Transforming growth factor beta1 and prostaglandin E2 concentrations are associated with bone formation markers in ulcerative colitis patients

Selenomethionine combined with allicin delays reactive oxidative stress-induced apoptosis, inflammation, endoplasmic reticulum stress, and barrier damage in IPEC-J2 cells via the GPX4 signaling pathway

To increase livestock productivity and improve economic efficiency, farms tend to focus on the growth rate of livestock and poultry. This strategy can result in a reduced resistance to reactive oxidative stress (ROS) and heat stress. Selenomethionine (SeMet) and allicin have antioxidant properties, but their excessive intake can lead to toxicity. Co-administration improves antioxidant protection and reduces side-effects but also reduces the cost of administration. We undertook a study to elucidate the antioxidant effect of glutathione peroxidase (GPX) 4 in SeMet and allicin. The synergistic antioxidant effect, attenuation of endoplasmic reticulum stress (ERS), enhancement of expression of tight-junction proteins, and inhibition of apoptosis, ferroptosis, inflammatory responses of SeMet and allicin were attenuated significantly after inhibition of GPX4 according to western blotting (P < 0.05). These results indicated that activation of the GPX4 pathway was the key to the synergistic maintenance of barrier function, attenuation of ERS, as well as inhibition of apoptosis, ferroptosis, and inflammatory responses by SeMet and allicin. SeMet and allicin could protect the intestinal barrier from oxidative damage by synergistically activating the GPX4 pathway, increasing antioxidant capacity, and improving growth performance. In conclusion, SeMet and allicin could be used as a new drug combination to alleviate diseases associated with intestinal ROS and aid in the development of new antioxidant feed additives.

Exploring the potential function of trace elements in human health: a therapeutic perspective

A trace element, known as a minor element, is a chemical element whose concentration is very low. They are divided into essential and non-essential classes. Numerous physiological and metabolic processes in both plants and animals require essential trace elements. These essential trace elements are so directly related to the metabolic and physiologic processes of the organism that either their excess or deficiency can result in severe bodily malfunction or, in the worst situations, death. Elements can be found in nature in various forms and are essential for the body to carry out its varied functions. Trace elements are crucial for biological, chemical, and molecular cell activity. Nutritional deficits can lead to weakened immunity, increased susceptibility to oral and systemic infections, delayed physical and mental development, and lower productivity. Trace element enzymes are involved in many biological and chemical processes. These compounds act as co-factors for a number of enzymes and serve as centers for stabilizing the structures of proteins and enzymes, allowing them to mediate crucial biological processes. Some trace elements control vital biological processes by attaching to molecules on the cell membrane's receptor site or altering the structure of the membrane to prevent specific molecules from entering the cell. Some trace elements are engaged in redox reactions. Trace elements have two purposes. They are required for the regular stability of cellular structures, but when lacking, they might activate alternate routes and induce disorders. Therefore, thoroughly understanding these trace elements is essential for maintaining optimal health and preventing disease.

Relationship between selenium status, selenoproteins and COVID-19 and other inflammatory diseases: A critical review

The antioxidant effects of selenium as a component of selenoproteins has been thought to modulate host immunity and viral pathogenesis. Accordingly, the association of low dietary selenium status with inflammatory and immunodeficiency has been reported in the literature; however, the causal role of selenium deficiency in chronic inflammatory diseases and viral infection is still undefined. The COVID-19, characterized by acute respiratory syndrome and caused by the novel coronavirus 2, SARS-CoV-2, has infected millions of individuals worldwide since late 2019. The severity and mortality from COVID-19 have been associated with several factor, including age, sex and selenium deficiency. However, available data on selenium status and COVID-19 are limited, and a possible causative role for selenium deficiency in COVID-19 severity has yet to be fully addressed. In this context, we review the relationship between selenium, selenoproteins, COVID-19, immune and inflammatory responses, viral infection, and aging. Regardless of the role of selenium in immune and inflammatory responses, we emphasize that selenium supplementation should be indicated after a selenium deficiency be detected, particularly, in view of the critical role played by selenoproteins in human health. In addition, the levels of selenium should be monitored after the start of supplementation and discontinued as soon as normal levels are reached. Periodic assessment of selenium levels after supplementation is a critical issue to avoid over production of toxic metabolites of selenide because under normal conditions, selenoproteins attain saturated expression levels that limits their potential deleterious metabolic effects.

