Intravenous calcitriol administration improves the liver redox status and attenuates ferroptosis in mice with high-fat diet-induced obesity complicated with sepsis.

Obesity aggravates ferroptosis, and vitamin D (VD) may inhibit ferroptosis. We hypothesized that weight reduction and/or calcitriol administration have benefits against the sepsis-induced liver redox imbalance and ferroptosis in obese mice. Mice were fed a high-fat diet for 11 weeks, then half of the mice continued to consume the diet, while the other half were transferred to a low-energy diet for 5 weeks. After feeding the respective diets for 16 weeks, sepsis was induced by cecal ligation and puncture (CLP). Septic mice were divided into four experimental groups: OS group, obese mice injected with saline; OD group, obese mice with calcitriol; WS group, weight-reduction mice with saline; and WD group, weight-reduction mice with calcitriol. Mice in the respective groups were euthanized at 12 or 24 h after CLP. Results showed that the OS group had the highest inflammatory mediators and lipid peroxide levels in the liver. Calcitriol treatment reduced iron content, enhanced the reduced glutathione/oxidized glutathione ratio, upregulated nuclear factor erythroid 2-related factor 2, ferroptosis-suppressing protein 1, and solute carrier family 7 member 11 expression levels. Also, mitochondrion-associated nicotinamide adenine dinucleotide phosphate oxidase 1, peroxisome proliferator-activated receptor-γ coactivator 1, hypoxia-inducible factor-1α, and heme oxidase-1 expression levels increased in the late phase of sepsis. These results were not noted in the WS group. These findings suggest that calcitriol treatment elicits a more-balanced glutathione redox status, alleviates liver ferroptosis, and enhances mitochondrial biogenesis-associated gene expressions. Weight reduction alone had minimal influences on liver ferroptosis and mitochondrial biogenesis in obese mice with sepsis.

Calcitriol attenuates poly(I:C)-induced lung injury in obese mice via modulating toll-like receptor 3- and renin-angiotensin system-associated signal pathways.

This study investigated the effects of calcitriol on polyinosinic-polycytidylic acid (poly(I:C))-induced acute lung injury (ALI) and its association with Toll-like receptor 3 (TLR3) and renin-angiotensin system (RAS) signal pathways in obese mice. Normal mice were fed a high-fat diet to induce obesity. Obese mice were divided into four groups: SS group, intratracheally instilled with saline and intravenous (IV) saline injection via tail vein; SD group, instilled with saline and IV calcitriol injection; PS group, instilled with poly(I:C) and IV saline injection; and PD group, instilled with poly(I:C) and IV calcitriol injection. All mice were sacrificed 12 or 24 h after poly(I:C) stimulation. The results showed that poly(I:C) instillation led to increased production of systemic inflammatory cytokines. In the lungs, the population of macrophages decreased, while more neutrophils were recruited. TLR3-associated genes including IRF3, nuclear factor-κB, interferon-ß and phosphorylated IRF3 expression levels, were upregulated. The RAS-associated AT1R and ACE2 protein levels increased, whereas AT2R, Ang(1-7), and MasR levels decreased. Also, reduced tight junction (TJ) proteins and elevated lipid peroxide levels were observed 24 h after poly(I:C) stimulation. Compared to the PS group, the PD group exhibited reduced systemic and lung inflammatory cytokine levels, increased macrophage while decreased neutrophil percentages, downregulated TLR3-associated genes and phosphorylated IRF3, and polarized toward the RAS-AT2R/Ang(1-7)/MasR pathway in the lungs. Higher lung TJ levels and lower injury scores were also noted. These findings suggest that calcitriol treatment after poly(I:C) instillation alleviated ALI in obese mice possibly by downregulating TLR3 expression and tending toward the RAS-associated anti-inflammatory pathway.

Fermented rice bran supplementation attenuates colonic injury through modulating intestinal aryl hydrocarbon receptor and innate lymphoid cells in mice with dextran sodium sulfate-induced acute colitis.

