Physical exercise attenuates age-related muscle atrophy and exhibits anti-ageing effects via the adiponectin receptor 1 signalling.

BACKGROUND: Although the adiponectin signalling exerts exercise-mimicking effects, whether this pathway contributes to the anti-ageing benefits of physical exercise has not been established yet. METHODS: Swim exercise training and wheel running were used to measure lifespan in the nematode Caenorhabditis elegans and skeletal muscle quality in mice, respectively. Muscle weight, muscle fibre cross-sectional area (CSA) and myonuclei number were used to evaluate muscle mass. RNA sequencing (RNA-Seq) analysis of skeletal muscle in exercised mice was used to study the underlying mechanisms. Western blot and immunofluorescence were performed to explore autophagy- and senescence-related markers. RESULTS: The C. elegans adiponectin receptor PAQR-1/AdipoR1, but not PAQR-2/AdipoR2, was activated (3.55-fold and 3.48-fold increases in p-AMPK on Days 1 and 6, respectively, P < 0.001), which was involved in lifespan extension in exercised worms. Exercise training increased skeletal muscle mass index (1.29-fold, P < 0.01), muscle weight (1.75-fold, P < 0.001), myonuclei number (1.33-fold, P < 0.05), muscle fibre CSA (1.39-fold, P < 0.05) and capillary abundance (2.19-fold, P < 0.001 for capillary density; 1.58-fold, P < 0.01 for capillary number) in aged mice. Physical exercise reduced protein (2.94-fold, P < 0.001) and mRNA levels (1.70-fold, P < 0.001) of p16INK4a , a marker for cellular senescence, in skeletal muscle of aged mice. These beneficial effects of exercise on skeletal muscle of mice were dependent on AdipoR1. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for differentially expressed genes in skeletal muscle between exercised mice with and without AdipoR1 knockdown by RNA-Seq analysis revealed that several KEGG pathways, such as 'AMPK signalling pathway' (P < 0.001), 'FOXO signalling pathway' (P < 0.001) and 'autophagy' (P < 0.001) were overrepresented. Knockdown of FoxO3a inhibited exercise-mediated beneficial effects on skeletal muscle quality of mice by inhibiting autophagy/mitophagy (3.81-fold reduction in LC3-II protein, P < 0.001; 1.53-fold reduction in BNIP3 protein, P < 0.05). Knockdown of daf-16, the FoxO homologue in C. elegans, reduced autophagy (2.77-fold and 2.06-fold reduction in GFP::LGG-1 puncta in seam cells and the intestine, respectively, P < 0.05) and blocked lifespan extension by exercise in worms. CONCLUSIONS: Our findings provide insights into how the AdipoR1 pathway has an impact on the anti-ageing benefits of exercise and implicate that activation of the AdipoR1 signalling may represent a potential therapeutic strategy for reducing age-related loss of skeletal muscle.

Secondary alloanti-D immunization post transfusion of "Asia type" DEL red blood cells.

BACKGROUND: "Asia type" DEL red blood cells (RBCs) express a very weak D antigen and cannot be detected by routine RhD typing. Thus, it is routinely typed as D-negative (D-) blood group and transfused to D- recipients. Here we described a case of secondary alloanti-D immunization that was associated with transfusion of DEL RBCs to D- recipients and was initially considered as primary alloanti-D immunization. CASE PRESENTATION: A 44-year-old D- woman (G2P2) with adenomyosis and anemia underwent transabdominal hysterectomy. She received four units of D- RBCs before operation. Before transfusion, the alloantibody screening test was negative. Four days after the first transfusion, she needed another RBC transfusion. Unexpectedly, the routine pre-transfusion alloantibody screening test became positive and anti-D (titer, 128-fold) was identified, indicating an alloanti-D immunization. The anti-D developed four days after the first transfusion was unexplained, so alloantibody identification was performed on the sample collected before the first transfusion, and weak anti-D combined with anti-E, which was not detectable during the previous routine pre-transfusion alloantibody screening test with non-enzyme-treated screening cells, was identified using bromelain-treated panel cells. The remaining blood samples of first transfusion in bag tails from two donors were collected for RHD genotyping analysis. One donor was later identified as "Asia type" DEL having RHD* 1227 A/01 N.01 genotype. CONCLUSION: Caution should be applied when we conclude that transfusion of "Asia type" DEL RBCs to true D- recipients could induce primary alloanti-D immunization, especially if the short time interval between transfusion and detection of anti-D is observed.