Regulation Of Immune Cell Function Research Articles

Is early enteral feeding in critical care feasible in the United Kingdom?

Enteral feeding is beneficial for preservation of gut integrity and regulation of immune-cell function [1]. Critically ill patients tend towards catabolism, and early enteral feeding has been found to reduce mortality in mechanically ventilated patients [2]. Other studies have also showed association with decreased mortality and decreased hospital and intensive care length of stay [3]. Our retrospective study in St George's General Intensive Care Unit (GICU) in London looked at whether we were meeting current guidelines on early enteral feeding. Local guidelines instruct for feeding within 12 hours but current European Society of Parenteral and Enteral Nutrition Guidelines (ESPEN) 2006 recommend feeding within 24 hours. We looked at the timing of feeding of patients admitted into the unit over a 6 week period. We defined early feeding as enteral feeding within 24 hours of admission and late feeding as feeding after 48 hours. In a 6 week period, 129 new patients were admitted into the 18 bedded GICU. 38 (29.5%) patients were elective post-operative patients versus 91 (70.5%) emergency admissions. Overall, 107 (82.9 %) patients were fed early. Feeding was mainly via the non-invasive oral route (56.6%) or nasogastric route (42.6%). Only one patient was fed via percutaneous endoscopic gastrostomy. In the elective admissions group, 35 (92%) patients were fed early vs 72 (79%) in the emergency group. Reasons for late feeding include patient declining feed, early return to theatre and slow communication with parent teams for clarification on feeding regime. Patients who were newly established on enteral feeding received the local standard starting regime. We hypothesise that early feeding was achieved in 83% of patients due to the stricter local guidelines. Feeding delay occurs more often in emergency admissions. When there are no contraindications, early feeding should be considered due to the benefits. Our results indicate that early enteral feeding in tertiary intensive care units in the UK is achieveable.

Hypoxia and inflammation

Uncontrolled or non-resolving inflammation is central to the pathophysiology of clinically important conditions including inflammatory bowel disease (IBD), psoriasis, atherosclerosis and arthritis. A combination of increased oxygen demand and decreased supply renders the local microenvironment of chronically inflamed tissues oxygen deprived (hypoxic), leading to the expression of a programme of genes that promote adaptation to the hypoxic challenge. This ancient and ubiquitous adaptive transcriptional pathway is governed by a transcription factor termed the hypoxia-inducible factor (HIF). Originally identified in the search for regulators of hypoxia-induced erythropoietin expression and adaptation to high altitude, HIF has been more recently recognized as a major regulator of immune cell function, which is central to the control of immunity and inflammation. Indeed, recent studies have demonstrated that the use of drugs targeting the HIF pathway may be of benefit in the treatment of chronic inflammatory disease.

Sphingolipids in neutrophil function and inflammatory responses: Mechanisms and implications for intestinal immunity and inflammation in ulcerative colitis.

Bioactive sphingolipids are regulators of immune cell function and play critical roles in inflammatory conditions including ulcerative colitis. As one of the major forms of inflammatory bowel disease, ulcerative colitis pathophysiology is characterized by an aberrant intestinal inflammatory response that persists causing chronic inflammation and tissue injury. Innate immune cells play an integral role in normal intestinal homeostasis but their dysregulation is thought to contribute to the pathogenesis of ulcerative colitis. In particular, neutrophils are key effector cells and are first line defenders against invading pathogens. While the activity of neutrophils in the intestinal mucosa is required for homeostasis, regulatory mechanisms are equally important to prevent unnecessary activation. In ulcerative colitis, unregulated neutrophil inflammatory mechanisms promote tissue injury and loss of homeostasis. Aberrant neutrophil function represents an early checkpoint in the detrimental cycle of chronic intestinal inflammation; thus, dissecting the mechanisms by which these cells are regulated both before and during disease is essential for understanding the pathogenesis of ulcerative colitis. We present an analysis of the role of sphingolipids in the regulation of neutrophil function and the implication of this relationship in ulcerative colitis.

Mycolactone subverts immunity by selectively blocking the Sec61 translocon

Mycolactone, an immunosuppressive macrolide released by the human pathogen Mycobacterium ulcerans, was previously shown to impair Sec61-dependent protein translocation, but the underlying molecular mechanism was not identified. In this study, we show that mycolactone directly targets the α subunit of the Sec61 translocon to block the production of secreted and integral membrane proteins with high potency. We identify a single-amino acid mutation conferring resistance to mycolactone, which localizes its interaction site near the lumenal plug of Sec61α. Quantitative proteomics reveals that during T cell activation, mycolactone-mediated Sec61 blockade affects a selective subset of secretory proteins including key signal-transmitting receptors and adhesion molecules. Expression of mutant Sec61α in mycolactone-treated T cells rescued their homing potential and effector functions. Furthermore, when expressed in macrophages, the mycolactone-resistant mutant restored IFN-γ receptor-mediated antimicrobial responses. Thus, our data provide definitive genetic evidence that Sec61 is the host receptor mediating the diverse immunomodulatory effects of mycolactone and identify Sec61 as a novel regulator of immune cell functions.

