Local Regulation of Adrenal Steroidogenesis: Subtle in vitro Effects of IL-1β on the Human Cell Line NCI-H295R Steroid Production along with Changes in MicroRNA Profile and Orphan Nuclear Receptors NR4As

Abstract

Introduction: IL-1β, a cytokine from the innate immune response, is well known for its proinflammatory effects and stimulating activity on the hypothalamus-pituitary-adrenal axis, leading to the pituitary synthesis of adrenocorticotropic hormone followed by cortisol (and dehydroepiandrosterone - DHEA) release by the adrenal gland. While IL-1β modulates the adrenal steroidogenesis at the central level, it is unclear whether it also exerts an effect on the adrenal gland. Method: We studied the effect of IL-1β on adrenal steroid production and steroidogenic enzyme RNA expression in the human cell line NCI-H295R. We also explored eventual changes in the microRNA (miRNA) profile from IL-1β-treated NCI-H295R cells. Results: Transcripts encoding IL-1β receptors 1 and 2 were noticeable in the cell line, with cortisol and DHEA production showing a subtle increase after cytokine treatment. Transcripts from key enzymes in the steroidogenic pathway were analyzed, with no noticeable changes on them. The miRNA profile was modified by IL-1β treatment to an extent which bears some relationship with the regulatory mechanisms underlying adrenal steroid production. Since orphan nuclear receptors NR4As have emerged as potential key factors for coordinating inflammatory and metabolic responses, cell expression studies were also carried out to show an NR4As transcript augmentation following IL-1β treatment. Discussion/Conclusions: The subtle increase in adrenal steroid production in response to IL-1β stimulation without any modification in the transcription of the steroidogenic enzymes analyzed suggests an additional inflammatory/anti-inflammatory loop, wherein NR4As receptors may participate. Besides its physiological role, this process might be implied in pathological states accompanied by an unbalanced immune-endocrine relationship.