E3 ubiquitin ligase TRIM31 alleviates dopaminergic neurodegeneration by promoting proteasomal degradation of VDAC1 in Parkinson's Disease model.

Mitochondrial dysfunction plays a pivotal role in the pathogenesis of Parkinson's disease (PD). As a mitochondrial governor, voltage-dependent anion channel 1 (VDAC1) is critical for cell survival and death signals and implicated in neurodegenerative diseases. However, the mechanisms of VDAC1 regulation are poorly understood and the role of tripartite motif-containing protein 31 (TRIM31), an E3 ubiquitin ligase which is enriched in mitochondria, in PD remains unclear. In this study, we found that TRIM31-/- mice developed age associated motor defects and dopaminergic (DA) neurodegeneration spontaneously. In addition, TRIM31 was markedly reduced both in nigrostriatal region of PD mice induced by MPTP and in SH-SY5Y cells stimulated by MPP+. TRIM31 deficiency significantly aggravated DA neurotoxicity induced by MPTP. Mechanistically, TRIM31 interacted with VDAC1 and catalyzed the K48-linked polyubiquitination to degrade it through its E3 ubiquitin ligase activity. In conclusion, we demonstrated for the first time that TRIM31 served as an important regulator in DA neuronal homeostasis by facilitating VDAC1 degradation through the ubiquitin-proteasome pathway. Our study identified TRIM31 as a novel potential therapeutic target and pharmaceutical intervention to the interaction between TRIM31 and VDAC1 may provide a promising strategy for PD.

OTUD1 ameliorates cerebral ischemic injury through inhibiting inflammation by disrupting K63-linked deubiquitination of RIP2.

BACKGROUND: Inflammatory response triggered by innate immunity plays a pivotal element in the progress of ischemic stroke. Receptor-interacting kinase 2 (RIP2) is implicated in maintaining immunity homeostasis and regulating inflammatory response. However, the underlying mechanism of RIP2 in ischemic stroke is still not well understood. Hence, the study investigated the role and the ubiquitination regulatory mechanism of RIP2 in ischemic stroke. METHODS: Focal cerebral ischemia was introduced by middle cerebral artery occlusion (MCAO) in wild-type (WT) and OTUD1-deficient (OTUD1-/-) mice, oxygen glucose deprivation and reoxygenation (OGD/R) models in BV2 cells and primary cultured astrocytes were performed for monitoring of experimental stroke. GSK2983559 (GSK559), a RIP2 inhibitor was intraventricularly administered 30 min before MCAO. Mice brain tissues were collected for TTC staining and histopathology. Protein expression of RIP2, OTUD1, p-NF-κB-p65 and IκBα was determined by western blot. Localization of RIP2 and OTUD1 was examined by immunofluorescence. The change of IL-1ß, IL-6 and TNF-α was detected by ELISA assay and quantitative real-time polymerase chain reaction. Immunoprecipitation and confocal microscopy were used to study the interaction of RIP2 and OTUD1. The activity of NF-κB was examined by dual-luciferase assay. RESULTS: Our results showed upregulated protein levels of RIP2 and OTUD1 in microglia and astrocytes in mice subjected to focal cerebral ischemia. Inhibition of RIP2 by GSK559 ameliorated the cerebral ischemic outcome by repressing the NF-κB activity and the inflammatory response. Mechanistically, OTUD1 interacted with RIP2 and sequentially removed the K63-linked polyubiquitin chains of RIP2, thereby inhibiting NF-κB activation. Furthermore, OTUD1 deficiency exacerbated cerebral ischemic injury in response to inflammation induced by RIP2 ubiquitination. CONCLUSIONS: These findings suggested that RIP2 mediated cerebral ischemic lesion via stimulating inflammatory response, and OTUD1 ameliorated brain injury after ischemia through inhibiting RIP2-induced NF-κB activation by specifically cleaving K63-linked ubiquitination of RIP2.

Identification of a small-molecule Tim-3 inhibitor to potentiate T cell-mediated antitumor immunotherapy in preclinical mouse models.

T cell immunoglobulin and mucin-containing molecule 3 (Tim-3), expressed in dysfunctional and exhausted T cells, has been widely acknowledged as a promising immune checkpoint target for tumor immunotherapy. Here, using a strategy combining virtual and functional screening, we identified a compound named ML-T7 that targets the FG-CC' cleft of Tim-3, a highly conserved binding site of phosphatidylserine (PtdSer) and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1). ML-T7 enhanced the survival and antitumor activity of primary CD8+ cytotoxic T lymphocytes (CTLs) and human chimeric antigen receptor (CAR) T cells and reduced their exhaustion in vitro and in vivo. In addition, ML-T7 promoted NK cells' killing activity and DC antigen-presenting capacity, consistent with the reported activity of Tim-3. ML-T7 strengthened DCs' functions through both Tim-3 and Tim-4, which is consistent with the fact that Tim-4 contains a similar FG-CC' loop. Intraperitoneal dosing of ML-T7 showed comparable tumor inhibitory effects to the Tim-3 blocking antibody. ML-T7 reduced syngeneic tumor progression in both wild-type and Tim-3 humanized mice and alleviated the immunosuppressive microenvironment. Furthermore, combined ML-T7 and anti-PD-1 therapy had greater therapeutic efficacy than monotherapy in mice, supporting further development of ML-T7 for tumor immunotherapy. Our study demonstrates a potential small molecule for selectively blocking Tim-3 and warrants further study.

