Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g. ill/critically ill, post-trauma, sepsis, exhausted athletes) it is currently difficult to determine whether glutamine parenteral or enteral supplementation should be recommended based on the amino acid plasma concentration (glutaminemia). Although the beneficial immune based effects of glutamine supplementation is already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review on how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism, action and important issues related to the effects of glutamine supplementation in catabolic situations.

Objective: Type I interferon receptor (IFNAR) signaling contributes to several autoimmune and vascular diseases such as atherosclerosis and stroke. The purpose of this study was to assess the influence of IFNAR1 deficiency on the formation and progression of experimental abdominal aortic aneurysms (AAAs). Methods: AAAs were induced in type I interferon receptor subunit 1 (IFNAR1) deficient and wild type control male mice via intra-infrarenal aortic infusion of porcine pancreatic elastase. Immunostaining for IFNAR1 was evaluated in experimental and clinical aneurysms. The initiation and progression of experimental AAAs was assessed via ultrasound imaging prior to (day 0) and 3-, 7-, and 14-days following elastase infusion. Aneurysmal histopathology was analyzed at sacrifice. Results: Increased aortic medial and adventitial IFNAR1 expression was present in both clinical AAAs harvested at surgery and experimental AAAs. Following AAA initiation, wild type mice experienced progressive, time-dependent infrarenal aortic enlargement. This progression was substantially attenuated in IFNAR1 deficient mice. On histological analyses, medial elastin degradation, smooth muscle cell depletion, leukocyte accumulation and neoangiogenesis were markedly diminished in IFNAR1 deficient as compared to wild type mice. Conclusion: IFNAR1 deficiency limited experimental AAA progression in response to intra-aortic elastase infusion. Combined with clinical observations, these results suggest a regulatory role for IFNAR1 activity in AAA pathogenesis.

Myeloperoxidase (MPO) belong to the family of heme containing peroxidases, produced mostly from polymorphonuclear neutrophils. The active enzyme (150 kD) is the product of MPO gene located on long arm of chromosome 17. The primary gene product undergoes several modifications like removal of introns and signal peptide and leads to the formation of enzymatically inactive glycosylated apoproMPO which complexes with chaperons, producing active proMPO by the insertion of heme moiety. The active enzyme is a homodimer of heavy and light chain protomers. This enzyme is released into extracellular fluid after oxidative stress and different inflammatory responses. MPO is the only type of peroxidase using H2O2 to oxidize several halides and pseudohalides to form different hypohalous acids. So the antibacterial activities of MPO involve the production of reactive oxygen and reactive nitrogen species. Controlled MPO release at the site of infection is of prime importance for its efficient activities. Any uncontrolled degranulation exaggerates the inflammation that can also lead to tissue damage even in absence of inflammation. Several types of tissue injuries and pathogenesis of several other major chronic diseases like rheumatoid arthritis, cardiovascular diseases, liver diseases, diabetes and cancer have been reported to be linked with myeloperoxidase derived oxidants. So the enhanced level of MPO activity is one of the best diagnostic tool of inflammatory and oxidative stress biomarkers among these commonly occurring diseases.

The study explores antibacterial, antiinflammatory and cytoprotective capacity of Pelargonium sidoides DC root extract (PSRE) and proanthocyanidin fraction from PSRE (PACN) under conditions characteristic for periodontal disease. Following previous finding that PACN exerts stronger suppression of Porphyromonas gingivalis compared to the effect on commensal Streptococcus salivarius, the current work continues antibacterial investigation on Staphylococcus aureus, Staphylococcus epidermidis, Aggregatibacter actinomycetemcomitans and Escherichia coli. PSRE and PACN are also studied for their ability to prevent gingival fibroblast cell death in the presence of bacteria or bacterial lipopolysaccharide (LPS), to block LPS- or LPS+IFNγ-induced release of inflammatory mediators, gene expression and surface antigen presentation. Both PSRE and PACN were more efficient in suppressing Staphylococcus and Aggregatibacter compared to Escherichia, prevented A. actinomycetemcomitans- and LPS induced death of fibroblasts, decreased LPS-induced release of interleukin 8 and prostaglandin E2 from fibroblasts and IL-6 from leukocytes, blocked expression of IL-1β, iNOS, and surface presentation of CD80 and CD86 in LPS+IFNγ-treated macrophages, and IL-1β and COX-2 expression in LPS-treated leukocytes. None of the investigated substances affected either the level of secretion or expression of TNFα. In conclusion, PSRE, and especially PACN, possess strong antibacterial, antiinflammatory and gingival tissue protecting properties under periodontitis mimicking conditions and are suggestable candidates for treatment of the disease.

Abstract: Viremia in coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is often only discussed in passing and there are very few references detailing its structural mechanisms. In addition to viremia in the classic closed cardiovascular system, the lymphatic system is discussed in relation to a possible “lympho-viremia”. The cells that comprise each of these separate but interacting systems will be examined and include endothelial cells, erythrocytes, leukocytes (monocytes/monocyte-derived macrophages and resident tissue macrophages) (lymphocytes) (neutrophils) and thrombocytes -platelets. The SARS-CoV-2 virus has been identified in multiple extrapulmonary target organs at autopsy in those with severe COVID-19 requiring intensive care. Vulnerable COVID-19 patients may suffer from multiple storms including viral/virion storm, redox storm, cytokine storm and thrombo-embolic storm. Therefore, it is important that the possible mechanisms of viremia be explored in greater detail and how these mechanisms might affect intravascular blood components, extracellular tissue interstitium and organ structural remodeling and function. While the co-morbidity of T2DM does not increase the risk of acquiring COVID-19, it is commonly accepted that T2DM increases the risk for COVID-19 admissions to hospitals, assisted ventilation, morbidity and mortality. Importantly, the co-existence of T2DM and COVID-19 may have synergistic detrimental outcomes.