Functional and Muscular Adaptations in an Experimental Model for Isometric Strength Training in Mice

Exercise training induces muscular adaptations that are highly specific to the type of exercise. For a systematic study of the differentiated exercise adaptations on a molecular level mouse models have been used successfully. The aim of the current study was to develop a suitable mouse model of isometric strength exercise training characterized by specific adaptations known from strength training. C57BL/6 mice performed an isometric strength training (ST) for 10 weeks 5 days/week. Additionally, either a sedentary control group (CT) or a regular endurance training group (ET) groups were used as controls. Performance capacity was determined by maximum holding time (MHT) and treadmill spirometry, respectively. Furthermore, muscle fiber types and diameter, muscular concentration of phosphofructokinase 1 (PFK), succinate dehydrogenase (SDHa), and glucose transporter type 4 (GLUT4) were determined. In a further approach, the effect of ST on glucose intolerance was tested in diabetic mice. In mice of the ST group we observed an increase of MHT in isometric strength tests, a type II fiber hypertrophy, and an increased GLUT4 protein content in the membrane fraction. In contrast, in mice of the ET group an increase of VO_2max, a shift to oxidative muscle fiber type and an increase of oxidative enzyme content was measured. Furthermore strength training was effective in reducing glucose intolerance in mice fed a high fat diet. An effective murine strength training model was developed and evaluated, which revealed marked differences in adaptations known from endurance training. This approach seems also suitable to test for therapeutical effects of strength training.     

Classical complement and inflammasome activation converge in CD14highCD16- monocytes in HIV associated TB-immune reconstitution inflammatory syndrome

Inflammasome-derived cytokines, IL-1β and IL-18, and complement cascade have been independently implicated in the pathogenesis of tuberculosis (TB)-immune reconstitution inflammatory syndrome (TB-IRIS), a complication affecting HIV⁺ individuals starting antiretroviral therapy (ART). Although sublytic deposition of the membrane attack complex (MAC) has been shown to promote NLRP3 inflammasome activation, it is unknown whether these pathways may cooperatively contribute to TB-IRIS. To evaluate the activation of inflammasome, peripheral blood mononuclear cells (PBMCs) from HIV-TB co-infected patients prior to ART and at the IRIS or equivalent timepoint were incubated with a probe used to assess active caspase-1/4/5 followed by screening of ASC (apoptosis-associated speck-like protein containing a CARD domain) specks as a readout of inflammasome activation by imaging flow cytometry. We found higher numbers of monocytes showing spontaneous caspase-1/4/5⁺ASC-speck formation in TB-IRIS compared to TB non-IRIS patients. Moreover, numbers of caspase-1/4/5⁺ASC-speck⁺ monocytes positively correlated with IL-1β/IL-18 plasma levels. Besides increased systemic levels of C1q and C5a, TB-IRIS patients also showed elevated C1q and C3 deposition on monocyte cell surface, suggesting aberrant classical complement activation. A clustering tSNE analysis revealed TB-IRIS patients are enriched in a CD14^highCD16^- monocyte population that undergoes MAC deposition and caspase-1/4/5 activation compared to TB non-IRIS patients, suggesting complement-associated inflammasome activation during IRIS events. Accordingly, PBMCs from patients were more sensitive to ex-vivo complement-mediated IL-1β secretion than healthy control cells in a NLRP3-dependent manner. Therefore, our data suggest complement-associated inflammasome activation may fuel the dysregulated TB-IRIS systemic inflammatory cascade and targeting this pathway may represent a novel therapeutic approach for IRIS or related inflammatory syndromes.     

Transformer 2β homolog (Drosophila) (TRA2B) Regulates Protein Kinase C δI (PKCδI) Splice Variant Expression during 3T3L1 Preadipocyte Cell Cycle

Obesity is characterized by adipocyte hyperplasia and hypertrophy. We previously showed that PKCδ expression is dysregulated in obesity (Carter, G., Apostolatos, A., Patel, R., Mathur, A., Cooper, D., Murr, M., and Patel, N. A. (2013) ISRN Obes. 2013, 161345). Using 3T3L1 preadipocytes, we studied adipogenesis in vitro and showed that expression of PKCδ splice variants, PKCδI and PKCδII, have different expression patterns during adipogenesis (Patel, R., Apostolatos, A., Carter, G., Ajmo, J., Gali, M., Cooper, D. R., You, M., Bisht, K. S., and Patel, N. A. (2013) J. Biol. Chem. 288, 26834–26846). Here, we evaluated the role of PKCδI splice variant during adipogenesis. Our results indicate that PKCδI expression level is high in preadipocytes and decreasing PKCδI accelerated terminal differentiation. Our results indicate that PKCδI is required for mitotic clonal expansion of preadipocytes. We next evaluated the splice factor regulating the expression of PKCδI during 3T3L1 adipogenesis. Our results show TRA2B increased PKCδI expression. To investigate the molecular mechanism, we cloned a heterologous splicing PKCδ minigene and showed that inclusion of PKCδ exon 9 is increased by TRA2B. Using mutagenesis and a RNA-immunoprecipitation assay, we evaluated the binding of Tra2β on PKCδI exon 9 and show that its association is required for PKCδI splicing. These results provide a better understanding of the role of PKCδI in adipogenesis. Determination of this molecular mechanism of alternative splicing presents a novel therapeutic target in the management of obesity and its co-morbidities.     

