Figure 4

Effect of MRP8 stimulation in combination with ER stress on IL-6 production by muscle cells. (A) MHC class 1 expression on muscle tissue from JDM patient and age- matched control. Bar represents 50 microns. (B) Human skeletal muscle cells LHCNM2 cultured for 2 to 24 hours in 0.05 μM thapsigargin (Thaps), mRNA expression of XBP-1 was determined at indicated times; HPRT mRNA was measured as a control. RT-PCR products were analysed on 1.5% agarose gel and stained with ethidium bromide to visualise spliced (S), 142 bp and un-spliced (US), 168 bp XBP-1 transcripts. (C) Mean IL-6 production by LHCNM2 myoblasts following culture in thapsigargin, stimulated with LPS alone or with LPS following four hours pre-incubation with thapsigargin. Bars represent SEM, data analysed using two-way ANOVA. (D) IL-6 concentration in supernatants from LHCNM2 cells cultured with or without thapsigargin, stimulated with MRP8 or LPS alone, or MRP8 and LPS after four hours pre-incubation with thapsigargin. Bars and lines represent mean and SEM. Data analysed by 1 way ANOVA and paired t test *P <0.05, **P <0.001. ANOVA, analysis of variance; JDM, juvenile dermatomyositis; LPS, lipopolysaccharide; MRP, myeloid related protein; SEM, standard error of the mean; XBP-1, x-box binding protein 1.