In scleroderma patients, isolated pulmonary hypertension (PHT) has been associated with selected HLA haplotypes, severe impairment of the diffusing capacity for carbon monoxide and the diagnosis of CREST. Most patients with CREST have a late-age onset of the disease, corresponding to the perimenopausal or postmenopausal period. We conducted a retrospective cohort study to determine the role of post-menopause and of the other known clinical and biological markers in the development of isolated pulmonary hypertension in Italian patients with systemic sclerosis. 189 female patients with scleroderma who had no ecographic signs of pulmonary hypertension (PHT) and radiographic signs of lung fibrosis at the first visit and did not develop significant pulmonary fibrosis during the observation time were included. Sixty-three out of 189 patients (33.3%) presented isolated pulmonary hypertension. A severe impairment of diffusing capacity for carbon monoxide at admission was found to be an early predictive element for its development. An increased risk was associated with postmenopausal condition (RR = 5.2, p = 0.000), CREST syndrome (RR = 2.8, p = 0.001) and haplotype HLA-B35 (RR = 2.8; p = 0.002). A significant positive interaction between postmenopausal condition and either HLA-B35 (RR = 15.2; p = 0.000) or the diagnosis of CREST (RR = 14.1; p = 0.000) was found. Postmenopausal condition alone or in combination with HLA-B35 and CREST syndrome is the main risk-factor for developing primary pulmonary hypertension in scleroderma patients. This suggests that hormonal replacement therapy could play a role in preventing isolated PHT in patients with systemic sclerosis.
HLA-B35 is associated with an increased risk for developing isolated pulmonary hypertension (iPHT) in systemic sclerosis, but the mechanisms underlying this association have not been fully elucidated yet. Endothelin-1 (ET-1) is the main pathogenetic molecule implied in the development of iPHT; therefore, we sought to determine if ECV304 cells transfected with the HLA-B35 allele produce increased amounts of ET-1 after incubation with physiological concentrations of interleukin-1 beta (IL-1beta). ECV304 cells transfected with HLA-B*3501 and HLA-B*0801 polymorphic alpha chain or with pIRESneo2 were incubated with 100 U/ml of IL-1beta for 6, 12, 24, 36 and 48 h. ET-1 levels were determined using EIA kit (CAYMAN Chemical, Ann Arbor, MI) in supernatants from different cell cultures; the relative expression of the preproendothelin-1 (PPET-1) gene was also determined by reverse transcription-polymerase chain reaction. Cells expressing the HLA-B35 allele showed significantly increased levels of ET-1 at all the selected times compared with controls or HLA-B8-transfected cells. The relative expression of the PPET-1 gene was also increased in a proportionally direct manner. The HLA-B35 allele influences the production of ET-1 in HLA-B35-transfected ECV304 cells by promoting the expression of its precursor, PPET-1. Our results provide an explanation for the epidemiological association existing between iPHT and HLA-B35.
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