Population In Mice Research Articles

Interleukin-17A deficient mice microbiota induced regulatory T cells and suppressed experimental autoimmune encephalomyelitis (EAE) in WT HLA-DR3 transgenic mice

Abstract Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system, and among all the genes associated with MS, HLA class II genes have the highest relative risk. Although IL-17A is thought to be a major cytokine in the pathogenesis of MS, the exact role of IL-17A in the MS is still poorly understood. Specifically, it is unclear whether IL-17A is required for disease initiation or disease severity or in both. Therefore, in the present study, utilizing HLA-DR3 transgenic mice lacking IL-17A (HLA-DR3.IL-17A−/−), we investigated the importance of IL-17A in disease development and progression in experimental autoimmune encephalomnyelitis (EAE) an animal model of MS. We observed that HLA-DR3.IL-17A−/− mice had a higher frequency of CD4+CD25+FoxP3+ regulatory T cells (Treg)s and developed milder EAE compared to IL-17 sufficient HLA-DR3 mice. Further characterization of mechanism identified a novel role of IL-17A in regulating the disease progression through modulation of immunoregulatory responses. We also identified an important role of gut microbiota in IL-17A dependent disease regulation specifically depletion of gut bacteria with ability to promote Treg population in IL-17A sufficient HLA-DR3 mice. Fecal transplantation of HLA.DR3 mice with HLA-DR3. IL17A−/− showed milder EAE and an increase in Treg cells in HLA-DR3 mice confirming a role of gut microbiota in shaping Treg repertoire and function. Additionally, we observed higher frequency of metabolic pathway involved with Treg promoting short chain fatty acid (SCFA) metabolism in HLA-DR3.IL17A−/− mice. Thus our study shows a novel role of IL-17A in immune homeostasis and inflammation by regulating levels of Tregs through modulation of gut microbiota.

Essential Role of ZIP8 in myeloid-mediated host defense against pneumococcal pneumonia

Abstract Zinc (Zn) is essential for proper immune function. Dietary deficiency increases susceptibility to bacterial infections, including Streptococcus pneumoniae, a leading cause of community acquired pneumonia. Zn homeostasis is tightly regulated by 24 Zn transporters. ZIP8, an importer, is rapidly upregulated in myeloid cells following bacterial infection and regulates immune function in a Zn-dependent manner. Knowing that myeloid cells (macrophages, neutrophils, and dendritic cells) play critical roles in host defense against S. pneumoniae, we hypothesized that ZIP8 loss would alter myeloid cell function and adversely impact the host response to pneumococcus. Using a myeloid-specific Zip8-KO mouse model, we observed that intranasal instillation of S. pneumoniae resulted in increased inflammation, lung injury and mortality with 40% of Zip8-KO animals succumbing to infection by day 4. Based on this, the immune response between 24 and 72 hours post infection was further examined. Analysis of BAL fluid revealed a significant increase in macrophages in Zip8-KO animals and lung homogenates revealed a significant increase in total lung leukocytes, macrophages and inflammatory DCs. The increase in myeloid cell populations in Zip8-KO mice was also associated with bacterial extravasation as measured by increased bacterial burden in the spleen. Collectively, these results indicate that ZIP8 loss aggravates the immune response through alteration of the myeloid cell landscape and lung architecture in response to S. pneumoniae. Further studies are warranted to determine how ZIP8 loss drives myeloid dysfunction, tissue damage and pathogen dissemination and whether genetic deficits in ZIP8 function can be overcome by Zn supplementation.

Hemolysis-associated phosphatidylserine exposure promotes polyclonal plasmablast differentiation.

