Disease tolerance as a defense strategy

Plasmodium falciparum infection induces T cell tolerance that is associated with decreased disease severity upon re-infection

Immunity to severe malaria is acquired quickly, operates independently of pathogen load, and represents a highly effective form of disease tolerance. The mechanism that underpins tolerance remains unknown. We used a human rechallenge model of falciparum malaria in which healthy adult volunteers were infected three times over a 12 mo period to track the development of disease tolerance in real-time. We found that parasitemia triggered a hardwired innate immune response that led to systemic inflammation, pyrexia, and hallmark symptoms of clinical malaria across the first three infections of life. In contrast, a single infection was sufficient to reprogram T cell activation and reduce the number and diversity of effector cells upon rechallenge. Crucially, this did not silence stem-like memory cells but instead prevented the generation of cytotoxic effectors associated with autoinflammatory disease. Tolerized hosts were thus able to prevent collateral tissue damage in the absence of antiparasite immunity.

To be or not to be: the non-antimicrobial properties of common antimicrobials

Antibiotics are diverse in their utility in clinical care. They are widely prescribed for their antimicrobial effect and used as modulators, although rarely, of non-infectious conditions, to influence immune responses, to decrease morbidity and improve quality of life. This review provides a concise summary of different classes of antibiotics and their unique properties that allow them to be used in the treatment of non-infectious conditions.

Effects on digestive enzyme activities in the house crickets Acheta domesticus exposed to graphene oxide in food for several generations

Increasing usage of nanoparticles or nanomaterials may lead to their release into the environment. The toxicity of these structures, classified as contaminants of emerging concern, is not yet sufficiently understood. However, as in the case of other environmental stressors, the effects of exposure to them should be analyzed on a multigenerational scale to predict the consequences for exposed populations. Therefore, this project aimed to assess the impact of graphene oxide (GO) nanomaterial on digestive enzyme activities in the house cricket Acheta domesticus as a model species, depending on GO concentration (0.2 or 0.02 µg·g-1 dry weight of food), previous selection for longevity and the number of generations (1-5) that have occurred since the beginning of exposure. The last and sixth generations were insects for which GO was withdrawn from the diet (recovery generation). Enzymatic activity was tested using API Zym kit modified for spectrophotometric reads. The tests revealed that GO intervenes with some digestive enzymes. Moreover, the effects of GO depend on the population's previous selection for longevity. The impact of mechanisms mitigating the consequences of aging supports the possible tolerance to GO intoxication. It demonstrated itself in diverse patterns of multigenerational response to GO in wild and long-lived insects. Also, multigenerational exposure revealed the 'third generation' effect. Finally, the impact of GO elimination depended on the concentration of nanomaterial used for the tests. Also, the potential impact of concentration-dependent agglomeration of GO in the context of hormesis has been discussed.

Nerve- and airway-associated interstitial macrophages mitigate SARS-CoV-2 pathogenesis via type I interferon signaling

Despite vaccines, rapidly mutating viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to threaten human health due to an impaired immunoregulatory pathway and a hyperactive immune response. Our understanding of the local immune mechanisms used by tissue-resident macrophages to safeguard the host from excessive inflammation during SARS-CoV-2 infection remains limited. Here, we found that nerve- and airway-associated interstitial macrophages (NAMs) are required to control mouse-adapted SARS-CoV-2 (MA-10) infection. Control mice restricted lung viral distribution and survived infection, whereas NAM depletion enhanced viral spread and inflammation and led to 100% mortality. Mechanistically, type I interferon receptor (IFNAR) signaling by NAMs was critical for limiting inflammation and viral spread, and IFNAR deficiency in CD169+ macrophages mirrored NAM-depleted outcomes and abrogated their expansion. These findings highlight the essential protective role of NAMs in regulating viral spread and inflammation, offering insights into SARS-CoV-2 pathogenesis and underscoring the importance of NAMs in mediating host immunity and disease tolerance.

Heterogeneity in and correlation between host transmissibility and susceptibility can greatly impact epidemic dynamics

While it is well established that host heterogeneity in transmission and host heterogeneity in susceptibility each individually impact disease dynamics in characteristic ways, it is generally unknown how disease dynamics are impacted when both types of heterogeneity are simultaneously present. Here we explore this question. We first conducted a systematic review of published studies from which we determined that the effects of correlations have been drastically understudied. We then filled in the knowledge gaps by developing and analyzing a stochastic, individual-based SIR model that includes both heterogeneity in transmission and susceptibility and flexibly allows for positive or negative correlations between transmissibility and susceptibility. We found that in comparison to the uncorrelated case, positive correlations result in major epidemics that are larger, faster, and more likely, whereas negative correlations result in major epidemics that are smaller and less likely. We additionally found that, counter to the conventional wisdom that heterogeneity in susceptibility always reduces outbreak size, heterogeneity in susceptibility can lead to major epidemics that are larger and more likely than the homogeneous case when correlations between transmissibility and susceptibility are positive, but this effect only arises at small to moderateR 0 . Moreover, positive correlations can frequently lead to major epidemics even with subcriticalR 0 . To illustrate the potential importance of heterogeneity and correlations, we developed an SEIR model to describe mpox disease dynamics in New York City, demonstrating that the dynamics of a 2022 outbreak can be reasonably well explained by the presence of positive correlations between susceptibility and transmissibility. Ultimately, we show that correlations between transmissibility and susceptibility profoundly impact disease dynamics.

Itaconate: A Potential Therapeutic Strategy for Autoimmune Disease

Itaconate is a metabolite of the Krebs cycle, and endogenous itaconate is driven by a variety of innate signals that inhibit the production of inflammatory cytokines. The key mechanism of action of itaconate was initially found to be the competitive inhibition of succinate dehydrogenase (SDH), which inhibits the production of inflammatory factors, as well as its antioxidant effects. With increasing research, it was discovered that it modifies cysteine residues of related proteins through the Michael addition, such as modifying the Kelch-like ECH-associated protein 1 (KEAP1) protein and activating the nuclear factor erythroid 2-related factor 2 (NRF2) signalling pathway, as well as glycolytic enzymes and cellular pathway-associated factors that attenuate inflammatory responses and oxidative stress. It also acts on a variety of immune cells, affecting their function and activity, and has been increasingly shown to play a therapeutic role in a variety of inflammatory and autoimmune diseases through a combination of these mechanisms. In conclusion, there has been a great breakthrough in the research of itaconate, from the initial industrial application to the redefinition of the biological functions of itaconate. However, with the deepening of the research, we also found that there are more questions: the mechanism of action of itaconate, more functions of itaconate, clinical application of itaconate, and the use of itaconate still needs to be solved.

