The pituitary gland prevents shock-associated death by controlling multiple inflammatory mediators

The immunology of sickness metabolism

Everyone knows that an infection can make you feel sick. Although we perceive infection-induced changes in metabolism as a pathology, they are a part of a carefully regulated process that depends on tissue-specific interactions between the immune system and organs involved in the regulation of systemic homeostasis. Immune-mediated changes in homeostatic parameters lead to altered production and uptake of nutrients in circulation, which modifies the metabolic rate of key organs. This is what we experience as being sick. The purpose of sickness metabolism is to generate a metabolic environment in which the body is optimally able to fight infection while denying vital nutrients for the replication of pathogens. Sickness metabolism depends on tissue-specific immune cells, which mediate responses tailored to the nature and magnitude of the threat. As an infection increases in severity, so do the number and type of immune cells involved and the level to which organs are affected, which dictates the degree to which we feel sick. Interestingly, many alterations associated with metabolic disease appear to overlap with immune-mediated changes observed following infection. Targeting processes involving tissue-specific interactions between activated immune cells and metabolic organs therefore holds great potential for treating both people with severe infection and those with metabolic disease. In this review, we will discuss how the immune system communicates in situ with organs involved in the regulation of homeostasis and how this communication is impacted by infection.

Sepsis-associated encephalopathy: From pathophysiology to clinical management

Sepsis-associated encephalopathy, which presents as delirium and coma, is a significant complication of sepsis characterized by acute brain dysfunction. The presence of inflammatory pathological changes in the brain of sepsis patients and animal models has been recognized since the 1920 s, initially attributed to the entry of microbial toxins into the brain. In the early 2000 s, attention shifted towards the impact of oxidative stress, the cholinergic system, and cytokines on brain function following sepsis onset. More recently, sepsis-associated encephalopathy has been defined as a diffuse brain dysfunction not directly caused by pathogenic infection of the brain. Currently, there is no evidence-based standard for diagnosing sepsis-associated encephalopathy, and clinical management is primarily focused on symptomatic and supportive measures. This review aims to explore the pathophysiology of sepsis-associated encephalopathy and establish the connection between pathophysiological mechanisms and clinical characteristics. We hope that this work will spark the interest of researchers from various fields and contribute to the advancement of sepsis-associated encephalopathy research.

Endocannabinoid System in the Neuroendocrine Response to Lipopolysaccharide-induced Immune Challenge

The endocannabinoid system plays a key role in the intersection of the nervous, endocrine, and immune systems, regulating not only their functions but also how they interplay with each other. Endogenous ligands, named endocannabinoids, are produced "on demand" to finely regulate the synthesis and secretion of hormones and neurotransmitters, as well as to regulate the production of cytokines and other proinflammatory mediators. It is well known that immune challenges, such as exposure to lipopolysaccharide, the main component of the Gram-negative bacteria cell wall, disrupt not only the hypothalamic-pituitary-adrenal axis but also affects other endocrine systems such as the hypothalamic-pituitary-gonadal axis and the release of oxytocin from the neurohypophysis. Here we explore which actors and molecular mechanisms are involved in these processes.

IL-27 Enhances γδ T Cell–Mediated Innate Resistance to Primary Hookworm Infection in the Lungs

IL-27 is a heterodimeric IL-12 family cytokine formed by noncovalent association of the promiscuous EBI3 subunit and selective p28 subunit. IL-27 is produced by mononuclear phagocytes and unfolds pleiotropic immune-modulatory functions through ligation to IL-27 receptor α (IL-27RA). Although IL-27 is known to contribute to immunity and to limit inflammation after various infections, its relevance for host defense against multicellular parasites is still poorly defined. Here, we investigated the role of IL-27 during infection with the soil-transmitted hookworm, Nippostrongylus brasiliensis, in its early host intrapulmonary life cycle. IL-27(p28) was detectable in bronchoalveolar lavage fluid of C57BL/6J wild-type mice on day 1 after s.c. inoculation. IL-27RA expression was most abundant on lung-invading γδ T cells. Il27ra^-/- mice showed increased lung parasite burden together with aggravated pulmonary hemorrhage and higher alveolar total protein leakage as a surrogate for epithelial-vascular barrier disruption. Conversely, injections of recombinant mouse (rm)IL-27 into wild-type mice reduced lung injury and parasite burden. In multiplex screens, higher airway accumulations of IL-6, TNF-α, and MCP-3 (CCL7) were observed in Il27ra^-/- mice, whereas rmIL-27 treatment showed a reciprocal effect. Importantly, γδ T cell numbers in airways were enhanced by endogenous or administered IL-27. Further analysis revealed a direct antihelminthic function of IL-27 on γδ T cells as adoptive intratracheal transfer of rmIL-27-treated γδ T cells during primary N. brasiliensis lung infection conferred protection in mice. In summary, this report demonstrates protective functions of IL-27 to control the early lung larval stage of hookworm infection.

