The obese healthy paradox: is inflammation the answer?
A paradoxical but common finding in the obesity clinic is the identification of individuals who can be considered 'inappropriately' healthy for their degree of obesity. We think that studying these obese but metabolically healthy individuals and comparing them with equally obese but insulin-resistant individuals could provide important insights into the mechanistic link between adipose tissue expansion and associated metabolic alterations. In the present study, we investigated whether there are differences in inflammatory and insulin signalling pathways in VAT (visceral adipose tissue) that could account for the metabolic differences exhibited by morbidly obese individuals who are either insulin-resistant (IR-MO) or paradoxically insulin-sensitive (NIR-MO). Our results indicate that there are pathways common to obesity and unrelated to insulin resistance and others that are discriminative for insulin resistance for a similar degree of obesity. For instance, all morbidly obese patients, irrespective of their insulin resistance, showed increased expression of TNFalpha (tumour necrosis factor alpha) and activation of JNK1/2 (c-Jun N-terminal kinase 1/2). However, the IR-MO group showed significantly elevated expression levels of IL (interleukin)-1beta and IL-6 and increased macrophage infiltrates compared with non-obese individuals and NIR-MO. IkappaBalpha [inhibitor of NF-kappaB (nuclear factor kappaB) alpha], the activation of ERK1/2 (extracellular-signal-regulated kinase 1/2) and NF-kappaB were discriminative of the state of insulin resistance and correlated with differential changes in IRS-1 (insulin receptor substrate 1) expression and Akt activation between IR-MO and NIR-MO individuals. Our results support the concept that NIR-MO individuals lack the inflammatory response that characterizes the IR-MO patient and that IL-6, IL-1beta, ERK and NF-kappaB are important effectors that mediate the inflammation effects promoting insulin resistance.
Hospital Virgen de la Victoria, Málaga, CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain. nuria.barbarroja.exts@juntadeandalucia.es
Nuria
N
Barbarroja
Rosario
R
López-Pedrera
Maria Dolores
MD
Mayas
Eduardo
E
García-Fuentes
Lourdes
L
Garrido-Sánchez
M
M
Macías-González
Rajaa
R
El Bekay
Antonio
A
Vidal-Puig
Francisco J
FJ
Tinahones
D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D020672:I-kappa B Proteins / Q000096:biosynthesis / Q000235:genetics; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D007328:Insulin / Q000502:physiology; D055504:Insulin Receptor Substrate Proteins / Q000096:biosynthesis / Q000235:genetics; D007333:Insulin Resistance; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000235:genetics; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D050152:Intra-Abdominal Fat / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology; D008297:Male; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics; D009767:Obesity, Morbid / Q000276:immunology* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D015415:Biomarkers; D020672:I-kappa B Proteins; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D053583:Interleukin-1beta; D015850:Interleukin-6; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases