Science translational medicine
Ko, KI;Merlet, JJ;DerGarabedian, BP;Zhen, H;Suzuki-Horiuchi, Y;Hedberg, ML;Hu, E;Nguyen, AT;Prouty, S;Alawi, F;Walsh, MC;Choi, Y;Millar, SE;Cliff, A;Romero, J;Garvin, MR;Seykora, JT;Jacobson, D;Graves, DT;
PMID: 35108061 | DOI: 10.1126/scitranslmed.abj0324
Skin is composed of diverse cell populations that cooperatively maintain homeostasis. Up-regulation of the nuclear factor κB (NF-κB) pathway may lead to the development of chronic inflammatory disorders of the skin, but its role during the early events remains unclear. Through analysis of single-cell RNA sequencing data via iterative random forest leave one out prediction, an explainable artificial intelligence method, we identified an immunoregulatory role for a unique paired related homeobox-1 (Prx1)+ fibroblast subpopulation. Disruption of Ikkb-NF-κB under homeostatic conditions in these fibroblasts paradoxically induced skin inflammation due to the overexpression of C-C motif chemokine ligand 11 (CCL11; or eotaxin-1) characterized by eosinophil infiltration and a subsequent TH2 immune response. Because the inflammatory phenotype resembled that seen in human atopic dermatitis (AD), we examined human AD skin samples and found that human AD fibroblasts also overexpressed CCL11 and that perturbation of Ikkb-NF-κB in primary human dermal fibroblasts up-regulated CCL11. Monoclonal antibody treatment against CCL11 was effective in reducing the eosinophilia and TH2 inflammation in a mouse model. Together, the murine model and human AD specimens point to dysregulated Prx1+ fibroblasts as a previously unrecognized etiologic factor that may contribute to the pathogenesis of AD and suggest that targeting CCL11 may be a way to treat AD-like skin lesions.
Nutritional regulation of oligodendrocyte differentiation regulates perineuronal net remodeling in the median eminence
Kohnke, S;Buller, S;Nuzzaci, D;Ridley, K;Lam, B;Pivonkova, H;Bentsen, MA;Alonge, KM;Zhao, C;Tadross, J;Holmqvist, S;Shimizo, T;Hathaway, H;Li, H;Macklin, W;Schwartz, MW;Richardson, WD;Yeo, GSH;Franklin, RJM;Karadottir, RT;Rowitch, DH;Blouet, C;
PMID: 34260928 | DOI: 10.1016/j.celrep.2021.109362
The mediobasal hypothalamus (MBH; arcuate nucleus of the hypothalamus [ARH] and median eminence [ME]) is a key nutrient sensing site for the production of the complex homeostatic feedback responses required for the maintenance of energy balance. Here, we show that refeeding after an overnight fast rapidly triggers proliferation and differentiation of oligodendrocyte progenitors, leading to the production of new oligodendrocytes in the ME specifically. During this nutritional paradigm, ME perineuronal nets (PNNs), emerging regulators of ARH metabolic functions, are rapidly remodeled, and this process requires myelin regulatory factor (Myrf) in oligodendrocyte progenitors. In genetically obese ob/ob mice, nutritional regulations of ME oligodendrocyte differentiation and PNN remodeling are blunted, and enzymatic digestion of local PNN increases food intake and weight gain. We conclude that MBH PNNs are required for the maintenance of energy balance in lean mice and are remodeled in the adult ME by the nutritional control of oligodendrocyte differentiation.
Cheadle L, Tzeng CP, Kalish BT, Harmin DA, Rivera S, Ling E, Nagy MA, Hrvatin S, Hu L, Stroud H, Burkly LC, Chen C, Greenberg ME.
PMID: 30033152 | DOI: 10.1016/j.neuron.2018.06.036
Sensory experience influences the establishment of neural connectivity through molecular mechanisms that remain unclear. Here, we employ single-nucleus RNA sequencing to investigate the contribution of sensory-driven gene expression to synaptic refinement in the dorsal lateral geniculate nucleus of the thalamus, a region of the brain that processes visual information. We find that visual experience induces the expression of the cytokine receptor Fn14 in excitatory thalamocortical neurons. By combining electrophysiological and structural techniques, we show that Fn14 is dispensable for early phases of refinement mediated by spontaneous activity but that Fn14 is essential for refinement during a later, experience-dependent period of development. Refinement deficits in mice lacking Fn14 are associated with functionally weaker and structurally smaller retinogeniculate inputs, indicating that Fn14 mediates both functional and anatomical rearrangements in response to sensory experience. These findings identify Fn14 as a molecular link between sensory-driven gene expression and vision-sensitive refinement in the brain.