This study investigated the effects of fermented rice bran (FRB) on modulating intestinal aryl hydrocarbon receptor (AhR) expression, innate lymphoid cell (ILC)3 populations, the fecal microbiota distribution, and their associations with dextran sodium sulfate (DSS)-induced acute colitis. C57BL/6 mice were assigned to four groups: 1) NC group, normal mice fed the AIN-93M diet; 2) FRB group, normal mice fed a diet supplemented with 5% FRB; 3) NCD group, DSS-treated mice fed AIN-93M; 4) FRBD group, DSS-treated mice fed a 5% FRB-supplemented diet. DSS was administered for 5 d and followed by 5 d for recovery. At the end of the experiment, mice were sacrificed. Their blood and intestinal tissues were collected. Results showed that there were no differences in colonic biological parameters and function between the NC and FRB groups. Similar fecal microbiota diversity was noted between these two groups. Compared to the non-DSS-treated groups, DSS administration led to increased intestinal permeability, enhanced inflammatory cytokine production and disease severity, whereas tight junctions and AhR, interleukin (IL)-22 expressions were downregulated, and the ILC3 population had decreased. Also, gut microbiota diversity differs from the non-DSS-treated groups and more detrimental bacterial populations exist when compared to the FRBD group. FRB supplementation in DSS-treated mice attenuated fecal microbial dysbiosis, decreased intestinal permeability, improved the barrier integrity, upregulated AhR and IL-22 expression, maintained the ILC3 population, and pathologically mitigated colonic injury. These findings suggest enhanced ILC3- and AhR-mediated functions may be partly responsible for the anti-colitis effects of FRB supplementation in DSS-induced colitis.

Potential therapeutic implications of calcitriol administration and weight reduction on CD4 T cell dysregulation and renin angiotensin system-associated acute lung injury in septic obese mice.

This study investigated the effects of weight reduction and/or calcitriol administration on regulating CD4 T cell subsets and renin-angiotensin system (RAS)-associated acute lung injury (ALI) in obese mice with sepsis. Half of the mice were fed a high-fat diet for 16 weeks, half of them had high-fat diet for 12 weeks then were transferred to a low-energy diet for 4 weeks. After feeding the respective diets, cecal ligation and puncture (CLP) were performed to induce sepsis. There were four sepsis groups: OSS group, obese mice injected with saline; OSD group, obese mice given calcitriol; WSS group, mice with weight reduction and saline; WSD group, mice with weight reduction and calcitriol. Mice were sacrificed after CLP. The findings showed that CD4 T subsets distribution did not differ among the experimental groups. Calcitriol-treated groups had higher RAS-associated AT2R, MasR, ACE2, and angiopoietin 1-7 (Ang(1-7)) levels in the lungs. Also, higher tight junction proteins were noted 12 h after CLP. At 24 h post-CLP, weight reduction and/or calcitriol treatment reduced plasma inflammatory mediator production. Calcitriol-treated groups had higher CD4/CD8, T helper (Th)1/Th2 and lower Th17/regulatory T (Treg) ratios than the groups without calcitriol. In the lungs, calcitriol-treated groups had lower AT1R levels, whereas the RAS anti-inflammatory protein levels were higher than those groups without calcitriol. Lower injury scores were also noted at this time point. These findings suggested weight reduction decreased systemic inflammation. However, calcitriol administration produced a more-balanced Th/Treg distribution, upregulated the RAS anti-inflammatory pathway, and attenuated ALI in septic obese mice.

Glutamine and leucine administration attenuates muscle atrophy in sepsis.

AIMS: This study investigated whether l-glutamine (Gln) and/or l-leucine (Leu) administration could attenuate muscle atrophy in a mouse model of cecal ligation and puncture (CLP)-induced sepsis. MATERIALS AND METHODS: Septic mice were given a daily intraperitoneal injection of Gln, Leu, or Gln plus Leu, and mice were sacrificed on either day 1 or 4 after CLP. Blood and muscles were collected for analysis of amino acid contents and markers related to protein degradation, muscle regeneration, and protein synthesis. KEY FINDINGS: Leu treatment alone increased both muscle mass and total muscle protein content on day 4 after CLP. Gln administration reduced muscular Gln contents on day 1 and enhanced plasma Gln levels on day 4. Higher plasma branched-chain amino acid (BCAA) abundances and lower muscular BCAA levels were observed in Leu-treated mice on day 4. Gln and Leu individually suppressed muscle expressions of the E3 ubiquitin ligase genes, Trim63 and Fbxo32, on day 4 after CLP. As to muscle expressions of myogenic genes, both Gln and Leu upregulated Myog expression on day 1, but Leu alone enhanced Myf5 gene expression, whereas Gln plus Leu increased MyoD and Myog expression levels on day 4. Akt/mammalian target of rapamycin (mTOR) signaling was only activated by Gln and Leu when individually administered. SIGNIFICANCE: Gln and/or Leu administration reduces sepsis-induced muscle degradation and promotes myogenic gene expressions. Leu treatment alone had more-pronounced effects on maintaining muscle mass during sepsis. A combination of Gln and Leu failed to show synergistic effects on alleviating sepsis-induced muscle atrophy.

