Proliferation and telomere length in acutely mobilized blood mononuclear cells in HIV infected patients

Impact of training status on LPS-induced acute inflammation in humans

The aim of the present study was to examine the impact of training status on the ability to induce a lipopolysaccharide (LPS)-induced inflammatory response systemically as well as in skeletal muscle (SkM) and adipose tissue (AT) in human subjects. Seventeen young (23.8 ± 2.5 yr of age) healthy male subjects were included in the study with eight subjects assigned to a trained (T) group and nine subjects assigned to an untrained (UT) group. On the experimental day, catheters were inserted in the femoral artery and vein of one leg for blood sampling and a bolus of 0.3 ng LPS/kg body wt was injected into an antecubital vein in the forearm. Femoral arterial blood flow was measured by ultrasound Doppler, and arterial and venous blood samples were drawn before (Pre) LPS injection and 30, 60, 90, and 120 min after the LPS injection. Vastus lateralis muscle and abdominal subcutaneous AT biopsies were obtained Pre and 60 and 120 min after the LPS injection. LPS increased the systemic plasma TNFα and IL-6 level as well as the TNFα and IL-6 mRNA content in SkM and AT of both UT and T. However, whereas the LPS-induced inflammatory response in SkM was enhanced in T subjects relative to UT, the inflammatory response systemically and in AT was somewhat delayed in T subjects relative to UT. The present findings highlight that training status affects the ability to induce a LPS-induced acute inflammatory response in a tissue-specific manner.

Targets of immune regeneration in rheumatoid arthritis

Many of the aging-related morbidities, including cancer, cardiovascular disease, neurodegenerative disease, and infectious susceptibility, are linked to a decline in immune competence with a concomitant rise in proinflammatory immunity, placing the process of immune aging at the center of aging biology. Immune aging affects individuals older than 50 years and is accelerated in patients with the autoimmune disease rheumatoid arthritis. Immune aging results in a marked decline in protective immune responses and a parallel increase in tissue inflammatory responses. By studying immune cells in patients with rheumatoid arthritis, several of the molecular underpinnings of the immune aging process have been delineated, such as the loss of telomeres and inefficiencies in the repair of damaged DNA. Aging T cells display a series of abnormalities, including the unopposed up-regulation of cytoplasmic phosphatases and the loss of glycolytic competence, that alter their response to stimulating signals and undermine their longevity. Understanding the connection between accelerated immune aging and autoimmunity remains an area of active research. With increasing knowledge of the molecular pathways that cause immunosenescence, therapeutic interventions can be designed to slow or halt the seemingly inevitable deterioration of protective immunity with aging.

Increased shelterin mRNA expression in peripheral blood mononuclear cells and skeletal muscle following an ultra-long-distance running event

Located at the end of chromosomes, telomeres are progressively shortened with each replication of DNA during aging. Integral to the regulation of telomere length is a group of proteins making up the shelterin complex, whose tissue-specific function during physiological stress is not well understood. In this study, we examine the mRNA and protein levels of proteins within and associated with the shelterin complex in subjects ( n = 8, mean age = 44 yr) who completed a physiological stress of seven marathons in 7 days. Twenty-two to 24 h after the last marathon, subjects had increased mRNA levels of DNA repair enzymes Ku70 and Ku80 ( P < 0.05) in both skeletal muscle and peripheral blood mononuclear cells (PBMCs). Additionally, the PBMCs displayed an increment in three shelterin protein mRNA levels (TRF1, TRF2, and Pot-1, P < 0.05) following the event. Seven days of ultrarunning did not result in changes in mean telomere length, telomerase activity, hTert mRNA, or hterc mRNAs found in PBMCs. Higher protein concentrations of TRF2 were found in skeletal muscle vs. PBMCs at rest. Mean telomere length in skeletal muscle did not change and did not contain detectable levels of htert mRNA or telomerase activity. Furthermore, changes in the PBMCs could not be attributed to changes in the proportion of subtypes of CD4+ or CD8+ cells. We have provided the first evidence that, in humans, proteins within and associated with the shelterin complex increase at the mRNA level in response to a physiological stress differentially in PBMCs and skeletal muscle.

Lymphocyte responses to maximal exercise: a physiological perspective

Exercise affects lymphocytes as reflected in total blood counts and the lymphocyte proliferative response. In addition, the production of immunoglobulins is impaired and during exercise the natural killer cell activity increases followed by suppression in the recovery period. Cardiopulmonary adjustments play a major role in lymphocyte response to physical activity. During intense exercise, the activated sympathetic nervous system increases blood flow to muscle as blood flow to splanchnic organs decreases. After exercise, sympathetic tone and blood pressure becomes reduced. The spleen contains lymphocytes and blood resides in gut vessels. A change in blood flow to these organs could affect the number of circulating lymphocytes. Reduced production of immunoglobulins results from suppressed B-cell function and, in response to exercise, mucosal immunity appears to decrease. Pulmonary hyperventilation and enhanced pressure in pulmonary vessels induce increased permeability of airway epithelium and stress failure of the alveolar-capillary membrane during intense exercise. A physiological perspective is of importance for evaluation of the exercise-induced change in lymphocyte function and, in turn, to post-exercise increased susceptibility to infections.