Lin, M;Hartl, K;Heuberger, J;Beccaceci, G;Berger, H;Li, H;Liu, L;Müllerke, S;Conrad, T;Heymann, F;Woehler, A;Tacke, F;Rajewsky, N;Sigal, M;
PMID: 37230989 | DOI: 10.1038/s41467-023-38780-3
The cellular organization of gastrointestinal crypts is orchestrated by different cells of the stromal niche but available in vitro models fail to fully recapitulate the interplay between epithelium and stroma. Here, we establish a colon assembloid system comprising the epithelium and diverse stromal cell subtypes. These assembloids recapitulate the development of mature crypts resembling in vivo cellular diversity and organization, including maintenance of a stem/progenitor cell compartment in the base and their maturation into secretory/absorptive cell types. This process is supported by self-organizing stromal cells around the crypts that resemble in vivo organization, with cell types that support stem cell turnover adjacent to the stem cell compartment. Assembloids that lack BMP receptors either in epithelial or stromal cells fail to undergo proper crypt formation. Our data highlight the crucial role of bidirectional signaling between epithelium and stroma, with BMP as a central determinant of compartmentalization along the crypt axis.
Hsu, LJ;Bertho, M;Kiehn, O;
PMID: 36797254 | DOI: 10.1038/s41467-023-36587-w
Locomotion empowers animals to move. Locomotor-initiating signals from the brain are funneled through descending neurons in the brainstem that act directly on spinal locomotor circuits. Little is known in mammals about which spinal circuits are targeted by the command and how this command is transformed into rhythmicity in the cord. Here we address these questions leveraging a mouse brainstem-spinal cord preparation from either sex that allows locating the locomotor command neurons with simultaneous Ca2+ imaging of spinal neurons. We show that a restricted brainstem area - encompassing the lateral paragigantocellular nucleus (LPGi) and caudal ventrolateral reticular nucleus (CVL) - contains glutamatergic neurons which directly initiate locomotion. Ca2+ imaging captures the direct LPGi/CVL locomotor initiating command in the spinal cord and visualizes spinal glutamatergic modules that execute the descending command and its transformation into rhythmic locomotor activity. Inhibitory spinal networks are recruited in a distinctly different pattern. Our study uncovers the principal logic of how spinal circuits implement the locomotor command using a distinct modular organization.
Osorio, MJ;Mariani, JN;Zou, L;Schanz, SJ;Heffernan, K;Cornwell, A;Goldman, SA;
PMID: 36334067 | DOI: 10.1002/glia.24291
Genomic analyses have revealed heterogeneity among glial progenitor cells (GPCs), but the compartment selectivity of human GPCs (hGPCs) is unclear. Here, we asked if GPCs of human grey and white brain matter are distinct in their architecture and associated gene expression. RNA profiling of NG2-defined hGPCs derived from adult human neocortex and white matter differed in their expression of genes involved in Wnt, NOTCH, BMP and TGFβ signaling, suggesting compartment-selective biases in fate and self-renewal. White matter hGPCs over-expressed the BMP antagonists BAMBI and CHRDL1, suggesting their tonic suppression of astrocytic fate relative to cortical hGPCs, whose relative enrichment of cytoskeletal genes presaged their greater morphological complexity. In human glial chimeric mice, cortical hGPCs assumed larger and more complex morphologies than white matter hGPCs, and both were more complex than their mouse counterparts. These findings suggest that human grey and white matter GPCs comprise context-specific pools with distinct functional biases.
Lecoin, L;Dempsey, B;Garancher, A;Bourane, S;Ruffault, PL;Morin-Surun, MP;Rocques, N;Goulding, M;Eychène, A;Pouponnot, C;Fortin, G;Champagnat, J;
PMID: 35672398 | DOI: 10.1038/s41467-022-30825-3
While apneas are associated with multiple pathological and fatal conditions, the underlying molecular mechanisms remain elusive. We report that a mutated form of the transcription factor Mafa (Mafa4A) that prevents phosphorylation of the Mafa protein leads to an abnormally high incidence of breath holding apneas and death in newborn Mafa4A/4A mutant mice. This apneic breathing is phenocopied by restricting the mutation to central GABAergic inhibitory neurons and by activation of inhibitory Mafa neurons while reversed by inhibiting GABAergic transmission centrally. We find that Mafa activates the Gad2 promoter in vitro and that this activation is enhanced by the mutation that likely results in increased inhibitory drives onto target neurons. We also find that Mafa inhibitory neurons are absent from respiratory, sensory (primary and secondary) and pontine structures but are present in the vicinity of the hypoglossal motor nucleus including premotor neurons that innervate the geniohyoid muscle, to control upper airway patency. Altogether, our data reveal a role for Mafa phosphorylation in regulation of GABAergic drives and suggest a mechanism whereby reduced premotor drives to upper airway muscles may cause apneic breathing at birth.