Extracellular Vesicles: Immunomodulatory messengers in the context of tissue repair/regeneration

Inflammation is a complex and highly regulated biological process, crucial for a variety of functions in the human body, from host response against infectious agents to initiation of repair/regeneration of injured tissues. In the context of tissue repair, the action of different immune cell populations and their interplay with tissue specific cells, including stem cells, is still being uncovered. Extracellular Vesicles (EV) are small membrane vesicles secreted by cells in a controlled manner, which can act locally and systemically. The ability of EV to influence tissue repair and regeneration has been proposed as a physiologically intelligent and targeted strategy of cell communication. Herein, the role of EV in tissue repair is reviewed, summarising first their contribution to the regulation of immune cell function, and discussing the implications for the resolution of inflammation during repair. Next, the impact of EV on cell proliferation and differentiation, and on extracellular matrix remodelling, key aspects of the subsequent phases of tissue repair, is addressed. Finally, EV-based therapies are discussed, focusing on the application of naturally produced EV, and the use of EV as delivery vehicles.

The CB2 receptor and its role as a regulator of inflammation.

The CB2 receptor is the peripheral receptor for cannabinoids. It is mainly expressed in immune tissues, highlighting the possibility that the endocannabinoid system has an immunomodulatory role. In this respect, the CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases. In this regard, numerous studies have reported that mice lacking the CB2 receptor have an exacerbated inflammatory phenotype. This suggests that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions. Herein, we review the pharmacology of the CB2 receptor, its expression pattern, and the signaling pathways induced by its activation. We next examine the regulation of immune cell functions by the CB2 receptor and the evidence obtained from primary human cells, immortalized cell lines, and animal models of inflammation. Finally, we discuss the possible therapies targeting the CB2 receptor and the questions that remain to be addressed to determine whether this receptor could be a potential target to treat inflammatory disease.

Effects of estrogen on intracellular calcium-related T-lymphocyte function.

Regulation of immune cell function is an important in the field of hormone-related tissue engineering and regenerative medicine. In this sense, hormonal regulation of immune cell function is a critical issue to be solved. It has been known that ovarian sex hormone play an important roles in immune function, however, little has been known whether estrogen affects T-lymphocyte function. Human Jurkat T cells were treated with estradiol (E2) at concentrations of 0, 10, 100, 1000 ng/mL, and calcium response was evaluated. Intracellular calcium concentrations after Fura-2 acetoxymethyl ester treatment show an increasing trend at higher E2 concentrations although these alterations did not reach a statistical significance. The expression of calcium channel-related gene CACNA1C did not show any significant changes according to the concentration of E2. Taken together, estrogen has an implication as a possible hormonal regulator of intracellular calcium release in human Jurkat T cells via non-genomic pathway. Further studies are necessary to investigate the combined effects of sex hormones and cytokines in both T- and B-lymphocytes.

Regulation of immune cell function by short-chain fatty acids.

Short-chain fatty acids (SCFAs) are bacterial fermentation products, which are chemically composed by a carboxylic acid moiety and a small hydrocarbon chain. Among them, acetic, propionic and butyric acids are the most studied, presenting, respectively, two, three and four carbons in their chemical structure. These metabolites are found in high concentrations in the intestinal tract, from where they are uptaken by intestinal epithelial cells (IECs). The SCFAs are partially used as a source of ATP by these cells. In addition, these molecules act as a link between the microbiota and the immune system by modulating different aspects of IECs and leukocytes development, survival and function through activation of G protein coupled receptors (FFAR2, FFAR3, GPR109a and Olfr78) and by modulation of the activity of enzymes and transcription factors including the histone acetyltransferase and deacetylase and the hypoxia-inducible factor. Considering that, it is not a surprise, the fact that these molecules and/or their targets are suggested to have an important role in the maintenance of intestinal homeostasis and that changes in components of this system are associated with pathological conditions including inflammatory bowel disease, obesity and others. The aim of this review is to present a clear and updated description of the effects of the SCFAs derived from bacteria on host immune system, as well as the molecular mechanisms involved on them.

