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Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections.
van Sadelhoff, JHJ, Wiertsema, SP, Garssen, J, Hogenkamp, A
Frontiers in immunology. 2020;:1007
Abstract
Breastfeeding is indicated to support neonatal immune development and to protect against neonatal infections and allergies. Human milk composition is widely studied in relation to these unique abilities, which has led to the identification of various immunomodulating components in human milk, including various bioactive proteins. In addition to proteins, human milk contains free amino acids (FAAs), which have not been well-studied. Of those, the FAAs glutamate and glutamine are by far the most abundant. Levels of these FAAs in human milk sharply increase during the first months of lactation, in contrast to most other FAAs. These unique dynamics are globally consistent, suggesting that their levels in human milk are tightly regulated throughout lactation and, consequently, that they might have specific roles in the developing neonate. Interestingly, free glutamine and glutamate are reported to exhibit immunomodulating capacities, indicating that these FAAs could contribute to neonatal immune development and to the unique protective effects of breastfeeding. This review describes the current understanding of the FAA composition in human milk. Moreover, it provides an overview of the effects of free glutamine and glutamate on immune parameters relevant for allergic sensitization and infections in early life. The data reviewed provide rationale to study the role of free glutamine and glutamate in human milk in the protection against neonatal allergies and infections.
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The Role of the Adipokine Leptin in Immune Cell Function in Health and Disease.
Kiernan, K, MacIver, NJ
Frontiers in immunology. 2020;:622468
Abstract
Leptin is a critical mediator of the immune response to changes in overall nutrition. Leptin is produced by adipocytes in proportion to adipose tissue mass and is therefore increased in obesity. Despite having a well-described role in regulating systemic metabolism and appetite, leptin displays pleiotropic actions, and it is now clear that leptin has a key role in influencing immune cell function. Indeed, many immune cells have been shown to respond to leptin directly via the leptin receptor, resulting in a largely pro-inflammatory phenotype. Understanding the role of adipose-tissue derived mediators in inflammation is critical to determining the pathophysiology of multiple obesity-associated diseases, such as type 2 diabetes, autoimmune disease, and infection. This review, therefore, focuses on the latest data regarding the role of leptin in modulating inflammation.
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New-onset refractory status epilepticus and febrile infection-related epilepsy syndrome.
Specchio, N, Pietrafusa, N
Developmental medicine and child neurology. 2020;(8):897-905
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Abstract
New-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) are relatively rare clinical presentations. They are characterized by de novo onset of refractory status epilepticus (RSE) without clearly identifiable acute or active cause (structural, toxic, or metabolic). We reviewed the literature using PubMed reports published between 2003 and 2019 and summarized the clinical, neurophysiological, imaging, and treatment findings. Focal motor seizures, which tend to evolve into status epilepticus, characterize the typical presentation. Disease course is biphasic: acute phase followed by chronic phase with refractory epilepsy and neurological impairment. Aetiology is unknown, but immune-inflammatory-mediated epileptic encephalopathy is suspected. Electroencephalograms show variety in discharges (sporadic or periodic, focal, generalized, or more frequently bilateral), sometimes with a multifocal pattern. About 70% of adult NORSE have abnormal magnetic resonance imaging (MRI); in paediatric series of FIRES, 61.2% of patients have a normal brain MRI at the beginning and only 18.5% during the chronic phase. No specific therapy for FIRES and NORSE currently exists; high doses of barbiturates and ketogenic diet can be used with some effectiveness. Recently, anakinra and tocilizumab, targeting interleukin pathways, have emerged as potential specific therapies. Mortality rate is around 12% in children and even higher in adults (16-27%).
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Role of Glutathionylation in Infection and Inflammation.