Mycoplasma gallisepticum (MG) infection inhibits mitochondrial respiratory function in a wild songbird

An animal's immune function is vital for survival but is potentially metabolically expensive. Some pathogens can manipulate their hosts' immune and metabolic responses. One example is Mycoplasma gallisepticum (MG), which infects both the respiratory system and conjunctiva of the eye in house finches (Haemorhous mexicanus). MG has been shown to exhibit immune- and metabolic-suppressive properties, but the physiological mechanisms are still unknown. Recent studies demonstrated that mitochondria could serve as powerhouses for both ATP production and immunity, notably inflammatory processes, by regulating complex II and its metabolites. Consequently, in this study, we investigate the short-term (3 days post-inoculation) and long-term (34 days post-inoculation) effects of MG infection on the hepatic mitochondrial respiration of house finches from two populations infected with two different MG isolates. After short-term infection, MG-infected birds had significantly lower state 2 and state 4 respiration, but only when using complex II substrates. After long-term infection, MG-infected birds exhibited lower state 3 respiration with both complex I and II substrates, resulting in a lower respiratory control ratio compared with uninfected controls, which aligned with the hypothesized metabolic-suppressive properties of MG. Interestingly, there were limited differences in mitochondrial respiration regardless of house finch population of origin, MG isolate and whether birds recovered from infection or not. We propose that MG targets mitochondrial complex II for its immune-suppressive properties during the early stages of infection and inhibits mitochondrial respiration for its metabolic-suppressive properties at a later stage of infection, both of which should delay recovery of the host and extend infectious periods.

Genetic estimates and genome-wide association studies of antibody response in Tanzanian dairy cattle

Identifying the genetic determinants of host defence against infectious pathogens is central to enhancing disease resilience and therapeutic efficacy in livestock. Here, we investigated immune response heritability to important infectious diseases affecting smallholder dairy cattle using variance component analysis. We also conducted genome-wide association studies (GWAS) to identify genetic variants that may help understand the underlying biology of these health traits. By assessing 668,911 single-nucleotide polymorphisms (SNPs) genotyped in 2,045 crossbred cattle sampled from six regions of Tanzania, we identified high levels of interregional admixture and European introgression, which may increase infectious disease susceptibility relative to indigenous breeds. Heritability estimates were low to moderate, ranging from 0.03 (SE ± 0.06) to 0.44 (SE ± 0.07), depending on the health trait. GWAS results revealed several loci associated with seropositivity to the viral diseases Rift Valley fever and bovine viral diarrhoea, the protozoan parasites Neospora caninum and Toxoplasma gondii, and the bacterial pathogens Brucella sp, Leptospira hardjo, and Coxiella burnetii. The identified quantitative trait loci mapped to genes involved in immune defence, tumour suppression, neurological processes, and cell exocytosis. We propose that our results provide a basis for future understanding of the cellular pathways contributing to general and taxon-specific infection responses, and for advancing selective breeding and therapeutic target design.

Assessment of Oxidative Stress and Associated Biomarkers in Wild Avian Species

Reactive oxygen species (ROS) are natural by-products of cellular metabolism and are also formed in response to environmental stressors such as pollution, extreme temperatures, and ultraviolet radiation exposure. Physiological factors such as intense activity, growth, reproduction, nutrient deficiency, captivity, and disease also contribute to ROS production. While ROS, including free radicals, play a key role in cell physiology, including immune defense, their excessive accumulation can damage cellular components and cause oxidative stress when antioxidant defenses are overwhelmed. To regulate ROS levels, wild birds rely on enzymatic (e.g., catalase, superoxide dismutase, glutathione peroxidase) and non-enzymatic antioxidants (e.g., vitamins C and E, carotenoids). Oxidative stress affects important aspects of wild bird biology, including health, reproduction, and survival, and is closely linked to overall fitness. It is also linked to physiological challenges such as migration and the progression of various diseases affecting wild bird populations. The study of oxidative stress in wild birds requires the use of appropriate biomarkers to assess its role in disease development. A deeper understanding of the balance between ROS production and antioxidant defenses is essential to determine how wild birds cope with environmental and physiological challenges. In this review, we summarize the mechanisms of oxidative stress in wild birds and the role of antioxidants in maintaining health and promoting longevity in wild bird populations.

A type 1 immune-stromal cell network mediates disease tolerance against intestinal infection

Type 1 immunity mediates host defense through pathogen elimination, but whether this pathway also impacts tissue function is unknown. Here, we demonstrate that rapid induction of interferon γ (IFNγ) signaling coordinates a multicellular response that is critical to limit tissue damage and maintain gut motility following infection of mice with a tissue-invasive helminth. IFNγ production is initiated by antigen-independent activation of lamina propria CD8+ T cells following MyD88-dependent recognition of the microbiota during helminth-induced barrier invasion. IFNγ acted directly on intestinal stromal cells to recruit neutrophils that limited parasite-induced tissue injury. IFNγ sensing also limited the expansion of smooth muscle actin-expressing cells to prevent pathological gut dysmotility. Importantly, this tissue-protective response did not impact parasite burden, indicating that IFNγ supports a disease tolerance defense strategy. Our results have important implications for managing the pathophysiological sequelae of post-infectious gut dysfunction and chronic inflammatory diseases associated with stromal remodeling.

Therapeutic activation of IL-22-producing innate lymphoid cells enhances host defenses to Clostridioides difficile infection

Clostridioides difficile causes debilitating colitis via secreted toxins that disrupt the intestinal barrier, and toxemia is associated with severe disease. Thus, therapies that fortify the intestinal barrier will reduce the severity of infection. Innate lymphoid cells (ILCs) are critical in the defense against acute C. difficile infection and represent a promising therapeutic target to limit disease. Here, we report that oral administration of the Toll-like receptor (TLR) 7 agonist R848 limits intestinal damage and protects mice from lethal C. difficile infection without impacting pathogen burden or altering the intestinal microbiome. R848 induced interleukin (IL)-22 secretion by ILCs, leading to STAT3 phosphorylation in the intestinal epithelium and increased stem cell proliferation. Genetic ablation of ILCs, IL-22, or epithelial-specific STAT3 abrogated R848-mediated protection. R848 reduced intestinal permeability following infection and limited systemic toxin dissemination. Combined, these data identify an immunostimulatory molecule that activates IL-22 production in ILCs to enhance host tissue defenses following C. difficile infection.

Host life stage susceptibility to the chytrid fungus in a Neotropical torrent frog

Pathogen-host systems become complex when they involve life histories with multiple stages. Understanding these complexities is particularly important for investigating the infection dynamics of the amphibian pathogen Batrachochytrium dendrobatidis (Bd). Here, we investigate whether Bd infection susceptibility differs between host life stages and determine the influence of environmental factors on Bd infection rates across remnant populations of a Neotropical torrent frog. We found that Bd infection probability varies between tadpoles and adults in Hylodes phyllodes, with tadpoles exhibiting a higher likelihood of infection. Tadpoles are tolerant to Bd, acting as zoospore reservoirs, potentially aiding in the pathogen's persistence in the environment and infecting other susceptible hosts. Topographic complexity, species richness, the human footprint, precipitation seasonality and diurnal temperature variations influenced Bd infection rates. Conservation strategies should encompass both host life stages, monitoring from larvae to adults, while also evaluating threats synergistically, such as the human footprint, to effectively predict and mitigate the impact of Bd on susceptible populations.

