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Inflammatory pain results from the heightened sensitivity and reduced threshold of nociceptor sensory neurons due to exposure to inflammatory mediators. However, the cellular and transcriptional diversity of immune cell and sensory neuron types makes it challenging to decipher the immune mechanisms underlying pain. Here we used single-cell transcriptomics to determine the immune gene signatures associated with pain development in three skin inflammatory pain models in mice: zymosan injection, skin incision and ultraviolet burn. We found that macrophage and neutrophil recruitment closely mirrored the kinetics of pain development and identified cell-type-specific transcriptional programs associated with pain and its resolution. Using a comprehensive list of potential interactions mediated by receptors, ligands, ion channels and metabolites to generate injury-specific neuroimmune interactomes, we also uncovered that thrombospondin-1 upregulated by immune cells upon injury inhibited nociceptor sensitization. This study lays the groundwork for identifying the neuroimmune axes that modulate pain in diverse disease contexts.
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Nociceptores , Dor , Animais , Camundongos , Dor/imunologia , Dor/metabolismo , Nociceptores/metabolismo , Transcriptoma , Camundongos Endogâmicos C57BL , Inflamação/imunologia , Masculino , Macrófagos/imunologia , Macrófagos/metabolismo , Modelos Animais de Doenças , Trombospondina 1/metabolismo , Trombospondina 1/genética , Pele/imunologia , Pele/metabolismo , Pele/patologia , Zimosan , Análise de Célula Única , Neuroimunomodulação , Perfilação da Expressão Gênica , Neutrófilos/imunologia , Neutrófilos/metabolismoRESUMO
The cytokine interleukin (IL)-1ß is a key mediator of antimicrobial immunity as well as autoimmune inflammation. Production of IL-1ß requires transcription by innate immune receptor signaling and maturational cleavage by inflammasomes. Whether this mechanism applies to IL-1ß production seen in T cell-driven autoimmune diseases remains unclear. Here, we describe an inflammasome-independent pathway of IL-1ß production that was triggered upon cognate interactions between effector CD4+ T cells and mononuclear phagocytes (MPs). The cytokine TNF produced by activated CD4+ T cells engaged its receptor TNFR on MPs, leading to pro-IL-1ß synthesis. Membrane-bound FasL, expressed by CD4+ T cells, activated death receptor Fas signaling in MPs, resulting in caspase-8-dependent pro-IL-1ß cleavage. The T cell-instructed IL-1ß resulted in systemic inflammation, whereas absence of TNFR or Fas signaling protected mice from CD4+ T cell-driven autoimmunity. The TNFR-Fas-caspase-8-dependent pathway provides a mechanistic explanation for IL-1ß production and its consequences in CD4+ T cell-driven autoimmune pathology.
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Autoimunidade/imunologia , Linfócitos T CD4-Positivos/imunologia , Inflamação/patologia , Interleucina-1beta/metabolismo , Células Mieloides/metabolismo , Animais , Caspase 1/genética , Caspase 8/metabolismo , Células Cultivadas , Células Dendríticas/imunologia , Proteína Ligante Fas/metabolismo , Imunidade Inata/imunologia , Inflamassomos/imunologia , Inflamação/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium tuberculosis/imunologia , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND: Postoperative pain and inflammation are significant complications following surgery. Strategies that aim to prevent excessive inflammation without hampering natural wound-healing are required for the management of postoperative pain and inflammation. However, the knowledge of the mechanisms and target pathways involved in these processes is lacking. Recent studies have revealed that autophagy in macrophages sequesters pro-inflammatory mediators, and it is therefore being recognized as a crucial process involved in regulating inflammation. In this study, we tested the hypothesis that autophagy in macrophages plays protective roles against postoperative pain and inflammation and investigated the underlying mechanisms. METHODS: Postoperative pain was induced by plantar incision under isoflurane anesthesia in mice lacking macrophage autophagy (Atg5flox/flox LysMCre +) and their control littermates (Atg5flox/flox). Mechanical and thermal pain sensitivity, changes in weight distribution, spontaneous locomotor activity, tissue inflammation, and body weight were assessed at baseline and 1, 3, and 7 days after surgery. Monocyte/macrophage infiltration at the surgical site and inflammatory mediator expression levels were evaluated. RESULTS: Atg5flox/flox LysMCre + mice compared with the control mice exhibited lower mechanical and thermal pain thresholds and surgical/non-surgical hindlimb weight-bearing ratios. The augmented neurobehavioral symptoms observed in the Atg5flox/flox LysMCre + mice were associated with more severe paw inflammation, higher pro-inflammatory mediator mRNA expression, and more monocytes/macrophages at the surgical site. CONCLUSION: The lack of macrophage autophagy augmented postoperative pain and inflammation, which were accompanied by enhanced pro-inflammatory cytokine secretion and surgical-site monocyte/macrophage infiltration. Macrophage autophagy plays a protective role in postoperative pain and inflammation and can be a novel therapeutic target.
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Inflamação , Macrófagos , Camundongos , Animais , Macrófagos/metabolismo , Inflamação/metabolismo , Dor Pós-Operatória/tratamento farmacológico , Autofagia , Limiar da DorRESUMO
Sensory neurons and immune cells share a common microenvironmental niche for surveying tissue integrity. The immune and nervous systems both sense deviations in homeostasis and initiate protective responses and, upon malfunction, also jointly contribute to disease. Barrier tissues are heavily innervated by nociceptors, the sensory neurons that detect noxious stimuli, leading to pain and itch. The same tissues are also home to diverse immune cells that respond to infections and injury. The physical proximity of nociceptors and immune cells allows for direct local interactions between the two, independent of the CNS. We discuss in this study their ligand-receptor-based interactions and propose the need to shift from studying individual neuroimmune interactions to exploring the reciprocal neuroimmune interaction network in its entirety: the "neuroimmune interactome." Identification of the nature of the interactome in health and its plasticity in disease will unravel the functional consequences of interactions between nociceptors and immune cells.
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Neuroimunomodulação/imunologia , Plasticidade Neuronal/fisiologia , Células Receptoras Sensoriais/fisiologia , Animais , HumanosRESUMO
INTRODUCTION: Coronavirus disease-2019 (COVID-19) systemic illness caused by a novel coronavirus severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has been spreading across the world. The objective of this study is to identify the clinical and laboratory variables as predictors of in-hospital death at the time of admission in a tertiary care hospital in India. MATERIALS AND METHODS: Demographic profile, clinical, and laboratory variables of 425 patients admitted from April to June 2020 with symptoms and laboratory-confirmed diagnosis through real-time polymerase chain reaction (RT-PCR) were studied. Descriptive statistics, an association of these variables, logistic regression, and CART models were developed to identify early predictors of in-hospital death. RESULTS: Twenty-two patients (5.17%) had expired in course of their hospital stay. The median age [interquartile range (IQR)] of the patients admitted was 49 years (21-77 years). Gender distribution was male - 73.38% (mortality rate 5.83%) and female-26.62% (mortality rate 3.34%). The study shows higher association for age (>47 years) [odds ratio (OR) 4.52], male gender (OR 1.78), shortness of breath (OR 2.02), oxygen saturation <93% (OR 9.32), respiratory rate >24 (OR 5.31), comorbidities like diabetes (OR 2.70), hypertension (OR 2.12), and coronary artery disease (OR 3.18) toward overall mortality. The significant associations in laboratory variables include lymphopenia (<12%) (OR 8.74), C-reactive protein (CRP) (OR 1.99), ferritin (OR 3.18), and lactate dehydrogenase (LDH) (OR 3.37). Using this statistically significant 16 clinical and laboratory variables, the logistic regression model had an area under receiver operating characteristic (ROC) curve of 0.86 (train) and 0.75 (test). CONCLUSION: Age above 47 years, associated with comorbidities like hypertension and diabetes, with oxygen saturation below 93%, tachycardia, and deranged laboratory variables like lymphopenia and raised CRP, LDH, and ferritin are important predictors of in-hospital mortality. HOW TO CITE THIS ARTICLE: Jain AC, Kansal S, Sardana R, Bali RK, Kar S, Chawla R. A Retrospective Observational Study to Determine the Early Predictors of In-hospital Mortality at Admission with COVID-19. Indian J Crit Care Med 2020;24(12):1174-1179.
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Activation of cells in the adaptive immune system is a highly orchestrated process dictated by multiples cues from the innate immune system. Although the fundamental principles of innate control of adaptive immunity are well established, it is not fully understood how innate cells integrate qualitative pathogenic information to generate tailored protective adaptive immune responses. In this review, we discuss complexities involved in the innate control of adaptive immunity that extend beyond TCR engagement, costimulation, and priming cytokine production but are critical for the generation of protective T cell immunity.