Effects of different routes and forms of vitamin D administration on CD4+ T cell homeostasis and renin-angiotensin system-associated lung injury in obese mice complicated with polymicrobial sepsis.

This study investigated the impacts of enteral cholecalciferol and/or intravenous calcitriol administration on the balance of cluster of differentiation 4-positive T cell subsets, the renin-angiotensin system (RAS), and the severity of acute lung injury (ALI) in obese mice with sepsis. Mice were fed a high-fat diet and then cecal ligation and puncture (CLP) was performed. Obese mice were divided into four sepsis groups: without vitamin D (VD) (S), with oral cholecalciferol 1 d before CLP (G), with intravenous calcitriol 1 h after CLP (V), and with both cholecalciferol before and intravenous calcitriol after CLP (GV). Mice were euthanized after CLP. The V and GV groups showed higher blood T helper (Th)1/Th2 and lower Th17/T regulatory (Treg) ratios than did the S and G groups. In the lungs, The V group had the lowest nuclear factor-κB and interleukin-1ß gene expressions among all groups 24 h post-CLP. In parallel, gene expressions of angiotensin type 2 receptor (AT2R), angiotensin-converting enzyme 2 (ACE2), and Mas receptor (MasR) were highest in the V group compared to other groups. The protein levels of MasR in the GV group and the AT2R/AT1R ratio in the V group were higher than those in the G and/or S groups. All of the VD-treated groups had lower injury scores than the S group. These findings suggest that calcitriol administration had more-pronounced impacts on regulating the homeostasis of Th/Treg cells and is prone to RAS-associated anti-inflammatory pathway in the lungs. However, both forms of VD attenuated sepsis-induced ALI in obese animals.

Effects of Different Routes and Forms of Vitamin D Administration on Mesenteric Lymph Node CD4+ T Cell Polarization and Intestinal Injury in Obese Mice Complicated with Polymicrobial Sepsis.

This study compared the efficacies of enteral cholecalciferol and/or intravenous (IV) calcitriol administration on mesenteric lymph node (MLN) cluster-of-differentiation-4-positive (CD4+) T cell distribution and intestinal barrier damage in obese mice complicated with sepsis. Mice were fed a high-fat diet for 16 weeks and then sepsis was induced by cecal ligation and puncture (CLP). Mice were divided into the following sepsis groups: without vitamin D (VD) (S); with oral cholecalciferol 1 day before CLP (G); with IV calcitriol 1 h after CLP (V); and with both cholecalciferol before and IV calcitriol after CLP (GV). All mice were sacrificed at 12 or 24 h after CLP. The findings show that the S group had a higher T helper (Th)17 percentage than the VD-treated groups at 12 h after CLP. The V group exhibited a higher Th1 percentage and Th1/Th2 ratio than the other groups at 24 h, whereas the V and GV groups had a lower Th17/regulatory T (Treg) ratio 12 h post-CLP in MLNs. In ileum tissues, the VD-treated groups had higher tight junction protein and cathelicidin levels, and higher mucin gene expression than the S group at 24 h post-CLP. Also, aryl hydrocarbon receptor (AhR) and its associated cytochrome P450 1A1 and interleukin 22 gene expressions were upregulated. In contrast, levels of lipid peroxides and inflammatory mediators in ileum tissues were lower in the groups with VD treatment after CLP. These results suggest that IV calcitriol seemed to have a more-pronounced effect on modulating the homeostasis of Th/Treg subsets in MLNs. Both oral cholecalciferol before and IV calcitriol after CLP promoted cathelicidin secretion, alleviated intestinal inflammation, and ameliorated the epithelial integrity in obese mice complicated with sepsis possibly via VD receptor and AhR signaling pathways.

Intravenous calcitriol treatment benefits the homeostasis of CD4+ T cells and attenuates kidney injury in obese mice complicated with polymicrobial sepsis.