The Essential Role of Selenoproteins in the Resolution of Citrobacter rodentium-Induced Intestinal Inflammation

Enteropathogenic Escherichia coli (EPEC) leads to adverse colonic inflammation associated with poor resolution of inflammation and loss of epithelial integrity. Micronutrient trace element selenium (Se) is incorporated into selenoproteins as the 21st amino acid, selenocysteine (Sec). Previous studies have shown that such an incorporation of Sec into the selenoproteome is key for the anti-inflammatory functions of Se in macrophages and other immune cells. An intriguing mechanism underlying the anti-inflammatory and pro-resolving effects of Se stems from the ability of selenoproteins to skew arachidonic acid metabolism from pro-inflammatory mediators, prostaglandin E₂ (PGE₂) toward anti-inflammatory mediators derived from PGD₂, such as 15-deoxy-Δ^{12, 14}- prostaglandin J₂ (15d-PGJ₂), via eicosanoid class switching of bioactive lipids. The impact of Se and such an eicosanoid-class switching mechanism was tested in an enteric infection model of gut inflammation by C. rodentium, a murine equivalent of EPEC. C57BL/6 mice deficient in Se (Se-D) experienced higher mortality when compared to those on Se adequate (0.08 ppm Se) and Se supplemented (0.4 ppm Se) diets following infection. Decreased survival was associated with decreased group 3 innate lymphoid cells (ILC3s) and T helper 17 (Th17) cells in colonic lamina propria of Se-D mice along with deceased expression of epithelial barrier protein Zo-1. Inhibition of metabolic inactivation of PGE₂ by 15-prostaglandin dehydrogenase blocked the Se-dependent increase in ILC3 and Th17 cells in addition to reducing epithelial barrier integrity, as seen by increased systemic levels of FITC-dextran following oral administration; while 15d-PGJ₂ administration in Se-D mice alleviated the effects by increasing ILC3 and Th17 cells. Mice lacking selenoproteins in monocyte/macrophages via the conditional deletion of the tRNA^[Sec] showed increased mortality post infection. Our studies indicate a crucial role for dietary Se in the protection against inflammation following enteric infection via immune mechanisms involving epithelial barrier integrity.

New Insights into the Role of Trace Elements in IBD

Micronutrient deficiencies are common in inflammatory bowel disease and have clinical impact, being both a sign of complicated disease and a cause of morbidity. The involved systemic inflammatory response is responsible for altering the concentration of a wide range of trace elements in the serum, including zinc and selenium. This review summarizes recent advances and evidence-based knowledge regarding the impact of selenium and zinc on oxidative stress and microbiota changes in IBD patients. Getting new insight into the impact of malnutrition, particularly on the micronutrients' impact on the development, composition, and metabolism of microbiota, as well as the influence of oxidative stress and the mucosal immune response, could help in implementing new management strategies for IBD patients, with focus on a more integrated approach.

Selenium and Selenoproteins in Gut Inflammation-A Review

Inflammatory bowel disease (IBD), characterized by severe flares and remissions, is a debilitating condition. While the etiology is unknown, many immune cells, such as macrophages, T cells and innate lymphoid cells, are implicated in the pathogenesis of the disease. Previous studies have shown the ability of micronutrient selenium (Se) and selenoproteins to impact inflammatory signaling pathways implicated in the pathogenesis of the disease. In particular, two transcription factors, nuclear factor-κB (NF-κB), and peroxisome proliferator activated receptor (PPAR)γ, which are involved in the activation of immune cells, and are also implicated in various stages of inflammation and resolution, respectively, are impacted by Se status. Available therapies for IBD produce detrimental side effects, resulting in the need for alternative therapies. Here, we review the current understanding of the role of NF-κB and PPARγ in the activation of immune cells during IBD, and how Se and selenoproteins modulate effective resolution of inflammation to be considered as a promising alternative to treat IBD.

Effect of γ-aminobutyric acid on isolated colonic smooth muscle from rats with experimental ulcerative colitis

AIM: To assess the effect of γ-aminobutyric acid (GABA) on isolated colonic smooth muscle from rats with experimental ulcerative colitis (UC).

METHODS: Seventeen Wistar rats were randomly divided into either a normal group (six rats) or a model group (eleven rats). The normal group was given distilled water, while the model group was given distilled water containing 3% dextran sulfate 5000. The body mass of the rats and the character of the stool were observed every day, and the disease active index (DIA) was scored. Nine days later, all the rats were killed to observe the changes of the gross morphology and the pathologic changes of the colon under a microscope by taking tissue specimens from serious lesion sites for HE staining. Meanwhile, colonic smooth muscle was isolated to observe the effect of muscimol, a receptor agonist of the GABA and GABA_A, bicuculline, an antagonist of the GABA_A, and baclofen, a receptor antagonist of the GABA_B on the isolated colonic smooth muscle using isometric tension as an indicator.

