•Genetic and epidemiological evidence supports a severe asthma-PTSD association.•Asthma, particularly severe forms, involve mixed T helper Th2 and Th17 immune cells.•Links between Th2/Th17, and ...behavior are seen in rodent models of asthma and PTSD.•Peripheral immune-brain pathways may translate asthma inflammation to PTSD.
Posttraumatic stress disorder (PTSD) is a highly prevalent, debilitating mental health condition. A better understanding of contributory neurobiological mechanisms will lead to effective treatments, improving quality of life for patients. Given that not all trauma-exposed individuals develop PTSD, identification of pre-trauma susceptibility factors that can modulate posttraumatic outcomes is important. Recent clinical evidence supports a strong link between inflammatory conditions and PTSD. A particularly strong association has been reported between asthma and PTSD prevalence and severity. Unlike many other PTSD-comorbid inflammatory conditions, asthma often develops in children, sensitizing them to subsequent posttraumatic pathology throughout their lifetime. Currently, there is a significant need to understand the neurobiology, shared mechanisms, and inflammatory mediators that may contribute to comorbid asthma and PTSD. Here, we provide a translational perspective of asthma and PTSD risk and comorbidity, focusing on clinical associations, relevant rodent paradigms and potential mechanisms that may translate asthma-associated inflammation to PTSD development.
Aberrant activation of CD4 TH2 cells and excessive production of TH2 cytokines such as IL-4 and IL-13 have been implicated in the pathogenesis of allergic diseases. Generally, IL-4 and IL-13 utilize ...Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways for induction of inflammatory gene expression and the effector functions associated with disease pathology in many allergic diseases. However, it is increasingly clear that JAK/STAT pathways activated by IL-4/IL-13 can themselves be modulated in the presence of other intracellular signaling programs, thereby changing the overall tone and/or magnitude of IL-4/IL-13 signaling. Apart from direct activation of the canonic JAK/STAT pathways, IL-4 and IL-13 also induce proinflammatory gene expression and effector functions through activation of additional signaling cascades. These alternative signaling cascades contribute to several specific aspects of IL-4/IL-13–associated cellular and molecular responses. A more complete understanding of IL-4/IL-13 signaling pathways, including the precise conditions under which noncanonic signaling pathways are activated, and the impact of these pathways on cellular- and host-level responses, will better allow us to design agents that target specific pathologic outcomes or tailor therapies for the treatment of uncommon disease endotypes.
Severe asthma is associated with the production of interleukin 17A (IL-17A). The exact role of IL-17A in severe asthma and the factors that drive its production are unknown. Here we demonstrate that ...IL-17A mediated severe airway hyperresponsiveness (AHR) in susceptible strains of mice by enhancing IL-13-driven responses. Mechanistically, we demonstrate that IL-17A and AHR were regulated by allergen-driven production of anaphylatoxins, as mouse strains deficient in complement factor 5 (C5) or the complement receptor C5aR mounted robust IL-17A responses, whereas mice deficient in C3aR had fewer IL-17-producing helper T cells (T(H)17 cells) and less AHR after allergen challenge. The opposing effects of C3a and C5a were mediated through their reciprocal regulation of IL-23 production. These data demonstrate a critical role for complement-mediated regulation of the IL-23-T(H)17 axis in severe asthma.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background Increased IL-17A production has been associated with more severe asthma; however, the mechanisms whereby IL-17A can contribute to IL-13–driven pathology in asthmatic patients remain ...unclear. Objective We sought to gain mechanistic insight into how IL-17A can influence IL-13–driven responses. Methods The effect of IL-17A on IL-13–induced airway hyperresponsiveness, gene expression, mucus hypersecretion, and airway inflammation was assessed by using in vivo models of IL-13–induced lung pathology and in vitro culture of murine fibroblast cell lines and primary fibroblasts and human epithelial cell lines or primary human epithelial cells exposed to IL-13, IL-17A, or both. Results Compared with mice given intratracheal IL-13 alone, those exposed to IL-13 and IL-17A had augmented airway hyperresponsiveness, mucus production, airway inflammation, and IL-13–induced gene expression. In vitro , IL-17A enhanced IL-13–induced gene expression in asthma-relevant murine and human cells. In contrast to the exacerbating influence of IL-17A on IL-13–induced responses, coexposure to IL-13 inhibited IL-17A–driven antimicrobial gene expression in vivo and in vitro . Mechanistically, in both primary human and murine cells, the IL-17A–driven increase in IL-13–induced gene expression was associated with enhanced IL-13–driven signal transducer and activator of transcription 6 activation. Conclusions Our data suggest that IL-17A contributes to asthma pathophysiology by increasing the capacity of IL-13 to activate intracellular signaling pathways, such as signal transducer and activator of transcription 6. These data represent the first mechanistic explanation of how IL-17A can directly contribute to the pathogenesis of IL-13–driven pathology.