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Imunidade Adaptativa , Imunidade Inata , Transdução de Sinais , Linfócitos T/imunologia , Animais , Citocinas/imunologia , Humanos , Camundongos , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
Activation of CD4 T cells by dendritic cells leads to their differentiation into various effector lineages. The nature of the effector lineage is determined by the innate cues provided by dendritic cells to newly primed T cells. Although the cytokines necessary for several effector lineages have been identified, the innate cues that drive T follicular helper (Tfh) lineage cell development remain unclear. Here we found that following priming, CD4 T cells undergoing clonal expansion acquire a transient Tfh-like phenotype before differentiating into other effector lineages. In addition, we found that T cell-intrinsic myeloid differentiation antigen 88 (MyD88) signaling, which occurs downstream of interleukin-1 (IL-1) and IL-18 receptors, is critical for the primed CD4 T cells to transition out of the temporary Tfh lineage. Mice with T cell-specific deletion of MyD88 have a higher proportion of Tfh cells and germinal center (GC) B cells. These exaggerated Tfh cell and GC B cell responses, however, do not lead to protective immunity against infections. We demonstrate that T cell-intrinsic MyD88 is critical for effector lineage differentiation as well as production of the cytokines that are necessary for class switching. Overall, our study establishes that following priming and clonal expansion, CD4 T cells undergo a transitional Tfh-like phase and that further differentiation into effector lineages is dictated by T cell-intrinsic MyD88-dependent cues.
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Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/fisiologia , Fator 88 de Diferenciação Mieloide/imunologia , Fator 88 de Diferenciação Mieloide/fisiologia , Folículo Ovariano/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/fisiologia , Diferenciação Celular/imunologia , Diferenciação Celular/fisiologia , Feminino , Humanos , Folículo Ovariano/fisiologiaRESUMO
Recognition of pathogen-associated molecular patterns by Toll-like receptors (TLRs) on dendritic cells (DCs) leads to DC maturation, a process involving up-regulation of MHC and costimulatory molecules and secretion of proinflammatory cytokines. All TLRs except TLR3 achieve these outcomes by using the signaling adaptor myeloid differentiation factor 88. TLR4 and TLR3 can both use the Toll-IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF)-dependent signaling pathway leading to IFN regulatory factor 3 (IRF3) activation and induction of IFN-ß and -α4. The TRIF signaling pathway, downstream of both of these TLRs, also leads to DC maturation, and it has been proposed that the type I IFNs act in cis to induce DC maturation and subsequent effects on adaptive immunity. The present study was designed to understand the molecular mechanisms of TRIF-mediated DC maturation. We have discovered that TLR4-TRIF-induced DC maturation was independent of both IRF3 and type I IFNs. In contrast, TLR3-mediated DC maturation was completely dependent on type I IFN feedback. We found that differential activation of mitogen-activated protein kinases by the TLR4- and TLR3-TRIF axes determined the type I IFN dependency for DC maturation. In addition, we found that the adjuvanticity of LPS to induce T-cell activation is completely independent of type I IFNs. The important distinction between the TRIF-mediated signaling pathways of TLR4 and TLR3 discovered here could have a major impact in the design of future adjuvants that target this pathway.
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Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Células Dendríticas/imunologia , Regulação da Expressão Gênica/imunologia , Transdução de Sinais/fisiologia , Receptor 3 Toll-Like/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Sequência de Bases , Western Blotting , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células/fisiologia , Células Dendríticas/citologia , Citometria de Fluxo , Lipopolissacarídeos , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Análise de Sequência de RNARESUMO
Physiological pain serves as a warning of exposure to danger and prompts us to withdraw from noxious stimuli to prevent tissue damage. Pain can also alert us of an infection or organ dysfunction and aids in locating such malfunction. However, there are instances where pain is purely pathological, such as unresolved pain following an inflammation or injury to the nervous system, and this can be debilitating and persistent. We now appreciate that immune cells are integral to both physiological and pathological pain, and that pain, in consequence, is not strictly a neuronal phenomenon. Here, we discuss recent findings on how immune cells in the skin, nerve, dorsal root ganglia, and spinal cord interact with somatosensory neurons to mediate pain. We also discuss how both innate and adaptive immune cells, by releasing various ligands and mediators, contribute to the initiation, modulation, persistence, or resolution of various modalities of pain. Finally, we propose that the neuroimmune axis is an attractive target for pain treatment, but the challenges in objectively quantifying pain preclinically, variable sex differences in pain presentation, as well as adverse outcomes associated with immune system modulation, all need to be considered in the development of immunotherapies against pain.
