ABSTRACT
Skeletal muscle satellite cell function is largely dictated by the surrounding environment following injury. Immune cell infiltration dominates the extracellular space in the injured area, resulting in increased cytokine concentrations. While increased pro-inflammatory cytokine expression has been previously established in the first 3 days following injury, less is known about the time course of cytokine expression and the specific mechanisms of cytokine induced myoblast function. Therefore, the expression of IL-1ß and IL-6 at several time points following injury, and their effects on myoblast proliferation, were examined. In order to do this, skeletal muscle was injured using barium chloride in mice and tissue was collected 1, 5, 10, and 28 days following injury. Mechanisms of cytokine induced proliferation were determined in cell culture using both primary and C2C12 myoblasts. It was found that there is a â¼20-fold increase in IL-1ß (p≤0.05) and IL-6 (pâ=â0.06) expression 5 days following injury. IL-1ß increased proliferation of both primary and C2C12 cells â¼25%. IL-1ß stimulation also resulted in increased NF-κB activity, likely contributing to the increased proliferation. These data demonstrate for the first time that IL-1ß alone can increase the mitogenic activity of primary skeletal muscle satellite cells and offer insight into the mechanisms dictating satellite cell function following injury.
Subject(s)
Myoblasts/cytology , Animals , Cell Line , Cell Proliferation/drug effects , Cells, Cultured , Interleukin-1beta/pharmacology , Interleukin-6/pharmacology , Male , Mice , Myoblasts/drug effects , Rats , Reverse Transcriptase Polymerase Chain Reaction , Tumor Necrosis Factor-alpha/pharmacologyABSTRACT
Adult chronic renal failure patients undergoing hemodialysis are at an increased risk of invasive Haemophilus influenzae type b (Hib) disease due to the lack of functionally active anti-Hib antibodies. The pediatric Hib polysaccharide-protein conjugate vaccine is highly immunogenic in these patients and can provide protection against invasive Hib infection for at least 1 year.
Subject(s)
Haemophilus Vaccines/administration & dosage , Haemophilus Vaccines/immunology , Haemophilus influenzae type b/immunology , Kidney Failure, Chronic/immunology , Adult , Aged , Aged, 80 and over , Antibodies, Bacterial/blood , Blood Bactericidal Activity , Female , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Kidney Failure, Chronic/therapy , Male , Middle Aged , Renal DialysisABSTRACT
Prior to the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, invasive Hib disease affected almost exclusively children. According to some recent studies, in the postvaccine era, adults, the elderly, and immunocompromised persons can be affected more often than children. As the production of type-specific anti-capsular polysaccharide antibodies is the major defense mechanism against Hib, individuals with defects in humoral immune responses have high susceptibility to infections caused by Hib. We hypothesized that nonvaccinated adults with chronic conditions causing immunosuppression may lack protective antibody to Hib. We assessed serum anti-Hib IgG levels and bactericidal activity in 59 patients with chronic renal failure, 30 patients with type 2 diabetes mellitus, 28 patients with chronic obstructive pulmonary disease (COPD), and 20 patients with multiple myeloma compared to 32 healthy controls of similar age. Considering antibody at >0.15 µg/ml as the protective correlate in unvaccinated individuals, we detected subprotective Hib antibody levels in 29% of chronic renal failure, 20% of diabetes, 14% of COPD, and 55% of myeloma patients compared to 3% of healthy controls. Additionally, 70% of myeloma and 58% of chronic renal failure patients did not have detectable serum bactericidal activity against Hib. Among individuals with severe diseases causing secondary immunodeficiency, patients with multiple myeloma and chronic renal failure are at an increased risk of invasive Hib disease. Considering that Hib continues to circulate in the population, this study provides a rationale for the immunization of some adult patients with secondary immunodeficiency with the pediatric Hib vaccine to achieve protective immunity.
Subject(s)
Haemophilus Infections/immunology , Haemophilus influenzae type b/immunology , Immunocompromised Host , Adult , Aged , Antibodies, Bacterial/blood , Bacterial Capsules/administration & dosage , Bacterial Capsules/immunology , Blood Bactericidal Activity , Diabetes Mellitus, Type 2/complications , Female , Haemophilus Infections/epidemiology , Haemophilus Vaccines/administration & dosage , Haemophilus Vaccines/immunology , Humans , Immunoglobulin G/blood , Male , Middle Aged , Multiple Myeloma/complications , Pulmonary Disease, Chronic Obstructive/complications , Renal Insufficiency/complications , Risk AssessmentABSTRACT
Pseudomonas aeruginosa is the major cause of chronic pulmonary disease in cystic fibrosis (CF) patients. During chronic infection, P. aeruginosa lose certain virulence factors, transform into a mucoid phenotype, and develop antibiotic resistance. We hypothesized that these genetic and phenotypic alterations of P. aeruginosa affect the airway epithelial responses. A549 cells were infected with 27 well-characterized isolates of P. aeruginosa from CF patients obtained during longitudinal observation, or with P. aeruginosa mutant strains lacking flagella, pili, lipopolysaccharide, or pyocyanin. Pseudomonas aeruginosa isolates from the early stages of the infection exhibited high adherence to A549 cells, were readily internalized, and able to induce reactive oxygen species (ROS) production, apoptosis of infected cells, and the release of granulocyte macrophage colony-stimulating factor. Late P. aeruginosa isolates collected from patients with chronic lung infection were shown to have reduced adherence to and internalization into A549 cells compared with bacteria from patients with intermittent P. aeruginosa colonization, and induced lower production of ROS and apoptosis, but caused high proinflammatory cytokine and adhesion molecule expression. Our findings suggest that despite the loss of virulence factors during the adaptation process in the CF lung by late P. aeruginosa strains, they retain high proinflammatory abilities that likely contribute to the disease pathogenesis.
Subject(s)
Cystic Fibrosis/complications , Epithelial Cells/microbiology , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/pathogenicity , Apoptosis , Bacterial Adhesion , Cell Line , Cytokines/metabolism , Epithelial Cells/immunology , Humans , Pseudomonas aeruginosa/immunology , Pseudomonas aeruginosa/isolation & purification , Reactive Oxygen Species/metabolismABSTRACT
Integrins are a large family of adhesion receptors that are known to be key signaling molecules in both physiological and pathological processes. Previous studies have demonstrated that the expression of integrin receptors in the pulmonary epithelium can change under various pathological conditions, such as injury, inflammation, or malignant transformation. We hypothesize that integrin expression can be altered by stimulation of lung epithelial cells with an opportunistic bacterial pathogen Pseudomonas aeruginosa. Using the A549 adenocarcinoma cell line that expressed a low level of several integrin subunits we have demonstrated that P. aeruginosa infection in vitro caused a rapid up-regulation of alpha5, alphav, beta1, and beta4 integrins at both the mRNA and protein level. Neither heat-killed P. aeruginosa strain PAK nor its live isogenic mutants lacking pili or lipopolysaccharide (LPS) core oligosaccharide showed any effect on integrin expression in A549 cells as compared to the use of the wild-type PAK strain. These results establish that up-regulation of integrin expression is dependent on the internalization of live bacteria possessing intact pili and LPS. Gene silencing of integrin-linked kinase in A549 cells caused a significant decrease in the release of proinflammatory cytokines in response to P. aeruginosa stimulation. Although further studies are warranted towards understanding the precise role of integrin receptors in prominent inflammation caused by P. aeruginosa, our findings suggest a possibility of using specific integrin inhibitors for therapy of pulmonary inflammatory conditions caused by pathogenic micro-organisms.