Bone-resorbing cytokines from peripheral blood mononuclear cells after hormone replacement therapy:: A longitudinal study

Conflicting results have been reported in several cross-sectional studies measuring cytokine production from adherent monocytes in pre- and postmenopausal women. Furthermore, the target cells for the action of estrogen are still debated. We therefore assessed in a longitudinal manner the cytokine production from different fractions of peripheral blood mononuclear cells (PBMC) cultured for 48 h. PBMC were obtained from 30 postmenopausal women before and after 6 months of hormone replacement therapy (HRT). Women were randomly allocated to two groups: an adherent PBMC group (n = 20) and a total PBMC group (n = 9). After 6 months of treatment, urinary pyridinoline levels were markedly decreased in both groups (353 +/- 24 vs 114 +/- 13 mug/mmol creatinine and 325 +/- 35 vs 164 +/- 31 mug/mmol creatinine respectively, p <0.01). Culture supernatants were assayed for interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), soluble IL-6 receptor (IL-6rs) and tumor necrosis factor alpha (TNF-alpha). In the adherent PBMC group, HRT induced a nonsignificant trend toward decreased levels of IL-1 beta (35 +/- 10 vs 13 +/- 5 pg/ml), TNF-alpha (333 +/- 58 vs 222 +/- 30 pg/ml) and IL-6 (115 +/- 70 vs 17 +/- 10 pg/ml). In contrast, in the total PBMC group, HRT induced a consistent and dramatic decrease in levels of IL-1 beta (104 +/- 22 vs 25 +/- 8 pg/ml), IL-6 (5950 +/- 1041 vs 1011 +/- 361 pg/ml), IL-6rs (148 +/- 33 vs 35 +/- 12 pg/ml) (p <0.01) and TNF-alpha (1468 +/- 315 vs 585 +/- 207 pg/ml, p = 0.05). We then evaluated whether HRT had the same effect in vitro. Adherent or total PBMC of 8 postmenopausal women were cultured with or without 10(-8)M 17 beta -estradiol or tibolone for 48 h. Production of IL- 1 beta, TNF-alpha, IL-6 and IL-6rs was not affected by the presence of 17 beta -estradiol or tibolone in cultures of these cell fractions. In conclusion, our data indicate that non-adherent PBMC could mediate the response to HRT. HRT may exert its action indirectly via noncirculating cells, as suggested by the absence of an in vitro effect.