OBJECTIVES: Sepsis is a lethal clinical condition with dysregulated cluster of differentiation (CD) 4+ T cells that leads to inflammation and multiorgan injury. Low vitamin D levels are commonly seen in patients with sepsis. Obesity is a state with oxidative stress and chronic inflammation. Both obesity and low vitamin D levels are associated with adverse outcomes in patients with sepsis. This study investigated the effects of calcitriol on CD4+ T-cell polarization and kidney injury during sepsis. METHODS: Mice were fed a high-fat diet to induce obesity. One group of obese mice served as the control group and in the other two groups (SS and SD) were performed cecal ligation and puncture (CLP) to induce sepsis. Mice in the SS group were injected with saline and those in the SD group with calcitriol 1 h after CLP via tail vein. Mice with sepsis were euthanized at 12 h and 24 h after CLP, respectively. RESULTS: Sepsis led to a decrease in circulating CD4+ T-cell percentage, and T helper (Th) 2, Th17, and regulatory T (Treg) cell percentages were upregulated. Compared with the SS group, the SD group maintained blood CD4+ T-cell levels, and were reduced the Th2 and Th17 percentages as well as the Th17:Treg ratio. Also, plasma levels of cathelicidin increased, but inflammatory chemokines and kidney injury markers were reduced. Higher arginase-1 and lower inducible nitric oxide synthase expressions in the SD group indicated M1 macrophage polarized toward the M2 type. CONCLUSIONS: These findings suggest that intravenous calcitriol administration after sepsis modulates the homeostasis of CD4+ T-cell subpopulations associated with alleviating sepsis-induced kidney injury in obese mice.

Intravenous Arginine Administration Attenuates the Inflammatory Response and Improves Metabolic Profiles in Diet-Induced Obese Mice after Sleeve Gastrectomy.

Sleeve gastrectomy (SG) is a bariatric surgery that can effectively reduce weight and improve obesity-associated comorbidities. However, surgical stress intensifies inflammation and imbalanced metabolic profiles. Arginine (Arg) is a nutrient with immunomodulatory and anti-inflammatory properties. This study evaluated the short-term effects of Arg administration on adipocyte inflammation and metabolic alterations in obese mice after SG. Mice were assigned to normal and high-fat diet (HFD) groups. After 16 weeks, the HFD group were divided to sham (SH), SG with saline (SS), or Arg (SA) groups. SS and SA groups were postoperatively injected with saline or Arg via the tail vein and sacrificed at day 1 or 3 after the SG, respectively. Results showed that obesity caused elevated plasma glucose and leptin levels. The SG operation enhanced the expression of inflammatory cytokines and macrophage infiltration in adipose tissues, whereas hepatocyte gene expressions associated with lipid ß-oxidation were downregulated. Arg treatment reversed the expressions of ß-oxidation-associated genes and reduced lipid peroxide production in the liver. Additionally, adipose tissue expressions of inflammatory chemokines were reduced, while the M2 macrophage marker increased after surgery. The findings suggest that postoperative Arg administration elicited more balanced hepatic lipid metabolism, polarized macrophages toward the anti-inflammatory type, and attenuated adipocyte inflammation shortly after SG.

Reply to the letter to the editor: Effects of adequate dietary protein with whey protein, leucine, and vitamin D supplementation on sarcopenia in older adults: An open-label, parallel-group study.

This is a response to the comment on our published article "Effects of adequate dietary protein with whey protein, leucine, and vitamin D supplementation on sarcopenia in older adults: An open-label, parallel-group study". Safer et al., questioned about the procedure and consistency of bioelectrical impedance analysis (BIA) measurement at the baseline and follow up visits. Also, they wondered whether the BIA device we used is validated in Taiwanese older adults with sarcopenia. We followed the standard protocols and the procedures were consistent at each measurement. Magnetic resonance image (MRI) and dual energy X ray absorptiometry (DXA) are gold standards for quantifying muscle mass. According to the clinical trials performed in Taiwan, the BIA device we used showed a significant correlation with MRI and DXA and is validated in older adults with sarcopenia in Taiwan. Trial registration: ClinicalTrials.gov NCT03860194.

Intravenous calcitriol administration modulates mesenteric lymph node CD4+ T-cell polarization and attenuates intestinal inflammation in obese mice complicated with polymicrobial sepsis.