Antimalarial antibody responses are essential for mediating the clearance of Plasmodium parasite-infected RBCs from infected hosts. However, the rapid appearance of large numbers of plasmablasts in Plasmodium-infected hosts can suppress the development and function of durable humoral immunity. Here, we identify that the formation of plasmablast populations in Plasmodium-infected mice is mechanistically linked to both hemolysis-induced exposure of phosphatidylserine on damaged RBCs and inflammatory cues. We also show that virus and Trypanosoma infections known to trigger hemolytic anemia and high-grade inflammation also induce exuberant plasmablast responses. The induction of hemolysis or administration of RBC membrane ghosts increases plasmablast differentiation. The phosphatidylserine receptor Axl is critical for optimal plasmablast formation, and blocking phosphatidylserine limits plasmablast expansions and reduces Plasmodium parasite burden in vivo. Our findings support that strategies aimed at modulating polyclonal B cell activation and phosphatidylserine exposure may improve immune responses against Plasmodium parasites and potentially other infectious diseases that are associated with anemia.

Expansion of an Unusual Virtual Memory CD8+ Subpopulation Bearing Vα3.2 TCR in Themis-Deficient Mice.

Deletion of the gene for Themis affects T cell selection in the thymus, which would be expected to affect the TCR repertoire. We found an increased proportion of cells expressing Vα3.2 (TRAV9N-3) in the peripheral CD8+ T cell population in mice with germline Themis deficiency. Analysis of the TCRα repertoire indicated it was generally reduced in diversity in the absence of Themis, whereas the diversity of sequences using the TRAV9N-3 V-region element was increased. In wild type mice, Vα3.2+ cells showed higher CD5, CD6 and CD44 expression than non-Vα3-expressing cells, and this was more marked in cells from Themis-deficient mice. This suggested a virtual memory phenotype, as well as a stronger response to self-pMHC. The Vα3.2+ cells responded more strongly to IL-15, as well as showing bystander effector capability in a Listeria infection. Thus, the unusually large population of Vα3.2+ CD8+ T cells found in the periphery of Themis-deficient mice reflects not only altered thymic selection, but also allowed identification of a subset of bystander-competent cells that are also present in wild-type mice.

Specific populations of basal ganglia output neurons target distinct brain stem areas while collateralizing throughout the diencephalon

Basal ganglia play a central role in regulating behavior, but the organization of their outputs to other brain areas is incompletely understood. We investigate the largest output nucleus, the substantia nigra pars reticulata (SNr), and delineate the organization and physiology of its projection populations in mice. Using genetically targeted viral tracing and whole-brain anatomical analysis, we identify over 40 SNr targets that encompass a roughly 50-fold range of axonal densities. Retrograde tracing from the volumetrically largest targets indicates that the SNr contains segregated subpopulations that differentially project to functionally distinct brain stem regions. These subpopulations are electrophysiologically specialized and topographically organized and collateralize to common diencephalon targets, including the motor and intralaminar thalamus as well as the pedunculopontine nucleus and the midbrain reticular formation. These findings establish that SNr signaling is organized as dense, parallel outputs to specific brain stem targets concurrent with extensive collateral branches that encompass the majority of SNr axonal boutons.

Genome Edited Sirt1-Overexpressing Human Mesenchymal Stem Cells Exhibit Therapeutic Effects in Treating Collagen-Induced Arthritis.

Even though mesenchymal stem cells (MSCs) are known for cartilage regeneration, their therapeutic efficacy needs to be enhanced. In the present study, we produced genome-edited silent information regulator 2 type 1 (Sirt1)-overexpressing MSCs, and evaluated their therapeutic potential in a damaged cartilage mouse liver fibrosis model. The Sirt1 gene was successfully inserted into a ‘safe harbor’ genomic locus in amniotic mesenchymal stem cells (AMMs), and the chondrogenic properties of the Sirt1 gene overexpressing AMMs (AMM/S) were characterized using quantitative PCR and histology. Therapeutic potentials were investigated in a collagen-induced arthritis (CIA) mouse model. Chondrocyte-differentiated AMM/S expressed cartilage-specific genes and were positive for Safranin O staining. Transplantation of AMM/S attenuated CIA progression and suppressed T helper (Th)-17 cell activation while increasing the Treg cell population in CIA mice. Pro-inflammatory factors, such as interleukin (IL)-1β, IL-6, monocyte chemoattractant protein (MCP)-1, and tumor necrosis factor (TNF)-α were significantly decreased in AMM/S-injected joint tissues. In conclusion, genome-edited AMM/S may represent a safe and alternative therapeutic option for the treatment and repair of damaged cartilage, or in inflammatory joint arthritis.

