Activation of the TCA Cycle to Provide Immune Protection in Zebrafish Immunized by High Magnesium-Prepared Vibrio alginolyticus Vaccine.

Vaccines are safe and efficient in controlling bacterial diseases in the aquaculture industry and are in line with green farming. The present study develops a previously unreported approach to prepare a live-attenuated V. alginolyticus vaccine by culturing bacteria in a high concentration of magnesium to attenuate bacterial virulence. Furthermore, metabolomes of zebrafish immunized with the live-attenuated vaccines were compared with those of survival and dying zebrafish infected by V. alginolyticus. The enhanced TCA cycle and increased fumarate were identified as the most key metabolic pathways and the crucial biomarker of vaccine-mediated and survival fish, respectively. Exogenous fumarate promoted expression of il1ß, il8, il21, nf-κb, and lysozyme in a dose-dependent manner. Among the five innate immune genes, the elevated il1ß, il8, and lysozyme are overlapped in the vaccine-immunized zebrafish and the survival from the infection. These findings highlight a way in development of vaccines and exploration of the underlying mechanisms.

Magnesium in Infectious Diseases in Older People.

Reduced magnesium (Mg) intake is a frequent cause of deficiency with age together with reduced absorption, renal wasting, and polypharmacotherapy. Chronic Mg deficiency may result in increased oxidative stress and low-grade inflammation, which may be linked to several age-related diseases, including higher predisposition to infectious diseases. Mg might play a role in the immune response being a cofactor for immunoglobulin synthesis and other processes strictly associated with the function of T and B cells. Mg is necessary for the biosynthesis, transport, and activation of vitamin D, another key factor in the pathogenesis of infectious diseases. The regulation of cytosolic free Mg in immune cells involves Mg transport systems, such as the melastatin-like transient receptor potential 7 channel, the solute carrier family, and the magnesium transporter 1 (MAGT1). The functional importance of Mg transport in immunity was unknown until the description of the primary immunodeficiency XMEN (X-linked immunodeficiency with Mg defect, Epstein-Barr virus infection, and neoplasia) due to a genetic deficiency of MAGT1 characterized by chronic Epstein-Barr virus infection. This and other research reporting associations of Mg deficit with viral and bacterial infections indicate a possible role of Mg deficit in the recent coronavirus disease 2019 (COVID-19) and its complications. In this review, we will discuss the importance of Mg for the immune system and for infectious diseases, including the recent pandemic of COVID-19.

How Pathogens Feel and Overcome Magnesium Limitation When in Host Tissues.

Host organisms utilize nutritional immunity to limit the availability of nutrients essential to an invading pathogen. Nutrients may include amino acids, nucleotide bases, and transition metals, the essentiality of which varies among pathogens. The mammalian macrophage protein Slc11a1 (previously Nramp1) mediates resistance to several intracellular pathogens. Slc11a1 is proposed to restrict growth of Salmonella enterica serovar Typhimurium in host tissues by causing magnesium deprivation. This is intriguing because magnesium is the most abundant divalent cation in all living cells. A pathogen's response to factors such as Slc11a1 that promote nutritional immunity may therefore reflect what the pathogen 'feels' in its cytoplasm, rather than the nutrient concentration in host cell compartments.

TRPM channels as potential therapeutic targets against pro-inflammatory diseases.

The immune system protects our body against foreign pathogens. However, if it overshoots or turns against itself, pro-inflammatory diseases, such as rheumatoid arthritis, inflammatory bowel disease, or diabetes develop. Ions, the most basic signaling molecules, shape intracellular signaling cascades resulting in immune cell activation and subsequent immune responses. Mutations in ion channels required for calcium signaling result in human immunodeficiencies and highlight those ion channels as valued targets for therapies against pro-inflammatory diseases. Signaling pathways regulated by melastatin-like transient receptor potential (TRPM) cation channels also play crucial roles in calcium signaling and leukocyte physiology, affecting phagocytosis, degranulation, chemokine and cytokine expression, chemotaxis and invasion, as well as lymphocyte development and proliferation. Therefore, this review discusses their regulation, possible interactions and whether they can be exploited as targets for therapeutic approaches to pro-inflammatory diseases.

Magnesium, C-reactive protein, and cortisol in drug-naïve patients with short illness-duration, first episode major depressive disorder: possible immunomodulatory role for magnesium.