Parasitic helminths are a major cause of chronic human disease, affecting more than 3 billion people worldwide. Host protection against most parasitic helminths relies upon Type 2 cytokine ...production, but the mechanisms that regulate interleukin (IL) 4 and 13 production from CD4⁺ R helper 2 cells (TH2) and innate lymphoid type 2 cells (ILC2s) remain incompletely understood. The epithelial cell-derived cytokines IL-25 and IL-33 promote Type 2 responses, but the extent of functional redundancy between these cytokines is unclear and whether Type 2 memory relies upon either IL-25 or IL-33 is unknown. Herein, we demonstrate a pivotal role for IL-33 in driving primary and anamnestic immunity against the rodent hookworm Nippostrongylus brasiliensis. IL-33-def icient mice have a selective defect in ILC2-derived IL-13 during both primary and secondary challenge infections but generate stronger canonical CD4⁺ T helper 2 cells responses (IL-4, IgE, mast cells, and basophils) than WT controls. Lack of IL-13 production in IL-33-deficient mice impairs resistin-like molecule beta (RELMβ) expression and eosinophil recruitment, which are two mechanisms that eliminate N. brasiliensis parasites from infected hosts. Thus, IL-33 is requisite for IL-13 but not IL-4-driven Type 2 responses during hookworm infection.
Mechanistically, Perkins et al9 demonstrate that reduced responsiveness to effector TH2 cytokines observed in RAGE-deficient mice or after pharmacologic inhibition of RAGE was not due to altered ...levels of expression of the IL-4/IL-13 receptor components or protein levels of the downstream signaling mediator signal transducer and activator of transcription 6 (STAT6). ...after a single in vivo pulmonary challenge with rIL-13, comparable levels of activated phosphorylated signal transducer and activator of transcription 6 (pSTAT6) were observed in the lung just after exposure (10 minutes to 1 hour). ...when primary differentiated human bronchial epithelial cells were stimulated with rIL-13, pSTAT6 was still detected 48 hours later, whereas no pSTAT6 was detected when RAGE was blocked with the FPS-ZM1 antagonist. Because antagonization of key intracellular signaling events associated with asthma pathogenesis would have important therapeutic implications, Perkins et al9 also explored the potential ligands mediating the ability of RAGE signaling to facilitate sustained signaling after TH2 cytokine exposure.
Resident tissue myeloid cells play a role in many aspects of physiology including development of the vascular systems. In the blood vasculature, myeloid cells use VEGFC to promote angiogenesis and ...can use Wnt ligands to control vascular branching and to promote vascular regression. Here we show that myeloid cells also regulate development of the dermal lymphatic vasculature using Wnt ligands. Using myeloid-specific deletion of the WNT transporter Wntless we show that myeloid Wnt ligands are active at two distinct stages of development of the dermal lymphatics. As lymphatic progenitors are emigrating from the cardinal vein and intersomitic vessels, myeloid Wnt ligands regulate both their numbers and migration distance. Later in lymphatic development, myeloid Wnt ligands regulate proliferation of lymphatic endothelial cells (LEC) and thus control lymphatic vessel caliber. Myeloid-specific deletion of WNT co-receptor Lrp5 or Wnt5a gain-of-function also produce elevated caliber in dermal lymphatic capillaries. These data thus suggest that myeloid cells produce Wnt ligands to regulate lymphatic development and use Wnt pathway co-receptors to regulate the balance of Wnt ligand activity during the macrophage-LEC interaction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Maladaptive, Th2-polarized inflammatory responses are integral to the pathogenesis of allergic asthma. As regulators of T cell activation, dendritic cells (DCs) are important mediators of allergic ...asthma, yet the precise signals which render endogenous DCs "pro-asthmatic", and the extent to which these signals are regulated by the pulmonary environment and host genetics, remains unclear. Comparative phenotypic and functional analysis of pulmonary DC populations in mice susceptible (A/J), or resistant (C3H) to experimental asthma, revealed that susceptibility to airway hyperresponsiveness is associated with preferential myeloid DC (mDC) allergen uptake, and production of Th17-skewing cytokines (IL-6, IL-23), whereas resistance is associated with increased allergen uptake by plasmacytoid DCs. Surprisingly, adoptive transfer of