USP7 Promotes deubiquitination and stabilization of MyD88 to enhance immune responses

Immunostimulatory activity of sea buckthorn polysaccharides via TLR2/4-mediated MAPK and NF-κB signaling pathways in vitro and in vivo

SP0.1-1, derived from Sea buckthorn (Hippophae rhamnoides L.), has been discovered to exhibit unique antioxidant activity. In this study, we investigated the immunomodulatory activity and mechanisms of SP0.1-1 on macrophage RAW 264.7 cells in vitro and immunosuppressive mice induced by cyclophosphamide in vivo. The results indicated SP0.1-1 strengthened the immune functions via promoting the proliferation of RAW264.7 cells and phagocytic activity, along with stimulating the release of NO, ROS and cytokines including TNF-α, IL-6, IL-1β and IFN-γ. Western blot and molecular docking analysis demonstrated that SP0.1-1 attached to the prime receptors TLR2 and TLR4 in RAW264.7 cells, and triggered the activation of MyD88-mediated MAPK and NF-κB signaling pathways, thereby exerting the immune response in RAW264.7 cells. However, the intervention of specific inhibitors against TLR2, TLR4, JNK, ERK, p38 and NF-κB blocked the TLR-mediated MAPK and NF-κB signaling pathways and downregulated the levels of NO and the aforementioned cytokines, thus suppressing the activation of macrophages. Therefore, it can be speculated that SP0.1-1 activated the macrophages principally via the TLR2/4-MyD88-mediated MAPK and NF-κB signaling pathways. Additionally, SP0.1-1 could protect against the cyclophosphamide-induced immunosuppression in mice, manifested by the improvement of body weight, immune organ indices, phagocytic index, and the relievement of spleen damage, along with the enhancement of cytokines TNF-α, IL-6, IFN-γ and immunoglobulin IgG and IgM. These findings will shed light on the molecular mechanism of SP0.1-1 on the immunoregulatory effect, and lay the foundation for exploiting a potential immunostimulatory agent of SP0.1-1.

The Role and Mechanism of Deubiquitinase USP7 in Tumor-Associated Inflammation

Deubiquitinating enzymes are a class of proteases that remove ubiquitin tags from proteins, thereby controlling protein stability and function. Tumor inflammation arises from interactions between tumor cells and their microenvironment, which trigger an inflammatory response. The deubiquitinating enzyme USP7 plays a central role in this process. Research suggests that USP7 may modulate various signaling pathways related to inflammatory responses through its deubiquitinating activity, thereby influencing tumor development and progression, including regulating T cell immune activity, improving macrophage anti-tumor activity, and regulating NF-κB signal pathways. Overall, describing the role and mechanism of USP7 in the tumor inflammatory response is of great importance for elucidating the regulatory mechanism of tumor inflammation and developing new therapeutic strategies. This article mainly reviews the structure, function, role, and mechanism of USP7 in the tumor inflammation response.

USP7-stabilised HIPK2 promotes high glucose-induced endothelial cell dysfunctions to accelerate diabetic foot ulcers

Background: This study aimed to explore the molecular mechanism of homeodomain-interacting protein kinase 2 (HIPK2) in diabetic foot ulcers (DFU).

Methods: High glucose (HG)-induced human umbilical vein endothelial cells (HUVECs) were used to construct DFU cell models. Cell functions were determined using CCK8 assay, EdU assay, flow cytometry, transwell assay, wound healing assay and tube formation assay. Quantitative real-time PCR and western blot were applied to measure the gene expression.

Results: HG treatment suppressed HUVECs proliferation, invasion, migration, and angiogenesis, while enhanced apoptosis. HIPK2 was overexpressed in DFU patients, and its knockdown alleviated HG-induced HUVECs dysfunctions. USP7 stabilised HIPK2 protein by reducing its ubiquitination. USP7 overexpression promoted HG-induced HUVECs dysfunctions, and HIPK2 upregulation also reversed the regulation of USP7 knockdown on HG-induced HUVECs dysfunctions. USP7/HIPK2 axis inhibited the activity of PI3K/AKT pathway.

Conclusion: Our study revealed that USP7-stabilised HIPK2 contributed to HG-induced HUVECs dysfunctions, thus accelerating DFU process.

Administration of USP7 inhibitor p22077 alleviates Angiotensin II (Ang II)-induced atrial fibrillation in Mice

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an important contributor to mortality and morbidity. Ubquitin-specific protease 7 (USP7), one of the most abundant ubiquitin-specific proteases (USP), participated in many cellular events, such as cell proliferation, apoptosis, and tumourigenesis. However, its role in AF remains unknown. Here, the mice were treated with Ang II infusion to induce the AF model. Echocardiography was used to measure the atrial diameter. Electrical stimulation was programmed to measure the induction and duration of AF. The changes in atrial remodeling were measured using routine histologic analysis. Here, a significant increase in USP7 expression was observed in Ang II-stimulated atrial cardiomyocytes and atrial tissues, as well as in atrial tissues from patients with AF. The administration of p22077, the inhibitor of USP7, attenuated Ang II-induced inducibility and duration of AF, atrial dilatation, connexin dysfunction, atrial fibrosis, atrial inflammation, and atrial oxidase stress, and then inhibited the progression of AF. Mechanistically, the administration of p22077 alleviated Ang II-induced activation of TGF-β/Smad2, NF-κB/NLRP3, NADPH oxidases (NOX2 and NOX4) signals, the up-regulation of CX43, ox-CaMKII, CaMKII, Kir2.1, and down-regulation of SERCA2a. Together, this study, for the first time, suggests that USP7 is a critical driver of AF and revealing USP7 may present a new target for atrial fibrillation therapeutic strategies.

Chicken adaptive response to nutrient density: immune function change revealed by transcriptomic analysis of spleen

Feed accounts for the largest portion (65-70%) of poultry production costs. The feed formulation is generally improved to efficiently meet the nutritional needs of chickens by reducing the proportion of crude protein (CP) and metabolizable energy (ME) levels in the diet. Although many studies have investigated the production performance during dietary restriction, there is a lack of research on the mechanisms by which immune cell function is altered. This study examined the effects of ME and CP restriction in the chicken diet on serum immunoglobulins and expression of immune function genes in spleen. Changes in serum immunoglobulins and immune-related gene expression were analyzed in 216 YS-909 broilers fed with 9 different dietary treatments, including experimental treatment diets containing low, standard, and high levels of ME or CP in the diet. At 42 days of age, serum immunoglobulins and expression of spleen immune genes in 6 female chickens selected randomly from each dietary treatment (3×3 factorial arrangement) group were measured by enzyme-linked immunosorbent assay (ELISA) and transcriptomic analysis using RNA sequencing, respectively. The results showed that the IgM level in the low ME group chickens was significantly (p < 0.05) lower than that in other groups. In addition, immune-related genes, such as MX1, USP18, TLR4, IFNG and IL18 were significantly upregulated when the dietary nutrient density was reduced, which may put the body in an inflammatory state. This study provided general information on the molecular mechanism of the spleen immune response to variable nutrient density.