Bone histomorphometric studies in relation to interleukin-6 and tumor necrosis factor alpha in pre- and postmenopausal women

Abstract EN

Objective : It is believed that there is a possible role of cytokines especially Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in the pathogenesis and the heterogeneity of postmenopausal osteoporosis.

Thus, it is worth while to determine their serum concentrations in pre- and post-menopausal women to identify their exact implications on bone histomorphometery and thereby, their role in the pathogenesis of postmenopausal osteoporosis.

Methodology : Eighteen postmenopausal women with ages ranging from 49 to 63 years (mean age 58 ± 4.6 years) and 7 premenopausal ages from 39 to 50 years (mean age 46 ± 4.2 years); were enrolled in the study.

Postmenopausal women were classified into two groups; early menopausal (10 subjects): menopause duration ≤ 5 years, and late menopausal (8 subjects): menopause duration ≥ 8 years.

Serum IL-6, TNF-α (using ELISA technique) and bone mineral density (BMD) of the femur and spine (using DEXA technique) of all participants were assessed clinically.

Iliac crest biopsy specimens were obtained and divided into 2 specimens to assess decalcified and decalcified bone parameters using an image analyzer.

Results : Postmenopausal women had higher serum levels of IL-6 and TNF-α than premenopausal women.

The differences between the three groups (pre-, early and late menopause) were statistically significant except when comparing IL-6 concentration between pre- with early menopause.

All bone desorption parameters ; eroded surface (ES / BS %) and osteoclastic surface (OSc / BS %) showed significant differences upon comparing the three studied groups.

Moreover, bone formation parameters; trabecular thickness (TBTh), osteoid surface (OS / BS %) and osteoblastic surface (OSb / BS %), showed decrement in their values in the early and late menopause.

The differences were statistically significant except for the (OSb / BS %) on comparing early and late menopause.

In early menopause, there was an inverse correlation between TNF-α Levels with (TBTh) and a positive correlation with (ES/BS %), while IL-6 did not correlate with any of bone parameters.

While in late menopause, TNF-α and IL-6 levels correlated positively with (ES / BS %), but IL-6 correlated inversely with (TBth) and (OS / BS %).

Conclusion : it is clear that IL-6 and TNF-α have a crucial role in the pathogenesis of postmenopausal osteoporosis but each of the cytokines acts effectively in different phases of menopause.

Also, histomorphometric data in our sample clarified that postmenopausal osteoporosis in women is mainly a net result from increase in bone resumption and to a lesser extent a decrease in bone formation.

It is advisable to increase the number of subjects to assess the degree and pattern of osteoporosis postmenopausal Egyptian female.