Glutamine in vitro supplementation partly reverses impaired macrophage function resulting from early weaning in mice

Metabolomic analysis reveals the influence of HMBOX1 on RAW264.7 cells proliferation based on UPLC-MS/MS

Macrophages are important effector cells in tumor progression and immune regulation. Previously, we demonstrated that the transcription suppressor homeobox containing 1(HMBOX1) exhibits immunosuppressive activity in LPS-induced acute liver injury by impeding macrophage infiltration and activation. We also observed a lower proliferation in HMBOX1-overexpressed RAW264.7 cells. However, the specific mechanism was unclear. Here, a work was performed to characterize HMBOX1 function related to cell proliferation from a metabolomics standpoint by comparing the metabolic profiles of HMBOX1-overexpressed RAW264.7 cells to those of the controls. Firstly, we assessed HMBOX1 anti-proliferation activity in RAW264.7 cells with CCK8 assay and clone formation. Then, we performed metabolomic analyses by ultra-liquid chromatography coupled with mass spectrometry to explore the potential mechanisms. Our results indicated that HMBOX1 inhibited the macrophage growth curve and clone formation ability. Metabolomic analyses showed significant changes in HMBOX1-overexpressed RAW264.7 metabolites. A total of 1312 metabolites were detected, and 185 differential metabolites were identified based on the criterion of OPLS-DA VIP > 1 and p value < 0.05. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that the elevated HMBOX1 in RAW264.7 inhibited the pathways of amino acid and nucleotide metabolism. Glutamine concentrations decreased significantly in HMBOX1-overexpressed macrophages, and glutamine-related transporter SLC1A5 was also downregulated. Furthermore, SLC1A5 overexpression reversed HMBOX1 inhibition of macrophage proliferation. This study demonstrated the potential mechanism of the HMBOX1/SLC1A5 pathway in cell proliferation by regulating glutamine transportation. The results may help provide a new direction for therapeutic interventions in macrophage-related inflammatory diseases.

Metabolic programming of macrophage functions and pathogens control

Macrophages (Mφ) are central players in mediating proinflammatory and immunomodulatory functions. Unchecked Mφ activities contribute to pathology across many diseases, including those caused by infectious pathogens and metabolic disorders. A fine balance of Mφ responses is crucial, which may be achieved by enforcing appropriate bioenergetics pathways. Metabolism serves as the provider of energy, substrates, and byproducts that support differential Mφ characteristics. The metabolic properties that control the polarization and response of Mφ remain to be fully uncovered for use in managing infectious diseases. Here, we review the various metabolic states in Mφ and how they influence the cell function.

Effects of glutamine, taurine and their association on inflammatory pathway markers in macrophages

The immune system is essential for the control and elimination of infections, and macrophages are cells that act as important players in orchestrating the various parts of the inflammatory/immune response. Amino acids play important role in mediating functionality of the inflammatory response, especially mediating macrophages functions and cytokines production. We investigated the influence of glutamine, taurine and their association on the modulation of inflammatory pathway markers in macrophages. The RAW 264.7 macrophage cell line was cultivated in the presence of glutamine and taurine and proliferation rates, cell viability, cell cycle phases, IL-1α, IL-6, IL-10 and TNF-α as well as H₂O₂ production and the expression of the transcription factor, NFκB, and its inhibitor, IκBα, were evaluated. Our results showed an increase in viable cells and increased proliferation rates of cells treated with glutamine concentrations over 2 mM, as well as cells treated with both glutamine and taurine. The cell cycle showed a higher percentage of cells in the phases S, G2 and M when they were treated with 2 or 10 mM glutamine, or with glutamine and taurine in cells stimulated with lipopolysaccharide. The pNFκB/NFκB showed reduced ratio expression when cells were treated with 10 mM of glutamine or with glutamine in association with taurine. These conditions also resulted in reduced TNF-α, IL-1α and H₂O₂ production, and higher production of IL-10. These findings demonstrate that glutamine and taurine are able to modulate macrophages inflammatory pathways, and that taurine can potentiate the effects of glutamine, illustrating their immunomodulatory properties.