Plasma magnesium concentration alterations, hypercortisolaemia, and systemic inflammation are observed in major depressive disorder (MDD). This exploratory study examined whether, and to what extent, plasma magnesium is related to C-reactive protein (CRP) levels and cortisolaemia in MDD. The concentrations of plasma magnesium, salivary CRP, and baseline plasma cortisol were studied in 20, treatment-naïve MDD patients with short-illness-duration, first affective episodes and 20 matched controls. Depressed patients showed a basal score higher than 20 on the Hamilton Rating Scale for Depression (HAMD-17). Significantly higher magnesium (p = 0.016) and baseline cortisol (p = 0.01) concentrations were observed in MDD as compared to controls. No significant difference in CRP concentrations between the MDD and control groups was observed. A significant negative correlation was seen between magnesium and CRP in MDD (p<0.01), whereas no correlation was found in controls. A significant positive correlation was found between cortisol and CRP, both in MDD subjects (p = 0.008) and controls (p = 0.004). No significant correlations were observed between magnesium and cortisol levels. The study supports data for hypercortisolaemia in MDD, but provides no evidence of primary hypomagnesaemia or elevated CRP levels in drug-naïve MDD patients with short-illness-duration. The study supports the hypothesis linking hypercortisolaemia to systemic inflammation, with hypermagnesaemia exerting an immunomodulatory action at early stages of the disease.

Dietary magnesium and copper affect survival time and neuroinflammation in chronic wasting disease.

Chronic wasting disease (CWD), the only known wildlife prion disease, affects deer, elk and moose. The disease is an ongoing and expanding problem in both wild and captive North American cervid populations and is difficult to control in part due to the extreme environmental persistence of prions, which can transmit disease years after initial contamination. The role of exogenous factors in CWD transmission and progression is largely unexplored. In an effort to understand the influence of environmental and dietary constituents on CWD, we collected and analyzed water and soil samples from CWD-negative and positive captive cervid facilities, as well as from wild CWD-endozootic areas. Our analysis revealed that, when compared with CWD-positive sites, CWD-negative sites had a significantly higher concentration of magnesium, and a higher magnesium/copper (Mg/Cu) ratio in the water than that from CWD-positive sites. When cevidized transgenic mice were fed a custom diet devoid of Mg and Cu and drinking water with varied Mg/Cu ratios, we found that higher Mg/Cu ratio resulted in significantly longer survival times after intracerebral CWD inoculation. We also detected reduced levels of inflammatory cytokine gene expression in mice fed a modified diet with a higher Mg/Cu ratio compared to those on a standard rodent diet. These findings indicate a role for dietary Mg and Cu in CWD pathogenesis through modulating inflammation in the brain.

Mg2+ regulates cytotoxic functions of NK and CD8 T cells in chronic EBV infection through NKG2D.

The magnesium transporter 1 (MAGT1) is a critical regulator of basal intracellular free magnesium (Mg(2+)) concentrations. Individuals with genetic deficiencies in MAGT1 have high levels of Epstein-Barr virus (EBV) and a predisposition to lymphoma. We show that decreased intracellular free Mg(2+) causes defective expression of the natural killer activating receptor NKG2D in natural killer (NK) and CD8(+) T cells and impairs cytolytic responses against EBV. Notably, magnesium supplementation in MAGT1-deficient patients restores intracellular free Mg(2+) and NKG2D while concurrently reducing EBV-infected cells in vivo, demonstrating a link between NKG2D cytolytic activity and EBV antiviral immunity in humans. Moreover, these findings reveal a specific molecular function of free basal intracellular Mg(2+) in eukaryotic cells.

The role of Mg2+ in immune cells.

The physiological and clinical relevance of Mg(2+) has evolved over the last decades. The molecular identification of multiple Mg(2+) transporters (Acdp2, MagT1, Mrs2, Paracellin-1, SLC41A1, SLC41A2, TRPM6 and TRPM7) and their biophysical characterization in recent years has improved our understanding of Mg(2+) homeostasis regulation and has provided a basis for investigating the role of Mg(2+) in the immune system. Deletions and mutations of Mg(2+) transporters produce severe phenotypes with more systemic symptoms than those seen with Ca(2+) channel deletions, which tend to be more specific and less profound. Deficiency of the Mg(2+) permeable ion channels TRPM6 or TRPM7 in mice is lethal at embryonic day 12.5 or at day 6.5, respectively, and, even more surprisingly, chicken DT40 B cells lacking TRPM7 die after 24-48 h. Recent progress made in Mg(2+) research has helped to define underlying mechanisms of two hereditary diseases, human Hypomagnesemia (TRPM6 deletion) and X-chromosomal immunodeficiency (MagT1 deletion), and has revealed a potential new role for Mg(2+) as a second messenger. Future elucidation of human Mg(2+) transporters (Mrs2, SLC41A1, SLC41A2, TRPM7) expressed in immunocytes, beyond MagT1 and TRPM6, will widen our knowledge about the potential role of Mg(2+) in the activation of the immune response.

