c+ CD163+) subset. Remarkably, a comparable population was found to be present in tumor lesions and enriched in the peripheral blood of metastatic CRC patients. Moreover, using EP2 and EP4 receptor antagonists and an anti-IL-6 neutralizing antibody, we determined that the observed phenotype shift is partially mediated by PGE2 and IL-6. Importantly, our system holds promise as a platform for testing therapies aimed at preventing or mitigating tumor-induced DC dysfunction. Overall, our study offers novel and relevant insights into cDC2 (dys)function in CRC that hold relevance for the design of therapeutic approaches.

2-Desaza-annomontine (C81) impedes angiogenesis through reduced VEGFR2 expression derived from inhibition of CDC2-like kinases.

Angiogenesis is a crucial process in the progression of various pathologies, like solid tumors, wet age-related macular degeneration, and chronic inflammation. Current anti-angiogenic treatments still have major drawbacks like limited efficacy in diseases that also rely on inflammation. Therefore, new anti-angiogenic approaches are sorely needed, and simultaneous inhibition of angiogenesis and inflammation is desirable. Here, we show that 2-desaza-annomontine (C81), a derivative of the plant alkaloid annomontine previously shown to inhibit endothelial inflammation, impedes angiogenesis by inhibiting CDC2-like kinases (CLKs) and WNT/ß-catenin signaling. C81 reduced choroidal neovascularization in a laser-induced murine in vivo model, inhibited sprouting from vascular endothelial growth factor A (VEGF-A)-activated murine aortic rings ex vivo, and reduced angiogenesis-related activities of endothelial cells in multiple functional assays. This was largely phenocopied by CLK inhibitors and knockdowns, but not by inhibitors of the other known targets of C81. Mechanistically, CLK inhibition reduced VEGF receptor 2 (VEGFR2) mRNA and protein expression as well as downstream signaling. This was partly caused by a reduction of WNT/ß-catenin pathway activity, as activating the pathway induced, while ß-catenin knockdown impeded VEGFR2 expression. Surprisingly, alternative splicing of VEGFR2 was not detected. In summary, C81 and other CLK inhibitors could be promising compounds in the treatment of diseases that depend on angiogenesis and inflammation due to their impairment of both processes.

Inhibition of CSF-1R and IL-6R prevents conversion of cDC2s into immune incompetent tumor-induced DC3s boosting DC-driven therapy potential.

The human dendritic cell (DC) family has recently been expanded by CD1c+CD14+CD163+ DCs, introduced as DC3s. DC3s are found in tumors and peripheral blood of cancer patients. Here, we report elevated frequencies of CD14+ cDC2s, which restore to normal frequencies after tumor resection, in non-small cell lung cancer patients. These CD14+ cDC2s phenotypically resemble DC3s and exhibit increased PD-L1, MERTK, IL-10, and IDO expression, consistent with inferior T cell activation ability compared with CD14- cDC2s. In melanoma patients undergoing CD1c+ DC vaccinations, increased CD1c+CD14+ DC frequencies correlate with reduced survival. We demonstrate conversion of CD5+/-CD1c+CD14- cDC2s to CD14+ cDC2s by tumor-associated factors, whereas monocytes failed to express CD1c under similar conditions. Targeted proteomics identified IL-6 and M-CSF as dominant drivers, and we show that IL-6R and CSF1R inhibition prevents tumor-induced CD14+ cDC2s. Together, this indicates cDC2s as direct pre-cursors of DC3-like CD1c+CD14+ DCs and provides insights into the importance and modulation of CD14+ DC3s in anti-tumor immune responses.

The show and tell of cross-presentation.