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Neurônios , Dor , Feminino , Masculino , Humanos , Cognição , Gânglios Espinais , ImunoterapiaRESUMO
Diabetic peripheral neuropathy (DPN) is a common complication of diabetes, causing sensory loss and debilitating neuropathic pain 1,2 . Although the onset and progression of DPN have been linked with dyslipidemia and hyperglycemia 3 , the contribution of inflammation in the pathogenesis of DPN has not been investigated. Here, we use a High Fat High Fructose Diet (HFHFD) to model DPN and the diabetic metabolic syndrome in mice. Diabetic mice develop persistent heat hypoalgesia after three months, but a reduction in epidermal skin innervation only manifests at 6 months. Using single-cell sequencing, we find that CCR2+ macrophages infiltrate the sciatic nerves of diabetic mice well before axonal degeneration is detectable. We show that these infiltrating macrophages share gene expression similarities with nerve crush-induced macrophages 4 and express neurodegeneration-associated microglia marker genes 5 although there is no axon loss or demyelination. Inhibiting this macrophage recruitment in diabetic mice by genetically or pharmacologically blocking CCR2 signaling results in a more severe heat hypoalgesia and accelerated skin denervation. These findings reveal a novel neuroprotective recruitment of macrophages into peripheral nerves of diabetic mice that delays the onset of terminal axonal degeneration, thereby reducing sensory loss. Potentiating and sustaining this early neuroprotective immune response in patients represents, therefore, a potential means to reduce or prevent DPN.
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The cerebral cortex is vital for the processing and perception of sensory stimuli. In the somatosensory axis, information is received primarily by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted perception. This suggests that responsiveness to particular somatosensory stimuli occurs in a modality specific fashion and we sought to determine additional cortical substrates. In this work, we identify in a mouse model that inhibition of S2 output increases mechanical and heat, but not cooling sensitivity, in contrast to S1. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and heat sensitivity without affecting motor performance or anxiety. Taken together, we show that S2 is an essential cortical structure that governs mechanical and heat sensitivity.
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Temperatura Alta , Córtex Somatossensorial , Camundongos , Animais , Córtex Somatossensorial/fisiologia , Córtex CerebralRESUMO
Postoperative pain affects most patients after major surgery and can transition to chronic pain. The considerable side effects and limited efficacy of current treatments underline the need for new therapeutic options. We observed increased amounts of the metabolites BH4 and serotonin after skin injury. Mast cells were primary postoperative sources of Gch1, the rate-limiting enzyme in BH4 synthesis, itself an obligate cofactor in serotonin production by tryptophan hydroxylase (Tph1). Mice deficient in mast cells or in mast cell-specific Gch1 or Tph1 showed drastically decreased postoperative pain. We found that injury induced the nociceptive neuropeptide substance P, mast cell degranulation, and granule nerve colocalization. Substance P triggered serotonin release in mouse and human mast cells, and substance P receptor blockade substantially ameliorated pain hypersensitivity. Our findings highlight the importance of mast cells at the neuroimmune interface and substance P-driven mast cell BH4 and serotonin production as a therapeutic target for postoperative pain treatment.
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Mastócitos , Dor Pós-Operatória , Serotonina , Mastócitos/imunologia , Serotonina/metabolismo , Animais , Dor Pós-Operatória/imunologia , Camundongos , Humanos , Camundongos Endogâmicos C57BL , Substância P/metabolismo , Masculino , Camundongos Knockout , Triptofano Hidroxilase/metabolismoRESUMO
Sensory neurons in the dorsal root ganglion (DRG) and trigeminal ganglion (TG) are specialized to detect and transduce diverse environmental stimuli to the central nervous system. Single-cell RNA sequencing has provided insights into the diversity of sensory ganglia cell types in rodents, nonhuman primates, and humans, but it remains difficult to compare cell types across studies and species. We thus constructed harmonized atlases of the DRG and TG that describe and facilitate comparison of 18 neuronal and 11 non-neuronal cell types across six species and 31 datasets. We then performed single-cell/nucleus RNA sequencing of DRG from both human and the highly regenerative axolotl and found that the harmonized atlas also improves cell type annotation, particularly of sparse neuronal subtypes. We observed that the transcriptomes of sensory neuron subtypes are broadly similar across vertebrates, but the expression of functionally important neuropeptides and channels can vary notably. The resources presented here can guide future studies in comparative transcriptomics, simplify cell-type nomenclature differences across studies, and help prioritize targets for future analgesic development.
