Metabolic changes of peripheral blood mononuclear cells are related to the high cytokine levels in patients with pulmonary arterial hypertension

Abstract

Recently, innate immune activation has been reported to be associated with the development of Pulmonary Arterial Hypertension (PAH); nevertheless, the relationship between metabolic changes and the activation of inflammatory processes is poorly understood. In this retrospective study, we analyzed the relationship of hypoxia-inducible factor 1α (HIF-1α) with changes in proteins related to oxidative and non-oxidative metabolism in peripheral blood mononuclear cells (PBMCs), as well as cytokines in patients with PAH. The mRNA was extracted from PBMCs to analyze the gene expression of AMPKα2, HIF-1α, GLUT1, PFK2, PDHp, MTCO1, CO4, and MTATP6 by RT-PCR. Levels of HIF-1α, AMPK, and subunits from OXPHOS complexes proteins were analyzed by western blots. In addition, the mitochondrial DNA (mtDNA) levels from PBMCs were quantified by qPCR. Finally, plasmatic inflammatory cytokines were quantified. Results show an increased gene expression of MTCO1 (p < 0.05) in patients with PAH. Furthermore, those patients showed significantly elevated protein levels of HIF-1α (p < 0.005), p-AMPK (p < 0.001), and subunits of OXPHOS complexes: CIII (p < 0.005), CIV (p < 0.05), and CV (p < 0.05). Correlation analysis of cytokine levels with those proteins showed a positive, moderate, or strong correlation with protein levels. Interestingly, HIF-1α and AMPK protein levels positively correlated with levels of OXPHOS complexes. Conclusion: a significant elevation of protein levels of HIF-1α, and OXPHOS complexes, as well as a high activity in AMPK in patients with PAH, indicates an adaptive response mechanism in mononuclear cells that, in turn, modifies the systemic inflammatory response.

Keywords: AMPK; Cardiovascular disease; Cytokines; Hypoxia inducible factor – 1α; Immunometabolism; PBMCs; Pulmonary hypertension.