Early Growth Response Factor 4 (EGR4) Expression in Gut Tissues and Regional Lymph Nodes of Cattle with Different Types of Paratuberculosis-Associated Lesions: Potential Role of EGR4 in Resilience to Paratuberculosis

Summary-data-based Mendelian randomization (SMR) analysis identified a novel cis-expression quantitative loci (cis-eQTL) associated with the upregulation of the expression of the early growth response factor 4 (EGR4) gene in animals with paratuberculosis (PTB)-associated multifocal lesions, which has been suggested to be modulating the NF-kβ-induced proinflammatory immune response to Mycobacterium avium subsp. paratuberculosis (Map) infection. To confirm these findings and to study the role of EGR4 expression in PTB resilience, the number of EGR4-expressing cells were analysed in paraffin-fixed gut tissues and regional lymph nodes of naturally Map-infected Holstein Friesian cows with focal, multifocal (subclinical and clinical), and diffuse lesions (intermediate and multibacillary), and in controls without lesions by quantitative anti-EGR4 immunohistochemistry. Subclinical animals with multifocal lesions showed a significantly higher number of EGR4-positive cells and were sacrificed at a significantly older average age than the remaining groups (p < 0.001 in all cases). We hypothesize that EGR4 could be mitigating the negative impact of Map infection on host clinical status through its involvement in three molecular mechanisms that promote resilience: (i) limiting NF-kβ-mediated proinflammatory responses, (ii) controlling tissue damage, acting as a brake on T-cell proliferation and cytokine production, and (iii) favouring tissue repair through interaction with epidermal growth factor receptor (EGFR).

STAT Signature Dish: Serving Immunity with a Side of Dietary Control

Immunity is a fundamental aspect of animal biology, defined as the host's ability to detect and defend against harmful pathogens and toxic substances to preserve homeostasis. However, immune defenses are metabolically demanding, requiring the efficient allocation of limited resources to balance immune function with other physiological and developmental needs. To achieve this balance, organisms have evolved sophisticated signaling networks that enable precise, context-specific responses to internal and external cues. These networks are essential for survival and adaptation in multicellular systems. Central to this regulatory architecture is the STAT (signal transducer and activator of Transcription) family, a group of versatile signaling molecules that govern a wide array of biological processes across eukaryotes. STAT signaling demonstrates remarkable plasticity, from orchestrating host defense mechanisms to regulating dietary metabolism. Despite its critical role, the cell-specific and context-dependent nuances of STAT signaling remain incompletely understood, highlighting a significant gap in our understanding. This review delves into emerging perspectives on immunity, presenting dynamic frameworks to explore the complexity and adaptability of STAT signaling and the underlying logic driving cellular decision-making. It emphasizes how STAT pathways integrate diverse physiological processes, from immune responses to dietary regulation, ultimately supporting organismal balance and homeostasis.

BMP-Dependent Mobilization of Fatty Acid Metabolism Promotes Caenorhabditis elegans Survival on a Bacterial Pathogen

The Bone Morphogenetic Proteins (BMPs) are secreted peptide ligands of the Transforming Growth Factor beta (TGF-β) family, initially identified for their roles in development and differentiation across animal species. They are now increasingly recognized for their roles in physiology and infectious disease. In the nematode Caenorhabditis elegans, the BMP ligand DBL-1 controls fat metabolism and immune response, in addition to its roles in body size regulation and development. DBL-1 regulates classical aspects of innate immunity, including the induction of anti-microbial peptides. We theorized that BMP-dependent regulation of fat metabolism could also promote resilience against microbial pathogens. We found that exposure to a bacterial pathogen alters total fat stores, lipid droplet dynamics, and lipid metabolism gene expression in a BMP-dependent manner. We further showed that fatty acid desaturation plays a major role in survival on a bacterial pathogen, while fatty acid β-oxidation plays a more minor role. We conclude that C. elegans mobilizes fatty acid metabolism in response to pathogen exposure to promote survival. Our investigation provides a framework to study potential metabolic interventions that could support therapeutics that are complementary to antibiotic strategies.

S100A9 in sepsis: A biomarker for inflammation and a mediator of organ damage

Sepsis is the body's response to infection, which can result in multiple organ failure. The immune imbalance in patients with sepsis leads to high mortality. Recent research has greatly advanced our understanding of sepsis pathophysiology, especially in the regulation of inflammatory pathways and immune suppression. S100A9, an alarmin, plays a critical role in modulating the immune response during sepsis and is associated with the potential for multiple organ dysfunction. In the early stage of sepsis, S100A9 can represent the occurrence of inflammation, while in the late stage of sepsis, S100A9 is related to immune suppression. This review summarizes the latest developments in S100A9 research, including its biological functions, role in immune responses, effects on organ damage across different systems during sepsis, and potential clinical applications. It provides insights into the interactions between S100A9 and the immune response and explores S100A9's involvement in sepsis-associated organ injuries. Additionally, this review outlines a framework for future applications of targeted S100A9 interventions and therapeutic strategies to reduce organ injury in sepsis.

Dissecting transmission to understand parasite evolution

Parasite transmission is a complex, multi-stage process that significantly impacts host-parasite dynamics. Transmission plays a key role in epidemiology and virulence evolution, where it is expected to trade off with virulence. However, the extent to which classical models on virulence-transmission relationships apply in the real world is unclear. This insight piece proposes a novel framework that breaks transmission into three distinct stages: within-host infectiousness, an intermediate between-host stage (biotic or abiotic), and new host infection. Each stage is influenced by intrinsic and extrinsic factors to the parasite, which together will determine its transmission success. Analyzing the transmission stages separately and how they affect each other might enhance our understanding of which host-, parasite- or environmental-driven factors might shape parasite evolution and inform us about new effectors to act on when designing disease control strategies.

Ambient temperature leads to differential immune strategies in the subterranean rodent Ctenomys talarum

Animal thermoregulation may have significant costs and compete directly or indirectly with other energetically demanding processes, such as immune function. Although the subterranean environment is characterized by thermally stable conditions, small changes in ambient temperature could be critical in shaping immunity. However, little is known about the effects of ambient temperature, in naturally varying ranges, on immunity of wild species. Therefore, to evaluate the effect of short-term exposure to ambient temperatures on energy metabolism and body temperature during the acute phase immune response (APR) in the subterranean rodent Ctenomys talarum, 70 adult animals were divided into three experimental groups and exposed twice for 1 h to 15, 25 or 32°C (below, at or near the upper limit of the thermoneutral zone, respectively) before and after injection with saline (control) or lipopolysaccharide (LPS, which induces the APR). Animals exposed to 25 and 32°C showed a similar APR pattern, characterized by fever (average: 37.1 and 37.7°C, respectively), a 16% increase in O2 consumption and an increase in the neutrophil/lymphocyte ratio (N/L). Body mass loss and symptoms of sickness behavior were detected from 3 and 1 h post-injection, respectively. Individuals exposed to 15°C increased their metabolic rate by 60%, showed frequent hypothermia (34.3°C on average) and the characteristic N/L increase was attenuated. Body mass loss and sickness behavior were mostly detected 24 h post-injection. Our results suggest that the thermoregulation costs in C. talarum may limit the energy available for immunity, leading to different strategies to cope with infection.

