RESUMO
Immune responses benefit organismal fitness by clearing parasites but also exact costs associated with immunopathology and energetic investment. Hosts manage these costs by tightly regulating the induction of immune signaling to curtail excessive responses and restore homeostasis. Despite the theoretical importance of turning off the immune response to mitigate these costs, experimentally connecting variation in the negative regulation of immune responses to organismal fitness remains a frontier in evolutionary immunology. In this study, we used a dose-response approach to manipulate the RNAi-mediated knockdown efficiency of cactus (IκBα), a central regulator of Toll pathway signal transduction in flour beetles (Tribolium castaneum). By titrating cactus activity across four distinct levels, we derived the shape of the relationship between immune response investment and traits associated with host fitness, including infection susceptibility, lifespan, fecundity, body mass, and gut homeostasis. Cactus knock-down increased the overall magnitude of inducible immune responses and delayed their resolution in a dsRNA dose-dependent manner, promoting survival and resistance following bacterial infection. However, these benefits were counterbalanced by dsRNA dose-dependent costs to lifespan, fecundity, body mass, and gut integrity. Our results allowed us to move beyond the qualitative identification of a trade-off between immune investment and fitness to actually derive its functional form. This approach paves the way to quantitatively compare the evolution and impact of distinct regulatory elements on life-history trade-offs and fitness, filling a crucial gap in our conceptual and theoretical models of immune signaling network evolution and the maintenance of natural variation in immune systems.
Assuntos
Parasitos , Tribolium , Animais , Aptidão Genética , Tribolium/genética , Tribolium/microbiologia , Fertilidade , Transdução de SinaisRESUMO
Invertebrates lack the immune machinery underlying vertebrate-like acquired immunity. However, in many insects past infection by the same pathogen can 'prime' the immune response, resulting in improved survival upon reinfection. Here, we investigated the mechanistic basis and epidemiological consequences of innate immune priming in the fruit fly Drosophila melanogaster when infected with the gram-negative bacterial pathogen Providencia rettgeri. We find that priming in response to P. rettgeri infection is a long-lasting and sexually dimorphic response. We further explore the epidemiological consequences of immune priming and find it has the potential to curtail pathogen transmission by reducing pathogen shedding and spread. The enhanced survival of individuals previously exposed to a non-lethal bacterial inoculum coincided with a transient decrease in bacterial loads, and we provide strong evidence that the effect of priming requires the IMD-responsive antimicrobial-peptide Diptericin-B in the fat body. Further, we show that while Diptericin B is the main effector of bacterial clearance, it is not sufficient for immune priming, which requires regulation of IMD by peptidoglycan recognition proteins. This work underscores the plasticity and complexity of invertebrate responses to infection, providing novel experimental evidence for the effects of innate immune priming on population-level epidemiological outcomes.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Imunidade Inata , Providencia , Animais , Drosophila melanogaster/microbiologia , Drosophila melanogaster/imunologia , Providencia/imunologia , Proteínas de Drosophila/imunologia , Feminino , Masculino , Infecções por Enterobacteriaceae/imunologia , Infecções por Enterobacteriaceae/transmissão , Peptídeos AntimicrobianosRESUMO
Host-associated microbiota play a fundamental role in the training and induction of different forms of immunity, including inducible as well as constitutive components. However, direct experiments analysing the relative importance of microbiota on diverse forms of evolved immune functions are missing. We addressed this gap by using experimentally evolved lines of Tribolium castaneum that either produced inducible immune memory-like responses (immune priming) or constitutively expressed basal resistance (without priming), as divergent counterstrategies against Bacillus thuringiensis infection. We altered the microbial communities present in the diet (i.e. wheat flour) of these evolved lines using UV irradiation and estimated the impact on the beetle's ability to mount a priming response versus basal resistance. Populations that had evolved immune priming lost the ability to mount a priming response upon alteration of diet microbiota. Microbiota manipulation also caused a drastic reduction in their reproductive output and post-infection longevity. In contrast, in pathogen-resistant beetles, microbiota manipulation did not affect post-infection survival or reproduction. The divergent evolution of immune responses across beetle lines was thus associated with divergent reliance on the microbiome. Whether the latter is a direct outcome of differential pathogen exposure during selection or reflects evolved immune functions remains unclear. We hope that our results will motivate further experiments to understand the mechanistic basis of these complex evolutionary associations between microbiota, host immune strategies and fitness outcomes.
