Distinct Secretory Activity and Clinical Impact of Subcutaneous Abdominal Adipose Tissue in Women with Rheumatoid Arthritis and Osteoarthritis

Abstract

In the general population, low-grade inflammation of adipose tissue accompanies obesity and contributes to cardiovascular disease (CVD) development, but the implication of this tissue in rheumatic disease pathology is unclear. Therefore, we characterized the secretory activity of subcutaneous abdominal adipose tissue (SAAT) of females with rheumatoid arthritis (RA) and osteoarthritis (OA) and searched for its relationship with intensity of systemic inflammation, body composition and comorbidity. The secretion of classical adipokines (leptin, adiponectin), pro- and anti-inflammatory factors, i.e. interleukin (IL)-6, IL-8, IL-10, tumour necrosis factor (TNF), macrophage migration inhibitory factor (MIF) and hepatocyte growth factor (HGF), from SAAT explants was measured by specific enzyme-linked immunosorbent assays. Patients' body composition was evaluated by bioelectric impendence technique. Rheumatoid SAAT secreted more adiponectin, IL-6, IL-10, TNF and MIF but less leptin than respective osteoarthritis tissues. In RA patients, TNF secretion correlated with cachectic body composition, HGF release was linked to secondary amyloidosis and visceral fat rating was an independent risk factor for CVD. In OA, secretion of leptin and HGF positively, while adiponectin inversely, correlated with systemic inflammation markers, and the release of MIF was an independent risk factor for CVD. This study reveals differences between RA and OA patients in SAAT secretory activity and suggests its different clinical impact in these diseases, characterized by high- and low-grade systemic inflammation, respectively. In RA, SAAT may directly or via an effect on body composition contribute to amyloidosis, cachexia or CVD co-occurring, while in OA SAAT-derived adipocytokines may rather regulate intensity of systemic inflammation and redound to CVD emergence.

Secretory activity of subcutaneous abdominal adipose tissue in male patients with rheumatoid arthritis and osteoarthritis – association with clinical and laboratory data

“…We recently reported similar differences between RA and OA female patients [14]. These observations are consistent with other findings recognizing OA and RA as chronic inflammatory rheumatic diseases characterized by low- and high-systemic inflammation, respectively [1–5].…”

“…Consistently, in this female patient cohort we identified two independent risk factors for CVD, i.e. F VSC in RA and SAAT-released MIF in OA, as well as SAAT-secreted HGF as an independent risk factor for amyloidosis in RA [14]. Unfortunately, due to the limited number of patients enrolled in the present study we were unable to confirm whether SAAT-secreted adipocytokines are independent risk factors for comorbidity in men affected with RA and OA.…”

“…Our recently published data concerning female patients suffering from rheumatic diseases showed a more cachectic body composition but higher basal and IL-1β-triggered secretory activity of SAAT in an RA than an OA cohort [14]. We concluded that these differences might result from stronger in vivo pre-exposure and higher reactivity of rheumatoid SAAT to pro-inflammatory challenge.…”

“…Patients’ characteristics are summarized in Table I. Specimens of subcutaneous abdominal fat were taken by 18 G needle biopsy from patients screened for amyloidosis, as previously described [14]. Body composition of patients was evaluated by measurement of total fat mass (tFM), fat-free mass (FFM), and visceral fat (F vsc ) rating by bioelectric impendence technique using the body composition analyzer Tanita BC-418 MA (Tanita Corp., Tokyo, Japan).…”

“…RA and OA. We have recently reported significant differences in secretory activity of subcutaneous abdominal adipose tissue (SAAT) and its different clinical impact in rheumatoid arthritis versus osteoarthritis in female patients [14]. It is worth pointing out that RA affects mostly women while in OA female gender predominates among older patients and in the cases of more severe form of illness.…”