Methionine enkephalin inhibits colorectal cancer by remodeling the immune status of the tumor microenvironment.

There is evidence that methionine enkephalin (MENK), an opioid peptide, promotes anti-tumor immune responses. In this study, the effect of MENK on colorectal cancer (CRC) and its mechanisms of action were examined in vivo. The intraperitoneal administration of 20 mg/kg MENK effectively inhibited MC38 subcutaneous colorectal tumor growth in mice. MENK inhibited tumor progression by increasing the immunogenicity and recognition of MC38 cells. MENK down-regulated the oncogene Kras and anti-apoptotic Bclxl and Bcl2, suppressed Il1b, Il6, iNOS, and Arg1 (encoding inflammatory cytokines), and increased Il17a and Il10 levels. MENK promoted a tumor suppressive state by decreasing the immune checkpoints Pd-1, Pd-l1, Lag3, Flgl1, and 2b4 in CRC. MENK also altered the immune status of the tumor immune microenvironment (TIME). It increased the infiltration of M1-type macrophages, CD8+T cells, and CD4+T cells and decreased the proportions of G-MDSCs, M-MDSCs, and M2-type macrophages. MENK accelerated CD4+TEM and CD8+TEM cell activation in the TIME and up-regulated IFN-γ, TNF-α, and IL-17A in CD4+T cells and Granzyme B in CD8+T cells. In addition, analyses of PD-1 and PD-L1 expression indicated that MENK promoted the anti-tumor immune response mediated by effector T cells. Finally, OGFr was up-regulated at the protein and mRNA levels by MENK, and the inhibitory effects of MENK on tumor growth were blocked by NTX, a specific blocker of OGFr. These finding indicate that MENK remodels the TIME in CRC to inhibit tumor progression by binding to OGFr. MENK is a potential therapeutic agent for CRC, especially for improving the efficacy of immunotherapy.

Oral S2-Ag85 DNA Vaccine Activated Intestinal Cell dsDNA and RNA Sensors to Promote the Presentation of Intestinal Antigen.

Objective: To explore the molecular mechanism by which oral S2-Ag85DNA vaccines present intestinal antigens. The oral S2-Ag85 vaccine has been shown to protect the human body and effectively improve the titration of the vaccine by acting on intestinal mucosa cells and enhancing their immunogenicity. Method: Mice were immunized with the recombinant S2-Ag85 vaccine, and antibody secretion was then detected in the intestinal tissue. The molecular mechanisms of in vitro detection sensor molecules RIG-1, Pol III, and related conductor transductor molecules DAI, STING, AIM2, IRF3, and IRF7 were determined by separating intestinal IEC, DC, and IELC cells. Results: The S2-Ag85A vaccine was effective in activating dsDNA and RNA transduction pathways in intestinal cells and improving intestinal antigen presentation in mice.

Combined nucleic acid assays for diagnosis of A19 vaccine-caused human brucellosis.

Brucellosis is a common zoonotic disease caused by Brucella and is an epidemic worldwide. Currently, the most effective way to prevent and control the disease in animals is to use live, attenuated vaccines A19 strain. In China, the live attenuated Brucella abortus vaccine is widely used in animal immunization. To detect and confirm which vaccine strain caused the infection, we developed a new method to distinguish A19 strain from non-A19 strains. By comparing the genomic sequences of A19 and wild strain 2,308, we identified signature sequences that are unique to A19. A PCR assay for specific A19 identification was developed based on the genetic marker ABC transporter permease gene. Samples from the outbreak patients were then analysed using the universal quantitative PCR and A19-specific PCR assay, and the A19 strain was successfully identified in them, providing pathogenic evidence of the vaccine-derived infection outbreak. This combined A19-specific differential diagnosis method can provide a means to distinguish between animal vaccine immunization, natural infection and human infection by the vaccine strain. This strategy also has applications in diagnosis, epidemiology and surveillance of A19-related immunizations or infections.