Absence of CD47 maintains brown fat thermogenic capacity and protects mice from aging-related obesity and metabolic disorder

Pinctada martensii Hydrolysate Modulates the Brain Neuropeptidome and Proteome in Diabetic (db/db) Mice via the Gut-Brain Axis

Pinctada martensii hydrolysate (PMH) has been proved to have the effect of ameliorating disorders of glucose and lipid metabolism in db/db mice, but the mechanism of its hyperglycemia effect is still unclear. Bacterial communities in fecal samples from a normal control group, a diabetic control group, and a PMH-treated diabetes mellitus type 2 (T2DM) group were analyzed by 16S gene sequencing. Nano LC-MS/MS was used to analyze mice neuropeptides and proteomes. The 16S rDNA sequencing results showed that PMH modulated the structure and composition of the gut microbiota and improved the structure and composition of Firmicutes and Bacteroidetes at the phylum level and Desulfovibrionaceae and Erysipelatoclostridiaceae at the family level. Furthermore, the expressions of functional proteins of the central nervous system, immune response-related protein, and proteins related to fatty acid oxidation in the brain disrupted by an abnormal diet were recovered by PMH. PMH regulates the brain neuropeptidome and proteome and further regulates blood glucose in diabetic mice through the gut-brain axis. PMH may be used as a prebiotic agent to attenuate T2DM, and target-specific microbial species may have unique therapeutic promise for metabolic diseases.

Tolerating CD47

Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor-multiligand interaction network. It is a focus of drug development to temper and accentuate CD47-driven immune cell liaisons, although consideration of on-target CD47 effects remain neglected. And yet, a late clinical trial of a CD47-blocking antibody was discontinued, existent trials were restrained, and development of CD47-targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer.

Sex differences in the effects of brown adipocyte CD47 deficiency on age-related weight change and glucose homeostasis

Our previous studies demonstrated that mice with global CD47 deficiency are lean and resistant to diet or aging-associated obesity and metabolic complications. This protective effect is partially through modulating brown fat function. To definitively determine the role of brown fat CD47 in age-related metabolic homeostasis, inducible brown adipocyte-specific cd47 deficient mice were generated by crossbreeding cd47 floxed mice with UCP1-CreERT2 mice and characterized in this study. Efficient knockdown of CD47 in brown fat was achieved in both male and female mice through tamoxifen administration. Intriguingly, our findings indicated that male mice lacking CD47 in brown fat displayed a notable reduction in body weight starting at 23 weeks of age when housed at a temperature of 22 °C, in comparison to control mice. This reduction in weight was accompanied by improved glucose tolerance. Remarkably, this phenotype persisted even when the male mice were housed under thermoneutral conditions (30 °C). Conversely, female knockout mice did not exhibit significant changes in weight throughout the study. In addition to the enhanced glucose homeostasis, brown fat CD47 deficiency in male mice also prevented age-related hypertriglyceridemia and non-alcoholic fatty liver disease. Furthermore, the brown fat tissue of male knockout mice exhibited reduced whitening, while maintaining comparable levels of thermogenic markers. This suggests the involvement of a thermogenesis-independent mechanism. Altogether, these findings highlight a sex difference in the impact of brown adipocyte CD47 deficiency on age-related weight changes and glucose homeostasis.

CD47 antisense oligonucleotide treatment attenuates obesity and its-associated metabolic dysfunction

Previous study from our lab has revealed a new role of CD47 in regulating adipose tissue function, energy homeostasis and the development of obesity and metabolic disease in CD47 deficient mice. In this study, the therapeutic potential of an antisense oligonucleotide (ASO) targeting to CD47 in obesity and its-associated complications was determined in two obese mouse models (diet induced and genetic models). In diet induced obesity, male C57BL6 mice were fed with high fat (HF) diet to induce obesity and then treated with CD47ASO or control ASO for 8 weeks. In genetic obese mouse model, male six-week old ob/ob mice were treated with ASOs for 9 weeks. We found that CD47ASO treatment reduced HF diet-induced weight gain, decreased fat mass, prevented dyslipidemia, and improved glucose tolerance. These changes were accompanied by reduced inflammation in white adipose tissue and decreased hepatic steatosis. This protection was also seen in CD47ASO treated ob/ob mice. Mechanistically, CD47ASO treatment increased mice physical activity and energy expenditure, contributing to weight loss and improved metabolic outcomes in obese mice. Collectively, these findings suggest that CD47ASO might serve as a new treatment option for obesity and its-associated metabolic complications.

Loss of CD47 alters CD8+ T cell activation in vitro and immunodynamics in mice

CD47 has established roles in the immune system for regulating macrophage phagocytosis and lymphocyte activation, with growing evidence of its cell-intrinsic regulatory roles in natural killer and CD8+ T cells. CD47 limits antigen-dependent cytotoxic activities of human and murine CD8+ T cells, but its role in T cell activation kinetics remains unclear. Using in vitro and in vivo models, we show here that CD47 differentially regulates CD8+ T cell responses to short- versus long-term activation. Although CD47 was not required for T cell development in mice and early activation in vitro, short-term stimuli elevated pathogen-reactive gene expression and enhanced proliferation and the effector phenotypes of Cd47-deficient relative to Cd47-sufficient CD8+ T cells. In contrast, persistent TCR stimulation limited the effector phenotypes of Cd47^−/− CD8+ T cells and enhanced their apoptosis signature. CD8+ T cell expansion and activation in vivo induced by acute lymphocytic choriomeningitis virus (LCMV) infection did not differ in the absence of CD47. However, the frequency and effector phenotypes of Cd47^−/− CD8+ T cells were constrained in chronic LCMV-infected as well as in mice bearing B16 melanoma tumors. Therefore, CD47 regulates CD8+ T cell activation, proliferation, and fitness in a context-dependent manner.