Background: The main challenge against patients with cancer to derive benefits from immune checkpoint inhibitors targeting PD-1/PD-L1 appears to be the immunosuppressive tumor microenvironment (TME), in which IL-33/ST2 signal fulfills critical functions. However, whether IL-33 limits the therapeutic efficacy of anti-PD-L1 remains uncertain. Methods: Molecular mechanisms of IL-33/ST2 signal on anti-PD-L1 treatment lewis lung carcinoma tumor model were assessed by RNA-seq, ELISA, WB and immunofluorescence (IF). A sST2-Fc fusion protein was constructed for targeting IL-33 and combined with anti-PD-L1 antibody for immunotherapy in colon and lung tumor models. On this basis, bifunctional fusion proteins were generated for PD-L1-targeted blocking of IL-33 in tumors. The underlying mechanisms of dual targeting of IL-33 and PD-L1 revealed by RNA-seq, scRNA-seq, FACS, IF and WB. Results: After anti-PD-L1 administration, tumor-infiltrating ST2⁺ regulatory T cells (Tregs) were elevated. Blocking IL-33/ST2 signal with sST2-Fc fusion protein potentiated antitumor efficacy of PD-L1 antibody by enhancing T cell responses in tumor models. Bifunctional fusion protein anti-PD-L1-sST2 exhibited enhanced antitumor efficacy compared with combination therapy, not only inhibited tumor progression and extended the survival, but also provided long-term protective antitumor immunity. Mechanistically, the superior antitumor activity of targeting IL-33 and PD-L1 originated from reducing immunosuppressive factors, such as Tregs and exhausted CD8⁺ T cells while increasing tumor-infiltrating cytotoxic T lymphocyte cells. Conclusions: In this study, we demonstrated that IL-33/ST2 was involved in the immunosuppression mechanism of PD-L1 antibody therapy, and blockade by sST2-Fc or anti-PD-L1-sST2 could remodel the inflammatory TME and induce potent antitumor effect, highlighting the potential therapeutic strategies for the tumor treatment by simultaneously targeting IL-33 and PD-L1.

Macrophages are the origin of most foam cells in the early stage of atherosclerotic plaques. However, the mechanism involved in the formation of macrophage-derived foam cell formation remains unclear. Here, we revealed that the hedgehog (Hh) signaling is critical in autophagy-lysosome pathway regulation and macrophage-derived foam cell formation. Inhibition of Hh signaling by vismodegib ameliorated lipid deposition and oxidative stress level in atherosclerotic plaques in high-fat diet-fed apoE^−/− mice. For mechanistic study, how the Hh signaling modulate the process of foam cell formation were accessed afterward. Unexpectedly, we found that suppression of Hh signaling in apoE^−/− mice had no significant impact on circulating cholesterol levels, indicating that Hh pathway modulate the procession of atherosclerotic plaque not through a traditional lipid-lowing mechanism. Instead, vismodegib was found to accelerate autophagosomes maturation as well as cholesterol efflux in macrophage-derived foam cell and in turn improve foam cell formation, while autophagy inhibitors (LY294002 or CQ) administration significantly attenuated vismodegib-induced cholesterol efflux and reversed the effect on foam cell formation. Therefore, our result demonstrated that inhibition of the Hh signaling pathway increases cholesterol efflux and ameliorates macrophage-derived foam cell formation by promoting autophagy in vitro. Our data thus suggested a novel therapeutic target of atherosclerosis and indicated the potential of vismodegib to treat atherosclerosis.

Non‐alcoholic fatty liver disease (NAFLD) is a prominent cause of various chronic metabolic hepatic diseases with limited therapeutics. Rubicon, an essential regulator in lysosomal degradation, is reported to exacerbate hepatic steatosis in NAFLD mice and patients, indicating its probability of being a therapeutic target for NAFLD treatment. In this study, the therapeutic potential of Rubicon blockage is investigated. Lipid nanoparticles carrying Rubicon‐specific CRISPR‐Cas9 components exhibited liver accumulation, cell internalization, and Rubicon knockdown. A single administration of the nanoparticles results in attenuated lipid deposition and hepatic steatosis, with lower circulating lipid levels and decreased adipocyte size in NAFLD mice. Furthermore, the increase of phosphatidylcholine and phosphatidylethanolamine levels can be observed in the NAFLD mice livers after Rubicon silencing, along with regulatory effects on metabolism‐related genes such as CD36, Gpcpd1, Chka, and Lpin2. The results indicate that knockdown of Rubicon improves glycerophospholipid metabolism and thereby ameliorates the NAFLD progression, which provides a potential strategy for NAFLD therapy via the restoration of Rubicon.

