Treponema pallidum protein Tp47 induced prostaglandin E2 to inhibit the phagocytosis in human macrophages.

BACKGROUND: During Treponema pallidum (T. pallidum) infection, the host's immune system actively engages in pursuit and elimination of T. pallidum, while T. pallidum skillfully employs various mechanisms to evade immune recognition. Macrophages exhibit incomplete clearance of T. pallidum in vitro and the underlying mechanism of how T. pallidum resists the attack of macrophage remains unclear. OBJECTIVES: To investigate the effect of T. pallidum membrane protein Tp47 on the phagocytosis of macrophages. METHODS: THP-1-derived macrophages were used to investigate the role of Tp47 in the secretion of Prostaglandin E2 (PGE2) in macrophages and the mechanism by which Tp47 induced the production of PGE2, as well as the impact of PGE2 on the macrophage's phagocytosis. RESULTS: Tp47 (1-10 µg/mL) significantly inhibited the phagocytosis of latex beads and T. pallidum in macrophages (p ≤ 0.05). PGE2 production by macrophages could be induced by Tp47, and the phagocytic function of macrophages could be restored using PGE2 antibody. Tp47 produced PGE2 by activating the PERK/NF-κB/COX-2 pathway in macrophages. Inhibitors targeting PERK, NF-κB and COX-2, respectively, reduced the level of PGE2 and restored the phagocytic function of macrophages. CONCLUSION: Tp47-induced PGE2 production via the PERK/NF-κB/COX-2 pathway contributed to macrophage phagocytosis inhibition, which potentially contributes to immune evasion during the T. pallidum infection.

Treponema pallidum-induced prostaglandin E2 secretion in skin fibroblasts leads to neuronal hyperpolarization: A cause of painless ulcers.

BACKGROUND: Primary syphilis is characterized by painless ulcerative lesions in the genitalia, the aetiology of painless remains elusive. OBJECTIVES: To investigate the role of Treponema pallidum in painless ulcer of primary syphilis, and the mechanisms underlying painless ulcers caused by T. pallidum. METHODS: An experimental rabbit model of primary syphilis was established to investigate its effects on peripheral nerve tissues. Human skin fibroblasts were used to examine the role of T. pallidum in modulating neurotransmitters associated with pain and to explore the signalling pathways related to neurotransmitter secretion by T. pallidum in vitro. RESULTS: Treponema pallidum infection did not directly lead to neuronal damage or interfere with the neuronal resting potential. Instead, it facilitated the secretion of prostaglandin E2 (PGE2) through endoplasmic reticulum stress in both rabbit and human skin fibroblasts, and upregulation of PGE2 induced the hyperpolarization of neurones. Moreover, the IRE1α/COX-2 signalling pathway was identified as the underlying mechanism by which T. pallidum induced the production of PGE2 in human skin fibroblasts. CONCLUSION: Treponema pallidum promotes PGE2 secretion in skin fibroblasts, leading to the excitation of neuronal hyperpolarization and potentially contributing to the pathogenesis of painless ulcers in syphilis.

Echinococcus infections in Chinese dogs: a comparison of coproantigen kits.

Coproantigen test kits for Echinococcus spp. worms in dogs, designed for commercial use, were obtained from three different Chinese producers, and were compared with a laboratory kit using reagents from New Zealand. None of the three producers would provide details of their test validation. From a known set of dog faeces obtained at necropsy from infected and uninfected dogs, and from faeces collected from dogs necropsied in the field, results differed between the kits. For field material, the Tiankang kit showed the best specificity but lacked sensitivity. The Combined kit showed best sensitivity but lacked specificity. Results for the Haitai kit were intermediate. With samples from experimentally infected dogs, both the Haitai and Combined kits lacked sensitivity. Kits will need to be validated by the user before they can be relied on to predict progress in Echinococcus spp. control in China or in other countries.