Host Disease Tolerance Predicts Transmission Probability for a Songbird Pathogen

Disease tolerance reduces the per-pathogen fitness costs of infection for hosts and is an important component of host adaptation to pathogens. However, how disease tolerance affects host transmission potential is not well understood, especially because there are many potential mechanisms that facilitate host tolerance. For example, tissue-specific host tolerance leads to the reduction of host pathology, regardless of pathogen load. Hosts may also exhibit behavioral tolerance, where normal behaviors are maintained even while harboring high pathogen loads. Here, we examined the impacts that tissue-specific and behavioral tolerance have on transmission in house finches (Haemorhous mexicanus) infected with a common and highly transmissible bacterial pathogen, Mycoplasma gallisepticum (MG). MG causes conjunctivitis in house finches and severely reduces population numbers after it arrives in a new area. Wild house finch populations differ in tissue-specific tolerance to MG and here we assessed how this variation in tolerance influences transmission success. We inoculated wild-captured, MG-naïve individuals from two populations that are on the extremes of tissue-specific tolerance to MG and determined the likelihood of these "index" individuals transmitting MG to an uninfected, susceptible cagemate. Higher tissue-specific tolerance results in reduced conjunctivitis, which is associated with decreased deposition and spread of MG. Thus, we predicted that individuals with high tissue-specific tolerance would be less likely to transmit MG. In contrast, we predicted that behavioral tolerance would be linked to higher transmission, as more tolerant individuals spent more time on a feeder shared with a susceptible individual despite high pathogen loads. In agreement with our prediction, individuals with high tissue-specific tolerance were less likely to transmit MG. However, there was no effect of behavioral tolerance on the likelihood of MG transmission. Our results highlight that it is key to consider how different mechanisms of tolerance affect transmission and, therefore, host-pathogen coevolution and epidemic dynamics.

Systemic infection by Candida albicans requires FASN-α subunit induced cell wall remodeling to perturb immune response

Invasive fungal infections are a leading cause of mortality and morbidity in patients with severely impaired host defenses, while treatment options remain limited. Fatty acid synthase (FASN), the key enzyme regulating de novo biosynthesis of fatty acids, is crucial for the lethal infection of fungi; however, its pathogenic mechanism is still far from clear. Here, we identified the α subunit of FASN as a potential immunotherapeutic target against systemic Candida albicans infection. The avirulence of the encoded gene (FAS2) -deleted mutant in a mouse model of systemic candidiasis is not due to its fitness defects, because sufficient exogenous fatty acids in serum can overcome FASN inhibition. However, the FAS2-deleted mutant displays increased circulating innate immune responses and enhances activated neutrophil fungicidal activity through the unmasking of immunogenic cell wall epitopes via the Rho-1 dependent Mkc1-MAPK signaling pathway, which facilitates fungal clearance, reduces renal tissue damage and inflammatory cell infiltration, ultimately lowers fungal pathogenicity. Priming with the FAS2-deleted mutant provided significant protection against subsequent lethal infection with wild-type C. albicans in mice as early as one week, and it was well-tolerated with limited toxicity. Our findings indicate that the FASN-α subunit plays key roles in the regulation of neutrophil-associated antifungal immunity and could be a potential target for immunotherapeutic intervention.

Quantifying intraspecific variation in host resistance and tolerance to a lethal pathogen

Testing for intraspecific variation for host tolerance or resistance in wild populations is important for informing conservation decisions about captive breeding, translocation, and disease treatment. Here, we test the importance of tolerance and resistance in multiple populations of boreal toads (Anaxyrus boreas boreas) against Batrachochytrium dendrobatidis (Bd), the amphibian fungal pathogen responsible for the greatest host biodiversity loss due to disease. Boreal toads have severely declined in Colorado (CO) due to Bd, but toad populations challenged with Bd in western Wyoming (WY) appear to be less affected. We used a common garden infection experiment to expose post-metamorphic toads sourced from four populations (2 in CO and 2 in WY) to Bd and monitored changes in mass, pathogen burden and survival for 8 weeks. We used a multi-state modelling approach to estimate weekly survival and transition probabilities between infected and cleared states, reflecting a dynamic infection process that traditional approaches fail to capture. We found that WY boreal toads are more tolerant to Bd infection with higher survival probabilities than those in CO when infected with identical pathogen burdens. WY toads also appeared more resistant to Bd with a higher probability of infection clearance and an average of 5 days longer to reach peak infection burdens. Our results demonstrate strong intraspecific differences in tolerance and resistance that likely contribute to why population declines vary regionally across this species. Our multi-state framework allowed us to gain inference on typically hidden disease processes when testing for host tolerance or resistance. Our findings demonstrate that describing an entire host species as 'tolerant' or 'resistant' (or lack thereof) is unwise without testing for intraspecific variation.

Metabolic T-cell phenotypes: from bioenergetics to function

It is well known that T-cell metabolism and function are intimately linked. Metabolic reprogramming is a dynamic process that provides the necessary energy and biosynthetic precursors while actively regulating the immune response of T cells. As such, aberrations and dysfunctions in metabolic (re)programming, resulting in altered metabolic endotypes, may have an impact on disease pathology in various contexts. With the increasing demand for personalized and highly specialized medicine and immunotherapy, understanding metabolic profiles and T-cell subset dependence on specific metabolites will be crucial to harness the therapeutic potential of immunometabolism and T cell bioenergetics. In this review, we dissect metabolic alterations in different T-cell subsets in autoimmune and viral inflammation, T cell and non-T-cell malignancies, highlighting potential anchor points for future treatment and therapeutic exploitation.

Nora virus proliferates in dividing intestinal stem cells and sensitizes flies to intestinal infection and oxidative stress

The digestive tract represents the most complex interface of an organism with its biotope. Food may be contaminated by pathogens and toxicants while an abundant and complex microbiota strives in the gut lumen. The organism must defend itself against potentially noxious biotic or abiotic stresses while preserving its microbiota, provided it plays a beneficial role. The presence of intestinal viruses adds another layer of complexity. Starting from a differential sensitivity of two lines from the same Drosophila wild-type strain to ingested Pseudomonas aeruginosa, we report here that the presence of Nora virus in the gut epithelium promotes the sensitivity to this bacterial pathogen as well as to an ingested oxidizing xenobiotic. The genotype, age, nature of the ingested food and to a limited extent the microbiota are relevant parameters that influence the effects of Nora virus on host fitness. Mechanistically, we detect the initial presence of viral proteins essentially in progenitor cells. Upon stress such as infection, exposure to xenobiotics, aging or feeding on a rich-food diet, the virus is then detected in enterocytes, which correlates with a disruption of the intestinal barrier function in aged flies. Finally, we show that the virus proliferates only when ISCs are induced to divide and that blocking either enterocyte apoptosis or JAK/STAT-driven ISC division leads to a drastically reduced Nora virus titer. In conclusion, it is important to check that experimental strains are devoid of intestinal viruses when monitoring survival/life span of fly lines or when investigating the homeostasis of the intestinal epithelium as these viruses can constitute significant confounding factors.

Prolonged exposure to heat enhances mosquito tolerance to viral infection

How and to what extent mosquito-virus interaction is influenced by climate change is a complex question of ecological and epidemiological relevance. We worked at the intersection between thermal biology and vector immunology and studied shifts in tolerance and resistance to the cell fusing agent virus (CFAV), a prominent component of the mosquito virome known to contribute to shaping mosquito vector competence, in warm-acclimated and warm-evolved Aedes albopictus mosquitoes. We show that the length of the thermal challenge influences the outcome of the infection with warm-evolved mosquitoes being more tolerant to CFAV infection, while warm-acclimated mosquitoes being more resistant and suffering from extensive fitness costs. These results highlight the importance of considering fluctuations in vector immunity in relation to the length of a thermal challenge to understand natural variation in vector response to viruses and frame realistic transmission models.