Minatoguchi, S;Saito, S;Furuhashi, K;Sawa, Y;Okazaki, M;Shimamura, Y;Kaihan, AB;Hashimoto, Y;Yasuda, Y;Hara, A;Mizutani, Y;Ando, R;Kato, N;Ishimoto, T;Tsuboi, N;Esaki, N;Matsuyama, M;Shiraki, Y;Kobayashi, H;Asai, N;Enomoto, A;Maruyama, S;
PMID: 35354870 | DOI: 10.1038/s41598-022-09331-5
Perivascular mesenchymal cells (PMCs), which include pericytes, give rise to myofibroblasts that contribute to chronic kidney disease progression. Several PMC markers have been identified; however, PMC heterogeneity and functions are not fully understood. Here, we describe a novel subset of renal PMCs that express Meflin, a glycosylphosphatidylinositol-anchored protein that was recently identified as a marker of fibroblasts essential for cardiac tissue repair. Tracing the lineage of Meflin+ PMCs, which are found in perivascular and periglomerular areas and exhibit renin-producing potential, showed that they detach from the vasculature and proliferate under disease conditions. Although the contribution of Meflin+ PMCs to conventional α-SMA+ myofibroblasts is low, they give rise to fibroblasts with heterogeneous α-SMA expression patterns. Genetic ablation of Meflin+ PMCs in a renal fibrosis mouse model revealed their essential role in collagen production. Consistent with this, human biopsy samples showed that progressive renal diseases exhibit high Meflin expression. Furthermore, Meflin overexpression in kidney fibroblasts promoted bone morphogenetic protein 7 signals and suppressed myofibroblastic differentiation, implicating the roles of Meflin in suppressing tissue fibrosis. These findings demonstrate that Meflin marks a PMC subset that is functionally distinct from classic pericytes and myofibroblasts, highlighting the importance of elucidating PMC heterogeneity.
Low, AYT;Goldstein, N;Gaunt, JR;Huang, KP;Zainolabidin, N;Yip, AKK;Carty, JRE;Choi, JY;Miller, AM;Ho, HST;Lenherr, C;Baltar, N;Azim, E;Sessions, OM;Ch'ng, TH;Bruce, AS;Martin, LE;Halko, MA;Brady, RO;Holsen, LM;Alhadeff, AL;Chen, AI;Betley, JN;
PMID: 34789878 | DOI: 10.1038/s41586-021-04143-5
The brain is the seat of body weight homeostasis. However, our inability to control the increasing prevalence of obesity highlights a need to look beyond canonical feeding pathways to broaden our understanding of body weight control1-3. Here we used a reverse-translational approach to identify and anatomically, molecularly and functionally characterize a neural ensemble that promotes satiation. Unbiased, task-based functional magnetic resonance imaging revealed marked differences in cerebellar responses to food in people with a genetic disorder characterized by insatiable appetite. Transcriptomic analyses in mice revealed molecularly and topographically -distinct neurons in the anterior deep cerebellar nuclei (aDCN) that are activated by feeding or nutrient infusion in the gut. Selective activation of aDCN neurons substantially decreased food intake by reducing meal size without compensatory changes to metabolic rate. We found that aDCN activity terminates food intake by increasing striatal dopamine levels and attenuating the phasic dopamine response to subsequent food consumption. Our study defines a conserved satiation centre that may represent a novel therapeutic target for the management of excessive eating, and underscores the utility of a 'bedside-to-bench' approach for the identification of neural circuits that influence behaviour.
