Treponema pallidum lipoprotein Tp0768 promotes the migration and adhesion of THP-1 cells to vascular endothelial cells through stress of the endoplasmic reticulum and the NF-κB/HIF-1α pathway.

Endothelial cell injury is a key factor in the spread of infection and pathogenicity of Treponema pallidum. The migration and adhesion reaction mediated by T. pallidum lipoprotein plays an important role. This study aimed to systematically explore the migration and adhesion effect of T. pallidum lipoprotein Tp0768 and its molecular mechanism. Stimulating vascular endothelial cells with Tp0768 increased the expression of ICAM-1, MCP-1, and IL-8. Moreover, it promoted the migration and adhesion of THP-1 cells to vascular endothelial cells. Our results revealed that Tp0768 promoted the THP-1 cells migrating and adhering to vascular endothelial cells by the PERK and IRE-1α pathways of endoplasmic reticulum (ER) stress. We further demonstrated that the inhibition of the NF-κB pathway and the downregulation of hypoxia-inducible factor 1 alpha (HIF-1α) reduced the mRNA levels of ICAM-1, MCP-1, and IL-8 induced by Tp0768. Also, the adhesion rate of THP-1 cells to endothelial cells decreased. After inhibiting ER stress, NF-κB p65 nuclear translocation was weakened, and the mRNA level of HIF-1α was also significantly downregulated. Our results indicated that T. pallidum lipoprotein Tp0768 promoted the migration and adhesion of THP-1 cells to vascular endothelial cells through ER stress and NF-κB/HIF-1α pathway.

Investigation of the immune escape mechanism of Treponema pallidum.

BACKGROUND: Syphilis is a chronic sexually transmitted disease caused by Treponema pallidum subspecies pallidum (T. pallidum), which is a public health problem that seriously affects human health worldwide. T. pallidum is characterized by early transmission and immune escape and is therefore termed an "invisible pathogen". METHODS: This review systematically summarizes the host's innate and adaptive immune responses to T. pallidum infection as well as the escape mechanisms of T. pallidum. PURPOSE: To lay the foundation for assessing the pathogenic mechanism and the systematic prevention and treatment of syphilis. CONCLUSION: The immune escape mechanism of T. pallidum plays an important role in its survival. Exploring the occurrence and development of these mechanisms has laid the foundation for the development of syphilis vaccine.

Recombinant Treponema pallidum protein Tp0768 promotes proinflammatory cytokine secretion of macrophages through ER stress and ROS/NF-κB pathway.

In response to danger signals, macrophages rapidly produce many inflammatory cytokines that trigger the cascade release of inflammatory mediators, leading to tissue damage, which is an important cause of clinical manifestations of syphilis at all stages. However, we still know very little about the specific mechanism of this process. Tp0768 is an infection-stage-dependent antigen that plays an important role in the infection of Treponema pallidum. In this study, we demonstrated that Tp0768 stimulation of macrophages can cause IL-1ß, IL-6, and IL-8 mRNA expression levels to increase in a dose- and time-dependent manner. Further research showed that Tp0768 activated ER stress and the ROS/NF-κB pathway in macrophages. Inhibition of ER stress and the ROS/NF-κB pathway inhibited the expression of IL-1ß, IL-6, and IL-8 induced by Tp0768. In addition, pretreatment with a PERK pathway inhibitor significantly reduced the expression of the NF-κB and JNK pathways, while also downregulating the expression of IL-1ß, IL-6, and IL-8. Tp0768 stimulation can activate IRE1α/XBP-1 signaling and participate in the induction of inflammatory cytokines through the JNK pathway. These findings indicate that Tp0768 promotes the secretion of proinflammatory cytokines IL-1ß, IL-6, and IL-8 by macrophages through ER stress and the ROS/NF-κB pathway, which are also involved in the activation of the NF-κB and JNK pathways that are induced by the PERK pathway and activation of IRE1α/XBP-1 signaling. KEY POINTS: • This study found for the first time that the recombinant Treponema pallidum protein Tp0768 promotes the production of IL-1ß, IL-6, and IL-8 by macrophages through ER stress. • Recombinant Treponema pallidum protein Tp0768 regulates the ROS/NF-κB pathway through ER stress. • ER stress-related pathway PERK induces the expression of IL-1ß, IL-6, and IL-8 by activating the NF-κB pathway and the JNK pathway. • IRE1α can induce the splicing of XBP-1mRNA and activate the JNK pathway.

[Optimization of tolerogenic dendritic cell preparation technique in rats with collagen-induced arthritis].

Objective To yield high-quality tolerogenic dendritic cells (TolDCs) for therapeutic intervention by a refined technique of TolDC preparation from the spleen of modified collagen-induced arthritis (CIA) rats. Methods The refinements took place amid monocellular cell isolation process, including both the preparation of single cell suspension and the adjustment of incubation time after plate seeding of mononuclear cells. TolDCs were induced by administration of NF-κB oligonucleotide (ODN) decoy at the initiation of cell culture. Cell morphology was examined under a microscope and cell viability was revealed by trypan blue staining. Expression of classical cell identity and activation makers, CD103 (OX62), CD80 and CD86 was determined by flow cytometry; meanwhile, DC-stimulated lymphocyte proliferation was measured by MTT assay following mixed lymphocyte reaction (MLR). Results With the established approach, the viability ratio of resulting cells reached over 90% and the proportion of OX62 positive ones was above 87.4%, which altogether confirmed their ideal DC phenotype. Functionally, the tolerogenic nature of the NF-κB ODN-treated DCs was further unveiled by the low expression of costimulatory molecules (CD80 and CD86) and the abrogated capacity of lymphocyte stimulation effect. Conclusion Compared with TolDCs generated by conventional protocol, CIA rat spleen-derived TolDCs isolated by the optimized splenic mononuclear cell preparation procedure and induced by NF-κB ODN decoy show the higher regulatory activity, higher phenotypic stability, higher purity and tolerogenic properties.

Amelioration of collagen-induced arthritis using antigen-loaded dendritic cells modified with NF-κB decoy oligodeoxynucleotides.

Dendritic cells (DCs) play an important role in the initiation of autoimmunity in rheumatoid arthritis (RA); therefore, the use of DCs needs to be explored to develop new therapeutic approaches for RA. Here, we investigated the therapeutic effect of bovine type II collagen (BIIC)-loaded DCs modified with NF-κB decoy oligodeoxynucleotides (ODNs) on collagen-induced arthritis (CIA) in rats and explored the underlying mechanisms. DCs treated with BIIC and NF-κB decoy ODNs exhibited features of immature DCs with low levels of costimulatory molecule (CD80 and CD86) expression. The development of arthritis in rats with CIA injected with BIIC + NF-κB decoy ODN-propagated DCs (BIIC-decoy DCs) was significantly ameliorated compared to that in rats injected with BIIC-propagated DCs or phosphate-buffered saline. We also found that the BIIC-decoy DCs exerted antiarthritis effects by inhibiting self-lymphocyte proliferative response and suppressing IFN-γ and anti-BIIC antibody production and inducing IL-10 antibody production. Additionally, antihuman serum antibodies were successfully produced in the rats treated with BIIC-decoy DCs but not in those treated with NF-κB decoy ODN-propagated DCs; moreover, the BIIC-decoy DCs did not affect immune function in the normal rats. These findings suggested that NF-κB decoy ODN-modified DCs loaded with a specific antigen might offer a practical method for the treatment of human RA.