Diet-induced obesity comorbidities such as Insulin resistance and hepatic steatosis, have been causally linked to adipose tissue recruited macrophages whose proinflammatory polarization is promoted during adipose tissue mass expansion (1,2). The voltage gated potassium channel Kv1.3 appeared as a putative anti-obesity target back in 2003 when it was shown that the total KO mice are resistant to high-fat diet (HFD) induced obesity (3). Kv1.3 overexpression triggered by proinflammatory stimuli is necessary for macrophages activation (4). Therefore, we aim to better the understanding of the Kv1.3 anti-obesity role by dissecting the specific contribution of macrophages. To do so, we crossed our unique Kv1.3 flox/flox mice with LysM-Cre mice (Jackson Laboratories) obtaining Kv1.3 flox/flox-LysM-Cre mice in which Kv1.3 is specifically knocked out in the myeloid cell lineage including macrophages (named MO-Kv1.3KO). We exposed parental and MO-Kv1.3KO 8-weeks old animals to 45%-high fat diet (HFD) for 12 weeks. At the end of the treatment, we performed glucose tolerance test, insulin tolerance test and sacrificed the animals to collect several fat pads and liver (all procedures were approved by the ethics committee for animal experiments at University of Padova).

After HFD, we could not observe differences in weight (28.22 ± 0.81 vs 27.61 ± 0.84 g; n = 17 vs 8) nor insulin sensitivity between parental and MO-Kv1.3KO female mice. On the contrary, MO-Kv1.3KO males showed a slightly reduced weight (40.32 ± 0.81 vs 37.6 ± 1 g; n = 11 vs 8) which associated to smaller fad pads (interscapular brown, inguinal white subcutaneous and perigonadal white visceral adipose tissues) and improved glucose clearance capacity and insulin sensitivity. When the stromal vascular fraction (SVF) of visceral white adipose tissue was obtained and interrogated using flow cytometry to assess macrophages infiltration, the previously observed sex differences were paralleled. While neither females nor males showed changes in the proportion of F480+ cells (macrophages) in the SVF, in MO-Kv1.3KO males, but not females, macrophages showed a reduced expression of the proinflammatory marker CD11c. This was associated with a lower BodiPY signal showing reduced lipid content only in MO-Kv1.3KO males macrophages. Therefore, affecting the expression of the channel in macrophages have a differential impact on females and males. Hence, our results show that kv1.3 silencing in macrophages does not impair its recruitment into the adipose tissue but disrupts, in a sex dependent way, the vicious cycle that associate fat expansion to insulin resistance.