Cross-presentation is the culmination of complex subcellular processes that allow the processing of exogenous proteins and the presentation of resultant peptides on major histocompatibility class I (MHC-I) molecules to CD8 T cells. Dendritic cells (DCs) are a cell type that uniquely specializes in cross-presentation, mainly in the context of viral or non-viral infection and cancer. DCs have an extensive network of endovesicular pathways that orchestrate the biogenesis of an ideal cross-presentation compartment where processed antigen, MHC-I molecules, and the MHC-I peptide loading machinery all meet. As a central conveyor of information to CD8 T cells, cross-presentation allows cross-priming of T cells which carry out robust adaptive immune responses for tumor and viral clearance. Cross-presentation can be canonical or noncanonical depending on the functional status of the transporter associated with antigen processing (TAP), which in turn influences the vesicular route of MHC-I delivery to internalized antigen and the cross-presented repertoire of peptides. Because TAP is a central node in MHC-I presentation, it is targeted by immune evasive viruses and cancers. Thus, understanding the differences between canonical and noncanonical cross-presentation may inform new therapeutic avenues against cancer and infectious disease. Defects in cross-presentation on a cellular and genetic level lead to immune-related disease progression, recurrent infection, and cancer progression. In this chapter, we review the process of cross-presentation beginning with the DC subsets that conduct cross-presentation, the signals that regulate cross-presentation, the vesicular trafficking pathways that orchestrate cross-presentation, the modes of cross-presentation, and ending with disease contexts where cross-presentation plays a role.

Glucose to lactate shift reprograms CDK-dependent mitotic decisions and its communication with MAPK Sty1 in Schizosaccharomyces pombe.

Cell cycle regulation in response to biochemical cues is a fundamental event associated with many diseases. The regulation of such responses in complex metabolic environments is poorly understood. This study reveals unknown aspects of the metabolic regulation of cell division in Schizosaccharomyces pombe. We show that changing the carbon source from glucose to lactic acid alters the functions of the cyclin-dependent kinase (CDK) Cdc2 and mitogen-activated protein kinase (MAPK) Sty1, leading to unanticipated outcomes in the behavior and fate of such cells. Functional communication of Cdc2 with Sty1 is known to be an integral part of the cellular response to aberrant Cdc2 activity in S. pombe. Our results show that cross-talk between Cdc2 and Sty1, and the consequent Sty1-dependent regulation of Cdc2 activity, appears to be compromised and the relationship between Cdc2 activity and mitotic timing is also reversed in the presence of lactate. We also show that the biochemical status of cells under these conditions is an important determinant of the altered molecular functions mentioned above as well as the altered behavior of these cells.

Modulation of Human Dendritic Cell Functions by Phosphodiesterase-4 Inhibitors: Potential Relevance for the Treatment of Respiratory Diseases.

Inhibitors of phosphodiesterase-4 (PDE4) are small-molecule drugs that, by increasing the intracellular levels of cAMP in immune cells, elicit a broad spectrum of anti-inflammatory effects. As such, PDE4 inhibitors are actively studied as therapeutic options in a variety of human diseases characterized by an underlying inflammatory pathogenesis. Dendritic cells (DCs) are checkpoints of the inflammatory and immune responses, being responsible for both activation and dampening depending on their activation status. This review shows evidence that PDE4 inhibitors modulate inflammatory DC activation by decreasing the secretion of inflammatory and Th1/Th17-polarizing cytokines, although preserving the expression of costimulatory molecules and the CD4+ T cell-activating potential. In addition, DCs activated in the presence of PDE4 inhibitors induce a preferential Th2 skewing of effector T cells, retain the secretion of Th2-attracting chemokines and increase the production of T cell regulatory mediators, such as IDO1, TSP-1, VEGF-A and Amphiregulin. Finally, PDE4 inhibitors selectively induce the expression of the surface molecule CD141/Thrombomodulin/BDCA-3. The result of such fine-tuning is immunomodulatory DCs that are distinct from those induced by classical anti-inflammatory drugs, such as corticosteroids. The possible implications for the treatment of respiratory disorders (such as COPD, asthma and COVID-19) by PDE4 inhibitors will be discussed.

CLK2 in GABAergic neurons is critical in regulating energy balance and anxiety-like behavior in a gender-specific fashion.