Intraoperative Low-Dose Glucocorticoids in Surgical Patients With Abdominal Sepsis: A Multicenter Retrospective Cohort Study

Background and Aims

Abdominal sepsis refers to a severe and potentially life-threatening condition characterized by the presence of infection, inflammation, and tissue damage within the abdominal cavity. Glucocorticoids (GCs) play an important role in regulation of the host immune and inflammation responses involved in sepsis and surgery. This study aimed to investigate the potential impact of intraoperative GCs administration on the clinical outcome of surgical patients with abdominal sepsis.

Methods

This retrospective cohort study included a 1:1 propensity score-matched cohort of surgical patients afflicted with abdominal sepsis at two medical centers from January 2008 to December 2022. Patients were classified into low-GCs, high-GCs, and non-GCs groups according to the dosage of steroids used intraoperatively, and in-hospital mortality was designated as the primary outcome.

Results

This study included a total of 476 patients, with 217 in the non-GCs group, 213 in the low-GCs group, and 46 in the high-GCs group. The overall in-hospital mortality rate was 7.56%. After propensity score matching (PSM), there were 168 cases in both the low-GCs group and the non-GCs group, with no significant differences observed between the groups regarding mortality rate, length of hospital-stay, and duration of intensive care unit (ICU) stay. In patients with septic shock, the use of low-dose GCs increased the urine output and decreased the requirements for vasopressors on the first postoperative day, however, it had no impact on the in-hospital mortality or ICU stay. Moreover, prophylactic use of GCs during anesthesia induction did not decrease the incidence of intraoperative hypotension or necessity of vasopressors use.

Conclusion

Intraoperative administration of low-dose GCs demonstrates a transient improvement in hemodynamics of patients with septic shock, however, it did not lead to improved clinical outcomes. Further research remains necessary to elucidate the optimal perioperative dosing strategy.

β-Glucan reprograms neutrophils to promote disease tolerance against influenza A virus

Disease tolerance is an evolutionarily conserved host defense strategy that preserves tissue integrity and physiology without affecting pathogen load. Unlike host resistance, the mechanisms underlying disease tolerance remain poorly understood. In the present study, we investigated whether an adjuvant (β-glucan) can reprogram innate immunity to provide protection against influenza A virus (IAV) infection. β-Glucan treatment reduces the morbidity and mortality against IAV infection, independent of host resistance. The enhanced survival is the result of increased recruitment of neutrophils via RoRγt+ T cells in the lung tissue. β-Glucan treatment promotes granulopoiesis in a type 1 interferon-dependent manner that leads to the generation of a unique subset of immature neutrophils utilizing a mitochondrial oxidative metabolism and producing interleukin-10. Collectively, our data indicate that β-glucan reprograms hematopoietic stem cells to generate neutrophils with a new 'regulatory' function, which is required for promoting disease tolerance and maintaining lung tissue integrity against viral infection.

VSTM1/SIRL-1: An Inhibitory Pattern Recognition Receptor Regulating Myeloid Cells

Innate immune cells express a plethora of inhibitory receptors, many of which recognize molecular patterns. An appropriate balance between signaling via activating and inhibitory pattern recognition receptors is important for a proper immune response while preventing immunopathology. V-set and transmembrane domain containing 1 (VSTM1), also known as signal inhibitory receptor on leukocytes-1 (SIRL-1), is an inhibitory receptor expressed on myeloid cells. VSTM1 can modulate the function of myeloid cells, by inhibiting reactive oxygen species and neutrophil extracellular trap formation. VSTM1 recognizes shared molecular patterns both from endogenous and microbial origin, defining it as an inhibitory pattern recognition receptor. VSTM1 is involved in various pathological conditions, including autoimmune disorders and cancer, and its restricted expression on myeloid cells highlights its potential as a specific therapeutic target. This review summarizes the characteristics and function of VSTM1 in health and disease.

Evolution of the ocular immune system

The evolution of the ocular immune system should be viewed within the context of the evolution of the immune system, and indeed organisms, as a whole. Since the earliest time, the most primitive responses of single cell organisms involved molecules such as anti-microbial peptides and behaviours such as phagocytosis. Innate immunity took shape ~2.5 billion years ago while adaptive immunity and antigen specificity appeared with vertebrate evolution ~ 500 million years ago. The invention of the microscope and the germ theory of disease precipitated debate on cellular versus humoral immunity, resolved by the discovery of B and T cells. Most recently, our understanding of the microbiome and consideration of the host existing symbiotically with trillions of microbial genes (the holobiont), suggests that the immune system is a sensor of homoeostasis rather than simply a responder to pathogens. Each tissue type in multicellular organisms, such as vertebrates, has a customised response to immune challenge, with powerful reactions most evident in barrier tissues such as the skin and gut mucosa, while the eye and brain occupy the opposite extreme where responses are attenuated. The experimental background which historically led to the concept of immune privilege is discussed in this review; however, we propose that the ocular immune response should not be viewed as unique but simply an example of how the tissues variably respond in nature, more or less to the same challenge (or danger).

Avoiding the tragedies of parasite tolerance in Darwinian beekeeping

Bee declines have been partly attributed to the impacts of invasive or emerging parasite outbreaks. For western honeybees, Apis mellifera, major losses are associated with the virus-vectoring mite, Varroa destructor. In response, beekeepers have focused breeding efforts aimed at conferring resistance to this key parasite. One method of many is survival-based beekeeping where colonies that survive despite significant Varroa infestations produce subsequent colonies. We argue that this 'hands-off' approach will not always lead to Varroa resistance evolving but rather tolerance. Tolerance minimizes host fitness costs of parasitism without reducing parasite abundance, whereas resistance either prevents parasitism outright or keeps parasitism intensity low. With clear epidemiological distinctions, and as honeybee disease dynamics impact other wild bees owing to shared pathogens, we discuss why tolerance outcomes in honeybee breeding have important implications for wider pollinator health. Crucially, we argue that unintentional selection for tolerance will not only lead to more spillover from honeybees but may also select for pathogens that are more virulent in wild bees leading to 'tragedies of tolerance'. These tragedies can be avoided through successful breeding regimes that specifically select for low Varroa. We emphasize how insights from evolutionary ecology can be applied in ecologically responsible honeybee management.

A Palearctic view of a bat fungal disease

The fungal infection causing white-nose disease in hibernating bats in North America has resulted in dramatic population declines of affected species, since the introduction of the causative agent Pseudogymnoascus destructans. The fungus is native to the Palearctic, where it also infects several bat species, yet rarely causes severe pathology or the death of the host. Pseudogymnoascus destructans infects bats during hibernation by invading and digesting the skin tissue, resulting in the disruption of torpor patterns and consequent emaciation. Relations among pathogen, host, and environment are complex, and individuals, populations, and species respond to the fungal pathogen in different ways. For example, the Nearctic Myotis lucifugus responds to infection by mounting a robust immune response, leading to immunopathology often contributing to mortality. In contrast, the Palearctic M. myotis shows no significant immunological response to infection. This lack of a strong response, resulting from the long coevolution between the hosts and the pathogen in the pathogen's native range, likely contributes to survival in tolerant species. After more than 15 years since the initial introduction of the fungus to North America, some of the affected populations are showing signs of recovery, suggesting that the fungus, hosts, or both are undergoing processes that may eventually lead to coexistence. The suggested or implemented management methods of the disease in North America have encompassed, for example, the use of probiotics and fungicides, vaccinations, and modifying the environmental conditions of the hibernation sites to limit the growth of the pathogen, intensity of infection, or the hosts' responses to it. Based on current knowledge from Eurasia, policy makers and conservation managers should refrain from disrupting the ongoing evolutionary processes and adopt a holistic approach to managing the epizootic.