Assuntos
Bacillus thuringiensis , Besouros , Microbiota , Tribolium , Animais , Farinha , Bacillus thuringiensis/fisiologia , Triticum , Tribolium/fisiologia , DietaRESUMO
The insect gut is frequently exposed to pathogenic threats and must not only clear these potential infections, but also tolerate relatively high microbe loads. In contrast to the mechanisms that eliminate pathogens, we currently know less about the mechanisms of disease tolerance. We investigated how well-described mechanisms that prevent, signal, control or repair damage during infection contribute to the phenotype of disease tolerance. We established enteric infections with the bacterial pathogen Pseudomonas entomophila in transgenic lines of Drosophila melanogaster fruit flies affecting dcy (a major component of the peritrophic matrix), upd3 (a cytokine-like molecule), irc (a negative regulator of reactive oxygen species) and egfr1 (epithelial growth factor receptor). Flies lacking dcy experienced the highest mortality, while loss of function of either irc or upd3 reduced tolerance in both sexes. The disruption of egfr1 resulted in a severe loss in tolerance in male flies but had no substantial effect on the ability of female flies to tolerate P. entomophila infection, despite carrying greater microbe loads than males. Together, our findings provide evidence for the role of damage limitation mechanisms in disease tolerance and highlight how sexual dimorphism in these mechanisms could generate sex differences in infection outcomes.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Animais , Bactérias/metabolismo , Drosophila , Proteínas de Drosophila/fisiologia , Drosophila melanogaster/fisiologia , Receptores ErbB , Feminino , MasculinoRESUMO
Evolutionary theory predicts a late-life decline in the force of natural selection, possibly leading to late-life deregulations of the immune system. A potential outcome of such deregulations is the inability to produce specific immunity against target pathogens. We tested this possibility by infecting multiple Drosophila melanogaster lines (with bacterial pathogens) across age groups, where either individual or different combinations of Imd- and Toll-inducible antimicrobial peptides (AMPs) were deleted using CRISPR gene editing. We show a high degree of non-redundancy and pathogen-specificity of AMPs in young flies: in some cases, even a single AMP could confer complete resistance. However, ageing led to drastic reductions in such specificity to target pathogens, warranting the action of multiple AMPs across Imd and Toll pathways. Moreover, use of diverse AMPs either lacked survival benefits or even accompanied survival costs post-infection. These features were also sexually dimorphic: females required a larger repertoire of AMPs than males but extracted equivalent survival benefits. Finally, age-specific expansion of the AMP-repertoire was accompanied with ageing-induced downregulation of negative-regulators of the Imd pathway and damage to renal function post-infection, as features of poorly regulated immunity. Overall, we could highlight the potentially non-adaptive role of ageing in producing less-specific AMP responses, across sexes and pathogens.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Animais , Feminino , Masculino , Envelhecimento , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Antimicrobianos , Drosophila melanogaster/genética , Imunidade InataRESUMO
Microbial metabolites produced by the gut microbiome, e.g. short-chain fatty acids (SCFA), have been found to influence lung physiology and injury responses. However, how lung immune activity is regulated by SCFA is unknown. We examined fresh human lung tissue and observed the presence of SCFA with interindividual variability. In vitro, SCFA were capable of modifying the metabolic programming in LPS-exposed alveolar macrophages (AM). We hypothesized that lung immune tone could be defined by baseline detection of lung intracellular IL-1ß. Therefore, we interrogated naïve mouse lungs with intact gut microbiota for IL-1ß mRNA expression and localized its presence within alveolar spaces, specifically within AM subsets. We established that metabolically active gut microbiota, which produce SCFA, can transmit LPS and SCFA to the lung and thereby could create primed lung immunometabolic tone. To understand how murine lung cells sensed and upregulated IL-1ß in response to gut microbiome-derived factors, we determined that, in vitro, AM and alveolar type II (AT2) cells expressed SCFA receptors, free fatty acid receptor 2 (FFAR2), free fatty acid receptor 3 (FFAR3), and IL-1ß but with distinct expression patterns and different responses to LPS. Finally, we observed that IL-1ß, FFAR2, and FFAR3 were expressed in isolated human AM and AT2 cells ex vivo, but in fresh human lung sections in situ, only AM expressed IL-1ß at rest and after LPS challenge. Together, this translational study using mouse and human lung tissue and cells point to an important role for the gut microbiome and their SCFA in establishing and regulating lung immune tone.
