Oncostatin M expression induced by bacterial triggers drives airway inflammatory and mucus secretion in severe asthma

[Figure: see text].

Nutrient Sensing in CD11c Cells Alters the Gut Microbiota to Regulate Food Intake and Body Mass

Microbial dysbiosis and inflammation are implicated in diet-induced obesity and insulin resistance. However, it is not known whether crosstalk between immunity and microbiota also regulates metabolic homeostasis in healthy animals. Here, we report that genetic deletion of tuberous sclerosis 1 (Tsc1) in CD11c⁺ myeloid cells (Tsc1^f/fCD11c^Cre mice) reduced food intake and body mass in the absence of metabolic disease. Co-housing and fecal transplant experiments revealed a dominant role for the healthy gut microbiota in regulation of body weight. 16S rRNA sequencing, selective culture, and reconstitution experiments further confirmed that selective deficiency of Lactobacillus johnsonii Q1-7 contributed to decreased food intake and body mass in Tsc1^f/fCD11c^Cre mice. Mechanistically, activation of mTORC1 signaling in CD11c cells regulated production of L. johnsonii Q1-7-specific IgA, allowing for its stable colonization in the gut. Together, our findings reveal an unexpected transkingdom immune-microbiota feedback loop for homeostatic regulation of food intake and body mass in mammals.

Energetic Trade-Offs and Hypometabolic States Promote Disease Tolerance

Host defenses against pathogens are energetically expensive, leading ecological immunologists to postulate that they might participate in energetic trade-offs with other maintenance programs. However, the metabolic costs of immunity and the nature of physiologic trade-offs it engages are largely unknown. We report here that activation of immunity causes an energetic trade-off with the homeothermy (the stable maintenance of core temperature), resulting in hypometabolism and hypothermia. This immunity-induced physiologic trade-off was independent of sickness behaviors but required hematopoietic sensing of lipopolysaccharide (LPS) via the toll-like receptor 4 (TLR4). Metabolomics and genome-wide expression profiling revealed that distinct metabolic programs supported entry and recovery from the energy-conserving hypometabolic state. During bacterial infections, hypometabolic states, which could be elicited by competition for energy between maintenance programs or energy restriction, promoted disease tolerance. Together, our findings suggest that energy-conserving hypometabolic states, such as dormancy, might have evolved as a mechanism of tissue tolerance.

Warming the mouse to model human diseases

Humans prefer to live within their thermal comfort or neutral zone, which they create by making shelters, wearing clothing and, more recently, by regulating their ambient temperature. These strategies enable humans to maintain a constant core temperature (a trait that is conserved across all endotherms, including mammals and birds) with minimal energy expenditure. Although this primordial drive leads us to seek thermal comfort, we house our experimental animals, laboratory mice (Mus musculus), under conditions of thermal stress. In this Review, we discuss how housing mice below their thermoneutral zone limits our ability to model and study human diseases. Using examples from cardiovascular physiology, metabolic disorders, infections and tumour immunology, we show that certain phenotypes observed under conditions of thermal stress disappear when mice are housed at thermoneutrality, whereas others emerge that are more consistent with human biology. Thus, we propose that warming the mouse might enable more predictive modelling of human diseases and therapies.

Adipocyte JAK2 mediates growth hormone-induced hepatic insulin resistance

For nearly 100 years, growth hormone (GH) has been known to affect insulin sensitivity and risk of diabetes. However, the tissue governing the effects of GH signaling on insulin and glucose homeostasis remains unknown. Excess GH reduces fat mass and insulin sensitivity. Conversely, GH insensitivity (GHI) is associated with increased adiposity, augmented insulin sensitivity, and protection from diabetes. Here, we induce adipocyte-specific GHI through conditional deletion of Jak2 (JAK2A), an obligate transducer of GH signaling. Similar to whole-body GHI, JAK2A mice had increased adiposity and extreme insulin sensitivity. Loss of adipocyte Jak2 augmented hepatic insulin sensitivity and conferred resistance to diet-induced metabolic stress without overt changes in circulating fatty acids. While GH injections induced hepatic insulin resistance in control mice, the diabetogenic action was absent in JAK2A mice. Adipocyte GH signaling directly impinged on both adipose and hepatic insulin signal transduction. Collectively, our results show that adipose tissue governs the effects of GH on insulin and glucose homeostasis. Further, we show that JAK2 mediates liver insulin sensitivity via an extrahepatic, adipose tissue-dependent mechanism.