Nutritional strategies to optimize dairy cattle immunity

Dairy cattle are susceptible to increased incidence and severity of both metabolic and infectious diseases during the periparturient period. A major contributing factor to increased health disorders is alterations in bovine immune mechanisms. Indeed, uncontrolled inflammation is a major contributing factor and a common link among several economically important infectious and metabolic diseases including mastitis, retained placenta, metritis, displaced abomasum, and ketosis. The nutritional status of dairy cows and the metabolism of specific nutrients are critical regulators of immune cell function. There is now a greater appreciation that certain mediators of the immune system can have a reciprocal effect on the metabolism of nutrients. Thus, any disturbances in nutritional or immunological homeostasis can provide deleterious feedback loops that can further enhance health disorders, increase production losses, and decrease the availability of safe and nutritious dairy foods for a growing global population. This review will discuss the complex interactions between nutrient metabolism and immune functions in periparturient dairy cattle. Details of how either deficiencies or overexposure to macro- and micronutrients can contribute to immune dysfunction and the subsequent development of health disorders will be presented. Specifically, the ways in which altered nutrient metabolism and oxidative stress can interact to compromise the immune system in transition cows will be discussed. A better understanding of the linkages between nutrition and immunity may facilitate the design of nutritional regimens that will reduce disease susceptibility in early lactation cows.

Mechanisms of Inflammation-Associated Depression: Immune Influences on Tryptophan and Phenylalanine Metabolisms.

Metabolic parameters have a direct role in the regulation of immune cell function. Thereby the inflammation-induced metabolism of aromatic amino acids, most importantly of tryptophan and phenylalanine, plays a central role. In addition, neuropsychiatric conditions that go along with disorders that are characterized by acute or chronic inflammation, such as the development of depression, decreased quality of life or cognitive impairments, are connected to disturbed amino acid and subsequent neurotransmitter metabolism.The bioanalytical procedures for the determination of concentrations of tryptophan and phenylalanine and their respective first stable intermediates kynurenine and tyrosine as well as some analytical finesses and potential sources of errors are discussed in this chapter. Monitoring of these immunometabolic parameters throughout therapies in addition to biomarkers of immune response and inflammation such as neopterin can be useful to determine disease progression but also to plan psychiatric interventions timely, thus to establish personalized treatments.

MiR-142-5p and miR-130a-3p are regulated by IL-4 and IL-13 and control profibrogenic macrophage program.

Macrophages play a pivotal role in tissue fibrogenesis, which underlies the pathogenesis of many end-stage chronic inflammatory diseases. MicroRNAs are key regulators of immune cell functions, but their roles in macrophage's fibrogenesis have not been characterized. Here we show that IL-4 and IL-13 induce miR-142-5p and downregulate miR-130a-3p in macrophages; these changes sustain the profibrogenic effect of macrophages. In vitro, miR-142-5p mimic prolongs STAT6 phosphorylation by targeting its negative regulator, SOCS1. Blocking miR-130a relieves its inhibition of PPARγ, which coordinates STAT6 signalling. In vivo, inhibiting miR-142-5p and increasing miR-130a-3p expression with locked nucleic acid-modified oligonucleotides inhibits CCL4-induced liver fibrosis and bleomycin-induced lung fibrosis in mice. Furthermore, macrophages from the tissue samples of patients with liver cirrhosis and idiopathic pulmonary fibrosis display increased miR-142-5p and decreased miR-130a-3p expression. Therefore, miR-142-5p and miR-130a-3p regulate macrophage profibrogenic gene expression in chronic inflammation.

Adipose triglyceride lipase acts on neutrophil lipid droplets to regulate substrate availability for lipid mediator synthesis

In humans, mutations in ATGL lead to TG accumulation in LDs of most tissues and cells, including peripheral blood leukocytes. This pathologic condition is called Jordans' anomaly, in which functional consequences have not been investigated. In the present study, we tested the hypothesis that ATGL plays a role in leukocyte LD metabolism and immune cell function. Similar to humans with loss-of-function mutations in ATGL, we found that global and myeloid-specific Atgl(-/-) mice exhibit Jordans' anomaly with increased abundance of intracellular TG-rich LDs in neutrophil granulocytes. In a model of inflammatory peritonitis, lipid accumulation was also observed in monocytes and macrophages but not in eosinophils or lymphocytes. Neutrophils from Atgl(-/-) mice showed enhanced immune responses in vitro, which were more prominent in cells from global compared with myeloid-specific Atgl(-/-) mice. Mechanistically, ATGL(-/-) as well as pharmacological inhibition of ATGL led to an impaired release of lipid mediators from neutrophils. These findings demonstrate that the release of lipid mediators is dependent on the liberation of precursor molecules from the TG-rich pool of LDs by ATGL. Our data provide mechanistic insights into Jordans' anomaly in neutrophils and suggest that ATGL is a potent regulator of immune cell function and inflammatory diseases.