Increased CD4+ T Cell Co-Inhibitory Immune Receptor CEACAM1 in Neonatal Sepsis and Soluble-CEACAM1 in Meningococcal Sepsis: A Role in Sepsis-Associated Immune Suppression?

The co-inhibitory immune receptor carcinoembryonic antigen-related cell-adhesion molecule 1 (CEACAM1) and its self-ligand CEACAM1 can suppress T cell function. Suppression of T cell function in sepsis is well documented. Late-onset neonatal sepsis in VLBW-infants was associated with an increased percentage CEACAM1 positive CD4⁺ T-cells. Meningococcal septic shock in children was associated with increased serum soluble CEACAM1. In conclusion our data demonstrate increased surface expression of the co-inhibitory immune receptor CEACAM1 in late-onset neonatal sepsis in VLBW-infants, and increased circulating soluble CEACAM1 in children with meningococcal sepsis. Increased T-cell CEACAM1 expression and increased circulating soluble CEACAM1 may contribute to sepsis-associated immune suppression.     

Tuberal Hypothalamic Neurons Secreting the Satiety Molecule Nesfatin-1 Are Critically Involved in Paradoxical (REM) Sleep Homeostasis

The recently discovered Nesfatin-1 plays a role in appetite regulation as a satiety factor through hypothalamic leptin-independent mechanisms. Nesfatin-1 is co-expressed with Melanin-Concentrating Hormone (MCH) in neurons from the tuberal hypothalamic area (THA) which are recruited during sleep states, especially paradoxical sleep (PS). To help decipher the contribution of this contingent of THA neurons to sleep regulatory mechanisms, we thus investigated in rats whether the co-factor Nesfatin-1 is also endowed with sleep-modulating properties. Here, we found that the disruption of the brain Nesfatin-1 signaling achieved by icv administration of Nesfatin-1 antiserum or antisense against the nucleobindin2 (NUCB2) prohormone suppressed PS with little, if any alteration of slow wave sleep (SWS). Further, the infusion of Nesfatin-1 antiserum after a selective PS deprivation, designed for elevating PS needs, severely prevented the ensuing expected PS recovery. Strengthening these pharmacological data, we finally demonstrated by using c-Fos as an index of neuronal activation that the recruitment of Nesfatin-1-immunoreactive neurons within THA is positively correlated to PS but not to SWS amounts experienced by rats prior to sacrifice. In conclusion, this work supports a functional contribution of the Nesfatin-1 signaling, operated by THA neurons, to PS regulatory mechanisms. We propose that these neurons, likely releasing MCH as a synergistic factor, constitute an appropriate lever by which the hypothalamus may integrate endogenous signals to adapt the ultradian rhythm and maintenance of PS in a manner dictated by homeostatic needs. This could be done through the inhibition of downstream targets comprised primarily of the local hypothalamic wake-active orexin- and histamine-containing neurons.     

Composition and temporal stability of the gut microbiota in older persons

The composition and function of the human gut microbiota has been linked to health and disease. We previously identified correlations between habitual diet, microbiota composition gradients and health gradients in an unstratified cohort of 178 elderly subjects. To refine our understanding of diet–microbiota associations and differential taxon abundance, we adapted an iterative bi-clustering algorithm (iterative binary bclustering of gene sets (iBBiG)) and applied it to microbiota composition data from 732 faecal samples from 371 ELDERMET cohort subjects, including longitudinal samples. We thus identified distinctive microbiota configurations associated with ageing in both community and long-stay residential care elderly subjects. Mixed-taxa populations were identified that had clinically distinct associations. Microbiota temporal instability was observed in both community-dwelling and long-term care subjects, particularly in those with low initial microbiota diversity. However, the stability of the microbiota of subjects had little impact on the directional change of the microbiota as observed for long-stay subjects who display a gradual shift away from their initial microbiota. This was not observed in community-dwelling subjects. This directional change was associated with duration in long-stay. Changes in these bacterial populations represent the loss of the health-associated and youth-associated microbiota components and gain of an elderly associated microbiota. Interestingly, community-associated microbiota configurations were impacted more by the use of antibiotics than the microbiota of individuals in long-term care, as the community-associated microbiota showed more loss but also more recovery following antibiotic treatment. This improved definition of gut microbiota composition patterns in the elderly will better inform the design of dietary or antibiotic interventions targeting the gut microbiota.