RESULTS: After four days of treatment with dextran sulfate 5000, the character of the stool of rats in the model group changed, with 30% of rats showing loose stool and 70% showing diarrhea. After six days, about 40% of rats had obvious bloody stool and an obvious decrease in activity and eating. In rats of the normal group, gross pathological examination revealed that the colon had no adhesion, the mucosa had mild hyperemia but no ulcers; microscopic pathological examination revealed intact tissue structure and regularly arranged glands. In rats of the model group, the number of glands decreased, the tissue structure was disorderly, the mucosa was erosive, bleeding, necrotic, and had large deep ulcers. Compared with the normal group, the DIA (3.83 ± 2.74 vs 1.23 ± 1.62, P < 0.05) and histopathologic score (2.52 ± 1.36 vs 0.41 ± 0.74, P < 0.05) were increased significantly in the model group. Treatment with GABA significantly inhibited the independent contraction activities of the isolated colonic smooth muscle from rats of both the normal and model groups (P < 0.05). Treatment with GABA at 0.01 mmol/L and 100 mmol/L resulted in inhibition rates of 20.00% ± 0.02% and 67.60% ± 0.03%, respectively, for the normal group, and 19.50% ± 0.02% and 64.50% ± 0.05% for the model group. There were no significant differences in the above inhibition rates between the two groups (P > 0.05). Treatment with 0.01 mmol/L bicuculline increased the contractile tension of the isolated colonic smooth muscle of the rats (1.25 g ± 0.03 g vs 0.77 g ± 0.04 g, P < 0.05), but treatment with 0.01 mmol/L muscimol or 0.01 mmol/L baclofen decreased the contractile tension significantly (0.38 g ± 0.03 g vs 0.75 g ± 0.06 g, P < 0.05; 0.45 g ± 0.05 g vs 0.75 g ± 0.04 g, P < 0.05).

CONCLUSION: GABA has inhibitory effects on the contraction of the isolated colonic smooth muscle of rats. There exist GABA_A and GABA_B in the isolated colonic smooth muscle of rats, and GABA has inhibitory effects on the muscle contraction when acting on GABA_A, but has stimulating effects when acting on GABA_B.

Crucial role of macrophage selenoproteins in experimental colitis

Inflammation is a hallmark of inflammatory bowel disease (IBD) that involves macrophages. Given the inverse link between selenium (Se) status and IBD-induced inflammation, our objective was to demonstrate that selenoproteins in macrophages were essential to suppress proinflammatory mediators, in part, by the modulation of arachidonic acid metabolism. Acute colitis was induced using 4% dextran sodium sulfate in wild-type mice maintained on Se-deficient (<0.01 ppm Se), Se-adequate (0.08 ppm; sodium selenite), and two supraphysiological levels in the form of Se-supplemented (0.4 ppm; sodium selenite) and high Se (1.0 ppm; sodium selenite) diets. Selenocysteinyl transfer RNA knockout mice (Trsp(fl/fl)LysM(Cre)) were used to examine the role of selenoproteins in macrophages on disease progression and severity using histopathological evaluation, expression of proinflammatory and anti-inflammatory genes, and modulation of PG metabolites in urine and plasma. Whereas Se-deficient and Se-adequate mice showed increased colitis and exhibited poor survival, Se supplementation at 0.4 and 1.0 ppm increased survival of mice and decreased colitis-associated inflammation with an upregulation of expression of proinflammatory and anti-inflammatory genes. Metabolomic profiling of urine suggested increased oxidation of PGE2 at supraphysiological levels of Se that also correlated well with Se-dependent upregulation of 15-hydroxy-PG dehydrogenase (15-PGDH) in macrophages. Pharmacological inhibition of 15-PGDH, lack of selenoprotein expression in macrophages, and depletion of infiltrating macrophages indicated that macrophage-specific selenoproteins and upregulation of 15-PGDH expression were key for Se-dependent anti-inflammatory and proresolving effects. Selenoproteins in macrophages protect mice from dextran sodium sulfate-colitis by enhancing 15-PGDH-dependent oxidation of PGE2 to alleviate inflammation, suggesting a therapeutic role for Se in IBD.