Second messenger role for Mg2+ revealed by human T-cell immunodeficiency.

The magnesium ion, Mg(2+), is essential for all life as a cofactor for ATP, polyphosphates such as DNA and RNA, and metabolic enzymes, but whether it plays a part in intracellular signalling (as Ca(2+) does) is unknown. Here we identify mutations in the magnesium transporter gene, MAGT1, in a novel X-linked human immunodeficiency characterized by CD4 lymphopenia, severe chronic viral infections, and defective T-lymphocyte activation. We demonstrate that a rapid transient Mg(2+) influx is induced by antigen receptor stimulation in normal T cells and by growth factor stimulation in non-lymphoid cells. MAGT1 deficiency abrogates the Mg(2+) influx, leading to impaired responses to antigen receptor engagement, including defective activation of phospholipase Cγ1 and a markedly impaired Ca(2+) influx in T cells but not B cells. These observations reveal a role for Mg(2+) as an intracellular second messenger coupling cell-surface receptor activation to intracellular effectors and identify MAGT1 as a possible target for novel therapeutics.

Comparison of morphological changes in efferent lymph nodes after implantation of resorbable and non-resorbable implants in rabbits.

BACKGROUND: Magnesium alloys as biodegradable implant materials received much interest in recent years. It is known that products of implant degradation can induce several types of immune response. Hence, the aim of this study was to examine the morphological changes of efferent lymph nodes after implantation of different resorbable magnesium alloys (MgCa0.8, LAE442) in comparison to commercially available resorbable (PLA) and non-resorbable (titanium) implant materials as well as control groups without implant material. METHODS: The different implant materials were inserted intramedullary into the rabbit tibia. After postoperative observation periods of three and six months, popliteal lymph nodes were examined histologically and immunhistologically and compared to lymph nodes of sham operated animals and animals without surgery. Haematoxylin and eosin staining was performed for cell differentiation. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection, mouse anti-CD68 primary antibodies for macrophage detection. Evaluation of all sections was performed applying a semi quantitative score. RESULTS: The histological evaluation demonstrated low and moderate levels of morphological changes for both magnesium alloys (LAE442 and MgCa0.8). Higher than moderate values were reached for titanium in sinus histiocytosis and histiocytic apoptosis (3 months) and for PLA in histiocytic apoptosis (3 and 6 months). The immune response to all investigated implants had a non-specific character and predominantly was a foreign-body reaction. LAE442 provoked the lowest changes which might be due to a lower degradation rate in comparison to MgCa0.8. Therewith it is a promising candidate for implants with low immunogenic potential. CONCLUSION: Both examined magnesium alloys did not cause significantly increased morphological changes in efferent lymph nodes in comparison to the widely used implant materials titanium and PLA. LAE442 induced even lower immunological reactions. Therewith MgCa0.8 and especially LAE442 are appropriate candidates for biomedical use.

Effects of degradable Mg-Ca alloys on dendritic cell function.

Degradable magnesium alloys are new materials for implants used in orthopedic and trauma surgery. The aim of this study was to investigate the influence of degradable magnesium alloys on the function of dendritic cells (DC) as these cells represent the major antigen presenting cells of the body. MgP (pure magnesium), MgCa 0.6 (0.6% calcium), MgCa 0.8 (0.8% calcium), MgCa 1.0 (1% calcium), and MgCa 1.2 (1.2% calcium) alloys were degraded in cell culture medium. In parallel, murine bone marrow-derived DC were incubated with increasing concentrations (0.1-10 mmol/L) of magnesium chloride and calcium chloride, respectively. Incubation of DC with degradation media over 6 days had no influence on cell viability and only marginal influence on DC migration. Also, the production of TNFα and expression of CD86 was not enhanced by incubation with degraded magnesium alloys. The mixed leukocyte reaction revealed that there was also no increase of the T-cell proliferation in comparison to untreated controls. However, there was a trend toward macrophage development at the expense of DC expansion and an enhanced DC migration was induced by incubation with higher magnesium concentrations. Particularly the latter should be verified in in vivo experiments.