Notch4 regulatory T cells and SARS-CoV-2 viremia shape COVID19 survival outcome

BACKGROUND

Immune dysregulation and SARS-CoV-2 plasma viremia have been implicated in fatal COVID-19 disease. However, how these two factors interact to shape disease outcomes is unclear.

METHODS

We carried out viral and immunological phenotyping on a prospective cohort of 280 patients with COVID-19 presenting to acute care hospitals in Boston, Massachusetts and Genoa, Italy between June 1, 2020 and February 8, 2022. Disease severity, mortality, plasma viremia, and immune dysregulation were assessed. A mouse model of lethal H1N1 influenza infection was used to analyze the therapeutic potential of Notch4 and pyroptosis inhibition in disease outcome.

RESULTS

Stratifying patients based on %Notch4+ Treg cells and/or the presence of plasma viremia identified four subgroups with different clinical trajectories and immune phenotypes. Patients with both high %Notch4+ Treg cells and viremia suffered the most disease severity and 90-day mortality compared to the other groups even after adjusting for baseline comorbidities. Increased Notch4 and plasma viremia impacted different arms of the immune response in SARS-CoV-2 infection. Increased Notch4 was associated with decreased Treg cell amphiregulin expression and suppressive function whereas plasma viremia was associated with increased monocyte cell pyroptosis. Combinatorial therapies using Notch4 blockade and pyroptosis inhibition induced stepwise protection against mortality in a mouse model of lethal H1N1 influenza infection.

CONCLUSIONS

The clinical trajectory and survival outcome in hospitalized patients with COVID-19 is predicated on two cardinal factors in disease pathogenesis: viremia and Notch4+ Treg cells. Intervention strategies aimed at resetting the immune dysregulation in COVID-19 by antagonizing Notch4 and pyroptosis may be effective in severe cases of viral lung infection.

Effects of gastrointestinal parasites on fecal glucocorticoids and behaviour in vervet monkeys (Chlorocebus pygerythrus)

Relationships between parasites, host physiology, and behaviours are complex. Parasites can influence host hormonal microenvironment and behaviour through "sickness behaviours" that generally conserve energy. Using a parasite removal experiment, we examined the effects of gastrointestinal parasites on fecal glucocorticoid metabolites (fGC) and behaviours of vervet monkeys (Chlorocebus pygerythrus) at Lake Nabugabo, Uganda. We collected parasitological, hormonal, and behavioural data from adult and subadult male and female vervets (N = 19) in 2014 across four study phases: pre-deworming, post-deworming, early reinfection, and late reinfection as well as in 2015. Overall, there was no decrease in fGC after deworming, but there was an increase following natural reinfection. There was no change in feeding across study phases; however, moving, grooming, and resting changed between the post-deworming and late reinfection phases, but not always in the predicted direction. Comparing behaviour across the same months in the following year as in the 2014 experimental study period, we found no differences in moving, feeding, grooming, and resting events. Despite behavioural variation between study phases, we cannot conclude that behavioural changes are due to parasitism rather than other seasonal variation. However, fGC increased following reinfection, which is consistent with parasitism being costly for hosts.

Damage sensing through TLR9 regulates inflammatory and antiviral responses during influenza infection

Host response aimed at eliminating the infecting pathogen, as well as the pathogen itself, can cause tissue injury. Tissue injury leads to the release of a myriad of cellular components including mitochondrial DNA (mtDNA), which the host senses through pattern recognition receptors. How the sensing of tissue injury by the host shapes the anti-pathogen response remains poorly understood. In this study, we utilized mice that are deficient in toll-like receptor-9 (TLR9), which binds to unmethylated CpG DNA sequences such as those present in bacterial and mtDNA. To avoid direct pathogen sensing by TLR9, we utilized the influenza virus, which lacks ligands for TLR9, to determine how damage sensing by TLR9 contributes to anti-influenza immunity. Our data showed that TLR9-mediated sensing of tissue damage promoted an inflammatory response during early infection, driven by epithelial and myeloid cells. Along with the diminished inflammatory response, the absence of TLR9 led to impaired viral clearance manifested as higher and prolonged influenza components in myeloid cells, including monocytes and macrophages, rendering them highly inflammatory. The persistent inflammation driven by infected myeloid cells led to persistent lung injury and impaired recovery in influenza-infected TLR9-/- mice. Further, we found elevated TLR9 ligands in the plasma samples of patients with influenza infection and its association with the disease severity in hospitalized patients, demonstrating its clinical relevance. Overall, we demonstrated an essential role of damage sensing through TLR9 in promoting anti-influenza immunity and inflammatory response. AUTHOR SUMMARY: Tissue damage is an inevitable outcome of clinically relevant lung infections, but the host mechanisms for detecting such damage during infection are not well understood. We investigated the role of Toll-like receptor 9 (TLR9) in sensing tissue damage caused by influenza. Since influenza lacks TLR9 ligands, we hypothesized that TLR9 signaling is driven by tissue damage molecules like mitochondrial DNA (mtDNA). Our data revealed that TLR9 deficiency reduces early inflammatory lung injury but impairs viral clearance, resulting in extensive infection of immune cells, persistent inflammation, and delayed recovery. Myeloid-specific TLR9 deletion ameliorated late-stage inflammatory responses. In humans, influenza-infected individuals exhibited elevated TLR9 activity and mtDNA levels in plasma compared to healthy controls, with higher TLR9 activation potential correlating with severe disease requiring ICU admission. These findings suggest that TLR9-mediated damage sensing triggers both inflammatory tissue injury and viral clearance. These data indicate that TLR9 activity can serve as a crucial biomarker and therapeutic target to limit influenza-induced tissue injury.

Food-Induced Adverse Reactions: A Review of Physiological Food Quality Control, Mucosal Defense Mechanisms, and Gastrointestinal Physiology

Although food is essential for the survival of organisms, it can also trigger a variety of adverse reactions, ranging from nutrient intolerances to celiac disease and food allergies. Food not only contains essential nutrients but also includes numerous substances that may have positive or negative effects on the consuming organism. To protect against potentially harmful components, all animals have evolved defense mechanisms, which are similar to antimicrobial defenses but often come at the cost of the organism's health. When these defensive responses are exaggerated or misdirected, they can lead to adverse food reactions, where the costs outweigh the benefits. Furthermore, due to the persistent toxicity of harmful food components, the failure of defense mechanisms can also result in pathological effects triggered by food. This article review presents a food quality control framework that aims to clarify how these reactions relate to normal physiological processes. Organisms utilize several systems to coexist with symbiotic microbes, regulate them, and concurrently avoid, expel, or neutralize harmful pathogens. Similarly, food quality control systems allow organisms to absorb necessary nutrients while defending against low-quality or harmful components in food. Although many microbes are lethal in the absence of antimicrobial defenses, diseases related to microbiome dysregulation, such as inflammatory bowel disease, have significantly increased. Antitoxin defenses also come with costs and may fail due to insufficiencies, exaggerations, or misdirected actions, ultimately leading to adverse food reactions. With the changes in human diet and lifestyle, the failure of defense mechanisms has contributed to the rising incidence of food intolerances. This review explores the mechanisms of antitoxin defenses and analyzes how their failure can lead to adverse food reactions, emphasizing the importance of a comprehensive understanding of food quality control mechanisms for developing more effective treatments for food-triggered diseases.

