Gonadal steroids modulate human monocyte interleukin-1 (IL-1) activity

Area of Science:

• Immunology
• Endocrinology
• Reproductive Biology

Background:

• Interleukin-1 (IL-1) is a key immune mediator produced by monocytes and macrophages.
• IL-1 levels rise during the luteal phase of the menstrual cycle, coinciding with progesterone (P) increase.
• The interplay between steroid hormones and immune responses warrants investigation.

Purpose of the Study:

• To investigate the relationship between steroidogenesis and IL-1 activity in human peripheral monocytes.
• To determine if estradiol (E2) and progesterone (P) modulate IL-1 production.
• To assess the impact of IL-1 on steroid production by granulosa-luteal cells.

Main Methods:

• IL-1 activity was quantified using the D-10 thymocyte stimulation bioassay.
• Dose-response curves were established for E2 and P effects on IL-1.
• Human granulosa-luteal cells were cultured with varying concentrations of IL-1, with and without human chorionic gonadotropin (hCG).

Main Results:

• Low concentrations of E2 and P maximally stimulated IL-1 production.
• Higher concentrations of E2 and P significantly reduced IL-1 activity (P < 0.05).
• Neither E2 nor P production by granulosa-luteal cells was affected by IL-1, even with hCG stimulation.

Conclusions:

• Human peripheral monocyte IL-1 activity is modulated by gonadal steroids (E2 and P).
• A reciprocal relationship where IL-1 affects gonadal steroidogenesis was not observed in this study.
• These findings highlight a unidirectional influence of sex steroids on monocyte-derived IL-1.