Production of metal ion-dependent monoclonal antibodies against peptides in bovine prothrombin fragment 1.

Bovine prothrombin fragment 1 (F-1: the amino-terminal 156 residues of prothrombin) is used as a model to study the Ca(II) and phospholipid binding of prothrombin. The 35-46 segment in F-1 posses an alpha-helical region and three aromatic residues, conserved in several vitamin K-dependent blood coagulation factors. These residues are believed to have a specific function and to be important in the phospholipid binding of F-1. The 47-62 region, a disulfide loop, is believed to stabilize the gamma-carboxyglutamic acid domain of the protein. Goals of this research were to produce monoclonal antibodies against the above two sequences, for later functional studies. Antibodies S9-32.8 and S9-5.5 were produced against the 35-46 sequence; antibody S11-23.4 was raised against the 47-62 region. Both S9-32.8 and S9-5.5 bound to F-1 immobilized on ELISA plates in the presence of 10 mM Ca(II) with higher affinity than to F-1 coated in the presence of 10 mM Mg(II) or in the absence of metal ions. S11-23.4 showed greatest binding to F-1 coated in the presence of 10 mM Mg(II). Thus, the epitopes of the antibodies are metal ion-dependent and are developed by Ca(II) binding to F-1.

Complement receptor of the Ig superfamily enhances complement-mediated phagocytosis in a subpopulation of tissue resident macrophages.

An important function of the complement cascade is to coat self and foreign particles with C3-proteins that serve as ligands for phagocytic receptors. Although tissue resident macrophages play an important role in complement-mediated clearance, the receptors coordinating this process have not been well characterized. In the present study, we identified a subpopulation of resident peritoneal macrophages characterized by high expression of complement receptor of the Ig superfamily (CRIg), a recently discovered complement C3 receptor. Macrophages expressing CRIg showed significantly increased binding and subsequent internalization of complement-opsonized particles compared with CRIg negative macrophages. CRIg internalized monovalent ligands and was able to bind complement-opsonized targets in the absence of Ca(2+) and Mg(2+), which differs from the beta(2)-integrin CR3 that requires divalent cations and polyvalent ligands for activation of the receptor. Although CRIg dominated in immediate binding of complement-coated particles, CRIg and CR3 contributed independently to subsequent particle phagocytosis. CRIg thus identifies a subset of tissue resident macrophages capable of increased phagocytosis of complement C3-coated particles, a function critical for immune clearance.

Simple method to reduce interference from excess magnesium in cadmium immunoassays.

In order to develop a rapid inexpensive test for cadmium in rice, we identified an antibody specific for cadmium-EDTA complexes; this antibody binds to cadmium-EDTA with a Kd of approximately 10(-8) M. Although the antibody's cross reactivity to magnesium was minimal (Kd approximately 10(-5) M), the high toxicity of cadmium coupled with the high natural occurrence of magnesium in rice resulted in a situation where magnesium interfered with cadmium determination and resulted in falsely elevated estimates of cadmium. Fortunately, the formation constant of EDTA for cadmium is approximately 5 x 10(7) times higher (at pH 7) than the formation constant of EDTA for magnesium, and we were able to eliminate the magnesium interference by judicious selection of the EDTA concentration used in the assay. The resulting equilibria are complex, but we show that a relatively simple two-step model in which cadmium and magnesium compete for EDTA followed by cadmium-EDTA and magnesium-EDTA competing for antibody provided a good fit to the measured data. These analyses enabled appropriate selection of the optimum EDTA concentration for an immunoassay with improved selectivity.

[Magnesium in skin allergy]. / Wplyw magnezu na reakcje alergiczne skóry.

Magnesium is involved in many biological processes within the body. Magnesium deficiency causes many disorders, including impairment of immunity. This review summarizes present knowledge on the relationship between magnesium and skin allergy reactions. Special focus is on allergy types I and IV. At present the best knowledge is on allergy I. Magnesium deficiency in experimental animals, mainly rats, leads to characteristic hyperemia, an increase in IgE, neutrophilia and eosinophilia, an increase in the level of proinflammatory cytokines, mastocyte degranulation, histaminemia, and splenomegaly. These symptoms observed in hypomagnesemic rats are similar to those in atopic patients. Data on the relationship between magnesium and other types of allergy are scarce. Clinical observations show the beneficial effect of topical and oral administration of magnesium salts in patients with skin allergy. All the presented data point to an important role of magnesium in allergy reactions. Other studies are needed to better understand the mechanism of magnesium's action. Well-controlled clinical protocols should also be conducted to assess the efficiency of magnesium supplementation in patients with skin allergy.