Checconi, P, Limongi, D, Baldelli, S, Ciriolo, MR, Nencioni, L, Palamara, AT
Nutrients. 2019;(8)
Abstract
Glutathionylation, that is, the formation of mixed disulfides between protein cysteines and glutathione (GSH) cysteines, is a reversible post-translational modification catalyzed by different cellular oxidoreductases, by which the redox state of the cell modulates protein function. So far, most studies on the identification of glutathionylated proteins have focused on cellular proteins, including proteins involved in host response to infection, but there is a growing number of reports showing that microbial proteins also undergo glutathionylation, with modification of their characteristics and functions. In the present review, we highlight the signaling role of GSH through glutathionylation, particularly focusing on microbial (viral and bacterial) glutathionylated proteins (GSSPs) and host GSSPs involved in the immune/inflammatory response to infection; moreover, we discuss the biological role of the process in microbial infections and related host responses.
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Gut microbes as future therapeutics in treating inflammatory and infectious diseases: Lessons from recent findings.
Mukherjee, S, Joardar, N, Sengupta, S, Sinha Babu, SP
The Journal of nutritional biochemistry. 2018;:111-128
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The human gut microbiota has been the interest of extensive research in recent years and our knowledge on using the potential capacity of these microbes are growing rapidly. Microorganisms colonized throughout the gastrointestinal tract of human are coevolved through symbiotic relationship and can influence physiology, metabolism, nutrition and immune functions of an individual. The gut microbes are directly involved in conferring protection against pathogen colonization by inducing direct killing, competing with nutrients and enhancing the response of the gut-associated immune repertoire. Damage in the microbiome (dysbiosis) is linked with several life-threatening outcomes viz. inflammatory bowel disease, cancer, obesity, allergy, and auto-immune disorders. Therefore, the manipulation of human gut microbiota came out as a potential choice for therapeutic intervention of the several human diseases. Herein, we review significant studies emphasizing the influence of the gut microbiota on the regulation of host responses in combating infectious and inflammatory diseases alongside describing the promises of gut microbes as future therapeutics.
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Cdc42 - A tryst between host cholesterol metabolism and infection.
Sviridov, D, Mukhamedova, N
Small GTPases. 2018;(3):237-241
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Emerging evidence points to an important connection between pathogenesis of intracellular infections and host cholesterol metabolism. In our study we demonstrated that human cytomegalovirus exploits host small GTPase Cdc42 to hijack cellular cholesterol efflux pathway. It appears that the virus uses host machinery to stimulate cholesterol efflux by modifying lipid rafts and altering properties of plasma membrane, but the altered pathway is controlled by the viral protein US28 instead of the host ATP binding cassette transporter A1. We speculate that virus-controlled remodeling of plasma membrane facilitates immune evasion, exocytosis of viral proteins and cell-to-cell transmission of human cytomegalovirus. These mechanisms may be not unique for the cytomegalovirus and subverting reverse cholesterol transport pathway may be a generic mechanism used by pathogens to alter properties of host plasma membrane adapting it for their purposes-to hide and disseminate.
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Validation of two multiplex platforms to quantify circulating markers of inflammation and endothelial injury in severe infection.
Leligdowicz, A, Conroy, AL, Hawkes, M, Zhong, K, Lebovic, G, Matthay, MA, Kain, KC
PloS one. 2017;(4):e0175130
Abstract
Biomarkers can prognosticate outcome and enable risk-stratification. In severe infection, focusing on multiple markers reflecting pathophysiological mechanisms of organ injury could enhance management and pathway-directed therapeutics. Limited data exist on the performance of multiplex biomarker platforms. Our goal was to compare endothelial and immune activation biomarkers in severe pediatric infections using two multiplex platforms. Frozen plasma from 410 children presenting to the Jinja Regional Hospital in Uganda with suspected infection was used to measure biomarkers of endothelial (Angiopoietin-2, sFlt-1, sVCAM-1, sICAM-1) and immune (IL-6, IP-10, sTNFR-1, CHI3L1) activation. Two multiplex platforms (Luminex®, EllaTM) based on monoclonal antibody sandwich immunoassays using biotin-streptavidin conjugate chemistry were selected with reagents from R&D Systems. The two platforms differed in ease and time of completion, number of samples per assay, and dynamic concentration range. Intra-assay variability assessed using a coefficient of variation (CV%) was 2.2-3.4 for Luminex® and 1.2-2.9 for EllaTM. Correlations for biomarker concentrations within dynamic range of both platforms were best for IL-6 (ρ = 0.96, p<0.0001), IP-10 (ρ = 0.94, p<0.0001) and sFlt-1 (ρ = 0.94, p<0.0001). Agreement between concentrations obtained by both methods assessed by the Bland-Altman test varied, with best agreement for CHI3L1. Our data suggest that biomarkers of endothelial and immune activation can be readily measured with multiplex platforms. Luminex® and EllaTM produced reliable results with excellent CV% values. The EllaTM platform was more automated and completed in 75 minutes, potentially compatible with near-patient use. Trends in concentrations obtained by these methods were highly correlated, although absolute values varied, suggesting caution is required when comparing data from different multiplex platforms.