Profil diagnostique et évolutif de l’insuffisance hépatique aigue sur chronique

INTRODUCTION

Acute decompensation represents a remarkable event in cirrhotic patients, particularly if it is complicated by Acute-on-Chronic Liver Failure (ACLF). Epidemiological data of ACLF are limited.

AIM

To determine the prevalence and predictive factors of ACLF in patients hospitalized for decompensated cirrhosis.

METHODS

We conducted a retrospective study. We included patients with decompensated cirrhosis. ACLF was defined according to the CLIF-C OF score. Prevalence and predictive factors of ACLF were determined.

RESULTS

We included 100 patients. The prevalence of ACLF was 37%. Renal failure was the most frequent organ failure. In univariate analysis, predictive factors for the occurrence of ACLF were female gender, hepatic encephalopathy, upper digestive haemorrhage, the presence of an infection, CRP level, bilirubin level and creatinine level. Prognostic scores (Child-Pugh, MELD, and CLIF-C OF) were also predictive of ACLF. In multivariate analysis, only creatinine level was an independent predictive factor of ACLF. The most frequent precipitating factor of ACLF was infection. The overall mortality rate for patients with ACLF was 65%.

CONCLUSION

Our study showed that the prevalence of ACLF was 37 %. The main predictive factor of ACLF was creatinine level. The mortality rate was high at 65 %.

Liver X receptor unlinks intestinal regeneration and tumorigenesis

Uncontrolled regeneration leads to neoplastic transformation1-3. The intestinal epithelium requires precise regulation during continuous homeostatic and damage-induced tissue renewal to prevent neoplastic transformation, suggesting that pathways unlinking tumour growth from regenerative processes must exist. Here, by mining RNA-sequencing datasets from two intestinal damage models4,5 and using pharmacological, transcriptomics and genetic tools, we identified liver X receptor (LXR) pathway activation as a tissue adaptation to damage that reciprocally regulates intestinal regeneration and tumorigenesis. Using single-cell RNA sequencing, intestinal organoids, and gain- and loss-of-function experiments, we demonstrate that LXR activation in intestinal epithelial cells induces amphiregulin (Areg), enhancing regenerative responses. This response is coordinated by the LXR-ligand-producing enzyme CYP27A1, which was upregulated in damaged intestinal crypt niches. Deletion of Cyp27a1 impaired intestinal regeneration, which was rescued by exogenous LXR agonists. Notably, in tumour models, Cyp27a1 deficiency led to increased tumour growth, whereas LXR activation elicited anti-tumour responses dependent on adaptive immunity. Consistently, human colorectal cancer specimens exhibited reduced levels of CYP27A1, LXR target genes, and B and CD8 T cell gene signatures. We therefore identify an epithelial adaptation mechanism to damage, whereby LXR functions as a rheostat, promoting tissue repair while limiting tumorigenesis.

Advancing oral immunology for improving oral health

Although substantial progress has been made in dentistry in terms of diagnosis and therapy, current treatment methods in periodontology, orthodontics, endodontics, and oral and maxillofacial surgery, nevertheless, suffer from numerous limitations, some of which are associated with a dramatic reduction in the quality of life. Many general mechanisms of inflammation and immunity also apply to the oral cavity and oral diseases. Nonetheless, there are special features here that are attributable, on the one hand, to developmental biology and, on the other hand, to the specific anatomical situation, which is characterized by a close spatial relationship of soft and hard tissues, exposure to oral microbiota, and to a rapid changing external environment. Currently, a comprehensive and overarching understanding is lacking about how the immune system functions in oral tissues (oral immunology) and how oral immune responses contribute to oral health and disease. Since advances in translational immunology have created a game-changing shift in therapy in rheumatology, allergic diseases, inflammatory bowel disease, and oncology in recent years, it is reasonable to assume that a better understanding of oral immunology might lead to practice-changing diagnostic procedures and therapies in dentistry and thereby also profoundly improve oral health in general.

Rethinking the Evolutionary Origin, Function, and Treatment of Cancer

Despite remarkable progress in basic oncology, practical results remain unsatisfactory. This discrepancy is partly due to the exclusive focus on processes within the cancer cell, which results in a lack of recognition of cancer as a systemic disease. It is evident that a wise balance is needed between two alternative methodological approaches: reductionism, which would break down complex phenomena into smaller units to be studied separately, and holism, which emphasizes the study of complex systems as integrated wholes. A consistent holistic approach has so far led to the notion of cancer as a special organ, stimulating debate about its function and evolutionary significance. This article discusses the role of cancer as a mechanism of purifying selection of the gene pool, the correlation between hereditary and sporadic cancer, the cancer interactome, and the role of metastasis in a lethal outcome. It is also proposed that neutralizing the cancer interactome may be a novel treatment strategy.

Physivitrins I-R, lanostane triterpenoids with anti-inflammatory activities from the fungus Physisporinus vitreus

Chemical investigation on the rice fermentation of the fungus Physisporinus vitreus led to the isolation of ten previously undescribed lanostane triterpenoids, physivitrins I-R, and three known analogues. The new structures were elucidated on the basis of extensive spectroscopic methods, including 1D & 2D NMR, HRESIMS, UV and ECD. Physivitrins I and P exhibited significant inhibitory activities against NO production in LPS-activated RAW267.4 macrophages with IC50 values of 8.2 and 11.5 μM, respectively. The comprehensive data indicated that P. vitreus is rich in lanostane triterpenes and has potential anti-inflammatory application prospects.

Clinical Implications of Inflammation in Patients With Cirrhosis

Cirrhosis-associated immune dysfunction refers to the concurrent systemic inflammation and immunoparesis evident across the disease spectrum of chronic liver disease, ranging from the low-grade inflammatory plasma milieu that accompanies compensated disease to the intense high-grade inflammatory state with coexistent severe immune paralysis that defines acute decompensation and acute-on-chronic liver failure. Systemic inflammation plays a crucial role in the disease course of cirrhosis and is a key driver for acute decompensation and the progression from compensated to decompensated cirrhosis. Severe systemic inflammation is fundamental to the development of organ dysfunction and failure and, in its most extreme form, acute-on-chronic liver failure. Systemic inflammation propagates the development of hepatic encephalopathy and hepatorenal syndrome-acute kidney injury. It may also be involved in the pathogenesis of further complications such as hepatocellular carcinoma and mental illness. Those patients with the most profound systemic inflammation have the worst prognosis. Systemic inflammation exerts its negative clinical effects through a number of mechanisms including nitric oxide-mediated increased splanchnic vasodilation, immunopathology, and metabolic reallocation.

Immunophenotyping of Leukocytes in Brain in Hypothyroid Mice

Hypothyroidism, characterized by inadequate production of thyroid hormones, and malaria, a mosquito-borne infectious disease caused by Plasmodium parasites, are significant health concerns worldwide. Understanding the interplay between these two conditions could offer insights into their complex relationship and potential therapeutic strategies. To induce hypothyroidism, pharmacological inhibition of thyroid hormone synthesis was employed. Subsequently, mice were infected with Plasmodium berghei ANKA to simulate cerebral malaria infection. It needs to monitor the progression of the disease in male mice before it can identify infiltrating immune system populations of interest in the brain by multiparametric techniques such as flow cytometry.