The activation of T lymphocytes is a crucial component of the immune response, and the presence of CD80, a membrane antigen, is necessary for T-cell activation. CD80 is usually expressed on antigen-presenting cells (APCs), which can interact with cluster of differentiation 28 (CD28) or programmed cell death ligand 1 (PD-L1) to promote T-cell proliferation, differentiation and function by activating costimulatory signal or blocking inhibitory signal. Simultaneously, CD80 on the APCs also interacts with cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) on the surface of T cells to suppress the response of specific effector T cells, particularly in the context of persistent antigenic stimulation. Due to the pivotal role of CD80 in the immune response, the CD80-Fc fusion protein has emerged as a promising approach for cancer immunotherapy. This review primarily focused on the crucial role of CD80 in the cancer immunotherapy. We also reviewed the current advancements in the research of CD80-Fc fusion proteins. Finally, we deliberated on the challenges encountered by CD80-Fc fusion proteins and proposed the potential strategies that could yield the benefits for patients.

Influenza A virus infection is usually associated with acute lung injury, which is typically characterized by tracheal mucosal barrier damage and an interleukin 17A (IL-17A)-mediated inflammatory response in lung tissues. Although targeting IL-17A has been proven to be beneficial for attenuating inflammation around lung cells, it still has a limited effect on pulmonary tissue recovery after influenza A virus infection. In this research, interleukin 22 (IL-22), a cytokine involved in the repair of the pulmonary mucosal barrier, was fused to the C-terminus of the anti-IL-17A antibody vunakizumab to endow the antibody with a tissue recovery function. The vunakizumab-IL22 (vmab-IL-22) fusion protein exhibits favorable stability and retains the biological activities of both the anti-IL-17A antibody and IL-22 in vitro. Mice infected with lethal H1N1 influenza A virus and treated with vmab-mIL22 showed attenuation of lung index scores and edema when compared to those of mice treated with saline or vmab or mIL22 alone. Our results also illustrate that vmab-mIL22 triggers the upregulation of MUC2 and ZO1, as well as the modulation of cytokines such as IL-1β, HMGB1 and IL-10, indicating the recovery of pulmonary goblet cells and the suppression of excessive inflammation in mice after influenza A virus infection. Moreover, transcriptome profiling analysis suggest the downregulation of fibrosis-related genes and signaling pathways, including genes related to focal adhesion, the inflammatory response pathway, the TGF-β signaling pathway and lung fibrosis upon vmab-mIL22 treatment, which indicates that the probable mechanism of vmab-mIL22 in ameliorating H1N1 influenza A-induced lung injury. Our results reveal that the bifunctional fusion protein vmab-mIL22 can trigger potent therapeutic effects in H1N1-infected mice by enhancing lung tissue recovery and inhibiting pulmonary inflammation, which highlights a potential approach for treating influenza A virus infection by targeting IL-17A and IL-22 simultaneously.

Acute liver failure (ALF) is a serious inflammatory disorder with high mortality rates, which poses a significant threat to human health. The IL-33/ST2 signal is a crucial regulator in inflammation responses associated with lipopolysaccharide (LPS)-induced macrophages. The IL-17A signaling pathway promotes the release of chemokines and inflammatory cytokines, recruiting neutrophils and T cells under LPS stimulation, thus facilitating inflammatory responses. Here, the potential therapeutic benefits of neutralizing the IL-17A signal and modulating the IL-33/ST2 signal in ALF were investigated. A novel dual-functional fusion protein, anti-IL-17A-sST2, was constructed, which displayed high purity and biological activities. The administration of anti-IL-17A-sST2 resulted in significant anti-inflammatory benefits in ALF mice, amelioration of hepatocyte necrosis and interstitial congestion, and reduction in TNF-α and IL-6. Furthermore, anti-IL-17A-sST2 injection downregulated the expression of TLR4 and NLRP3 as well as important molecules such as MyD88, caspase-1, and IL-1β. The results suggest that anti-IL-17A-sST2 reduced the secretion of inflammatory factors, attenuated the inflammatory response, and protected hepatic function by regulating the TLR4/MyD88 pathway and inhibiting the NLRP3 inflammasome, providing a new therapeutic approach for ALF.