Tiliroside Ameliorates Ulcerative Colitis by Restoring the M1/M2 Macrophage Balance via the HIF-1α/glycolysis Pathway.

Macrophages polarized to different phenotypes critically contribute to colitis development by coordinating inflammatory and anti-inflammatory processes. Herein, targeting the balance between the pro-inflammatory M1 and the anti-inflammatory M2 macrophage phenotypes can be a novel therapeutic approach for colitis. In the present study, we firstly demonstrated that tiliroside possessed the ability to alleviate the clinical symptoms of colitis as evidenced by decreased disease activity index (DAI) scores, longer colon length, reduced myeloperoxidase (MPO) activity, and improvement of colonic pathological damage in vivo. Furthermore, we showed that tiliroside modulated the balance between M1 and M2 macrophages toward a more anti-inflammatory status in colonic lamina propria but has little effect on the T cell population and epithelial barrier function in colitis mice. The macrophage depletion study further showed the protective effect of tiliroside was macrophage dependent in vivo. Mechanistically, our study demonstrated that tiliroside regulated cellular metabolism by inhibiting aerobic glycolysis in LPS and IFNγ stimulated macrophages. At the molecular level, tiliroside facilitated the proteasomal degradation of HIF-1α and downregulated mRNA expressions of HIF-1α dependent glycolytic enzymes in macrophages. Collectively, our data highlight the aberrant M1/M2 macrophage polarization in the initiation and development of ulcerative colitis and put forth the stage for considering tiliroside as a metabolic regulator in reprogramming macrophage polarization, which may serve as a promising therapeutic approach for treatment of inflammation-associated and metabolic disorders.

TTARGIT AAVs mediate the sensitive and flexible manipulation of intersectional neuronal populations in mice.

While Cre-dependent viral systems permit the manipulation of many neuron types, some cell populations cannot be targeted by a single DNA recombinase. Although the combined use of Flp and Cre recombinases can overcome this limitation, insufficient recombinase activity can reduce the efficacy of existing Cre+Flp-dependent viral systems. We developed a sensitive dual recombinase-activated viral approach: tTA-driven Recombinase-Guided Intersectional Targeting (tTARGIT) adeno-associated viruses (AAVs). tTARGIT AAVs utilize a Flp-dependent tetracycline transactivator (tTA) 'Driver' AAV and a tetracycline response element-driven, Cre-dependent 'Payload' AAV to express the transgene of interest. We employed this system in Slc17a6FlpO;LeprCre mice to manipulate LepRb neurons of the ventromedial hypothalamus (VMH; LepRbVMH neurons) while omitting neighboring LepRb populations. We defined the circuitry of LepRbVMH neurons and roles for these cells in the control of food intake and energy expenditure. Thus, the tTARGIT system mediates robust recombinase-sensitive transgene expression, permitting the precise manipulation of previously intractable neural populations.

Multiorgan Signaling Mobilizes Tumor-Associated Erythroid Cells Expressing Immune Checkpoint Molecules.

Hematopoietic-derived cells are integral components of the tumor microenvironment and serve as critical mediators of tumor-host interactions. Host cells derived from myeloid and lymphoid lineages perform well-established functions linked to cancer development, progression, and response to therapy. It is unclear whether host erythroid cells also contribute to shaping the path that cancer can take, but emerging evidence points to this possibility. Here, we show that tumor-promoting environmental stress and tumor-induced hemodynamic changes trigger renal erythropoietin production and erythropoietin-dependent expansion of splenic erythroid cell populations in mice. These erythroid cells display molecular features indicative of an immature erythroid phenotype, such as the expression of both CD71 and TER119 and the retention of intact nuclei, and express genes encoding immune checkpoint molecules. Nucleated erythroid cells with similar properties are present in mouse and human tumor tissues. Antibody-mediated erythropoietin blockade reduces tumor-responsive erythroid cell induction and tumor growth. These findings reveal the potential of tumor-induced erythropoietin and erythroid cells as targets for cancer treatment. IMPLICATIONS: : Our study identifies erythropoietin and erythroid cells as novel players in tumor-host interactions and highlights the involvement of multiorgan signaling events in their induction in response to environmental stress and tumor growth.