Immunophenotyping of Hematopoietic Cells in the Spleen in Hypothyroid Mice

Hypothyroidism, which is characterized by insufficient production of thyroid hormones, and malaria, a mosquito-borne infectious disease caused by Plasmodium parasites, are significant global health challenges. Studying how these two conditions interact could provide valuable insights into their complex relationship and potential treatment options.To induce hypothyroidism in the research, scientists used drugs to block the production of thyroid hormones. Then, they infected mice with Plasmodium berghei ANKA to mimic cerebral malaria infection. The spleen is essential in the body's immune response to malaria. It is involved in both innate and adaptive immunity, iron recycling, and the removal of old red blood cells or damaged cells infected with Plasmodium. Monitoring disease progression in male mice is crucial for early detection, and techniques like flow cytometry can help identify specific immune system populations within the spleen that are relevant to the research.

Sexual Signaling and Sociosexual Behaviors in Relation to Rank, Parasites, Hormones, and Age in Male Vervet Monkeys (Chlorocebus pygerythrus) in Uganda

Secondary sexual characteristics, and the extent to which they are expressed, can convey information about the signaller. The blue scrotum and red penis of male vervet monkeys (Chlorocebus pygerythrus) make them a good species in which to examine inter- and intramale variation in signal expression. We quantified genital hue and luminance of male vervets at Lake Nabugabo, Uganda from standardized photos of male genitalia taken in May to June 2016, January to March 2019, and April to June 2019 to examine how dominance rank, fecal androgens (fARMs), fecal glucocorticoids (fGCMs), and parasitism related to achromatic (i.e., luminance) and chromatic (i.e., hue) aspects of scrotal and penile coloration, as well as how genital color related to sociosexual behaviors. We examined 182 photoshoots, 214 fecal samples for hormone analyses, and 152 for parasite analyses. Linear models indicate that genital color is linked to male dominance rank; high-ranking males had a more luminant (i.e., brighter) scrotum and a redder penis. Within males, color characteristics remained relatively stable over the short-term and changed moderately over the long-term. The direction of change was inconsistent for all color characteristics except scrotal luminance, which increased in all males over the long-term. Males with a darker penis received more mating presentations, while higher-ranking males received more mating refusals than low-ranking males, suggesting that females pay attention to penile color. We did not find support for any parasite or hormone mediation of color, and while there was a correlation between fGCM and fARMs, this was positive rather than negative as predicted by the stress-linked immunocompetence handicap hypothesis. Overall, our results indicate that the production of genital color may serve as an intra- and/or intersexual signal of male dominance rank and age in vervets.

Molecular profiles of blood from numerous species that differ in sensitivity to acute inflammation

Vertebrates differ over 100,000-fold in responses to pro-inflammatory agonists such as bacterial lipopolysaccharide (LPS), complicating use of animal models to study human sepsis or inflammatory disorders. We compared transcriptomes of resting and LPS-exposed blood from six LPS-sensitive species (rabbit, pig, sheep, cow, chimpanzee, human) and four LPS-resilient species (mice, rats, baboon, rhesus), as well as plasma proteomes and lipidomes. Unexpectedly, at baseline, sensitive species already had enhanced expression of LPS-responsive genes relative to resilient species. After LPS stimulation, maximally different genes in resilient species included genes that detoxify LPS, diminish bacterial growth, discriminate sepsis from SIRS, and play roles in autophagy and apoptosis. The findings reveal the molecular landscape of species differences in inflammation. This may inform better selection of species for pre-clinical models and could lead to new therapeutic strategies that mimic mechanisms in inflammation-resilient species to limit inflammation without causing immunosuppression.

Regulation of host metabolism and defense strategies to survive neonatal infection

Two distinct defense strategies, disease resistance (DR) and disease tolerance (DT), enable a host to survive infectious diseases. Newborns, constrained by limited energy reserves, predominantly rely on DT to cope with infection. However, this approach may fail when pathogen levels surpass a critical threshold, prompting a shift to DR that can lead to dysregulated immune responses and sepsis. The mechanisms governing the interplay between DR and DT in newborns remain poorly understood. Here, we compare metabolic traits and defense strategies between survivors and non-survivors in Staphylococcus epidermidis (S. epidermidis)-infected preterm piglets, mimicking infection in preterm infants. Compared to non-survivors, survivors displayed elevated DR during the initial phase of infection, followed by stronger DT in later stages. In contrast, non-survivors showed clear signs of respiratory and metabolic acidosis and hyperglycemia, together with exaggerated inflammation and organ dysfunctions. Hepatic transcriptomics revealed a strong association between the DT phenotype and heightened oxidative phosphorylation in survivors, coupled with suppressed glycolysis and immune signaling. Plasma metabolomics confirmed the findings of metabolic regulations associated with DT phenotype in survivors. Our study suggests a significant association between the initial DR and subsequent DT, which collectively contributes to improved infection survival. The regulation of metabolic processes that optimize the timing and balance between DR and DT holds significant potential for developing novel therapeutic strategies for neonatal infection.

Nutrition influences immunity: Diet and host-parasite interactions

Nutrition plays a major role in host immune responses and in pathogen resistance. Understanding the network that modulates the relationship between nutrition and immunity remains a challenge. Several pathways govern the direct effects of nutrition on host immunity and the indirect effects mediated by pathogen populations. We note host microbiota also influence the intricate relationships between nutrition and immunity. The purpose of this review is to discuss recent findings from nutritional research in relation to insect immunology. We outline the relationship between diet, immunity, disease, and microbiota in insects and emphasize the significance of utilizing an integrative, multifaceted approach to grasping the influence of nutrition on immunity.

Reduced insulin/IGF-1 signalling upregulates two anti-viral immune pathways, decreases viral load and increases survival under viral infection in C. elegans

Reduced insulin/IGF-1 signalling (rIIS) improves survival across diverse taxa and there is a growing interest in its role in regulating immune function. Whilst rIIS can improve anti-bacterial resistance, the consequences for anti-viral immunity are yet to be systematically examined. Here, we show that rIIS in adult Caenorhabditis elegans increases the expression of key genes in two different anti-viral immunity pathways, whilst reducing viral load in old age, increasing survival and reducing rate-of-senescence under infection by naturally occurring positive-sense single-stranded RNA Orsay virus. We found that both drh-1 in the anti-viral RNA interference (RNAi) pathway and cde-1 in the terminal uridylation-based degradation of viral RNA pathway were upregulated in early adulthood under rIIS and increased anti-viral resistance was not associated with reproductive costs. Remarkably, rIIS increased anti-viral gene expression only in infected worms, potentially to curb the costs of constitutively upregulated immunity. RNA viruses are found across taxa from plants to mammals and we demonstrate a novel role for rIIS in regulating resistance to viral infection. We therefore highlight this evolutionarily conserved signalling pathway as a promising therapeutic target to improve anti-viral immunity.

SARS-CoV-2 reprograms murine alveolar macrophages to dampen flu

Innate immune cells that are epigenetically reprogrammed by infection can modify host responses to subsequent infections. Lercher et al. have identified epigenetic reprogramming of murine airway-resident macrophages following recovery from SARS-CoV-2 infection, conferring protection from pathology and lethality following secondary influenza A virus (IAV) challenge without reducing viral titers.