Targeting epidermal fatty acid binding protein for treatment of experimental autoimmune encephalomyelitis.

BackgroundMultiple sclerosis (MS) is an autoimmune disease in which dysregulated immune cells attack myelin in the central nervous system (CNS), leading to irreversible neuronal degeneration. Our previous studies have demonstrated that epidermal fatty acid binding protein (E-FABP), widely expressed in immune cells, in particular in dendritic cells (DCs) and T lymphocytes, fuels the overactive immune responses in the mouse model of experimental autoimmune encephalomyelitis (EAE).MethodsIn the present study, we conducted an intensive computational docking analysis to identify novel E-FABP inhibitors for regulation of immune cell functions and for treatment of EAE.ResultsWe demonstrate that compound [2-(4-acetylphenoxy)-9,10-dimethoxy-6,7-dihydropyrimido[6,1-a]isoquinolin-4-one; designated as EI-03] bound to the lipid binding pocket of E-FABP and enhanced the expression of peroxisome proliferator-activating receptor (PPAR) γ. Further in vitro experiments showed that EI-03 regulated DC functions by inhibition of TNFα production while promoting IL-10 secretion. Moreover, EI-03 treatment counterregulated T cell balance by decreasing effector T cell differentiation (e.g. Th17, Th1) while increasing regulatory T cell development. Most importantly, mice treated with this newly identified compound exhibited reduced clinical symptoms of EAE in mouse models.ConclusionsTaken together, we have identified a new compound which displays a potential therapeutic benefit for treatment of MS by targeting E-FABP.

Bactericidal/Permeability-increasing protein fold-containing family member A1 in airway host protection and respiratory disease.

Bactericidal/permeability-increasing protein fold-containing family member A1 (BPIFA1), formerly known as SPLUNC1, is one of the most abundant proteins in respiratory secretions and has been identified with increasing frequency in studies of pulmonary disease. Its expression is largely restricted to the respiratory tract, being highly concentrated in the upper airways and proximal trachea. BPIFA1 is highly responsive to airborne pathogens, allergens, and irritants. BPIFA1 actively participates in host protection through antimicrobial, surfactant, airway surface liquid regulation, and immunomodulatory properties. Its expression is modulated in multiple lung diseases, including cystic fibrosis, chronic obstructive pulmonary disease, respiratory malignancies, and idiopathic pulmonary fibrosis. However, the role of BPIFA1 in pulmonary pathogenesis remains to be elucidated. This review highlights the versatile properties of BPIFA1 in antimicrobial protection and its roles as a sensor of environmental exposure and regulator of immune cell function. A greater understanding of the contribution of BPIFA1 to disease pathogenesis and activity may clarify if BPIFA1 is a biomarker and potential drug target in pulmonary disease.

A role for Hox5 genes in T cell function during chronic allergic inflammation (HYP7P.268)

Abstract Allergic asthma is a significant health burden in western countries, and continues to increase in prevalence. T helper 2 (Th2) cells contribute to the development of disease through release of the cytokines interleukin (IL)-4, IL-5 and IL-13, resulting in increased airway eosinophils and mucus hypersecretion. While many factors are involved in the development of allergic asthma, the molecular mechanisms behind the disease remain largely unknown. As the three members of the Hox5 gene family (Hoxa5, Hoxb5 and Hoxc5) have been shown to play a role in lung development, we asked whether these genes also play a role in the adult lung in response to disease. We found that Hox5-deficient mice show exacerbated pathology compared to wild-type controls in a chronic allergen model, with an increased Th2 response as well as changes in lung tissue pathology. Examination of T cells from naïve wild-type or Hox5-deficient mice in Th2 polarizing conditions showed increased proliferation, enhanced Gata3 expression and production of IL-4, IL-5 and IL-13 in Hox5-deficient mice compared to wild-type controls. Overexpression of FLAG-tagged HOX5 proteins in Jurkat cells demonstrated HOX5 binding to the Gata3 locus, supporting a role for HOX5 proteins in direct transcriptional control of Th2 development. These results reveal a novel role for Hox5 genes as developmental regulators of immune cell function and Th2-induced pathology during allergic disease in the lung.