Weight loss with exercise improves muscle architecture and progenitor cell populations compared with weight loss alone in mice with preneoplastic colorectal lesions.

Weight loss and exercise reduce colorectal cancer (CRC) risk in persons with obesity. Whether weight loss and exercise effect myofiber characteristics and muscle stem/progenitor cell populations in mice with preneoplastic colorectal lesions, a model of CRC risk, is unknown. To address this gap, male C57Bl/6J mice were fed a high-fat diet (HFD) to induce obesity or a control (CON) diet prior to azoxymethane injection to induce preneoplastic colorectal lesions. The HFD group was then randomized to weight loss conditions that included (1) switching to the CON diet only (HFD-SED) or switching to the CON diet with treadmill exercise training (HFD-EX). Average myofiber cross-sectional area was not different between groups. There were more smaller-sized fibres in HFD-EX (p < 0.05 vs. CON), and more fibrosis in HFD-SED (p < 0.05 vs. HFD-EX and CON). There was a trend for more committed (Pax7+MyoD+) myoblasts (p = 0.059) and more fibro-adipogenic progenitors in HFD-EX (p < 0.05 vs. CON). Additionally, the canonical pro-inflammatory marker p-NF-κB was markedly reduced in the interstitium of HFD-EX (p < 0.05 vs. CON and HFD-SED). Our findings suggest that in mice with preneoplastic colorectal lesions, HFD followed by weight loss with exercise reduces muscle fibrosis and results in a higher content of muscle stem/progenitor cells. Novelty: Exercise improves muscle architecture in mice with preneoplastic colorectal lesion Exercise increases fibro/adipogenic progenitors and reduces inflammatory signaling in mice with preneoplastic colorectal lesions.

Intrinsic Neuronal Activity during Migration Controls the Recruitment of Specific Interneuron Subtypes in the Postnatal Mouse Olfactory Bulb.

Neuronal activity has been identified as a key regulator of neuronal network development, but the impact of activity on migration and terminal positioning of interneuron subtypes is poorly understood. The absence of early subpopulation markers and the presence of intermingled migratory and postmigratory neurons make the developing cerebral cortex a difficult model to answer these questions. Postnatal neurogenesis in the subventricular zone (SVZ) offers a more accessible and compartmentalized model. Neural stem cells regionalized along the border of the lateral ventricle produce two main subtypes of neural progenitors, granule cells and periglomerular neurons that migrate tangentially in the rostral migratory stream (RMS) before migrating radially in the olfactory bulb (OB) layers. Here, we used targeted postnatal electroporation to compare the migration of these two populations in male and female mice. We do not observe any obvious differences regarding the mode of tangential or radial migration between these two subtypes. However, we find a striking increase of intrinsic calcium activity in granule cell precursors (GC-Ps) when they switch from tangential to radial migration. By decreasing neuronal excitability in GC-Ps, we find that neuronal activity has little effect on migration but is required for normal positioning and survival of GC-Ps in the OB layers. Strikingly, decreasing activity of periglomerular neuron precursors (PGN-Ps) did not impact their positioning or survival. Altogether these findings suggest that neuronal excitability plays a subtype specific role during the late stage of migration of postnatally born OB interneurons.SIGNIFICANCE STATEMENT While neuronal activity is a critical factor regulating different aspects of neurogenesis, it has been challenging to study its role during the migration of different neuronal subpopulations. Here, we use postnatal targeted electroporation to label and manipulate the two main olfactory bulb (OB) interneuron subpopulations during their migration: granule cell and periglomerular neuron precursors (PGN-Ps). We find a very striking increase of calcium activity only in granule cell precursors (GC-Ps) when they switch from tangential to radial migration. Interestingly, blocking activity in GC-Ps affected mainly their positioning and survival while PGN-Ps were not affected. These results suggest that neuronal activity is required specifically for the recruitment of GC-Ps in the OB layers.