Generation of a uniform thymic malignant lymphoma model with C57BL/6J p53 gene deficient mice.

Lymphoma is the third most common cancer diagnosed in children, and T-cell lymphoma has the worst prognosis based on clinical observations. To date, a lymphoma model with uniform penetrance has not yet been developed. In this study, we generated a p53 deficient mouse model by targeting embryonic stem cells derived from a C57BL/6J mouse strain. Homozygous p53 deficient mice exhibited a higher rate of spontaneous tumorigenesis, with a high spontaneous occurrence rate (93.3%) of malignant lymphoma. Because tumor models with high phenotypic consistency are currently needed, we generated a lymphoma model by a single intraperitoneal injection of 37.5 or 75 mg/kg N-methyl-N-nitrosourea to p53 deficient mice. Lymphoma and retinal degeneration occurred in 100% of p53 +/- mice administered with higher concentrations of N-methyl-N-nitrosourea, a much greater response than those of previously reported models. The main anatomic sites of lymphoma were the thymus, spleen, bone marrow, and lymph nodes. Both induced and spontaneous lymphomas in the thymus and spleen stained positive for CD3 antigen, and flow cytometry detected positive CD4 and/or CD8 cells. Based on our observations and previous data, we hypothesize that mice with a B6 background are prone to lymphomagenesis.

5-HMF induces anaphylactoid reactions in vivo and in vitro.

AIM: Excessive exposure to 5-hydroxymethylfurfural (5-HMF), which is a common impurity in various sugar-containing products, induces serious side effects. Our previous study revealed that 5-HMF exerted immune sensitizing potential when injected into rodents. In this study, we explored 5-HMF mediated anaphylactoid reactions and its underlying molecular mechanisms. METHODS: We investigated anaphylactoid reactions in Brown Norway (BN) rats and Institute of Cancer Research (ICR) mice to identify 5-HMF mediated in vivo anaphylactoid reactions. RBL-2H3 and P815 cell degranulation models were also established, and degranulation, enzyme-linked immunosorbent, filamentous actin (F-actin) microfilament staining, and western blot assays were performed in these cells. RESULTS: We showed that 5-HMF induced anaphylactoid reactions by increasing blood vessel permeability in mice, and significantly elevating histamine (His) and glutathione peroxidase-1 (Gpx-1) levels in rat serum. Moreover, after incubation with 5-HMF, ß-hexosaminidase (ß-Hex), His, IL-4 and IL-6 levels were all significantly increased, thereby inducing cellular degranulation in RBL-2H3 and P815 cells. Finally, 5-HMF also upregulated Lyn, Syk, p38 and JNK protein phosphorylation levels. CONCLUSIONS: Our findings suggest that 5-HMF induces anaphylactoid reactions both in vivo and in vitro, therefore 5-HMF limits in sugar-containing products should receive more regulatory attention.

Breast cancer cells promote CD169+ macrophage-associated immunosuppression through JAK2-mediated PD-L1 upregulation on macrophages.

Macrophages are recognized as one of the major cell types in tumor microenvironment, and macrophage infiltration has been predominantly associated with poor prognosis among patients with breast cancer. Using the murine models of triple-negative breast cancer in CD169-DTR mice, we found that CD169+ macrophages support tumor growth and metastasis. CD169+ macrophage depletion resulted in increased accumulation of CD8+ T cells within tumor, and produced significant expansion of CD8+ T cells in circulation and spleen. In addition, we observed that CD169+ macrophage depletion alleviated tumor-induced splenomegaly in mice, but had no improvement in bone loss and repression of bone marrow erythropoiesis in tumor-bearing mice. Cancer cells and tumor associated macrophages exploit the upregulation of the immunosuppressive protein PD-L1 to subvert T cell-mediated immune surveillance. Within the tumor microenvironment, our understanding of the regulation of PD-L1 protein expression is limited. We showed that there was a 5-fold higher relative expression of PD-L1 on macrophages as compared with 4T1 tumor cells; coculture of macrophages with 4T1 cells augmented PD-L1 levels on macrophages, but did not upregulate the expression of PD-L1 on 4T1 cells. JAK2/STAT3 signaling pathway was activated in macrophages after coculture, and we further identified the JAK2 as a critical regulator of PD-L1 expression in macrophages during coculture with 4T1 cells. Collectively, our data reveal that breast cancer cells and CD169+ macrophages exhibit bidirectional interactions that play a critical role in tumor progression, and inhibition of JAK2 signaling pathway in CD169+ macrophages may be potential strategy to block tumor microenvironment-derived immune escape.

Neuroprotective Effects and Mechanisms of Zhenlong Xingnao Capsule in In Vivo and In Vitro Models of Hypoxia.

