Muscle wasting and the temporal gene expression pattern in a novel rat intensive care unit model

<p>Abstract</p> <p>Background</p> <p>Acute quadriplegic myopathy (AQM) or critical illness myopathy (CIM) is frequently observed in intensive care unit (ICU) patients. To elucidate duration-dependent effects of the ICU intervention on molecular and functional networks that control the muscle wasting and weakness associated with AQM, a gene expression profile was analyzed at time points varying from 6 hours to 14 days in a unique experimental rat model mimicking ICU conditions, i.e., post-synaptically paralyzed, mechanically ventilated and extensively monitored animals.</p> <p>Results</p> <p>During the observation period, 1583 genes were significantly up- or down-regulated by factors of two or greater. A significant temporal gene expression pattern was constructed at short (6 h-4 days), intermediate (5-8 days) and long (9-14 days) durations. A striking early and maintained up-regulation (6 h-14d) of muscle atrogenes (muscle ring-finger 1/tripartite motif-containing 63 and F-box protein 32/atrogin-1) was observed, followed by an up-regulation of the proteolytic systems at intermediate and long durations (5-14d). Oxidative stress response genes and genes that take part in amino acid catabolism, cell cycle arrest, apoptosis, muscle development, and protein synthesis together with myogenic factors were significantly up-regulated from 5 to 14 days. At 9-14 d, genes involved in immune response and the caspase cascade were up-regulated. At 5-14d, genes related to contractile (myosin heavy chain and myosin binding protein C), regulatory (troponin, tropomyosin), developmental, caveolin-3, extracellular matrix, glycolysis/gluconeogenesis, cytoskeleton/sarcomere regulation and mitochondrial proteins were down-regulated. An activation of genes related to muscle growth and new muscle fiber formation (increase of myogenic factors and JunB and down-regulation of myostatin) and up-regulation of genes that code protein synthesis and translation factors were found from 5 to 14 days.</p> <p>Conclusions</p> <p>Novel temporal patterns of gene expression have been uncovered, suggesting a unique, coordinated and highly complex mechanism underlying the muscle wasting associated with AQM in ICU patients and providing new target genes and avenues for intervention studies.</p

Monoclonal auto-antibodies and sera of autoimmune patients react with Plasmodium falciparum and inhibit its in vitro growth

The relationship between autoimmunity and malaria is not well understood. To determine whether autoimmune responses have a protective role during malaria, we studied the pattern of reactivity to plasmodial antigens of sera from 93 patients with 14 different autoimmune diseases (AID) who were not previously exposed to malaria. Sera from patients with 13 different AID reacted against Plasmodium falciparum by indirect fluorescent antibody test with frequencies varying from 33-100%. In addition, sera from 37 AID patients were tested for reactivity against Plasmodium yoelii 17XNL and the asexual blood stage forms of three different P. falciparum strains. In general, the frequency of reactive sera was higher against young trophozoites than schizonts (p < 0.05 for 2 strains), indicating that the antigenic determinants targeted by the tested AID sera might be more highly expressed by the former stage. The ability of monoclonal auto-antibodies (auto-Ab) to inhibit P. falciparum growth in vitro was also tested. Thirteen of the 18 monoclonal auto-Ab tested (72%), but none of the control monoclonal antibodies, inhibited parasite growth, in some cases by greater than 40%. We conclude that autoimmune responses mediated by auto-Ab may present anti-plasmodial activity

Anti-PCNA autoantibodies preferentially recognize C-terminal of PCNA in patients with chronic hepatitis B virus infection

We previously reported anti-PCNA autoantibodies in sera from patients with chronic HBV and HCV infection. To analyse the antigenic regions on proliferating cell nuclear antigen (PCNA) that confer autoantibody binding in patients with chronic hepatitis B (HBV) and C (HCV) infection, eight constructs including one wild type PCNA, one mutant type Y114A_PCNA and six C- or N-terminal PCNA truncations were generated. Sera from 185 patients with systemic lupus erythematosus (SLE), 178 with chronic HBV and 163 with chronic HCV infection, and 68 healthy individuals were examined for the presentation of anti-PCNA antibodies by enzyme linked immunosorbent assay (ELISA). By ELISA, anti-PCNA positive sera from patients with SLE, chronic HBV and HCV infection preferentially recognized the wild type PCNA more than the mutant type Y114A_PCNA (P< 0·05). The inhibition of binding by purified full-length rPCNA proteins with anti-PCNA positive sera was shown to exceed 70%. The inhibition of binding by purified truncated rPCNA proteins with sera from patients with chronic HBV and HCV infection and SLE was shown to confer dominant binding in T(L2) and T(L3). Moreover, the higher frequency of inhibition by using T(L3) was found in patients with chronic HBV infection. These data indicate that anti-PCNA autoantibodies preferentially recognize C-terminal of PCNA in patients with chronic HBV infection and may also provide advanced understanding between viral infection and autoimmunity for further study