Recognition of antimicrobial peptides by a bacterial sensor kinase.

PhoQ is a membrane bound sensor kinase important for the pathogenesis of a number of Gram-negative bacterial species. PhoQ and its cognate response regulator PhoP constitute a signal-transduction cascade that controls inducible resistance to host antimicrobial peptides. We show that enzymatic activity of Salmonella typhimurium PhoQ is directly activated by antimicrobial peptides. A highly acidic surface of the PhoQ sensor domain participates in both divalent-cation and antimicrobial-peptide binding as a first step in signal transduction across the bacterial membrane. Identification of PhoQ signaling mutants, binding studies with the PhoQ sensor domain, and structural analysis of this domain can be incorporated into a model in which antimicrobial peptides displace divalent cations from PhoQ metal binding sites to initiate signal transduction. Our findings reveal a molecular mechanism by which bacteria sense small innate immune molecules to initiate a transcriptional program that promotes bacterial virulence.

Demonstration of alternative and classical complement pathway activity in colostrum from buffalo (Bubalus bubalis).

Buffalo colostrum caused lysis of unsensitized red blood cells (RBC) from sheep, goats, rabbits and chickens. RBC from cattle and buffalo were resistant to lysis. That lysis was due to the presence of natural antibodies to these RBC was ruled out since there was no reduction in haemolytic titres even after adsorption with the respective RBC. The addition of EGTA to the diluent had no effect on the haemolytic activity. These findings indicate the presence of alternative complement pathway (ACP) activity in buffalo colostrum. The haemolytic activity of buffalo complement for unsensitized rabbit RBC was reduced to very low levels by heating at 50 degrees C for 45 min. Treatment with zymosan also inhibited the haemolytic activity, while inulin had no effect. The maximum activity of ACP occurred in the presence of 4 mmol/L Mg(2+) in the diluent. The range of ACP activities in colostrum from buffaloes varied from 4.06 to 8.48 CH50 units/ml. Using a standard system for titrating the classical complement pathway and rabbit red blood cells sensitized with goat haemolysin, the range of complement activity in buffalo colostrum was 4.81-6.77 CH50/ml.

The role of zinc in the binding of killer cell Ig-like receptors to class I MHC proteins.

The binding of killer cell Ig-like Receptors (KIR) to their Class I MHC ligands was shown previously to be characterized by extremely rapid association and dissociation rate constants. During experiments to investigate the biochemistry of receptor-ligand binding in more detail, the kinetic parameters of the interaction were observed to alter dramatically in the presence of Zn(2+) but not other divalent cations. The basis of this phenomenon is Zn(2+)-induced multimerization of the KIR molecules as demonstrated by BIAcore, analytical ultracentrifugation, and chemical cross-linking experiments. Zn(2+)-dependent multimerization of KIR may be critical for formation of the clusters of KIR and HLA-C molecules, the "natural killer (NK) cell immune synapse," observed at the site of contact between the NK cell and target cell.

Interactions between magnesium and vitamin D: possible implications in the immune system.

Evidence clearly shows that magnesium and vitamin D [1 alpha, 25-dihydroxyvitamin D3; 1,25(OH)2D3] independently affect numerous aspects of the immune system. Although no reports of interactive effects on components of immunity have been found, there is evidence that the two nutrients interact in other biosystems, sometimes involving calcium. Furthermore, this paper identifies numerous places in common where both magnesium and vitamin D reportedly affect immune function. Fundamental sites for possible interaction within the immune system include cell transformation, regulation of the cell cycle, stabilization of nuclear DNA/chromatin, production of reactive oxygen species (ROS), and effects on enzymatic and hormonal actions. The presence of different functional, chemical forms of both of the nutrients within biological systems, and the availability of synthetic drug relatives of both to introduce into such systems, complicate interactive studies because such differing forms may not necessarily interact similarly or interact at all within the immune system or elsewhere. Regardless, there are compelling reasons to believe that examining interactions between magnesium and vitamin D within the immune system could prove rewarding, especially since the physiological statuses of both nutrients in human populations are less than optimum. Such human populations include the elderly whose immune function may be compromised.