BACKGROUND: Sepsis is a lethal syndrome with T-cell dysregulation, imbalanced inflammatory reactions, and gastrointestinal dysfunction. Obesity coexistent with sepsis can cause more-deleterious disease outcomes. Vitamin D is a nutrient with immunomodulatory ability and helps maintain intestinal homeostasis. This study investigated treatment with calcitriol on mesenteric lymph node (MLN) CD4+ T-cell polarization and intestinal injury in obese mice with sepsis. METHODS: Mice received a high-fat diet for 10 weeks; then, mice were separated into an obese control group without sepsis and sepsis groups that underwent cecal ligation and puncture (CLP). Septic mice were subdivided into a group that was injected with saline (SS group) or a group that was injected with calcitriol (SD group) via a tail vein 1 h after CLP. Obese mice with sepsis were euthanized at 12 or 24 h post CLP. RESULTS: Sepsis resulted in increased percentages of type 2 T helper (Th2), Th17, and regulatory T (Treg) cells in MLNs. Also, inflammation-associated genes were upregulated and tight junction genes downregulated in the intestines after CLP. Compared with the SS group, the SD group exhibited reduced Th2, Th17, and Treg percentages in MLNs. Also, intestinal inflammatory chemokine expressions were reduced, whereas MUC2, ZO-1, and occludin had increased after CLP. Lower inflammatory cytokine levels in peritoneal lavage fluid in the ileum were also noted in the SD group. CONCLUSIONS: Intravenous calcitriol treatment after sepsis can elicit more-balanced CD4 T-cell subsets in lymph nodes near the intestines and alleviate intestinal inflammation and injury in obese mice complicated with sepsis.

Protective Effects of Glutamine and Leucine Supplementation on Sepsis-Induced Skeletal Muscle Injuries.

This study investigated the effects of l-glutamine (Gln) and/or l-leucine (Leu) administration on sepsis-induced skeletal muscle injuries. C57BL/6J mice were subjected to cecal ligation and puncture to induce polymicrobial sepsis and then given an intraperitoneal injection of Gln, Leu, or Gln plus Leu beginning at 1 h after the operation with re-injections every 24 h. All mice were sacrificed on either day 1 or day 4 after the operation. Blood and muscles were collected for analysis of inflammation and oxidative damage-related biomolecules. Results indicated that both Gln and Leu supplementation alleviated sepsis-induced skeletal muscle damage by reducing monocyte infiltration, calpain activity, and mRNA expression levels of inflammatory cytokines and hypoxia-inducible factor-1α. Furthermore, septic mice treated with Gln had higher percentages of blood anti-inflammatory monocytes and muscle M2 macrophages, whereas Leu treatment enhanced the muscle expressions of mitochondrion-related genes. However, there were no synergistic effects when Gln and Leu were simultaneously administered. These findings suggest that both Gln and Leu had prominent abilities to attenuate inflammation and degradation of skeletal muscles in the early and/or late phases of sepsis. Moreover, Gln promoted the switch of leukocytes toward an anti-inflammatory phenotype, while Leu treatment maintained muscle bioenergetic function.

Intravenous calcitriol administration regulates the renin-angiotensin system and attenuates acute lung injury in obese mice complicated with polymicrobial sepsis.

Calcitriol, an active form of vitamin D, has immunomodulatory and anti-inflammatory properties. Vitamin D levels have inverse correlation with sepsis outcomes and obesity may aggravate the severity of the diseases. This study administered calcitriol to investigate its impact on sepsis-induced acute lung injury (ALI) in obese mice. Mice were fed a high-fat diet to induce obesity and were randomly assigned to control or sepsis groups, which were intravenously administered either saline (SS) or calcitriol (SD). Sepsis was induced by cecal ligation and puncture (CLP). Saline or calcitriol was injected 1 h after CLP via tail vein. Mice were sacrificed at either 12 or 24 h post-CLP and survival rates were observed. The results demonstrated that sepsis caused upregulation of inflammatory mediators and downregulation of renin-angiotensin system (RAS)-associated gene expressions in the lungs of obese mice. Cluster of differentiation 68 (CD68) expression and myeloperoxidase (MPO) activities also increased. Calcitriol treatment lowered expressions of blood and lung inflammatory mediators at 12 and/or 24 h after CLP. The RAS-proinflammatory-associated angiotensin type 1 receptor (AT1R) was lower while anti-inflammatory Mas receptor and AT2R expressions were higher at 12 h after CLP than those in the SS group. In addition, the SD group exhibited lower CD68 expression and MPO activity. Lower lung injury scores and higher survival rates were also noted in the SD group. The findings suggest that calcitriol treatment after sepsis induction upregulated RAS-associated anti-inflammatory pathway and decreased immune cell infiltration, which may have alleviated the severity of ALI of obese mice.