The MAVS Immune Recognition Pathway in Viral Infection and Sepsis

Significance: It is estimated that close to 50 million cases of sepsis result in over 11 million annual fatalities worldwide. The pathognomonic feature of sepsis is a dysregulated inflammatory response arising from viral, bacterial, or fungal infections. Immune recognition of pathogen-associated molecular patterns is a hallmark of the host immune defense to combat microbes and to prevent the progression to sepsis. Mitochondrial antiviral signaling protein (MAVS) is a ubiquitous adaptor protein located at the outer mitochondrial membrane, which is activated by the cytosolic pattern recognition receptors, retinoic acid-inducible gene I (RIG-I) and melanoma differentiation associated gene 5 (MDA5), following binding of viral RNA agonists. Recent Advances: Substantial progress has been made in deciphering the activation of the MAVS pathway with its interacting proteins, downstream signaling events (interferon [IFN] regulatory factors, nuclear factor kappa B), and context-dependent type I/III IFN response. Critical Issues: In the evolutionary race between pathogens and the host, viruses have developed immune evasion strategies for cleavage, degradation, or blockade of proteins in the MAVS pathway. For example, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) M protein and ORF9b protein antagonize MAVS signaling and a protective type I IFN response. Future Directions: The role of MAVS as a sensor for nonviral pathogens, host cell injury, and metabolic perturbations awaits better characterization in the future. New technical advances in multidimensional single-cell analysis and single-molecule methods will accelerate the rate of new discoveries. The ultimate goal is to manipulate MAVS activities in the form of immune-modulatory therapies to combat infections and sepsis. Antioxid. Redox Signal. 35, 1376-1392.

Intrauterine growth restriction leads to a high-corticosterone producing offspring: An implication for pulmonary infection susceptibility

AIMS

Although intrauterine growth restriction (IUGR) impairs immune system homeostasis and lung development, its relationship with the susceptibility to pulmonary infections remains unclear. Thus, this study aimed to investigate the impact of IUGR on acute lung inflammatory response induced by bacterial stimulus.

MATERIALS AND METHODS

Pregnant female Wistar rats were subjected to 50% caloric-protein food restriction during gestation. To mimic bacterial lung infection, adult male offspring (12 weeks old) were challenged with a single lipopolysaccharide (LPS) intranasal instillation, and 6 h later, we assessed the acute inflammatory response. Normal birth weight (NBW) animals represent the control group.

KEY FINDINGS

LPS instillation increased the protein levels in the airways of both the NBW and low birth weight (LBW) groups, indicating vascular leakage. LBW animals exhibited a lower number of neutrophils, reduced production of interleukin-6 and macrophage-inflammatory protein-2 and decreased upregulation of intercellular adhesion molecule-1 gene expression in lung tissues. Further analysis revealed that the LBW group produced lower levels of prostaglandin-E₂ and failed to secrete leukotriene-B₄ upon LPS stimulation, which correlated with impaired cyclooxygenase-2 and 5-lipoxygenase expression. These results were probably associated with their inability to upregulate the expression of Toll-like receptor-4 and downstream signaling proteins, such as nuclear factor kappa-B, in the lungs. The LBW group also exhibited abnormal airway thickening and high corticosterone levels under basal conditions.

SIGNIFICANCE

This study suggests that IUGR-induced foetal programming in LBW offspring threatens HPA axis physiology and corticosterone biodisponibility, and impairs the innate response to bacterial antigens, increasing future susceptibility to pulmonary infection.