Zhenlong Xingnao Capsule (ZXC) is a Tibetan medicine used to treat ischemic stroke. In this study, we determined the in vitro and in vivo effects of ZXC on reactive oxygen species (ROS) in a mouse BV-2 microglial cell hypoxia-reoxygenation and rat middle cerebral artery occlusion infarction models. We aimed to clarify the role of ZXC in cerebral ischemia protection; reveal amino acid neurotransmitter changes in the frontal cortex after drug intervention; determine mRNA and protein expression changes in Bcl-2, Bax, caspase-3, P38, and nuclear factor (NF)-кB in the frontal cortex and changes in antioxidant indices in the brain; and elucidate the mechanisms underlying ZXC action. After hypoxia-reoxygenation, ROS levels were significantly increased in BV-2 cells, and their levels decreased after treatment with ZXC. ZXC had protective effects on ischemic/anoxic injury in vitro and in vivo by downregulating the expressions of caspase-3 and NF-кB mRNA during ischemia and reperfusion and that of p38 and caspase-3 during acute ischemia and reperfusion as well as the steady-state levels of excitatory amino acids/inhibitory amino acids and by improving the total antioxidant capacity and total superoxide dismutase activities during ischemia. These findings provide new molecular evidence for the mechanisms underlying ZXC action.

In silico and in vitro genotoxicity evaluation of descarboxyl levofloxacin, an impurity in levofloxacin.

It is important to establish the safety of impurities in drug substances or drug products. The assessment of genotoxicity of impurities and the determination of acceptable limits for genotoxic impurities was addressed in some recent guidances as a difficult issue. Descarboxyl levofloxacin is an impurity isolated from levofloxacin, which may impose a risk without associated benefit. However, there is insufficient toxic information about descarboxyl levofloxacin. This study investigated the genotoxicity of this impurity by in silico and in vitro methods. We used Derek, a commercial structure-activity relationship software package, as an in silico tool. The results showed that there was a structural alert (quinoline) in this impurity. Then, the in vitro genotoxicity of descarboxyl levofloxacin was investigated by a modified Ames test and by a chromosomal aberration test, using Chinese hamster lung (CHL) cells. Both assays were conducted in the presence or absence of S-9 mix. The results showed that the test impurity was not mutagenic in the Ames test (31.25-500 µg/plate). Whereas there was a statistically significant increase in the number of metaphase CHL cells with structural aberrations at the concentration of 1 mg/mL with S-9 mix, the aberrations rate was 7.5%. It did not significantly increase the number of structural aberration in CHL cells in the presence (at 250 and 500 µg/mL) or absence of S-9 mix. Based on these assays, descarboxyl levofloxacin could be controlled as a nongenotoxic impurity.

In silico and in vitro genotoxicity evaluation of levofloxacin n-oxide, an impurity in levofloxacin.

Impurities in drug substances and drug products generally do not have beneficial effects and may impose a risk without associated benefit. Levofloxacin n-oxide is an impurity isolated from levofloxacin. However there is insufficient toxic information about levofloxacin n-oxide. This study investigates the genotoxicity of this impurity by in silico and in vitro methods. We used Derek, a commercial structure-activity relationship software package as an in silico tool. The results showed that there was a structural alert (quinolone-3-carboxylic acid or naphthyridine analogue) in this impurity. Then the mouse lymphoma assay (MLA) and chromosome aberration assay in Chinese hamster lung (CHL) cells were conducted in vitro. Both assays were conducted in the presence or absence of S-9 mix. The test impurity was not mutagenic in the test of MLA. While there was a statistically significant increase in the number of metaphase CHL cells with structural aberrations at the concentration of 1 mg/mL with S-9 mix, and the aberrations rate is 6.5%. It did not significantly increase the number of structural aberration in CHL cells in the presence (at other two doses) or absence of S-9 mix. Based on these assays, levofloxacin n-oxide could be controlled as a non-genotoxic impurity despite the DEREK alert for quinolone-3-carboxylic acid or naphthyridine analogue.

Development of patch and spray formulations for enhancing topical delivery of sinomenine hydrochloride.

The purpose of this work was to investigate feasibility of a promising topical drug delivery system (TDDS) for sinomenine hydrochloride (SMH), extracted from the Chinese medicinal plant sinomenine acutum and currently used for the treatment of rheumatoid arthritis. It was found that SMH was a weak base (pK(a), 7.98 +/- 0.04) with pH-dependent solubility and partition coefficient. The result of in vitro permeation studies demonstrated that the permeation enhancer azone was the most effective. In contrast, spray had higher accumulative permeated amounts of SMH than patch, but permeated duration of spray was shorter than that of patch. The efficacy on Freund's complete adjuvant-induced arthritis suggested that there was near arthritis index for SMH spray with medium dose (i.e., 15 mg/rat) and oral solution at a dose of 12 mg/rat, indicating that topical SMH delivery system could achieve the similar anti-inflammatory efficacy with oral administration. Pharmacokinetic parameters including C(max) and AUC for both topical preparations were lower than those for oral preparation, which hinted that systemic side effect could be ignored. Therefore, the spray and patch were promising formulations for successful topical delivery of SMH through the skin instead of oral administration with side effects.