Thermoneutral Housing Accelerates Metabolic Inflammation to Potentiate Atherosclerosis but Not Insulin Resistance

Chronic, low-grade inflammation triggered by excess intake of dietary lipids has been proposed to contribute to the pathogenesis of metabolic disorders, such as obesity, insulin resistance, type 2 diabetes, and atherosclerosis. Although considerable evidence supports a causal association between inflammation and metabolic diseases, most tests of this link have been performed in cold-stressed mice that are housed below their thermoneutral zone. We report here that thermoneutral housing of mice has a profound effect on the development of metabolic inflammation, insulin resistance, and atherosclerosis. Mice housed at thermoneutrality develop metabolic inflammation in adipose tissue and in the vasculature at an accelerated rate. Unexpectedly, this increased inflammatory response contributes to the progression of atherosclerosis but not insulin resistance. These findings not only suggest that metabolic inflammation can be uncoupled from obesity-associated insulin resistance, but also point to how thermal stress might limit our ability to faithfully model human diseases in mice.

Metabolic regulation of immune responses

The immune system defends against pathogens and maintains tissue homeostasis for the life of the organism. These diverse functions are bioenergetically expensive, requiring precise control of cellular metabolic pathways. Although initial observations in this area were made almost a century ago, studies over the past decade have elucidated the molecular basis for how extracellular signals control the uptake and catabolism of nutrients in quiescent and activated immune cells. Collectively, these studies have revealed that the metabolic pathways of oxidative metabolism, glycolysis, and glutaminolysis preferentially fuel the cell fate decisions and effector functions of immune cells. Here, we discuss these findings and provide a general framework for understanding how metabolism fuels and regulates the maturation of immune responses. A better understanding of the metabolic checkpoints that control these transitions might provide new insights for modulating immunity in infection, cancer, or inflammatory disorders.

Hypothalamic inflammation and the central nervous system control of energy homeostasis

The control of energy homeostasis relies on robust neuronal circuits that regulate food intake and energy expenditure. Although the physiology of these circuits is well understood, the molecular and cellular response of this program to chronic diseases is still largely unclear. Hypothalamic inflammation has emerged as a major driver of energy homeostasis dysfunction in both obesity and anorexia. Importantly, this inflammation disrupts the action of metabolic signals promoting anabolism or supporting catabolism. In this review, we address the evidence that favors hypothalamic inflammation as a factor that resets energy homeostasis in pathological states.

Adipose tissue macrophages: Amicus adipem?

Chronic overnutrition drives complex adaptations within both professional metabolic and bystander tissues that, despite intense investigation, are still poorly understood. Xu et al. (2013) now describe the unexpected ability of adipose tissue macrophages to buffer lipids released from obese adipocytes in a manner independent of inflammatory macrophage activation.

TGF-β1 limits the onset of innate lung inflammation by promoting mast cell-derived IL-6

TGF-β1 is an important suppressive mediator of inflammation, but it can also drive fibrosis and remodeling in the lung. In response to intratracheal LPS, neutrophils migrate into the lung, and TGF-β1 was suggested to protect against the ensuing injury. However, the mechanisms for this protective role remain unknown. Using a model of acute lung injury, we demonstrate that TGF-β1 decreases neutrophil numbers during the onset of injury. This was due to increased apoptosis rather than reduced migration. We demonstrate that TGF-β1 does not directly regulate neutrophil apoptosis but instead functions through IL-6 to promote neutrophil clearance. rIL-6 is sufficient to promote neutrophil apoptosis and reduce neutrophilia in bronchoalveolar lavage fluid, while IL-6 increases rapidly following LPS-induced injury. Mast cells are a critical source of IL-6, because mast cell-deficient mice exhibit increased neutrophil numbers that are reduced by reconstitution with wild-type, but not IL-6(-/-), mast cells. Although IL-6 diminishes neutrophilia in mast cell-deficient mice, TGF-β1 is ineffective, suggesting that these effects were mast cell dependent. Taken together, our findings establish a novel pathway through which TGF-β1, likely derived from resident regulatory T cells, controls the severity and magnitude of early innate inflammation by promoting IL-6 from mast cells.

Regulatory T cells enhance mast cell production of IL-6 via surface-bound TGF-β

Mast cell degranulation is a hallmark of allergic reactions, but mast cells can also produce many cytokines that modulate immunity. Recently, CD25(+) regulatory T cells (Tregs) have been shown to inhibit mast cell degranulation and anaphylaxis, but their influence on cytokine production remained unknown. In this study, we show that, rather than inhibit, Tregs actually enhance mast cell production of IL-6. We demonstrate that, whereas inhibition of degranulation was OX40/OX40 ligand dependent, enhancement of IL-6 was due to TGF-β. Interestingly, our data demonstrate that the Treg-derived TGF-β was surface-bound, because the interaction was contact dependent, and no TGF-β was detectable in the supernatant. Soluble TGF-β1 alone was sufficient to enhance mast cell IL-6 production, and these supernatants were sufficient to promote Th17 skewing, but those from Treg-mast cell cultures were not, supporting this being surface-bound TGF-β from the Tregs. Interestingly, the augmentation of IL-6 production occurred basally or in response to innate stimuli (LPS or peptidoglycan), adaptive stimuli (IgE cross-linking by specific Ag), and cytokine activation (IL-33). We demonstrate that TGF-β led to enhanced transcription and de novo synthesis of IL-6 upon activation without affecting IL-6 storage or mRNA stability. In vivo, the adoptive transfer of Tregs inhibited mast cell-dependent anaphylaxis in a model of food allergy but promoted intestinal IL-6 and IL-17 production. Consequently, our findings establish that Tregs can exert divergent influences upon mast cells, inhibiting degranulation via OX40/OX40 ligand interactions while promoting IL-6 via TGF-β.

Immunocomplexes down-modulate the induction of food allergy in mouse through CD32b- and IL-21-dependent mechanisms. (55.7)

Food allergy is an adverse Th2 response whose incidence has been increasing dramatically. Previously, we have demonstrated that immunocomplexes(IC) decrease the food allergic responses. Thus, we hypothesize that inhibitory FcR is triggered by IC in food allergy. Here we investigated the contribution of CD32b signaling in the down-modulatory effect of IC in a mouse food allergy model. Wild type(WT) or CD16-/- or CD64-/- or CD32b-/- or IL-21R-/-mice were sensitized by gavage for 8 weeks with SEB, SEB+OVA or SEB+OVA-IC and challenged on the 9th week with OVA. We demonstrated that OVA-IC-sensitized WT, CD16-/- or CD64-/- mice produced lower levels of serum IgE, IL-4, IL-5, and have decreased blood eosinophilia compared to OVA group. In contrast, OVA-IC-sensitized CD32b-/- mice did present food allergic responses similar to OVA group. In addition, IL-21 levels were high in OVA-IC-sensitized WT, CD16-/-, CD64-/- mice, but in CD32-/- mice, in comparison to OVA group. Besides, OVA-IC-sensitized IL-21R-/- mice restored the food allergic responses, similar to OVA group. In conclusion, IC down-regulates the food allergic response in WT, CD16-/-, CD64-/- mice but in CD32b-/- indicating that CD32b plays a role in the down-modulatory effect of IC. Besides, IC stimulate the production of IL-21 and up-regulate food allergic responses in IL-21R-/- mice, suggesting that down-modulation induced by IC is mediated by IL-21-dependent mechanism.

Regulatory T cells enhance mast cell production of IL6 via a TGFβ dependent innate mechanism (168.20)

Recently, Tregs have been proposed to limit mast cell degranulation upon antigen stimulation. However, mast cells also produce many cytokines that regulate both innate and adaptive immunity. Here we show that Tregs inhibit mast cell (BMMC) degranulation but, surprisingly, promotes IL6 in response to innate (LPS or PGN) and adaptive (IgE) activation. This required cell-cell contact and did not require activation via the TCR. Blockade of OX40/OX40L pathway inhibited the Treg effects on BMMC degranulation but had no effect on IL6 production. Conversely, blockade of surface bound-TGFβ ablated IL6 production, suggesting that Tregs influence mast cell responses via distinct mechanisms. Furthermore, TGFβ was sufficient to promote enhanced IL6 but had no effect on degranulation. In innate immunity, IL6 and Tregs have been suggested to influence neutrophil clearance and resolution of inflammation. In an LPS-driven model of lung injury, Treg depletion elevated lung neutrophilia in response to LPS. Similarly, mast cell deficient mice displayed significantly elevated neutrophilia in the lung that was fully corrected upon reconstitution with wildtype mast cells but not by IL6 deficient mast cells, suggesting a critical role for mast cell derived IL-6 in neutrophil clearance during innate inflammation. Our data suggests that Tregs are important in limiting the severity of the inflammatory response during innate activation and that they may do so by promoting mast cell production of IL-6.

Immunocomplexes down-modulate the induction of food allergy in mouse. (97.12)

Food allergy is an adverse Th2 response whose incidence has been increasing dramatically over the past decade. We have demonstrated that signaling triggered by immunocomplexes (IC) through CD16 (FcgRIII) in conjunction with TLR4 prime dendritic cells (DCs) to drive Th2 responses. To address our hypothesis that IgG plays a role in the pathogenesis of food allergy in a murine model, we investigated the contribution of CD16 signaling. Wild type (WT) or CD16-/- mice were sensitized by gavage for 8 weeks with SEB, SEB+OVA or SEB+OVA-IC and challenged on the 9th week. To analyze the systemic responses, blood eosinophilia and OVA-specific serum IgE and IgG1 levels were measured. We found that CD16-/- had reduced responses compared to WT, however, both SEB+OVA-IC-immunized WT and CD16-/- mice had lower responses compared to SEB+OVA immunized controls. To investigate the effect of IC in DC functions, naïve WT and CD16-/- BMDCs were stimulated with SEB with either OVA or OVA-IC, and DC maturation and survival were determined. Compared to SEB-OVA stimulation, SEB+OVA-IC-stimulated WT and CD16-/- BMDCs have similar maturation, but a decrease in late apoptotic cells. Our findings suggest that ICs down-regulate the allergic response in the gut of WT and CD16-/- mice leading to lower systemic responses, and yet preserves DC functions. Thus, IC might induce a regulatory network in the gut mucosal that allows sensitization, but fails to trigger an exacerbated inflammatory response.

Ameliorative effect of DRDE 07 and its analogues on the systemic toxicity of sulphur mustard and nitrogen mustard in rabbit

Despite extensive research efforts, there is no unanimous approval of any animal model to evaluate the toxicity of sulphur mustard [SM; bis (2-chloroethyl) sulphide] or nitrogen mustard [HN-3; tris-(2-chloroethyl) amine] and screening of various prophylactic and therapeutic agents against them. In this study, differential toxicity of mustard agents in higher animal model that is male rabbit was determined. Protective efficacy of DRDE 07 [S-2(2-aminoethylamino) ethyl phenyl sulphide] and its analogues were also evaluated against SM and HN-3 toxicity. Differential toxicity study of SM and HN-3 reveals that both the compounds were more toxic by percutaneous route as compared to subcutaneous route. Till date, there is no recommended drug to counteract SM induced toxicity or mortality in vivo. However, DRDE 07 (an amifostine analogue) and its analogues are found to be very effective protective agents against percutaneously exposed SM in rabbits. The present experiments also showed that SM does not cause skin injury alone but also can cause systemic toxicity as well. DRDE 07 and many of its analogues may prove as prototype compounds for the development of better prophylactic and therapeutic drugs to counter the toxicity of SM or HN-3. In conclusion, rodents and rabbits can be used for the screening of drugs against the blistering agents.

Impairing oral tolerance promotes allergy and anaphylaxis: a new murine food allergy model

BACKGROUND

Food allergy is a disorder in which antigenic food proteins elicit immune responses. Animal models of food allergy have several limitations that influence their utility, including failure to recapitulate several key immunologic hallmarks. Consequently, little is known regarding the pathogenesis and mechanisms leading to food allergy. Staphylococcus aureus-derived enterotoxins, a common cause of food contamination, are associated with antigen responses in atopic dermatitis.

OBJECTIVE

We hypothesized that S aureus-derived enterotoxins might influence the development of food allergy. We examined the influence of administration of staphylococcal enterotoxin B (SEB) with food allergens on immunologic responses and compared these responses with those elicited by a cholera toxin-driven food allergy model.

METHODS

Oral administration of ovalbumin or whole peanut extract with or without SEB was performed once weekly. After 8 weeks, mice were challenged with oral antigen alone, and the physiologic and immunologic responses to antigen were studied.

RESULTS

SEB administered with antigen resulted in immune responses to the antigen. Responses were highly T(H)2 polarized, and oral challenge with antigen triggered anaphylaxis and local and systemic mast cell degranulation. SEB-driven sensitization induced eosinophilia in the blood and intestinal tissues not observed with cholera toxin sensitization. SEB impaired tolerance specifically by impairing expression of TGF-beta and regulatory T cells, and tolerance was restored with high-dose antigen.

CONCLUSIONS

We demonstrate a new model of food allergy to oral antigen in common laboratory strains of mice that recapitulates many features of clinical food allergy that are not seen in other models. We demonstrate that SEB impairs oral tolerance and permits allergic responses.