Glutamine Administration Attenuates Kidney Inflammation in Obese Mice Complicated with Polymicrobial Sepsis.

Obesity is a well-known public health issue around the world. Sepsis is a lethal clinical syndrome that causes multiorgan failure. Obesity may aggravate inflammation in septic patients. Glutamine (GLN) is a nutrient with immune regulatory and anti-inflammatory properties. Since sepsis is a common contributing factor for acute kidney injury (AKI), this study investigated the effects of GLN administration on sepsis-induced inflammation and AKI in obese mice. A high-fat diet which consists of 60% of calories from fat was provided for 10 weeks to induce obesity in the mice. Then, the obese mice were subdivided into sepsis with saline (SS) or GLN (SG) groups. Cecal ligation and puncture (CLP) was performed to produce sepsis. The SS group was intravenously injected with saline while the SG group was administered GLN one or two doses after CLP. Obese mice with sepsis were sacrificed at 12, 24, or 48 h post-CLP. Results revealed that sepsis resulted in upregulated high-mobility group box protein-1 pathway-associated gene expression in obese mice. Also, expressions of macrophage/neutrophil infiltration markers and inflammatory cytokines in kidneys were elevated. Obese mice treated with GLN after sepsis reversed the depletion of plasma GLN, reduced production of lipid peroxides, and downregulated macrophage/neutrophil infiltration and the inflammatory-associated pathway whereas tight junction gene expression increased in the kidneys. These findings suggest that intravenously administered GLN to obese mice after sepsis alleviated inflammation and attenuated AKI. This model may have clinical application to obese patients with a risk for infection in abdominal surgery.

Effects of adequate dietary protein with whey protein, leucine, and vitamin D supplementation on sarcopenia in older adults: An open-label, parallel-group study.

BACKGROUND & AIMS: Sarcopenia is defined as a syndrome characterized by declines in skeletal muscle mass and strength or an alteration in physical function. Although some studies showed nutritional supplementation alone might have health benefits for older sarcopenic patients, their results were inconsistent and remain controversial. The objective of this study was to evaluate if a diet with high protein supplementation (Supp) can lead to better improvement than additional protein intake via dietary counseling (Diet) in maintaining the muscle mass and strength among sarcopenic elders. METHODS: This was an open-label, parallel-group (Supp vs. Diet) trial. In total, 56 sarcopenic elders completed this study. All subjects were advised to achieve adequate protein intake (1.2-1.5 g/kg body weight/day). This amount of protein is recommended for the elderly and is thought to prevent or retard muscle loss due to aging. The diet group (n = 28) was recommended to consume an ordinary protein-rich diet via counselling whereas the Supp group (n = 28) received a vitamin D- and leucine-enriched whey protein supplement for 12 weeks. The appendicular muscle mass index (AMMI), handgrip strength, gait speed, and calorie and macronutrients intake were evaluated after 4 and 12 weeks of the diet intervention. RESULTS: Total energy and protein intake increased in both groups. The Supp group had higher intake than the Diet group. The AMMI increased in both groups, and handgrip strength improved in the Diet group. However, no significant differences in AMMI or handgrip strength were found between the two groups. Compared to the Diet group, the Supp group had better improvement in gait speed after 12 weeks of the supplement intervention especially in subjects younger than 75 years. CONCLUSIONS: The AMMI can be improved as long as sufficient protein is consumed (1.2-1.5 g/kg body weight/day) in sarcopenic elders. Nutritional supplement allows the sarcopenic elderly to more conveniently meet their protein requirements. Supplementation with whey protein and vitamin D can further improve gait speed in elderly sarcopenic subjects, especially in the "younger" age group. TRIAL REGISTRATION: ClinicalTrials.gov NCT03860194.

