B cell activation factor (BAFF) is a novel adipokine that links obesity and inflammation

B cell activation factor (BAFF) is a novel member of the TNF ligand superfamily, mainly produced by myeloid cells. BAFF has been shown to participate in B-cell survival and B- and T-cell maturation. BAFF expression in adipocytes has been recently demonstrated. In the current study, we verified that BAFF expression is increased during adipocyte differentiation. BAFF expression was augmented by TNF-alpha treatment and was decreased by rosiglitazone treatment. BAFF secretion in lean and in ob/ob mice sera were compared and smaller amount of BAFF was secreted in ob/ob mice. mRNA and protein expression were different between epididymal and visceral adipose tissue. BAFF expression was also increased in ob/ob mouse adipose tissue. We sought to identify known BAFF receptors (BAFF-R, BCMA, and TACI) in adipocytes, and determined that all three were present and upregulated during adipocyte differentiation. However, the expression of TACI was distinct from that of BAFF-R and BCMA under TNF-alpha and BAFF ligand treatment. BAFF-R and BCMA expression levels were upregulated under pro-inflammatory conditions, but TACI was reduced. Conversely, BAFF-R and BCMA expression levels were downregulated by rosiglitazone treatment, but TACI was increased. Taken together, our results suggest that BAFF may be a new adipokine, representing a link between obesity and inflammation.

TACI:Fc scavenging B cell activating factor (BAFF) alleviates ovalbumin-induced bronchial asthma in mice

Asthma was induced by the sensitization and challenge with ovalbumin (OVA) in mice. B-cell activating factor (BAFF) plays a role in mature B cell generation and maintenance. Here, we investigated whether, BAFF expression was changed in OVA-induced mice and whether the control of BAFF expression level alleviates the symptom of bronchial asthma. BAFF expression was detected in alveolar-associated cells surrounding bronchi of OVA-induced mouse lung tissues. BAFF protein was also increased in OVA-induced mouse serum. The increased BAFF transcripts was detected in OVA-induced mouse splenocytes. OVA-induced asthma was associated with the increased number of eosinophils in bronchoalveolar lavage fluid (BALF). When TACI:Fc scavenging soluble BAFF was injected to OVA-induced mice, a significant inhibition was detected in the thickness of airway smooth muscle and glycol-containing cellular elements in airway that were visualized by hematoxylin/eosin Y and periodic acid-Schiff staining, respectively. In addition, when mice were treated with TACI:Fc protein, BAFF protein level was decreased in alveolar-associated cells surrounding bronchi of OVA-induced mouse lung tissues compared to control mice. When compared to OVA-induced control, TACI:Fc treatment reduced the percentage of non-lymphoid cells and no changes were detected in lymphoid cell population. Hypodiploid cell formation in BALF was decreased by OVA-challenge but it was recovered by TACI:Fc treatment. Collectively, data suggest that asthmatic symptom could be alleviated by scavenging BAFF and then BAFF could be a novel target for the develpoment of anti-asthmatic agents.