Assuntos
Ácidos Graxos Voláteis/farmacologia , Trato Gastrointestinal/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Interleucina-1beta/metabolismo , Lipopolissacarídeos/farmacologia , Pulmão/imunologia , Receptores Acoplados a Proteínas G/metabolismo , Animais , Feminino , Humanos , Interleucina-1beta/genética , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Receptores Acoplados a Proteínas G/genéticaRESUMO
In many insects, individuals primed with low doses of pathogens early in life have higher survival after exposure to the same pathogen later in life. Yet, our understanding of the evolutionary and ecological history of priming of immune response in natural insect populations is limited. Previous work demonstrated population-, sex- and stage-specific variation in the survival benefit of priming response in flour beetles (Tribolium castaneum) infected with their natural pathogen Bacillus thuringiensis. However, the evolutionary forces responsible for this natural variation remained unclear. In the present work, we tested whether the strength of the priming response (measured as the survival benefit after priming and subsequent infection, relative to unprimed controls) was associated with multiple fitness parameters and immune components across 10 flour beetle populations collected from different locations in India. Our results suggest two major selective pressures that may explain the observed inter-population variation in priming: (a) Basal pathogen susceptibility - populations that were more susceptible to infection produced a stronger priming response, and (b) Short-term early reproductive success - populations where primed females produced more offspring early in life (measured over 2 days) had lower survival benefit (measured over 120 days), suggesting a potential trade-off between early reproduction and priming response. However, the negative association between survival and reproduction is limited to priming and infection in adults, but not in larvae. While other components of beetle fitness (starvation resistance and larval development) and immune function (haemolymph antibacterial activity and antimicrobial quinone secretion) also varied widely across populations, none of them was correlated with the variation in priming responses across populations. Our work is the first systematic empirical demonstration of multiple selective pressures that may govern the evolution of immune priming in the wild. We hope that this motivates further experiments to establish the role of pathogen-imposed selection and fitness costs in the evolution of priming in natural insect populations.
Assuntos
Bacillus thuringiensis , Besouros , Tribolium , Animais , Feminino , Índia , LarvaRESUMO
N-Arachidonoyl dopamine (NADA) is an endogenous lipid that potently activates the transient receptor potential vanilloid 1 (TRPV1), which mediates pain and thermosensation. NADA is also an agonist of cannabinoid receptors 1 and 2. We have reported that NADA reduces the activation of cultured human endothelial cells by LPS and TNF-α. Thus far, in vivo studies using NADA have focused on its neurologic and behavioral roles. In this article, we show that NADA potently decreases in vivo systemic inflammatory responses and levels of the coagulation intermediary plasminogen activator inhibitor 1 in three mouse models of inflammation: LPS, bacterial lipopeptide, and polymicrobial intra-abdominal sepsis. We also found that the administration of NADA increases survival in endotoxemic mice. Additionally, NADA reduces blood levels of the neuropeptide calcitonin gene-related peptide but increases the neuropeptide substance P in LPS-treated mice. We demonstrate that the anti-inflammatory effects of NADA are mediated by TRPV1 expressed by nonhematopoietic cells and provide data suggesting that neuronal TRPV1 may mediate NADA's anti-inflammatory effects. These results indicate that NADA has novel TRPV1-dependent anti-inflammatory properties and suggest that the endovanilloid system might be targeted therapeutically in acute inflammation.
Assuntos
Ácidos Araquidônicos/farmacologia , Dopamina/análogos & derivados , Inflamação/metabolismo , Canais de Cátion TRPV/metabolismo , Doença Aguda , Animais , Ácidos Araquidônicos/metabolismo , Peptídeo Relacionado com Gene de Calcitonina/sangue , Modelos Animais de Doenças , Dopamina/metabolismo , Dopamina/farmacologia , Inflamação/imunologia , Lipopeptídeos/imunologia , Lipopolissacarídeos/imunologia , Camundongos , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Sepse/metabolismo , Substância P/sangueRESUMO
Under strong pathogen pressure, insects often evolve resistance to infection. Many insects are also protected via immune memory (immune priming), whereby sublethal exposure to a pathogen enhances survival after secondary infection. Theory predicts that immune memory should evolve when the pathogen is highly virulent, or when pathogen exposure is relatively rare. However, there are no empirical tests of these hypotheses, and the adaptive benefits of immune memory relative to direct resistance against a pathogen are poorly understood. To determine the selective pressures and ecological conditions that shape immune evolution, we imposed strong pathogen selection on flour beetle (Tribolium castaneum) populations, infecting them with Bacillus thuringiensis (Bt) for 11 generations. Populations injected first with heat-killed and then live Bt evolved high basal resistance against multiple Bt strains. By contrast, populations injected only with a high dose of live Bt evolved a less effective but strain-specific priming response. Control populations injected with heat-killed Bt did not evolve priming; and in the ancestor, priming was effective only against a low Bt dose. Intriguingly, one replicate population first evolved priming and subsequently evolved basal resistance, suggesting the potential for dynamic evolution of different immune strategies. Our work is the first report showing that pathogens can select for rapid modulation of insect priming ability, allowing hosts to evolve divergent immune strategies (generalized resistance versus specific immune memory) with potentially distinct mechanisms.
Assuntos
Bacillus thuringiensis/fisiologia , Evolução Biológica , Interações Hospedeiro-Patógeno , Memória Imunológica , Tribolium/imunologia , Animais , Tribolium/microbiologiaRESUMO
In most animals, ageing is associated with a decline in immune function (immune senescence). However, different components of the immune system seem to age differentially, and many studies do not measure the ultimate fitness consequences of immune function after infection. Previous work shows that immune function may be traded off with other fitness components such as reproduction. It is possible that age alters the nature of these trade-offs, particularly in conjunction with factors such as gender and mating that can also affect investment in immune function. We tested the impact of age, sex and mating on post-infection survivorship in Tribolium castaneum flour beetles, as well as the components of baseline constitutive innate immunity and external (secreted) immune function in uninfected individuals. We also tested whether the reproductive ability of uninfected females is traded off with immune function (baseline innate and external immunity) and post-infection survivorship across age groups. We found that age, sex and mating significantly affected immune components and infection outcome, although the magnitude and nature of the impact varied in each case. We found that older beetles were more susceptible to infection by the pathogen Bacillus thuringiensis even though major components of the constitutive innate immune defence (antibacterial and phenoloxidase activity) remained unchanged or improved with age. Thus, these aspects of innate immunity cannot explain the observed decline in post-infection survival of older beetles. We did not find trade-offs between the reproductive ability of uninfected females and their immune function. In contrast to innate immunity, external immunity showed an overall decline with age but was also affected by sex and mating. Finally, we show that bacterial infection alters external immunity via complex interactions between age, sex and mating status. Our work uncovers novel interactions between age, sex and mating that can determine the evolution and outcome of immunosenescence by affecting the time course of relative investment in different immune and fitness components.
Assuntos
Bacillus thuringiensis/fisiologia , Imunossenescência , Tribolium/microbiologia , Tribolium/fisiologia , Fatores Etários , Animais , Feminino , Imunidade Inata , Longevidade , Masculino , Fatores Sexuais , Comportamento Sexual Animal , Tribolium/imunologiaRESUMO
The early sequence of events leading to the development of the acute respiratory distress syndrome (ARDS) in patients with sepsis remains inadequately understood. The purpose of this study was to identify changes in gene expression early in the course of illness, when mechanisms of injury may provide the most relevant treatment and prognostic targets. We collected whole blood RNA in critically ill patients admitted from the Emergency Department to the intensive care unit within 24 h of admission at a tertiary care center. Whole genome expression was compared in patients with sepsis and ARDS to patients with sepsis alone. We selected genes with >1 log2 fold change and false discovery rate <0.25, determined their significance in the literature, and performed pathway analysis. Several genes were upregulated in 29 patients with sepsis with ARDS compared with 28 patients with sepsis alone. The most differentially expressed genes included key mediators of the initial neutrophil response to infection: olfactomedin 4, lipocalin 2, CD24, and bactericidal/permeability-increasing protein. These gene expression differences withstood adjustment for age, sex, study batch, white blood cell count, and presence of pneumonia or aspiration. Pathway analysis demonstrated overrepresentation of genes involved in known respiratory and infection pathways. These data indicate that several neutrophil-related pathways may be involved in the early pathogenesis of sepsis-related ARDS. In addition, identifiable gene expression differences occurring early in the course of sepsis-related ARDS may further elucidate understanding of the neutrophil-related mechanisms in progression to ARDS.
Assuntos
Síndrome do Desconforto Respiratório/sangue , Sepse/sangue , Transcriptoma , Proteínas de Fase Aguda/genética , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Feminino , Humanos , Lipocalina-2 , Lipocalinas/sangue , Lipocalinas/genética , Masculino , Pessoa de Meia-Idade , Anotação de Sequência Molecular , Neutrófilos/fisiologia , Proteínas Proto-Oncogênicas/sangue , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/sangue , RNA Mensageiro/genética , Síndrome do Desconforto Respiratório/etiologia , Síndrome do Desconforto Respiratório/genética , Síndrome do Desconforto Respiratório/imunologia , Sepse/complicações , Sepse/genética , Sepse/imunologiaRESUMO
Gut microbial products are known to act both locally within the intestine and get absorbed into circulation, where their effects can extend to numerous distant organ systems. Short-chain fatty acids (SCFA) are one class of metabolites produced by gut microbes during the fermentation of indigestible dietary fiber. They are now recognized as important contributors to how the gut microbiome influences extra-intestinal organ systems via the gut-lung, gut-brain, and other gut-organ axes throughout the host. SCFAs are absorbed from the colon, through intestinal tissue, into the portal vein (PV). They then pass through the liver, and are consumed in various organs such as the brain, muscle, adipose tissue, and lungs. SCFAs are most easily measured in the expelled fecal material however, more accurate measurements have been obtained from intra-colonic fecal contents. Here we propose that sampling PV and systemic circulating plasma of a single subject may be preferable for studying the absorption, transport, and systemic levels of SCFAs in mice. We present a new technique for efficient blood sampling from the PV and inferior vena cava (IVC) that allows for the collection of relatively large volumes of blood from the portal and systemic circulations. This is accomplished by ligating the PV, thereby allowing for the dilation or enlargement of the PV as it backfills from the mesenteric veins that drain into it. Using this method, we were able to improve the rate of successful collection as well as the total amount of blood collected (up to 0.3 mL from IVC and 0.5 mL from PV).
Assuntos
Microbioma Gastrointestinal , Veia Porta , Veia Cava Inferior , Animais , Camundongos , Veia Porta/metabolismo , Microbioma Gastrointestinal/fisiologia , Veia Cava Inferior/metabolismo , Ácidos Graxos Voláteis/metabolismo , Ácidos Graxos Voláteis/análise , Coleta de Amostras Sanguíneas/métodos , MasculinoRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Rheumatoid arthritis (RA) is a multifactorial, polygenic inflammatory disease. Mesua assamica (King & Prain) Kosterm. (MA) is an endangered medicinal plant indigenous to South Asia, primarily to Assam in India. The tree bark is claimed to possess anti-inflammatory, anti-diabetic, anti-cancer, and anti-malarial properties; nevertheless, its role in RA has not been elucidated. Hence, this study aims to investigate the in-vitro and in-vivo anti-arthritic effects of Mesua assamica bark ethanolic extract (MAE). AIM OF THE STUDY: This study aims to investigate the anti-rheumatic potential of MAE in-vitro on RAW 264.7 cells for its anti-oxidant and anti-inflammatory activities and in-vivo on the CFA-induced adjuvant arthritis in the rat model. MATERIALS AND METHODS: We investigated the possible therapeutic effects of MAE in-vitro using RAW 264.7 cells triggered by LPS. Meanwhile, adult Wistar rats were injected intradermally with 100 µl of CFA to induce arthritis, and they were given MAE orally at doses of 100 and 200 mg/kg for up to 28 days. Paw volume analysis, X-ray radiography, anti-oxidant levels analysis, gene and protein expression studies, and histological analysis were carried out to assess the effects of MAE in-vivo. RESULTS: MAE significantly mitigated the inflammation by reducing ROS levels and dropped the nitrite, PGE2, and COX-2 levels enhanced by LPS in-vitro. At the same time, MAE treatment reduced the paw and joint inflammation and increased the immune organ index in the CFA rats. Histopathology data revealed that MAE mitigated the CFA-induced lesions of the ankle joints and synovial tissues. Similarly, MAE significantly abated the secretion of pro-inflammatory cytokines, inhibited the protein expression of TLR4, NF-кB, COX-2, and iNOS, as well as improved the Nrf2 and HO-1 levels in-vitro and in-vivo. CONCLUSION: All the results highlighted the anti-rheumatic potential of MAE in RA in-vitro and in-vivo by inhibiting the TLR4/NF-кB/COX-2/iNOS and promoting the Nrf2/HO-1 signaling axis.
Assuntos
Artrite Experimental , Artrite Reumatoide , Ciclo-Oxigenase 2 , Etanol , Fator 2 Relacionado a NF-E2 , NF-kappa B , Casca de Planta , Extratos Vegetais , Receptor 4 Toll-Like , Animais , Extratos Vegetais/farmacologia , Células RAW 264.7 , Camundongos , Casca de Planta/química , Receptor 4 Toll-Like/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Artrite Reumatoide/tratamento farmacológico , NF-kappa B/metabolismo , Artrite Experimental/tratamento farmacológico , Artrite Experimental/patologia , Etanol/química , Ciclo-Oxigenase 2/metabolismo , Masculino , Ratos , Ratos Wistar , Regulação para Baixo/efeitos dos fármacos , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/isolamento & purificação , Antioxidantes/farmacologia , Transdução de Sinais/efeitos dos fármacos , Heme Oxigenase (Desciclizante)/metabolismo , Antirreumáticos/farmacologia , Antirreumáticos/isolamento & purificação , Heme Oxigenase-1/metabolismo , Proteínas de MembranaRESUMO
Gummies belong to a confectionery category characterized by a hydrocolloid, acting as a stabilizer, forming a network to retain a high-moisture sugar syrup, and hydrocolloids play a key role in shaping the visual appeal, flavour release, and texture of the gel network. This study investigates the potential substitution of gelatin in gummies with plant-based hydrocolloids like agar-agar and guar gum. It is also aimed at optimizing the level of functional ingredients like curcumin and piperine in standardized gummies through incorporation of turmeric and black pepper, respectively. These plant-based gelling agents mimic gelatin's chewable, firm, and elastic texture, catering to broader consumption and suitability for versatile use. Consumer interest in healthier diets has spurred the transition towards plant-based functional foods, leading to the replacement of gelatin gummies with plant-based alternatives. Agar-agar significantly influences gummy texture by contributing to firmness, elasticity, and stable gel formation, imparting essential strength and consistency. Guar gum, recognized as a plant-based hydrocolloid, enhances gummy texture, consistency, and moisture retention through thickening and stabilization. While agar-agar and guar gum individually fell short in achieving the desired textural attributes in the gummies, their combined use (1% agar-agar and 5.5% guar gum) yielded optimal chewiness (1,455.12 ± 1.75 N), gumminess (2251.11 ± 2.14 N), and high overall acceptability (8.96), resembling gelatin-based gummies. The optimized formulation included 40% sugar, 2% citric acid, 2% turmeric, and 0.6% black pepper. The developed vegan gummies contained 56.9 ± 0.09 mg/100 g total phenols, 37.27 ± 1.4% antioxidant capacity, 0.054 ± 0.0012% curcumin, and 0.02 ± 0.008% piperine. Consequently, the combined use of agar-agar and guar gum emerged as stable and effective gelling agents, offering an alternative to gelatin for creating turmeric and black pepper-infused gummies with desirable texture and functional attributes.
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Energetic resources fuel immune responses and parasite growth within organisms, but it is unclear whether energy allocation is sufficient to explain changes in infection outcomes under the threat of multiple parasites. We manipulated diet in flour beetles (Tribolium confusum) infected with two natural parasites to investigate the role of resources in shifting metabolic and immune responses after single and co-infection. Our results suggest that gregarine parasites alter the within-host energetic environment, and by extension juvenile development time, in a diet-dependent manner. Gregarines do not affect host resistance to acute bacterial infection but do stimulate the expression of an alternative set of immune genes and promote damage to the gut, ultimately contributing to reduced survival regardless of diet. Thus, energy allocation is not sufficient to explain the immunological contribution to coinfection outcomes, emphasizing the importance of mechanistic insight for predicting the impact of coinfection across levels of biological organization.
