RETN and Cachexia: However, leptin is predominantly secreted by white adipose tissue in response to various nutritional and inflammatory mediators and its low production in cachexia may be associated with adipose tissue mass degradation, while humans resistin is mainly expressed in bone marrow, trophoblastic cells of placenta, synovial tissue and fluid, epithelial cells of gastrointestinal tract, and circulating blood [20, 21].