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Gânglios Espinais , Transcriptoma , Gânglio Trigeminal , Animais , Humanos , Gânglios Espinais/citologia , Gânglios Espinais/metabolismo , Gânglio Trigeminal/citologia , Gânglio Trigeminal/metabolismo , Análise de Célula Única/métodos , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/citologia , Especificidade da Espécie , Camundongos , Atlas como Assunto , Perfilação da Expressão Gênica , RatosRESUMO
BACKGROUND: Central line-associated bloodstream infection (CLABSI) rates in intensive care units (ICUs) across Latin America exceed those in high-income countries significantly. METHODS: We implemented the INICC multidimensional approach, incorporating an 11-component bundle, in 122 ICUs spanning nine Asian countries. We computed the CLABSI rate using the CDC/NSHN definition and criteria. The CLABSI rate per 1000 CL-days was calculated at baseline and throughout different phases of the intervention, including the 2nd month, 3rd month, 4-16 month, and 17-29 month periods. A two-sample t-test was employed to compare baseline CLABSI rates with intervention rates. Additionally, we utilized a generalized linear mixed model with a Poisson distribution to analyze the association between exposure and outcome. RESULTS: A total of 124,946 patients were hospitalized over 717,270 patient-days, with 238,595 central line (CL)-days recorded. The rates of CLABSI per 1000 CL-days significantly decreased from 16.64 during the baseline period to 6.51 in the 2nd month (RR = 0.39; 95% CI = 0.36-0.42; p < 0.001), 3.71 in the 3rd month (RR = 0.22; 95% CI = 0.21-0.25; p < 0.001), 2.80 in the 4-16 month (RR = 0.17; 95% CI = 0.15-0.19; p < 0.001), and 2.18 in the 17-29 month (RR = 0.13; 95% CI = 0.11-0.15; p < 0.001) intervals. A multilevel Poisson regression model demonstrated a sustained, continuous, and statistically significant decrease in ratios of incidence rates, reaching 0.35 (p < 0.0001) during the 17-29 month period. Moreover, the all-cause in-ICU mortality rate significantly decreased from 13.23% to 10.96% (p = 0.0001) during the 17-29 month period. CONCLUSIONS: Our intervention led to an 87% reduction in CLABSI rates, with a 29-month follow-up.
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BACKGROUND: Identify urinary catheter (UC)-associated urinary tract infections (CAUTI) incidence and risk factors (RF) in 235 ICUs in 8 Asian countries: India, Malaysia, Mongolia, Nepal, Pakistan, the Philippines, Thailand, and Vietnam. METHODS: From January 1, 2014, to February 12, 2022, we conducted a prospective cohort study. To estimate CAUTI incidence, the number of UC days was the denominator, and CAUTI was the numerator. To estimate CAUTI RFs, we analyzed 11 variables using multiple logistic regression. RESULTS: 84,920 patients hospitalized for 499,272 patient days acquired 869 CAUTIs. The pooled CAUTI rate per 1,000 UC-days was 3.08; for those using suprapubic-catheters (4.11); indwelling-catheters (2.65); trauma-ICU (10.55), neurologic-ICU (7.17), neurosurgical-ICU (5.28); in lower-middle-income countries (3.05); in upper-middle-income countries (1.71); at public-hospitals (5.98), at private-hospitals (3.09), at teaching-hospitals (2.04). The following variables were identified as CAUTI RFs: Age (adjusted odds ratio [aOR] = 1.01; 95% CI = 1.01-1.02; P < .0001); female sex (aOR = 1.39; 95% CI = 1.21-1.59; P < .0001); using suprapubic-catheter (aOR = 4.72; 95% CI = 1.69-13.21; P < .0001); length of stay before CAUTI acquisition (aOR = 1.04; 95% CI = 1.04-1.05; P < .0001); UC and device utilization-ratio (aOR = 1.07; 95% CI = 1.01-1.13; P = .02); hospitalized at trauma-ICU (aOR = 14.12; 95% CI = 4.68-42.67; P < .0001), neurologic-ICU (aOR = 14.13; 95% CI = 6.63-30.11; P < .0001), neurosurgical-ICU (aOR = 13.79; 95% CI = 6.88-27.64; P < .0001); public-facilities (aOR = 3.23; 95% CI = 2.34-4.46; P < .0001). DISCUSSION: CAUTI rate and risk are higher for older patients, women, hospitalized at trauma-ICU, neurologic-ICU, neurosurgical-ICU, and public facilities. All of them are unlikely to change. CONCLUSIONS: It is suggested to focus on reducing the length of stay and the Urinary catheter device utilization ratio, avoiding suprapubic catheters, and implementing evidence-based CAUTI prevention recommendations.
