Citations

The tyrosine kinase inhibitor sorafenib improves hepatopulmonary syndrome (HPS) in an experimental model. However, the efficacy and adverse effect profile in patients with HPS are unknown. We aimed to determine the effect of sorafenib on the alveolar‐arterial oxygen gradient (AaPO2) at 3 months in patients with HPS. We performed a randomized, double‐blind, placebo‐controlled parallel trial of sorafenib in patients with HPS at 7 centers. A total of 28 patients with HPS were randomized to sorafenib 400 mg by mouth daily or a matching placebo in a 1:1 ratio. We found no statistically significant difference in the median change in AaPO2 from baseline to 12 weeks between the patients allocated to sorafenib (4.5 mm Hg; IQR, –3.8 to 7.0 mm Hg) and those allocated to placebo (–2.4 mm Hg; IQR, –4.8 to 8.2 mm Hg; P = 0.70). There was also no difference between the groups in terms of degree of intrapulmonary shunting by contrast echocardiography. Sorafenib significantly reduced circulating levels of angiogenic markers, including vascular endothelial growth factor receptors (P < 0.01) and TIE2‐expressing M2 monocytes (P = 0.03), but it reduced the mental component scores of the Short Form 36 (P = 0.04), indicating a worse quality of life. In conclusion, sorafenib did not change the AaPO2 or other disease markers at 3 months in patients with HPS. Alternative antiangiogenic therapies or treatments targeting other pathways should be investigated.

Abstract Follicular Th (Tfh) cells are a distinct subset of Th cells that help B cells produce class-switched antibodies. Studies have demonstrated that Tfh cells are highly prone to HIV infection and replication. However, the molecular mechanisms underlying this phenomenon are largely unclear. Here, we show that murine and human Tfh cells have diminished constitutive expression of IFN-stimulated genes (ISGs) inclusive of antiviral resistance factor MX dynamin-like GTPase 2 (MX2) and IFN-induced transmembrane 3 (IFITM3) compared with non-Tfh cells. A lower antiviral resistance in Tfh was consistent with a higher susceptibility to retroviral infections. Mechanistically, we found that BCL6, a master regulator of Tfh cell development, binds to ISG loci and inhibits the expression of MX2 and IFITM3 in Tfh cells. We demonstrate further that inhibition of the BCL6 BR-C, ttk, and bab (BTB) domain function increases the expression of ISGs and suppresses HIV infection and replication in Tfh cells. Our data reveal a regulatory role of BCL6 in inhibiting antiviral resistance factors in Tfh cells, thereby promoting the susceptibility Tfh cells to viral infections. Our results indicate that the modulation of BCL6 function in Tfh cells could be a potential strategy to enhance Tfh cell resistance to retroviral infections and potentially decrease cellular reservoirs of HIV infection.