HLA-A, -B and -DRB1 polymorphism in Koreans defined by sequence-based typing of 4128 cord blood units.

Human leucocyte antigen (HLA) alleles and haplotypes differ significantly among different ethnic groups, and high-resolution typing methods allow for the detection of a wider spectrum of HLA variations. In this study, HLA-A, -B and -DRB1 genotypes were analysed in 4128 cord blood units obtained from Korean women using the sequence-based typing method. A total of 44 HLA-A, 67 HLA-B and 48 HLA-DRB1 most probable alleles were identified. Of these, high-frequency alleles found at a frequency of ≥5% were 6 HLA-A (A*02:01, A*02:06, A*11:01, A*24:02, A*31:01, A*33:03), 5 HLA-B (B*15:01, B*44:03, B*51:01, B*54:01, B*58:01) and 7 HLA-DRB1 (DRB1*01:01, DRB1*04:05, DRB1*07:01, DRB1*08:03, DRB1*09:01, DRB1*13:02, DRB1*15:01) alleles. At each locus, A*02, B*15 and DRB1*04 generic groups were most diverse at allelic level, consisting of 8, 11 and 10 different alleles, respectively. Two- and three-locus haplotypes estimated by the maximum likelihood method revealed 73 A-B, 74 B-DRB1 and 42 A-B-DRB1 haplotypes with frequencies of ≥0.3%. A total of 193 A-B-DRB1 haplotypes found at a frequency of ≥0.1% were presented, and the six most common haplotypes were A*33:03-B*44:03-DRB1*13:02 (4.6%), A*33:03-B*58:01-DRB1*13:02 (3.0%), A*24:02-B*07:02-DRB1*01:01 (2.7%), A*33:03-B*44:03-DRB1*07:01 (2.5%), A*30:01-B*13:02-DRB1*07:01 (2.2%) and A*24:02-B*52:01-DRB1*15:02 (2.1%). Compared with previous smaller scale studies, this study further delineated the allelic and haplotypic diversity in Koreans including low-frequency alleles and haplotypes. Information obtained in this study will be useful for the search for unrelated bone marrow donors and for anthropologic and disease association studies.

Tp47-Induced Monocyte-Derived Microvesicles Promote the Adherence of THP-1 Cells to Human Umbilical Vein Endothelial Cells via an ERK1/2-NF-κB Signaling Cascade.

The Treponema pallidum membrane protein Tp47 induces immunocyte adherence to vascular cells and contributes to vascular inflammation. However, it is unclear whether microvesicles are functional inflammatory mediators between vascular cells and immunocytes. Microvesicles that were isolated from Tp47-treated THP-1 cells using differential centrifugation were subjected to adherence assays to determine the adhesion-promoting effect on human umbilical vein endothelial cells (HUVECs). Intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) levels in Tp47-induced microvesicle (Tp47-microvesicle)-treated HUVECs were measured, and the related intracellular signaling pathways of Tp47-microvesicle-induced monocyte adhesion were investigated. Tp47-microvesicles promoted THP-1 cell adhesion to HUVECs (P < 0.01) and upregulated ICAM-1 and VCAM-1 expression in HUVECs (P < 0.001). The adhesion of THP-1 cells to HUVECs was inhibited by anti-ICAM-1 and anti-VCAM-1 neutralizing antibodies. Tp47-microvesicle treatment of HUVECs activated the extracellular signal-regulated kinase 1/2 (ERK1/2) and NF-κB signaling pathways, whereas ERK1/2 and NF-κB inhibition suppressed the expression of ICAM-1 and VCAM-1 and significantly decreased the adhesion of THP-1 cells to HUVECs. IMPORTANCE Tp47-microvesicles promote the adhesion of THP-1 cells to HUVECs through the upregulation of ICAM-1 and VCAM-1 expression, which is mediated by the activation of the ERK1/2 and NF-κB pathways. These findings provide insight into the pathophysiology of syphilitic vascular inflammation.