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TLR2 activation induces cellular and organ inflammation and affects lung function. Because deranged endothelial function and coagulation pathways contribute to sepsis-induced organ failure, we studied the effects of bacterial lipoprotein TLR2 agonists, including peptidoglycan-associated lipoprotein, Pam3Cys, and murein lipoprotein, on endothelial function and coagulation pathways in vitro and in vivo. TLR2 agonist treatment induced diverse human endothelial cells to produce IL-6 and IL-8 and to express E-selectin on their surface, including HUVEC, human lung microvascular endothelial cells, and human coronary artery endothelial cells. Treatment of HUVEC with TLR2 agonists caused increased monolayer permeability and had multiple coagulation effects, including increased production of plasminogen activator inhibitor-1 (PAI-1) and tissue factor, as well as decreased production of tissue plasminogen activator and tissue factor pathway inhibitor. TLR2 agonist treatment also increased HUVEC expression of TLR2 itself. Peptidoglycan-associated lipoprotein induced IL-6 production by endothelial cells from wild-type mice but not from TLR2 knockout mice, indicating TLR2 specificity. Mice were challenged with TLR2 agonists, and lungs and plasmas were assessed for markers of leukocyte trafficking and coagulopathy. Wild-type mice, but not TLR2 mice, that were challenged i.v. with TLR2 agonists had increased lung levels of myeloperoxidase and mRNAs for E-selectin, P-selectin, and MCP-1, and they had increased plasma PAI-1 and E-selectin levels. Intratracheally administered TLR2 agonist caused increased lung fibrin levels. These studies show that TLR2 activation by bacterial lipoproteins broadly affects endothelial function and coagulation pathways, suggesting that TLR2 activation contributes in multiple ways to endothelial activation, coagulopathy, and vascular leakage in sepsis.
Assuntos
Anticoagulantes/fisiologia , Coagulação Sanguínea/imunologia , Endotélio Vascular/fisiologia , Proteínas de Escherichia coli/fisiologia , Lipoproteínas/fisiologia , Peptidoglicano/farmacologia , Transdução de Sinais/imunologia , Receptor 2 Toll-Like/agonistas , Animais , Anticoagulantes/agonistas , Anticoagulantes/farmacologia , Permeabilidade Capilar/imunologia , Linhagem Celular , Endotélio Vascular/citologia , Endotélio Vascular/imunologia , Proteínas de Escherichia coli/agonistas , Humanos , Imunofenotipagem , Lipoproteínas/agonistas , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor 2 Toll-Like/deficiência , Receptor 2 Toll-Like/fisiologia , Regulação para Cima/imunologiaRESUMO
Disease tolerance describes an infected host's ability to maintain health independently of the ability to clear microbe loads. The Jak/Stat pathway plays a pivotal role in humoral innate immunity by detecting tissue damage and triggering cellular renewal, making it a candidate tolerance mechanism. Here, we find that in Drosophila melanogaster infected with Pseudomonas entomophila disrupting ROS-producing dual oxidase (duox) or the negative regulator of Jak/Stat Socs36E, render male flies less tolerant. Another negative regulator of Jak/Stat, G9a - which has previously been associated with variable tolerance of viral infections - did not affect the rate of mortality with increasing microbe loads compared to flies with functional G9a, suggesting it does not affect tolerance of bacterial infection as in viral infection. Our findings highlight that ROS production and Jak/Stat signalling influence the ability of flies to tolerate bacterial infection sex-specifically and may therefore contribute to sexually dimorphic infection outcomes in Drosophila.
Assuntos
Proteínas de Drosophila , Drosophila , Masculino , Animais , Drosophila melanogaster , Transdução de Sinais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Janus Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fatores de Transcrição STAT/metabolismoRESUMO
Immune responses benefit organismal fitness by clearing parasites but also exact costs associated with immunopathology and energetic investment. Hosts manage these costs by tightly regulating the induction of immune signaling to curtail excessive responses and restore homeostasis. Despite the theoretical importance of turning off the immune response to mitigate these costs, experimentally connecting variation in the negative regulation of immune responses to organismal fitness remains a frontier in evolutionary immunology. In this study, we used a dose-response approach to manipulate the RNAi-mediated knockdown efficiency of cactus (IκBα), a central regulator of Toll pathway signal transduction in flour beetles (Tribolium castaneum). By titrating cactus activity along a continuous gradient, we derived the shape of the relationship between immune response investment and traits associated with host fitness, including infection susceptibility, lifespan, fecundity, body mass, and gut homeostasis. Cactus knock-down increased the overall magintude of inducible immune responses and delayed their resolution in a dsRNA dose-dependent manner, promoting survival and resistance following bacterial infection. However, these benefits were counterbalanced by dsRNA dose-dependent costs to lifespan, fecundity, body mass, and gut integrity. Our results allowed us to move beyond the qualitative identification of a trade-off between immune investment and fitness to actually derive its functional form. This approach paves the way to quantitatively compare the evolution and impact of distinct regulatory elements on life-history trade-offs and fitness, filling a crucial gap in our conceptual and theoretical models of immune signaling network evolution and the maintenance of natural variation in immune systems.