Targeting epidermal fatty acid binding protein for treatment of experimental autoimmune encephalomyelitis (THER7P.947)

Abstract Multiple sclerosis (MS) is an autoimmune disease in which dysregulated immune cells attack myelin in the central nervous system (CNS), leading to irreversible neuronal degeneration. Our previous studies have demonstrated that epidermal fatty acid binding protein (E-FABP) widely expressed in immune cells, in particular in dendritic cells (DCs) and T lymphocytes, fuels their overactive immune responses in the mouse model of experimental autoimmune encephalomyelitis (EAE). In the present study, we conducted an intensive computational docking analysis to identify novel E-FABP inhibitors for regulation of immune cell functions and for treatment of EAE. We demonstrate that compound [2-(4-acetylphenoxy)-9,10-dimethoxy-6,7-dihydropyrimido[6,1-a]isoquinolin-4-one; designated as EI-03] binded lipid binding pocket of E-FABP and enhanced the expression of peroxisome proliferator-activating receptor (PPAR) γ. Further in vitro experiments showed that EI-03 regulated DC functions by inhibition of TNFα production while promoting IL-10 secretion. Moreover, EI-03 treatment counterregulated T cell balance by decreasing effector T cell differentiation (e.g. Th17, Th1) but increasing regulatory T cell development. Most importantly, mice treated with this newly identified compound exhibited reduced clinical symptoms of EAE in different mouse models. Taken together, we have identified a new compound which displays a potential therapeutic benefit for treatment of MS by targeting E-FABP.

Stress, metabolism and cancer: integrated pathways contributing to immune suppression.

The potential for immune cells to control cancers has been recognized for many decades, but only recently has real excitement begun to spread through the oncology community following clear evidence that therapeutic blockade of specific immune-suppressive mechanisms is enough to make a real difference in survival for patients with several different advanced cancers. However, impressive and encouraging as these new clinical data are, it is clear that more effort should be devoted toward understanding the full spectrum of factors within cancer patients, which have the potential to block or weaken antitumor activity by immune cells. The goal of this brief review is to highlight recent literature revealing interactive stress and metabolic pathways, particularly those mediated by the sympathetic nervous system, which may conspire to block immune cells from unleashing their full killing potential. There is exciting new information regarding the role of neurogenesis by tumors and adrenergic signaling in cancer progression (including metabolic changes associated with cachexia and lipolysis) and in regulation of immune cell function and differentiation. However, much more work is needed to fully understand how the systemic metabolic effects mediated by the brain and nervous system can be targeted for therapeutic efficacy in the setting of immunotherapy and other cancer therapies.

The Role of microRNAs in Bovine Infection and Immunity.

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that are recognized as critical regulators of immune gene expression during infection. Many immunologically significant human miRNAs have been found to be conserved in agriculturally important species, including cattle. Discovering how bovine miRNAs mediate the immune defense during infection is critical to understanding the etiology of the most prevalent bovine diseases. Here, we review current knowledge of miRNAs in the bovine genome, and discuss the advances in understanding of miRNAs as regulators of immune cell function, and bovine immune response activation, regulation, and resolution. Finally, we consider the future perspectives on miRNAs in bovine viral disease, their role as potential biomarkers and in therapy.

Syk interacts with and phosphorylates nucleolin to stabilize Bcl-x(L) mRNA and promote cell survival.

The Syk protein tyrosine kinase, a well-characterized regulator of immune cell function, plays an increasingly recognized role in tumorigenesis as a promoter of cell survival in both hematological and nonhematological malignancies. We show here that the expression of Syk in MCF7 or MDA-MB-231 breast cancer cells or in DG75 B-lymphoma cells protects cells from apoptosis induced by oxidative or genotoxic stress by stabilizing the mRNA for Bcl-x(L), an antiapoptotic protein. Syk binds robustly to nucleolin and phosphorylates it on tyrosine, enhancing its ability to bind the Bcl-x(L) mRNA. Consequently, reducing the level of nucleolin by RNA interference attenuates the ability of Syk to protect cells from stress-induced cell death.

Siglec-mediated regulation of immune cell function in disease.

All mammalian cells display a diverse array of glycan structures that differ from those that are found on microbial pathogens. Siglecs are a family of sialic acid-binding immunoglobulin-like receptors that participate in the discrimination between self and non-self, and that regulate the function of cells in the innate and adaptive immune systems through the recognition of their glycan ligands. In this Review, we describe the recent advances in our understanding of the roles of Siglecs in the regulation of immune cell function in infectious diseases, inflammation, neurodegeneration, autoimmune diseases and cancer.