Effects of the Glutamine Administration on T Helper Cell Regulation and Inflammatory Response in Obese Mice Complicated with Polymicrobial Sepsis.

This study investigated the impacts of GLN on inflammation and T cell dysregulation in obese mice complicated with sepsis. Mice were divided into normal control (NC) and high-fat diet groups. The high-fat diet provided 60% of energy from fat and was administered for 10 weeks to induce obesity. Mice fed with a high-fat diet were then assigned to sham (SH) and sepsis with saline (SS) or GLN (SG) groups. The SH group was subjected to laparotomy, while the sepsis group underwent cecal ligation and puncture (CLP). The SS group was intravenously injected with saline. The SG group was intravenously administered GLN after CLP. Mice were sacrificed at 12, 24, or 48 h post-CLP, respectively. Results demonstrated that in the presence of obesity, sepsis drove CD4+ T cells toward the helper T (Th)2 and Th17 lineages. Also, expressions of inflammatory cytokines and macrophage infiltration markers in adipose tissues and lungs were elevated. Treatment of obese mice with GLN after sepsis reversed Th polarization and downregulated macrophage infiltration and inflammatory cytokine, whereas the tight junction-associated protein expression increased in the lungs. These findings suggest that the intravenous administration of GLN to obese mice after sepsis modulated a more balanced Th cell lineage, alleviated inflammation, and attenuated lung injury.

Intravenous Glutamine Administration Improves Glucose Tolerance and Attenuates the Inflammatory Response in Diet-Induced Obese Mice after Sleeve Gastrectomy.

Obesity is a health problem associated with many metabolic disorders. Weight reduction can effectively alleviate obesity-associated complications. Sleeve gastrectomy is a commonly used bariatric surgery and is considered safe and effective for improving outcomes. Glutamine (GLN) is an amino acid with anti-oxidative and anti-inflammatory properties. This study used a mouse model of sleeve gastrectomy to investigate the impacts of intravenous GLN administration on glucose tolerance and adipocyte inflammation short-term after surgery. C57BL6 male mice were divided into normal control (NC) and high-fat diet groups. The high-fat diet provided 60% of energy from fat for 10 weeks to induce obesity. Mice fed the high-fat diet were then assigned to a sham (SH) or sleeve gastrectomy with saline (S) or GLN (G) groups. The S group was intravenously injected with saline, while the G group was administered GLN (0.75 g/kg body weight) via a tail vein postoperatively. Mice in the experimental groups were sacrificed on day 1 or 3 after the surgery. Results showed that obesity resulted in fat accumulation, elevated glucose levels, and adipokines production. Sleeve gastrectomy aggravated expressions of inflammatory cytokine and macrophage infiltration markers, cluster of differentiation 68 (CD68), epidermal growth factor-like module-containing mucin-like hormone receptor-like 1 (EMR-1), and macrophage chemoattractant protein-1, in adipose tissues. Treatment of obese mice with GLN downregulated hepatic proteomic profiles associated with the gluconeogenesis pathway and improved glucose tolerance. Moreover, macrophage infiltration and adipose tissue inflammation were attenuated after the sleeve gastrectomy. These findings imply that postoperative intravenous GLN administration may improve glucose tolerance and attenuate inflammation shortly after the bariatric surgery in subjects with obesity.

Intravenous Arginine Administration Downregulates NLRP3 Inflammasome Activity and Attenuates Acute Kidney Injury in Mice with Polymicrobial Sepsis.

Acute kidney injury (AKI) is a major complication of sepsis. Nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasomes are multiprotein complexes that mediate septic AKI. L-arginine (Arg) is a conditionally essential amino acid in catabolic conditions and a substrate for nitric oxide (NO) production; however, its use in sepsis is controversial. This study investigated the effect of intravenous Arg supplementation on modulating NLRP3 inflammasome activity in relation to septic AKI. Mice were divided into normal control (NC), sham, sepsis saline (SS), and sepsis Arg (SA) groups. In order to investigate the role of NO, L-N6-(1-iminoethyl)-lysine hydrochloride (L-NIL), an inducible NO synthase inhibitor, was administered to the sepsis groups. Sepsis was induced using cecal ligation and puncture (CLP). The SS and SA groups received saline or Arg via tail vein 1 h after CLP. Mice were sacrificed at 6, 12, and 24 h after sepsis. The results showed that compared to the NC group, septic mice had higher plasma kidney function parameters and lower Arg levels. Also, renal NLRP3 inflammasome protein expression and tubular injury score increased. After Arg treatment, plasma Arg and NO levels increased, kidney function improved, and expressions of renal NLRP3 inflammasome-related proteins were downregulated. Changes in plasma NO and renal NLRP3 inflammasome-related protein expression were abrogated when L-NIL was given to the Arg sepsis groups. Arg plus L-NIL administration also attenuated kidney injury after CLP. The findings suggest that intravenous Arg supplementation immediately after sepsis restores plasma Arg levels and is beneficial for attenuating septic AKI, partly via NO-mediated NLRP3 inflammasome inhibition.