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Infecções Relacionadas a Cateter , Infecção Hospitalar , Infecções Urinárias , Humanos , Feminino , Estudos Prospectivos , Infecção Hospitalar/prevenção & controle , Incidência , Infecções Relacionadas a Cateter/epidemiologia , Infecções Relacionadas a Cateter/prevenção & controle , Infecções Urinárias/prevenção & controle , Unidades de Terapia Intensiva , Cateteres de Demora/efeitos adversos , Fatores de Risco , Paquistão/epidemiologiaRESUMO
The cerebral cortex is vital for the perception and processing of sensory stimuli. In the somatosensory axis, information is received by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted mechanical and cooling perception. Using optogenetics and chemogenetics, we find that in contrast to S1, an inhibition of S2 output increases mechanical and heat, but not cooling sensitivity. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and thermal sensitivity without affecting motor or cognitive function. This suggests that while S2, like S1, encodes specific sensory information, that S2 operates through quite distinct neural substrates to modulate responsiveness to particular somatosensory stimuli and that somatosensory cortical encoding occurs in a largely parallel fashion.
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Inflammatory pain associated with tissue injury and infections, results from the heightened sensitivity of the peripheral terminals of nociceptor sensory neurons in response to exposure to inflammatory mediators. Targeting immune-derived inflammatory ligands, like prostaglandin E2, has been effective in alleviating inflammatory pain. However, the diversity of immune cells and the vast array of ligands they produce make it challenging to systematically map all neuroimmune pathways that contribute to inflammatory pain. Here, we constructed a comprehensive and updatable database of receptor-ligand pairs and complemented it with single-cell transcriptomics of immune cells and sensory neurons in three distinct inflammatory pain conditions, to generate injury-specific neuroimmune interactomes. We identified cell-type-specific neuroimmune axes that are common, as well as unique, to different injury types. This approach successfully predicts neuroimmune pathways with established roles in inflammatory pain as well as ones not previously described. We found that thrombospondin-1 produced by myeloid cells in all three conditions, is a negative regulator of nociceptor sensitization, revealing a non-canonical role of immune ligands as an endogenous reducer of peripheral sensitization. This computational platform lays the groundwork to identify novel mechanisms of immune-mediated peripheral sensitization and the specific disease contexts in which they act.