Adsorptive removal of water poisons from contaminated water by adsorbents

Adsorptive removal of water poisons such as Pb(II), Cu(II), Mn(II), Hg(II), CN(-), microbes, nerve and blister agents (concentration range from 100 to 1000 mg/L) were studied by using adsorbents such as active carbon, impregnated carbon and bentonite loaded fabric strip. Removal of water poisons (99.5%) could be achieved with an optimum stirring time of 5-15 min and weight of adsorbent of 0.8-8.0 g/100mL contaminated water, respectively. However, 85% bentonite loading was found to be most effective for Pb(II) removal. Effect of contaminants concentration was also studied.

Phosphorus 31 solid state NMR characterization of oligonucleotides covalently bound to a solid support

31P cross polarization (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra were acquired for various linear and branched di- and tri-nucleotides attached to a controlled pore glass (CPG) solid support. The technique readily distinguishes the oxidation state of the phosphorus atom (phosphate versus phosphate), the presence or absence of a protecting group attached directly to phosphorus (cyanoethyl), and other large changes in the phosphorus chemistry (phosphate versus phosphorothioate). However, differences in configurational details remote from the phosphorus atom, such as the attachment position of the ribose sugar (2'5' versus 3'5'), or the particulars of the nucleotide bases (adenine versus uridine versus thymine), could not be resolved. When different stages of the oligonucleotide synthetic cycle were examined, 31P CPMAS NMR revealed that the cyanoethyl protecting group is removed during the course of chain assembly.

Yeast lariat debranching enzyme. Substrate and sequence specificity

Yeast RNA lariat debranching enzyme has been purified to near homogeneity using a bacterial overproducer of the enzyme. The enzyme is capable of digesting a variety of branched nucleic acid substrates, including group II intron lariats, multicopy single-stranded DNAs (msDNAs), and a variety of synthetic branched RNAs. A trinucleotide release assay using radiolabeled msDNA substrates was developed and used to determine the basic biochemical parameters for the enzyme. The debranching enzyme shows a strong preference for purines at the 2'-position in both msDNA and synthetic branched RNA substrates, in accord with the structure of its native substrate, which always has a 2'-G residue. The use of small synthetic branched RNA substrates will allow systematic mechanistic and structural studies of this unique enzyme.

Solid-phase synthesis of branched oligoribonucleotides related to messenger RNA splicing intermediates

The chemical synthesis of oligoribonucleotides containing vicinal (2'-5')- and (3'-5')-phosphodiester linkages is described. The solid-phase method, based on silyl-phosphoramidite chemistry, was applied to the synthesis of a series of branched RNA [(Xp)nA2' (pN)n3'(pN)n] related to the splicing intermediates derived from Saccharomyces cerevisiae rp51a pre-messenger RNA. The branched oligonucleotides have been thoroughly characterized by nucleoside and branched nucleotide composition analysis. Branched oligoribonucleotides will be useful in the study of messenger RNA splicing and in determining the biological role of RNA 'lariats' and 'forks' in vivo.

Recognition of neuropeptides FMRFamide and LPLRFamide by chicken cerebellum avian pancreatic polypeptide binding sites

Binding isotherms were constructed for the binding of synthetic tetrapeptide and pentapeptide fragments to membranes prepared from chicken cerebellar tissue. Both the tetrapeptide (FMRFamide), which was originally isolated from ganglia of mollusks, and the pentapeptide (LPLRFamide) previously isolated from chicken brain are known to increase blood pressure and modulate brain neurons in rats. The C-terminal dipeptide sequences of the two peptides are identical and both show similarity to the dipeptide sequence established for the pancreatic polypeptide (PP) family. Specific high-affinity binding sites exist for the latter peptide, sites which are competed for (though with less affinity) by neuropeptide Y (NPY). Affinity for cerebellar membranes was virtually equivalent for the synthetic peptide LPLRFamide and FRMFamide; the binding affinities (IC50) of all fragments tested (C-terminal pentapeptides of avian PP and NPY, and FMRFamide and LPLRFamide) fell in the same approximate range. Since the N-terminal residues of FMRFamide and LPLRFamide are not homologous with equivalent residues of APP or NPY, our results indicate that only Arg-Tyr-NH2 or Arg-Phe-NH2 sequences are necessary for binding of the carboxy terminus peptides of the PP family. In this respect, these sequences are functionally equivalent.