Relationships between age-related biochemical markers of bone turnover and OPG, TGF-β1 and TGF-β2 in native Chinese women

Osteoprotegerin (OPG), transforming growth factor-β1 (TGF-β1) and TGF-β2 are cytokines closely associated with bone metabolism. However, their association with bone turnover markers in native Chinese women remains unknown. The study aims to investigate the relationship between bone metabolism related cytokines including OPG, TGF-β1, TGF-β2 and bone turnover markers in native Chinese women. The cross-sectional study was conducted on 691 healthy Chinese women (20-80 years old). Levels of OPG, TGF-β1, TGF-β2, serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), cross-linked N-terminal telopeptides of type I collagen (sNTX), cross-linked C-terminal telopeptides of type I collagen (sCTX), urinary NTX (uNTX), urinary CTX (uCTX) and total urinary deoxypyridinoline (uDPD) were determined. The present study showed that OPG and TGF-β2 had positive correlation with BAP, OC, uNTX, uCTX and uDPD, while TGF-β1 showed negative correlation with BAP, OC, sCTX, uNTX and uCTX, and most of the coefficients of partial correlation remained significant after adjustments for age and body mass index (BMI). Multiple linear regression stepwise analysis showed that OPG and TGF-β2 were positive determinative factors for BAP, sCTX, uNTX and uCTX, which could explain 0.6-16.6% of the variation in these markers. TGF-β1 was a negative determinative factor for BAP, OC, sCTX and uCTX, which could explain 0.7-7.3% of the variation in these markers. This study suggested that measuring bone turnover indicators and serum cytokines simultaneously might help evaluating changes in bone turnover rate caused by aging or menopause in women.

Relationship between Serum Levels of OPG and TGF- β with Decreasing Rate of BMD in Native Chinese Women

The objective of this study was to investigate the relationship between serum levels of OPG, TGF- β 1, and TGF- β 2 and BMD decrease rate (BDR) in native Chinese women. This cross-sectional study was performed on 465 healthy native Chinese women aged 35-80 years. Serum levels of OPG, TGF- β 1, and TGF- β 2 were determined. BDR was measured by DXA at the posteroanterior spine, hip, and distal forearm. At all skeletal sites tested, there was a negative correlation between BDR and serum levels of both OPG (r = -0.122 to -0.230, all P = 0.007-0.000) and TGF- β 2 (r = -0.100 to -0.173, all P = 0.029-0.000) and a positive correlation between BDR and serum TGF- β 1 (r = 0.245 - 0.365, all P = 0.000). After adjustment for age and BMI, there were no statistically significant correlations between serum levels of OPG or TGF- β 2 and BDR. However, statistically significant correlations between serum TGF- β 1 and BDR at the lumbar spine and ultradistal forearm remained. Multiple linear regression stepwise analysis showed that serum OPG could explain 1.4-3.7% of BDR variation. Serum TGF- β 1 was a positive determinant of BDR and could explain 5.3-13.3% of BDR variation.

High levels of serum prostaglandin E2 in children with osteogenesis imperfecta are reduced by neridronate treatment

Prostaglandin E2 (PGE2) is an activator of bone remodeling, and increase levels of PGE2 are found in several disorders characterized by chronic inflammation. Bisphosphonates are used in the treatment of osteogenesis imperfecta (OI), an inherited disorder characterized by bone fragility and low bone mass. We evaluated the serum PGE2 (ng/mL) level in 16 children affected by OI (11 with mild and 5 with severe forms) at basal time and during treatment with neridronate. The levels of PGE2 in mild and severe forms were increased at basal time compared with controls (13.14 +/- 4.2 versus 0.72 +/- 0.05, p < 0.01; 15.1 +/- 1.5 versus 0.72 +/- 0.05, p < 0.01, respectively) and showed a significant decrease after the second (T1) cycle of treatment (mild: 4.97 +/- 5.0 versus 13.14 +/- 4.2, p < 0.01; severe: 5.32 +/- 4.5 versus 15.1 +/- 1.5, p < 0.01) with a further significant decrease after the fourth (T2) cycle. The high basal PGE2 levels in OI, a noninflammatory disorder, could be explained by stress-induced release mediated by inducible cyclooxygenase-2-catalyzed pathway. The reduction obtained by treatment with bisphosphonates could be attributed to a direct pharmacological effect since these drugs has been reported to modulate the release of proinflammatory mediators.