RESUMO
Ulcerative colitis (UC) is an idiopathic, chronic disorder of the intestines characterized by excessive inflammation and oxidative stress. Loganic acid (LA) is an iridoid glycoside reported to have antioxidant and anti-inflammatory properties. However, the beneficial effects of LA on UC are unexplored yet. Thus, this study aims to explore the potential protective effects of LA and its possible mechanisms. In-vitro models were employed using LPS-stimulated RAW 264.7 macrophage cells, and Caco-2 cells, whereas an in-vivo model of ulcerative colitis was employed using 2.5% DSS in BALB/c mice. Results indicated that LA significantly suppressed the intracellular ROS levels and inhibited the phosphorylation of NF-κB in both RAW 264.7 and Caco-2 cells, contrarily LA activated the Nrf2 pathway in RAW 264.7 cells. In DSS-induced colitis mice, LA significantly alleviated the inflammation and colonic damage by decreasing the pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α, and IFN-γ), oxidative stress markers (MDA, and NO), and also expression levels of various inflammatory proteins (TLR4 and NF-кB) which was evidenced by immunoblotting. On the contrary, the release of GSH, SOD, HO-1, and Nrf2 were profoundly increased upon LA treatment.Subsequently, molecular docking studies showed that LA interacts with active site regions of target proteins (TLR4, NF-κB, SIRT1, and Nrf2) through hydrogen bonding and salt bridge interaction. The current findings demonstrated that LA could exhibit a protective effect in DSS-induced ulcerative colitis through its anti-inflammatory and anti-oxidant effects via inactivating the TLR4/NF-κB signaling pathway and activating the SIRT1/Nrf2 pathways.
Assuntos
Colite Ulcerativa , Humanos , Camundongos , Animais , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/tratamento farmacológico , NF-kappa B/metabolismo , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Fator 2 Relacionado a NF-E2/metabolismo , Receptor 4 Toll-Like/metabolismo , Sirtuína 1 , Simulação de Acoplamento Molecular , Células CACO-2 , Inflamação/tratamento farmacológico , Anti-Inflamatórios/efeitos adversos , Sulfato de DextranaRESUMO
Lung immune tone, i.e. the immune state of the lung, can vary between individuals and over a single individual's lifetime, and its basis and regulation in the context of inflammatory responses to injury is poorly understood. The gut microbiome, through the gut-lung axis, can influence lung injury outcomes but how the diet and microbiota affect lung immune tone is also unclear. We hypothesized that lung immune tone would be influenced by the presence of fiber-fermenting short-chain fatty acid (SCFA)-producing gut bacteria. To test this hypothesis, we conducted a fiber diet intervention study followed by lung injury in mice and profiled gut microbiota using 16S sequencing, metabolomics, and lung immune tone. We also studied germ-free mice to evaluate lung immune tone in the absence of microbiota and performed in vitro mechanistic studies on immune tone and metabolic programming of alveolar macrophages exposed to the SCFA propionate (C3). Mice on high-fiber diet were protected from sterile lung injury compared to mice on a fiber-free diet. This protection strongly correlated with lower lung immune tone, elevated propionate levels and enrichment of specific fecal microbiota taxa; conversely, lower levels of SCFAs and an increase in other fatty acid metabolites and bacterial taxa correlated with increased lung immune tone and increased lung injury in the fiber-free group. In vitro , C3 reduced lung alveolar macrophage immune tone (through suppression of IL-1ß and IL-18) and metabolically reprogrammed them (switching from glycolysis to oxidative phosphorylation after LPS challenge). Overall, our findings reveal that the gut-lung axis, through dietary fiber intake and enrichment of SCFA-producing gut bacteria, can regulate innate lung immune tone via IL-1ß and IL-18 pathways. These results provide a rationale for the therapeutic development of dietary interventions to preserve or enhance specific aspects of host lung immunity.