Fgf15 neurons of the dorsomedial hypothalamus control glucagon secretion and hepatic gluconeogenesis
Picard, A;Metref, S;Tarussio, D;Dolci, W;Berney, X;Croizier, S;Labouebe, G;Thorens, B;
PMID: 33883213 | DOI: 10.2337/db20-1121
The counterregulatory response to hypoglycemia is an essential survival function. It is controlled by an integrated network of glucose responsive neurons, which trigger endogenous glucose production to restore normoglycemia. The complexity of this gluco-regulatory network is, however, only partly characterized. In a genetic screen of a panel of recombinant inbred mice we previously identified Fgf15, expressed in neurons of the dorsomedial hypothalamus, as a negative regulator of glucagon secretion. Here, we report on the generation of Fgf15CretdTomato mice and their use to further characterize these neurons. We showed that they were glutamatergic and comprised glucose inhibited and glucose excited neurons. When activated by chemogenetics, Fgf15 neurons prevented the increase in vagal nerve firing and the secretion of glucagon normally triggered by insulin-induced hypoglycemia. On the other hand, they increased the activity of the sympathetic nerve in the basal state and prevented its silencing by glucose overload. Higher sympathetic tone increased hepatic Creb1 phosphorylation, Pck1 mRNA expression, and hepatic glucose production leading to glucose intolerance. Thus, Fgf15 neurons of the dorsomedial hypothalamus participate in the counterregulatory response to hypoglycemia by a direct adrenergic stimulation of hepatic glucose production while suppressing vagally-induced glucagon secretion. This study provides new insights into the complex neuronal network that prevents the development of hypoglycemia.
Fluri F, Mützel T, Schuhmanna MK, Krstić M, Endres H, Volkmann J.
PMID: 28842194 | DOI: 10.1016/j.jneumeth.2017.08.024
Abstract
BACKGROUND:
Commercial neurostimulators for clinical use are effective in patients; however they are too large and prohibitively expensive for preclinical studies. Thus, there is an urgent need of a small inexpensive and wireless microstimulator which is fully programmable in frequency, pulse width and amplitude for rodent experiments.
NEW METHODS:
Rats were subjected to a photothrombotic stroke of the right sensorimotor cortex and a microelectrode was implanted in the right mesencephalic locomotor region. The microstimulator was connected with the head plug of the rat. Three different stimulation frequencies were applied and different stimulating amplitudes were chosen. Under these conditions, gait velocity and locomotor behavior of six rats were examined on a beam.
RESULTS:
The head-mounted microstimulator allowed freedom in all motor activities performed spontaneously by the tested rats. Increasing either the frequency or the stimulating amplitude increased gait velocity and ameliorated locomotor behavior after stroke.
COMPARISON WITH EXISTING METHODS:
Other devices for DBS in rodents must be implanted under the skin or worn in an animal jacket on the back by the tested rat. Some available systems require even a tethering of the tested animal via a cable to an external stimulation system, which limits the freedom of movement.
CONCLUSION:
Here, we present a freely programmable microstimulator including DBS-typical stimulating parameters. The lightweight device is connected by a simple plug to the head allowing full freedom of movement and exchange of batteries for long-term experiments. The design of this stimulator is suitable for sophisticated behavior tests requiring balance and skilled walking.
Liu, X;Wang, Y;Zeng, Y;Wang, D;Wen, Y;Fan, L;He, Y;Zhang, J;Sun, W;Liu, Y;Tao, A;
PMID: 36876522 | DOI: 10.1111/all.15699
Spinal astrocytes contribute to chronic itch via sensitization of itch-specific neurons expressing gastrin-releasing peptide receptor (GRPR). However, whether microglia-neuron interactions contribute to itch remains unclear. In this study, we aimed to explore how microglia interact with GRPR+ neurons and promote chronic itch.RNA sequencing, quantitative real-time PCR, western blot, immunohistochemistry, RNAscope ISH, pharmacologic and genetic approaches were performed to examine the roles of spinal NLRP3 (The NOD-like receptor family, pyrin-containing domain 3) inflammasome activation and IL-1β-IL1R1 signaling in chronic itch. Grpr-eGFP and Grpr KO mice were used to investigate microglia-GRPR+ neuron interactions.We observed NLRP3 inflammasome activation and IL-1β production in spinal microglia under chronic itch conditions. Blockade of microglial activation and the NLRP3/caspase-1/IL-1β axis attenuated chronic itch and neuronal activation. Type 1 IL-1 receptor (IL-1R1) was expressed in GRPR+ neurons, which are essential for the development of chronic itch. Our studies also find that IL-1β+ microglia are localized in close proximity to GRPR+ neurons. Consistently, intrathecal injection of IL1R1 antagonist or exogenous IL-1β indicate that the IL-1β-IL-1R1 signaling pathway enhanced the activation of GRPR+ neurons. Furthermore, our results demonstrate that the microglial NLRP3/caspase-1/IL-1β axis contributes to several different chronic itches triggered by small molecules and protein allergens from the environment and drugs.Our findings reveal a previously unknown mechanism in which microglia enhances the activation of GRPR+ neurons through the NLRP3/caspase-1/IL-1β/IL1R1 axis. These results will provide new insights into the pathophysiology of pruritus and novel therapeutic strategies for patients with chronic itch.