Bacteroides ovatus Promotes IL-22 Production and Reduces Trinitrobenzene Sulfonic Acid–Driven Colonic Inflammation

The intestinal microbiota influences the development and function of the mucosal immune system. However, the exact mechanisms by which commensal microbes modulate immunity is not clear. We previously demonstrated that commensal Bacteroides ovatus ATCC 8384 reduces mucosal inflammation. Herein, we aimed to identify immunomodulatory pathways employed by B. ovatus. In germ-free mice, mono-association with B. ovatus shifted the CD11b+/CD11c+ and CD103+/CD11c+ dendritic cell populations. Because indole compounds are known to modulate dendriticcells, B. ovatus cell-free supernatant was screened for tryptophan metabolites by liquid chromatography-tandem mass spectrometry and larger quantities of indole-3-acetic acid were detected. Analysis of cecal and fecal samples from germ-free and B. ovatus mono-associated mice confirmed that B. ovatus could elevate indole-3-acetic acid concentrations invivo. Indole metabolites have previously been shown to stimulate immune cells to secrete the reparative cytokine IL-22. Addition of B. ovatus cell-free supernatant to immature bone marrow-derived dendritic cells stimulated IL-22 secretion. The ability of IL-22 to drive repair in the intestinal epithelium was confirmed using a physiologically relevant human intestinal enteroid model. Finally, B. ovatus shifted the immune cell populations in trinitrobenzene sulfonic acid-treated mice and up-regulated colonic IL-22 expression, effects that correlated with decreased inflammation. Our data suggest that B. ovatus-produced indole-3-acetic acid promotes IL-22 production by immune cells, yielding beneficial effects on colitis.

Human amnion-derived mesenchymal stem cells attenuate xenogeneic graft-versus-host disease by preventing T cell activation and proliferation

Acute graft-versus-host disease (GVHD) is characterized by severe tissue damage that is a life-threatening complication of allogeneic hematopoietic stem cell transplantation. Due to their immunosuppressive properties, mesenchymal stem cells (MSC) have been increasingly examined for the treatment of immune-related diseases. We aimed to assess the immunosuppressive effects of human amnion-derived MSC (AMSC) in a xenogeneic GVHD NOD/Shi-scid IL2rγnull mouse model using human peripheral blood mononuclear cells (PBMC). Additionally, we used human bone marrow-derived MSC (BMSC) as comparative controls to determine differences in immunomodulatory functions depending on the MSC origin. Administration of AMSC significantly prolonged survival, and reduced human tumor necrosis factor-α (TNF-α) concentration and percentage of programmed cell death protein-1 receptor (PD-1)+CD8+ T cell populations compared with in GVHD control mice. Furthermore, colonic inflammation score and percentage of human CD8+ T cell populations in AMSC-treated mice were significantly lower than in GVHD control and BMSC-treated mice. Interestingly, gene expression and protein secretion of the PD-1 ligands were higher in AMSC than in BMSC. These findings are the first to demonstrate that AMSC exhibit marked immunosuppression and delay acute GVHD progression by preventing T cell activation and proliferation via the PD-1 pathway.

A further study on a disturbance of intestinal epithelial cell population and kinetics in APC1638T mice.

Adenomatous polyposis coli (APC), a well-known anti-oncogene, is considered to have multiple functions through its several binding domains. We have continuingly studied APC1638T/1638T mice (APC1638T mice) to elucidate the functions of APC other than tumor suppression. A distinctive feature of the APC1638T mice is they are tumor free and live as long as APC+/+ mice (WT mice). Previously, we found the length of crypt-villus axis in the jejunum was significantly elongated in APC1638T mice compared with that of WT mice. The populations of goblet cells, Paneth cells, and enteroendocrine cells were also disordered in APC1638T mice. Here, we further analyzed the intestinal dyshomeostasis in APC1638T mice, focusing on the proliferation and differentiation of intestinal stem cell (ISC) lineages, and apoptotic cell shedding at the villus tips. We found that the proliferation of ISC lineages was normally controlled; however, the shedding process of apoptosis cells was significantly delayed in the APC1638T mouse jejunum. Furthermore, the number of microfold cells (M cells) was significantly increased in the APC1638T mouse jejunum. Our data suggested both differentiation process of ISCs and turnover process of intestinal epithelia were disturbed in APC1638T mice, and that contributed to the villus elongation in the APC1638T mouse jejunum.

