Fig. 1.

HLA-B*35 correlates with higher expression of selected ER stress/UPR genes. PBMCs were isolated from HC (n = 49), lcSSc (n = 97, NoPAH n = 53 and PAH n = 44), and grouped according to the presence of the HLA-B*35 allele: HC B35+ (n =9), HC B35- (n = 40); lcSSc B35+ (n =26), lcSSc B35- (n =71); lcSSc NoPAH B35+ (n =14), lcSSc NoPAH B35- (n = 39), lcSSc PAH B35+ (n = 12) and lcSSc PAH B35- (n = 32). mRNA levels of BiP (left panel), DNAJB1 (middle panel), and ATF4 (right panel) were measured by qPCR. Expression of the housekeeping genes β-actin, GADPH, and 18S served as internal positive controls. Data are expressed as the fold-change normalized to mRNA expression in a single HC sample. Each data point represents a single subject; horizontal lines show the mean. ER endoplasmic reticulum, PBMCs peripheral blood mononuclear cells, HC healthy controls, lcSSc limited cutaneous systemic sclerosis, PAH pulmonary arterial hypertension, ATF4 activating transcription factor 4