Introduction: Cdc2-like kinase (CLK2) is a member of CLK kinases expressed in hypothalamic neurons and is activated in response to refeeding, leptin, or insulin. Diet-induced obesity and leptin receptor-deficient db/db mice lack CLK2 signal in the hypothalamic neurons. The neurotransmiter gamma-aminobutyric acid (GABA) is among the most prevalent in the central nervous system (CNS), particularly in the hypothalamus. Given the abundance of GABA-expressing neurons and their potential influence on regulating energy and behavioral homeostasis, we aimed to explore whether the deletion of CLK2 in GABAergic neurons alters energy homeostasis and behavioral and cognitive functions in both genders of mice lacking CLK2 in Vgat-expressing neurons (Vgat-Cre; Clk2loxP/loxP) on chow diet. Methods: We generated mice lacking Clk2 in Vgat-expressing neurons (Vgat-Cre; Clk2loxP/loxP) by mating Clk2loxP/loxP mice with Vgat-IRES-Cre transgenic mice and employed behavior, and physiological tests, and molecular approaches to investigate energy metabolism and behavior phenotype of both genders. Results and discussion: We showed that deletion of CLK2 in GABAergic neurons increased adiposity and food intake in females. The mechanisms behind these effects were likely due, at least in part, to hypothalamic insulin resistance and upregulation of hypothalamic Npy and Agrp expression. Besides normal insulin and pyruvate sensitivity, Vgat-Cre; Clk2loxP/loxP females were glucose intolerant. Male Vgat-Cre; Clk2loxP/loxP mice showed an increased energy expenditure (EE). Risen EE may account for avoiding weight and fat mass gain in male Vgat-Cre; Clk2loxP/loxP mice. Vgat-Cre; Clk2loxP/loxP mice had no alteration in cognition or memory functions in both genders. Interestingly, deleting CLK2 in GABAergic neurons changed anxiety-like behavior only in females, not males. These findings suggest that CLK2 in GABAergic neurons is critical in regulating energy balance and anxiety-like behavior in a gender-specific fashion and could be a molecular therapeutic target for combating obesity associated with psychological disorders in females.

Complement C1q essential for aeroallergen sensitization via CSF1R+ conventional dendritic cells type 2.

BACKGROUND: Dendritic cells (DCs) are heterogeneous, comprising multiple subsets with unique functional specifications. Our previous work has demonstrated that the specific conventional type 2 DC subset, CSF1R+cDC2s, plays a critical role in sensing aeroallergens. OBJECTIVE: It remains to be understood how CSF1R+cDC2s recognize inhaled allergens. We sought to elucidate the transcriptomic programs and receptor-ligand interactions essential for function of this subset in allergen sensitization. METHODS: We applied single-cell RNA sequencing to mouse lung DCs. Conventional DC-selective knockout mouse models were employed, and mice were subjected to inhaled allergen sensitization with multiple readouts of asthma pathology. Under the clinical arm of this work, human lung transcriptomic data were integrated with mouse data, and bronchoalveolar lavage (BAL) specimens were collected from subjects undergoing allergen provocation, with samples assayed for C1q. RESULTS: We found that C1q is selectively enriched in lung CSF1R+cDC2s, but not in other lung cDC2 or cDC1 subsets. Depletion of C1q in conventional DCs significantly attenuates allergen sensing and features of asthma. Additionally, we found that C1q binds directly to human dust mite allergen, and the C1q receptor CD91 (LRP1) is required for lung CSF1R+cDC2s to recognize the C1q-allergen complex and induce allergic lung inflammation. Lastly, C1q is enriched in human BAL samples following subsegmental allergen challenge, and human RNA sequencing data demonstrate close homology between lung IGSF21+DCs and mouse CSF1R+cDC2s. CONCLUSIONS: C1q is secreted from the CSF1R+cDC2 subset among conventional DCs. Our data indicate that the C1q-LRP1 axis represents a candidate for translational therapeutics in the prevention and suppression of allergic lung inflammation.