Breast cancer is marked by specific, Public T-cell receptor CDR3 regions shared by mice and humans.

The partial success of tumor immunotherapy induced by checkpoint blockade, which is not antigen-specific, suggests that the immune system of some patients contain antigen receptors able to specifically identify tumor cells. Here we focused on T-cell receptor (TCR) repertoires associated with spontaneous breast cancer. We studied the alpha and beta chain CDR3 domains of TCR repertoires of CD4 T cells using deep sequencing of cell populations in mice and applied the results to published TCR sequence data obtained from human patients. We screened peripheral blood T cells obtained monthly from individual mice spontaneously developing breast tumors by 5 months. We then looked at identical TCR sequences in published human studies; we used TCGA data from tumors and healthy tissues of 1,256 breast cancer resections and from 4 focused studies including sequences from tumors, lymph nodes, blood and healthy tissues, and from single cell dataset of 3 breast cancer subjects. We now report that mice spontaneously developing breast cancer manifest shared, Public CDR3 regions in both their alpha and beta and that a significant number of women with early breast cancer manifest identical CDR3 sequences. These findings suggest that the development of breast cancer is associated, across species, with biomarker, exclusive TCR repertoires.

ILC3-derived acetylcholine promotes protease-driven allergic lung pathology

ILC3-derived acetylcholine promotes protease-driven allergic lung pathology

Development of hematopoietic syndrome mice model for localized radiation exposure

Current models to study the hematopoietic syndrome largely rely on the uniform whole-body exposures. However, in the radio-nuclear accidents or terrorist events, exposure can be non-uniform. The data available on the non-uniform exposures is limited. Thus, we have developed a mice model for studying the hematopoietic syndrome in the non-uniform or partial body exposure scenarios using the localized cobalt60 gamma radiation exposure. Femur region of Strain ‘A’ male mice was exposed to doses ranging from 7 to 20 Gy. The 30 day survival assay showed 19 Gy as LD100 and 17 Gy as LD50. We measured an array of cytokines and important stem cell markers such as IFN-γ, IL-3, IL-6, GM-CSF, TNF-α, G-CSF, IL-1α, IL-1β, CD 34 and Sca 1. We found significant changes in IL-6, GM-CSF, TNF-α, G-CSF, and IL-1β levels compared to untreated groups and amplified levels of CD 34 and Sca 1 positive population in the irradiated mice compared to the untreated controls. Overall, we have developed a mouse model of the hematopoietic acute radiation syndrome that might be useful for understanding of the non-uniform body exposure scenarios. This may also be helpful in the screening of drugs intended for individuals suffering from radiation induced hematopoietic syndrome.

Differential Roles for Diploid and Polyploid Hepatocytes in Acute and Chronic Liver Injury.

Hepatocytes are the primary functional cells of the liver that perform essential roles in homeostasis, regeneration, and injury. Most mammalian somatic cells are diploid and contain pairs of each chromosome, but there are also polyploid cells containing additional sets of chromosomes. Hepatocytes are among the best described polyploid cells, with polyploids comprising more than 25 and 90% of the hepatocyte population in humans and mice, respectively. Cellular and molecular mechanisms that regulate hepatic polyploidy have been uncovered, and in recent years, diploid and polyploid hepatocytes have been shown to perform specialized functions. Diploid hepatocytes accelerate liver regeneration induced by resection and may accelerate compensatory regeneration after acute injury. Polyploid hepatocytes protect the liver from tumor initiation in hepatocellular carcinoma and promote adaptation to tyrosinemia-induced chronic injury. This review describes how ploidy variations influence cellular activity and presents a model for context-specific functions for diploid and polyploid hepatocytes.