BCG vaccination-induced emergency granulopoiesis provides rapid protection from neonatal sepsis

Death from sepsis in the neonatal period remains a serious threat for millions. Within 3 days of administration, bacille Calmette-Guérin (BCG) vaccination can reduce mortality from neonatal sepsis in human newborns, but the underlying mechanism for this rapid protection is unknown. We found that BCG was also protective in a mouse model of neonatal polymicrobial sepsis, where it induced granulocyte colony-stimulating factor (G-CSF) within hours of administration. This was necessary and sufficient to drive emergency granulopoiesis (EG), resulting in a marked increase in neutrophils. This increase in neutrophils was directly and quantitatively responsible for protection from sepsis. Rapid induction of EG after BCG administration also occurred in three independent cohorts of human neonates.

Nanomedicine: A Diagnostic and Therapeutic Approach to COVID-19

The SARS-CoV-2 virus is causing devastating morbidity and mortality worldwide. Nanomedicine approaches have a high potential to enhance conventional diagnostics, drugs and vaccines. In fact, lipid nanoparticle/mRNA vaccines are already widely used to protect from COVID-19. In this review, we present an overview of the taxonomy, structure, variants of concern, epidemiology, pathophysiology and detection methods of SARS-CoV-2. The efforts of repurposing, tailoring, and adapting pre-existing medications to battle COVID-19 and the state of vaccine developments are presented. Next, we discuss the broad concepts and limitations of how nanomedicine could address the COVID-19 threat. Nanomaterials are particles in the nanometer scale (10-100 nm) which possess unique properties related to their size, polarity, structural and chemical composition. Nanoparticles can be composed of precious metals (copper, silver, gold), inorganic materials (graphene, silicon), proteins, carbohydrates, lipids, RNA/DNA, or conjugates, combinations and polymers of all of the aforementioned. The advanced biochemical features of these nanoscale particles allow them to directly interact with virions and irreversibly disrupt their structure, which can render a virus incapable of replicating within the host. Virus-neutralizing coats and surfaces impregnated with nanomaterials can enhance personal protective equipment, hand sanitizers and air filter systems. Nanoparticles can enhance drug-based therapies by optimizing uptake, stability, target cell-specific delivery, and magnetic properties. In fact, recent studies have highlighted the potential of nanoparticles in different aspects of the fight against SARS-CoV-2, such as enhancing biosensors and diagnostic tests, drug therapies, designing new delivery mechanisms, and optimizing vaccines. This article summarizes the ongoing research on diagnostic strategies, treatments, and vaccines for COVID-19, while emphasizing the potential of nanoparticle-based pharmaceuticals and vaccines.

IL-18 expression in clinical human pituitary adenoma

BACKGROUND

IL-18 is known as an interferon-inducing factor that belongs to the IL-1 family, and is synthesized as an inactive precursor protein.

OBJECTIVE

The present study aims to investigate the expression of IL-18, IL-18R, R and IL-18 binding protein (BP) mRNA in various types of human pituitary tumors, such as adrenocorticotropic hormone (ACTH), growth hormone (GH), prolactin (PRL), thyroid stimulating hormone (TSH)-producing adenomas and non-function adenomas.

METHODS

Pituitary adenoma tissues were obtained during the surgery of 41 patients: nine patients had ACTH-producing pituitary adenomas, nine patients had GH-producing pituitary adenomas, five patients had TSH-producing pituitary adenomas, seven patients had PRL-producing pituitary adenomas, and 11 patients had non-functioning adenomas. The mRNA expression levels of IL-18, IL-18BP, IL-18R and IL-18R were quantified using real-time quantitative PCR.

RESULTS

The mRNA expression of IL-18 was significantly higher in ACTH-, GH- and PRL-producing adenomas, when compared to non-function tumors. Similarly, a significantly higher mRNA expression of IL-18BP and IL-18R was observed in ACTH-, GH- and PRL-producing adenomas, when compared with non-functional adenomas. In contrast, no upregulation of IL-18R mRNA was observed in any of the pituitary adenomas.

CONCLUSIONS

The mRNA levels of IL-18, IL-18BP and IL-18R are significantly elevated in clinical pituitary tumors, such as ACTH-, GH- and PRL-producing adenomas, when compared to non-functional adenomas. These present results suggest the possibility that IL-18 may be involved in the pathogenesis of pituitary adenoma.