Intravenous Arginine Administration Benefits CD4+ T-Cell Homeostasis and Attenuates Liver Inflammation in Mice with Polymicrobial Sepsis.

This study investigated the effects of a single dose of arginine (Arg) administration at the beginning of sepsis on CD4+ T-cell regulation and liver inflammation in C57BL/6J mice. Mice were divided into normal control (NC), sham (SH), sepsis saline (SS), and sepsis Arg (SA) groups. An inducible nitric oxide (NO) synthase (iNOS) inhibitor was administered to additional sepsis groups to evaluate the role of NO during sepsis. Sepsis was induced using cecal ligation and puncture (CLP). The SS and SA groups received saline or Arg (300 mg/kg body weight) via tail vein 1 h after CLP. Mice were euthanized at 12 and 24 h post-CLP. Blood, para-aortic lymph nodes, and liver tissues were collected for further measurement. The findings showed that sepsis resulted in decreases in blood and para-aortic lymph node CD4+ T-cell percentages, whereas percentages of interleukin (IL)-4- and IL-17-expressing CD4+ T cells were upregulated. Compared to the SS group, Arg administration resulted in maintained circulating and para-aortic lymph node CD4+ T cells, an increased Th1/Th2 ratio, and a reduced Th17/Treg ratio post-CLP. In addition, levels of plasma liver injury markers and expression of inflammatory genes in liver decreased. These results suggest that a single dose of Arg administered after CLP increased Arg availability, sustained CD4+ T-cell populations, elicited more-balanced Th1/Th2/Th17/Treg polarization in the circulation and the para-aortic lymph nodes, and attenuated liver inflammation in sepsis. The favorable effects of Arg were abrogated when an iNOS inhibitor was administered, which indicated that NO may be participated in regulating the homeostasis of Th/Treg cells and subsequent liver inflammation during sepsis.

Antecedent Dietary Glutamine Supplementation Benefits Modulation of Liver Pyroptosis in Mice with Polymicrobial Sepsis.

The liver is the main organ responsible for bacterial and endotoxin clearance. Pyroptosis is a form of proinflammatory programmed cell death activated by caspase-1/11 and gasdermin D (GadD). Pyroptosis protects the host against bacterial infection; however, overactive pyroptosis can lead to organ injury. Glutamine (GLN) is a specific amino acid with anti-inflammatory and immunomodulatory properties. This study investigated the effects of GLN pretreatment on liver pyroptosis in a mouse model of polymicrobial sepsis. Mice were assigned to sham, sepsis control (Sepsis-C), and sepsis GLN (Sepsis-G) groups. The sham and Sepsis-C groups were fed the AIN-93G diet. The Sepsis-G group was provided with identical diet components except that part of the casein was replaced by GLN. After feeding the respective diets for 2 weeks, a cecal ligation and puncture (CLP) procedure was performed in the sepsis groups. An antibiotic was administered after CLP. Mice were sacrificed at either 24 or 72 h after CLP. The results showed that sepsis resulted in upregulated liver caspase-1/11 expression. Compared to the Sepsis-C group, the Sepsis-G group had higher liver caspase-11 and NLRP3 gene expressions at 24 h and lower active caspase-1/11 and cleaved GadD protein levels at 72 h after sepsis. Additionally, liver inflammatory cytokine gene expressions had decreased by 72 h post-CLP. The findings suggest that prophylactic administration of GLN initially upregulated liver pyroptosis to eradicate pathogens, yet the process of pyroptosis was suppressed in the late phase of sepsis. This may have beneficially attenuated liver inflammation and injury in an antibiotic-treated septic condition.