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Iron Localization and Infectious Disease in Chronic Kidney Disease Patients.
Nakanishi, T, Kuragano, T, Nanami, M, Hasuike, Y
American journal of nephrology. 2016;(4):237-44
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For patients on dialysis, infection is the second leading cause of mortality. Iron metabolism should be considered in the pathogenesis of infectious disease, as high local iron concentrations favor the growth of many microbes. This review is intended to provide information regarding iron metabolism and infection in chronic kidney disease (CKD) patients. There are 2 reasons these patients may be vulnerable to infection: (1) the excessive iron administered to treat renal anemia could be associated with impairments of the host's innate immune response, (2) CKD-associated inflammation could cause dysregulated iron metabolism. Pathogenic microorganisms can be categorized as extracellular or intracellular pathogens. The proliferation site may determine the degree of virulence. In cases of mainly extracellular microbial growth, the host's strategy of sequestering iron in cells may efficiently inhibit proliferation. However, the same strategy may favor the intracellular growth of microorganisms. The administration of excessive amounts of iron may modify iron localization by an increase in the hepcidin concentration. We conclude that there is a need for large multicenter randomized controlled trials to evaluate the long-term safety of different iron administration patterns that allow for a lower infection rate while still producing efficient erythropoiesis in CKD patients.
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Stored red blood cell transfusions: Iron, inflammation, immunity, and infection.
Hod, EA, Spitalnik, SL
Transfusion clinique et biologique : journal de la Societe francaise de transfusion sanguine. 2012;(3):84-9
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The potential adverse effects of transfusion of red blood cells after prolonged storage have been hotly debated. During refrigerated storage, red blood cells are damaged, a process known as the red blood cell "storage lesion." We hypothesized that the delivery of a bolus of iron derived from these rapidly cleared, damaged, red blood cells is responsible for some of the adverse effects of transfusion. Iron may play a role in producing a pro-inflammatory response to transfused red blood cells, potentially through the effects of reactive oxygen species on stress pathways and inflammasome activation. Furthermore, the excess iron may impair the host's ability to combat infection by its innate iron-withholding pathways. This symposium paper summarizes the background for the "iron hypothesis" as it relates to transfusion of red blood cells after prolonged refrigerated storage. It also includes a summary of the data from recent murine and human studies, and concludes with a discussion of several unresolved questions arising from these published studies.
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Inhibitory receptors on lymphocytes: insights from infections.
Odorizzi, PM, Wherry, EJ
Journal of immunology (Baltimore, Md. : 1950). 2012;(7):2957-65
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Costimulatory and inhibitory receptors are critical regulators of adaptive immune cell function. These pathways regulate the initiation and termination of effective immune responses to infections while limiting autoimmunity and/or immunopathology. This review focuses on recent advances in our understanding of inhibitory receptor pathways and their roles in different diseases and/or infections, emphasizing potential clinical applications and important unanswered mechanistic questions. Although significant progress has been made in defining the influence of inhibitory receptors at the cellular level, relatively little is known about the underlying molecular pathways. We discuss our current understanding of the molecular mechanisms for key inhibitory receptor pathways, highlight major gaps in knowledge, and explore current and future clinical applications.