Effects of dietary glutamine supplementation on the body composition and protein status of early-weaned mice inoculated with Mycobacterium bovis Bacillus Calmette-Guerin

Glutamine, one of the most abundant amino acids found in maternal milk, favors protein anabolism. Early-weaned babies are deprived of this source of glutamine, in a period during which endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress, mainly during infections. The objective of this study was to verify the effects of dietary glutamine supplementation on the body composition and visceral protein status of early-weaned mice inoculated with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). Mice were weaned early on their 14th day of life and seperated into two groups, one of which was fed a glutamine-free diet (n = 16) and the other a glutamine-supplemented diet (40 g/kg diet) (n = 16). At 21 days of age, some mice were intraperitoneally injected with BCG. Euthanasia was performed at the 28th day of age. BCG inoculation significantly reduced body weight (P < 0.001), lean mass (P = 0.002), water (P = 0.006), protein (P = 0.007) and lipid content (P = 0.001) in the carcass. Dietary glutamine supplementation resulted in a significant increase in serum IGF-1 (P = 0.019) and albumin (P = 0.025) concentration, muscle protein concentration (P = 0.035) and lipid content (P = 0.002) in the carcass. In conclusion, dietary glutamine supplementation had a positive influence on visceral protein status but did not affect body composition in early-weaned mice inoculated with BCG.

O desmame precoce afeta o ganho de peso e a composição corporal em camundongos adultos?

OBJETIVO: Avaliar o efeito do desmame precoce sobre o ganho de peso e a composição corporal de camundongos adultos jovens. MÉTODOS: Camundongos Swiss Webster, machos, foram desmamados precocemente (14º dia de vida) ou amamentados até o 21º dia de vida (grupo controle). Após o desmame, os animais foram alimentados com ração elaborada para roedores em crescimento até o 63º dia de vida, quando então foram sacrificados. RESULTADOS: O peso corporal dos animais do grupo desmamado de forma precoce foi significantemente maior no 28º, 35º e no 63º dias de vida em relação ao grupo controle (p<0,05). Porém, o consumo de ração não diferiu entre os grupos. A concentração sérica de proteínas totais, albumina e ferro, bem como a concentração hepática, muscular e cerebral de proteínas, ácido desoxirribonucléico e a relação proteína/ácido ribonucléico, não diferiram significantemente entre os grupos. O grupo desmamado precocemente apresentou maior quantidade absoluta de massa magra, lipídeos, proteínas e cinzas, em comparação ao grupo controle (p<0,05). A quantidade relativa de umidade, lipídeos, massa magra, proteínas e cinzas não diferiu entre os grupos. CONCLUSÃO: O desmame precoce, associado à ingestão de ração elaborada para roedores em crescimento, resultou em aumento do ganho de peso, porém não afetou a composição corporal de camundongos adultos.

Early weaning impairs body composition in male mice

This study aimed to evaluate the effect of early weaning on body composition and on parameters related to nutritional status in mice. The experimental group consisted of male Swiss Webster mice that were weaned early (at postnatal day fourteen) and fed an appropriate diet for growing rodents until postnatal day twenty-one (EW group). The control group consisted of male mice breastfed until postnatal day twenty-one (CON group). All animals were sacrificed on the twenty-first day of life. The EW group showed a decrease in liver and muscle protein content and concentration, brain protein concentration, brain DNA content and concentration, as well as liver and muscle protein/RNA ratio (p<0.05). Concerning body composition, the EW mice showed increased moisture content, increased moisture and lipid percentage, and a smaller percentage and content of protein and ash in the carcass (p<0.05). These results indicate that early weaning impairs body composition and parameters related to nutritional status, which may be explained by retarded chemical maturation processes. This data may contribute to the overall understanding of the influence of breastfeeding versus feeding with artificial milk on body composition and on nutritional status.