syngeneic HDM-pulsed bone marrow derived mDCs (BMDCs) to the lungs of C3H mice markedly enhanced lung IL-17A production, and rendered them susceptible to allergen-driven airway hyperresponsiveness. Characterization of these BMDCs revealed levels of antigen uptake, and Th17 promoting cytokine production similar to that observed in pulmonary mDCs from susceptible A/J mice. Collectively these data demonstrate that the lung environment present in asthma-resistant mice promotes robust pDC allergen uptake, activation, and limits Th17-skewing cytokine production responsible for driving pathologic T cell responses central to the development of allergen-induced airway hyperresponsiveness.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background Carbon dioxide (CO2 ) inhalation, a biological challenge and pathologic marker in panic disorder, evokes intense fear and panic attacks in susceptible individuals. The molecular ...identity and anatomic location of CO2 -sensing systems that translate CO2 -evoked fear remain unclear. We investigated contributions of microglial acid sensor T cell death–associated gene-8 (TDAG8) and microglial proinflammatory responses in CO2 -evoked behavioral and physiological responses. Methods CO2 -evoked freezing, autonomic, and respiratory responses were assessed in TDAG8-deficient (–/– ) and wild-type (+/+ ) mice. Involvement of TDAG8-dependent microglial activation and proinflammatory cytokine interleukin (IL)-1β with CO2 -evoked responses was investigated using microglial blocker, minocycline, and IL-1β antagonist IL-1RA. CO2 -chemosensitive firing responses using single-cell patch clamping were measured in TDAG8–/– and TDAG8+/+ mice to gain functional insights. Results TDAG8 expression was localized in microglia enriched within the sensory circumventricular organs. TDAG8–/– mice displayed attenuated CO2 -evoked freezing and sympathetic responses. TDAG8 deficiency was associated with reduced microglial activation and proinflammatory cytokine IL-1β within the subfornical organ. Central infusion of microglial activation blocker minocycline and IL-1β antagonist IL-1RA attenuated CO2 -evoked freezing. Finally, CO2 -evoked neuronal firing in patch-clamped subfornical organ neurons was dependent on acid sensor TDAG8 and IL-1β. Conclusions Our data identify TDAG8-dependent microglial acid sensing as a unique chemosensor for detecting and translating hypercapnia to fear-associated behavioral and physiological responses, providing a novel mechanism for homeostatic threat detection of relevance to psychiatric conditions such as panic disorder.
Atopic status of the mother and maternal exposure to environmental factors are associated with increased asthma risk. Moreover, animal models demonstrate that exposure to allergens in strongly ...sensitized mothers influences offspring asthma development, suggesting that in utero exposures can influence offspring asthma. However, it is unclear whether maternal exposure to common human allergens such as house dust mite (HDM), in the absence of additional adjuvants, influences offspring asthma development.
We sought to determine whether maternal HDM exposure influences asthma development in offspring.
Pregnant female mice were exposed to PBS or HDM during pregnancy. Using offspring of PBS- or HDM-exposed mothers, the magnitude of HDM or Aspergillus fumigatus (AF) extract–induced airway hyperresponsiveness (AHR), airway inflammation, immunoglobulin production, TH2-associated cytokine synthesis, and pulmonary dendritic cell activity was assessed.
Compared with offspring of PBS-exposed mothers, offspring of HDM-exposed mothers demonstrate increased AHR, airway inflammation, TH2 cytokine production, and immunoglobulin levels and a modest decrease in the phagocytic capacity of pulmonary macrophage populations following HDM exposure. Increased sensitivity to AF-induced airway disease was not observed. Offspring of HDM-exposed B-cell–deficient mothers also demonstrated increased HDM-induced AHR, suggesting that transfer of maternal immunoglobulins is not required.
Our data demonstrate that maternal exposure to HDM during pregnancy increases asthma sensitivity in offspring in an HDM-specific manner, suggesting that vertical transmission of maternal immune responses may be involved. These findings have important implications for regulation of asthma risk, and suggest that exposure to HDM in the developed world may have underappreciated influences on the overall prevalence of allergic asthma.
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