Centrally circulating α-klotho inversely correlates with human obesity and modulates arcuate cell populations in mice

ObjectiveOur laboratory recently identified the centrally circulating α-klotho protein as a novel hypothalamic regulator of food intake and glucose metabolism in mice. The current study aimed to investigate novel molecular effectors of central α-klotho in the arcuate nucleus of the hypothalamus (ARC), while further deciphering its role regulating energy balance in both humans and mice. MethodsCerebrospinal fluid (CSF) was collected from 22 adults undergoing lower limb orthopedic surgeries, and correlations between body weight and α-klotho were determined using an α-klotho enzyme-linked immunosorbent assay (ELISA) kit. To investigate the effects of α-klotho on energy expenditure (EE), 2-day intracerebroventricular (ICV) treatment was performed in diet-induced obesity (DIO) mice housed in TSE Phenomaster indirect calorimetry metabolic cages. Immunohistochemical staining for cFOS and patch clamp electrophysiology were used to determine the effects of central α-klotho on proopiomelanocortin (POMC) and tyrosine hydroxylase (TH) neurons. Additional stainings were performed to determine novel roles for central α-klotho to regulate non-neuronal cell populations in the ARC. Lastly, ICV pretreatment with fibroblast growth factor receptor (FGFR) or PI3kinase inhibitors was performed to determine the intracellular signaling involved in α-klotho-mediated regulation of ARC nuclei. ResultsObese/overweight human subjects had significantly lower CSF α-klotho concentrations compared to lean counterparts (1,044 ± 251 vs. 1616 ± 218 pmol/L, respectively). Additionally, 2 days of ICV α-klotho treatment increased EE in DIO mice. α-Klotho had no effects on TH neuron activity but elicited varied responses in POMC neurons, with 44% experiencing excitatory and 56% experiencing inhibitory effects. Inhibitor experiments identified an α-klotho→FGFR→PI3kinase signaling mechanism in the regulation of ARC POMC and NPY/AgRP neurons. Acute ICV α-klotho treatment also increased phosphorylated ERK in ARC astrocytes via FGFR signaling. ConclusionOur human CSF data provide the first evidence that impaired central α-klotho function may be involved in the pathophysiology of obesity. Furthermore, results in mouse models identify ARC POMC neurons and astrocytes as novel molecular effectors of central α-klotho. Overall, the current study highlights prominent roles of α-klotho→FGFR→PI3kinase signaling in the homeostatic regulation of ARC neurons and whole-body energy balance.

Sectm1a Facilitates Protection against Inflammation-Induced Organ Damage through Promoting TRM Self-Renewal

Tissue-resident macrophages (TRMs) are sentinel cells for maintaining tissue homeostasis and organ function. In this study, we discovered that lipopolysaccharide (LPS) administration dramatically reduced TRM populations and suppressed their self-renewal capacities in multiple organs. Using loss- and gain-of-function approaches, we define Sectm1a as a novel regulator of TRM self-renewal. Specifically, at the earlier stage of endotoxemia, Sectm1a deficiency exaggerated acute inflammation-induced reduction of TRM numbers in multiple organs by suppressing their proliferation, which was associated with more infiltrations of inflammatory monocytes/neutrophils and more serious organ damage. By contrast, administration of recombinant Sectm1a enhanced TRM populations and improved animal survival upon endotoxin challenge. Mechanistically, we identified that Sectm1a-induced upregulation in the self-renewal capacity of TRM is dependent on GITR-activated T helper cell expansion and cytokine production. Meanwhile, we found that TRMs may play an important role in protecting local vascular integrity during endotoxemia. Our study demonstrates that Sectm1a contributes to stabling TRM populations through maintaining their self-renewal capacities, which benefits the host immune response to acute inflammation. Therefore, Sectm1a may serve as a new therapeutic agent for the treatment of inflammatory diseases.