Interleukins 6 and 15 Levels Are Higher in Subcutaneous Adipose Tissue, but Obesity Is Associated with Their Increased Content in Visceral Fat Depots

• Published in: International journal of molecular sciences 2015-10, Vol.16 (10), p.25817-25830
• Main Authors: Jonas, Marta Izabela, Kurylowicz, Alina, Bartoszewicz, Zbigniew, Lisik, Wojciech, Jonas, Maurycy, Wierzbicki, Zbigniew, Chmura, Andrzej, Pruszczyk, Piotr, Puzianowska-Kuznicka, Monika
• Format: Article
• Language: English
• Subjects: Adipocytes; Adult; Body fat; Case-Control Studies; Female; Humans; Interleukin-15 - genetics; Interleukin-15 - metabolism; Interleukin-6 - metabolism; Intra-Abdominal Fat - metabolism; Male; Middle Aged; Obesity; Obesity - metabolism; Subcutaneous Fat, Abdominal - metabolism; Tissues
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms161025817

Excess adiposity is associated with chronic inflammation, which takes part in the development of obesity-related complications. The aim of this study was to establish whether subcutaneous (SAT) or visceral (VAT) adipose tissue plays a major role in synthesis of pro-inflammatory cytokines. Concentrations of interleukins (IL): 1β, 6, 8 and 15 were measured at the protein level by an ELISA-based method and on the mRNA level by real-time PCR in VAT and SAT samples obtained from 49 obese (BMI > 40 kg/m²) and 16 normal-weight (BMI 20-24.9 kg/m²) controls. IL-6 and IL-15 protein concentrations were higher in SAT than in VAT for both obese (p = 0.003 and p < 0.0001, respectively) and control individuals (p = 0.004 and p = 0.001, respectively), while for IL-1β this was observed only in obese subjects (p = 0.047). What characterized obese individuals was the higher expression of IL-6 and IL-15 at the protein level in VAT compared to normal-weight controls (p = 0.047 and p = 0.016, respectively). Additionally, obese individuals with metabolic syndrome had higher IL-1β levels in VAT than did obese individuals without this syndrome (p = 0.003). In conclusion, concentrations of some pro-inflammatory cytokines were higher in SAT than in VAT, but it was the increased pro-inflammatory activity of VAT that was associated with obesity and metabolic syndrome.