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BACKGROUND AND PURPOSE: Peripheral sensitization contributes to pathological pain. While prostaglandin E2 (PGE2) and nerve growth factor (NGF) sensitize peptidergic C-nociceptors (TRPV1+), glial cell line-derived neurotrophic factor (GDNF) sensitizes non-peptidergic C-neurons (IB4+). The sigma-1 receptor (sigma-1R) is a Ca2+ -sensing chaperone known to modulate opoid analgesia. This receptor binds both to TRPV1 and the µ opioid receptor, although the functional repercussions of these physical interactions in peripheral sensitization are unknown. EXPERIMENTAL APPROACH: We tested the effects of sigma-1 antagonism on PGE2-, NGF-, and GDNF-induced mechanical and heat hyperalgesia in mice. We used immunohistochemistry to determine the presence of endomorphin-2, an endogenous µ receptor agonist, on dorsal root ganglion (DRG) neurons. Recombinant proteins were used to study the interactions between sigma-1R, µ- receptor, and TRPV1. We used calcium imaging to study the effects of sigma-1 antagonism on PGE2-induced sensitization of TRPV1+ nociceptors. KEY RESULTS: Sigma1 antagonists reversed PGE2- and NGF-induced hyperalgesia but not GDNF-induced hyperalgesia. Endomorphin-2 was detected on TRPV1+ but not on IB4+ neurons. Peripheral opioid receptor antagonism by naloxone methiodide or administration of an anti-endomorphin-2 antibody to a sensitized paw reversed the antihyperalgesia induced by sigma-1 antagonists. Sigma-1 antagonism transfers sigma-1R from TRPV1 to µ receptors, suggesting that sigma-1R participate in TRPV1-µ receptor crosstalk. Moreover, sigma-1 antagonism reversed, in a naloxone-sensitive manner, PGE2-induced sensitization of DRG neurons to the calcium flux elicited by capsaicin, the prototypic TRPV1 agonist. CONCLUSION AND IMPLICATIONS: Sigma-1 antagonism harnesses endogenous opioids produced by TRPV1+ neurons to reduce hyperalgesia by increasing µ receptor activity.
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Analgesia , Nociceptores , Camundongos , Animais , Nociceptores/metabolismo , Hiperalgesia/metabolismo , Receptores Opioides mu/metabolismo , Analgésicos Opioides/farmacologia , Fator de Crescimento Neural/metabolismo , Cálcio/metabolismo , Dinoprostona/metabolismo , Dor/metabolismo , Peptídeos Opioides/metabolismo , Canais de Cátion TRPV/metabolismo , Gânglios Espinais/metabolismo , Receptor Sigma-1RESUMO
The cerebral cortex is vital for the perception and processing of sensory stimuli. In the somatosensory axis, information is received by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted mechanical and cooling perception. Using optogenetics and chemogenetics, we find that in contrast to S1, an inhibition of S2 output increases mechanical and heat, but not cooling sensitivity. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and thermal sensitivity without affecting motor or cognitive function. This suggests that while S2, like S1, encodes specific sensory information, that S2 operates through quite distinct neural substrates to modulate responsiveness to particular somatosensory stimuli and that somatosensory cortical encoding occurs in a largely parallel fashion.
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OBJECTIVE: To identify risk factors for mortality in intensive care units (ICUs) in Asia. DESIGN: Prospective cohort study. SETTING: The study included 317 ICUs of 96 hospitals in 44 cities in 9 countries of Asia: China, India, Malaysia, Mongolia, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, and Vietnam. PARTICIPANTS: Patients aged >18 years admitted to ICUs. RESULTS: In total, 157,667 patients were followed during 957,517 patient days, and 8,157 HAIs occurred. In multiple logistic regression, the following variables were associated with an increased mortality risk: central-line-associated bloodstream infection (CLABSI; aOR, 2.36; P < .0001), ventilator-associated event (VAE; aOR, 1.51; P < .0001), catheter-associated urinary tract infection (CAUTI; aOR, 1.04; P < .0001), and female sex (aOR, 1.06; P < .0001). Older age increased mortality risk by 1% per year (aOR, 1.01; P < .0001). Length of stay (LOS) increased mortality risk by 1% per bed day (aOR, 1.01; P < .0001). Central-line days increased mortality risk by 2% per central-line day (aOR, 1.02; P < .0001). Urinary catheter days increased mortality risk by 4% per urinary catheter day (aOR, 1.04; P < .0001). The highest mortality risks were associated with mechanical ventilation utilization ratio (aOR, 12.48; P < .0001), upper middle-income country (aOR, 1.09; P = .033), surgical hospitalization (aOR, 2.17; P < .0001), pediatric oncology ICU (aOR, 9.90; P < .0001), and adult oncology ICU (aOR, 4.52; P < .0001). Patients at university hospitals had the lowest mortality risk (aOR, 0.61; P < .0001). CONCLUSIONS: Some variables associated with an increased mortality risk are unlikely to change, such as age, sex, national economy, hospitalization type, and ICU type. Some other variables can be modified, such as LOS, central-line use, urinary catheter use, and mechanical ventilation as well as and acquisition of CLABSI, VAE, or CAUTI. To reduce mortality risk, we shall focus on strategies to reduce LOS; strategies to reduce central-line, urinary catheter, and mechanical ventilation use; and HAI prevention recommendations.