Relevance in biology and mechanisms of immune and treatment evasion of Treponema pallidum

Persistence of Treponema pallidum IgM antibodies in serum: What is their meaning?

We studied the detection of Treponema pallidum (TP)-IgM antibodies in the serum of 69 patients treated for syphilis. The persistence of TP-IgM antibodies in serum for more than 3 years was the only clue to suspect an active infection and, therefore, to investigate a central nervous system involvement.

Insight into the invasion process and immune-protective evaluation of Tp0971, a membrane lipoprotein from Treponema pallidum

IMPORTANCE

The past two decades have seen a worldwide resurgence in infections caused by Treponema pallidum (T. pallidum) subsp. pallidum, the syphilis spirochete. The well-recognized capacity of the syphilis spirochete for early dissemination and immune evasion has earned it the designation "the stealth pathogen." There are many hurdles to studying syphilis pathogenesis, most notably the difficulty of culturing and genetically manipulating T. pallidum, as well as the absence of an effective vaccine for T. pallidum prevention. T. pallidum infection in humans is a complex and lengthy process. In this study, we investigated the invasion process and the function of the infection-dependent antigen Tp0971 as an immunogen to inhibit the dissemination of T. pallidum in an animal infection model. This enables a better understanding of the specific pathogenic mechanism of this pathogen, syphilis pathogenesis, and vaccine research.

Exposure to Treponema pallidum Infection among Adolescent and Young Adult Women in Roraima, Amazon Region of Brazil

BACKGROUND

Syphilis is a chronic infectious disease, and its prevalence has been described since the 15th century. Because of the high prevalence of this infection in Brazil, this study aimed to evaluate the prevalence of syphilis and its associated factors among adolescent and young women living in the city of Boa Vista, Roraima, Brazil.

METHODS

The present study was cross-sectional, descriptive, analytical and quantitative. It involved 200 young and adolescent women. Laboratory tests were performed to diagnose syphilis, and a sociodemographic and epidemiological questionnaire was employed.

RESULTS

In the studied sample, 10 women had a positive result for syphilis, characterizing a prevalence of 5% for infection with Treponema pallidum. There was a statistically significant association between a monthly family income of less than 1 minimum wage and syphilis (p = 0.0449) and between illicit drug use and syphilis (p = 0.0234).

CONCLUSIONS

These results indicate the need for public health interventions, action plans, and the implementation of risk reduction strategies focused on this population.

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.

Effects of HBeAg Status on cellular immune function of patients with Hepatitis B virus/Treponema Pallidum Co-infectio

Objectives

This study was aimed at exploring the effects of hepatitis B envelope antigen (HBeAg) status on the cellular immune function of patients with hepatitis B virus/treponema pallidum (HBV/TP) co-infection.

Methods

The clinical data of 79 patients with HBV/TP co-infection admitted to our hospital from January 2019 to January 2020 were retrospectively analyzed. These patients were divided into two groups according to the different HBeAg statuses before the treatment: 41 HBeAg+ patients were included in the HBeAg+ group, while 38 HBeAg- patients were included in the HBeAg- group. The levels of HBV-DNA, T lymphocyte subsets represented by NK cells and cytokines associated with T cells in the peripheral blood (PB) of the patients were compared between both groups.

Results

The HBV-DNA levels in the HBeAg+ group were significantly higher than those in the HBeAg- group (P < 0.05). The levels of CD3⁺, CD4⁺, CD4⁺/CD8⁺ and natural killer (NK) cells in the HBeAg+ group were higher than those in the HBeAg- group (P < 0.05), while the levels of CD8⁺ cells were lower than those in the HBeAg- group (P < 0.05). Moreover, the levels of interferon-γ (IFN-γ), tumor necrosis factor (TNF-α), interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-17 (IL-17), transforming growth factor-β (TGF-β) in the HBeAg+ group were all significantly higher than those in the HBeAg- group (P < 0.05), but there was no significant difference in the levels of interleukin-4 (IL-4) and interleukin-10 (IL-10) between the HBeAg+ group and the HBeAg- group (P > 0.05).

Conclusion

HBeAg+ can increase the HBV-DNA levels in the PB of patients with HBV/TP co-infection, in turn triggering the body to initiate cellular immunity, increasing the levels of T lymphocyte subsets, and promote the secretion of cytokines.

Syphilitic infection impairs immunity by inducing both apoptosis and pyroptosis of CD4+ and CD8+ T lymphocytes

Syphilis is an important health problem worldwide; however, few studies have probed the impact of syphilitic infection on T cell turnover. The mechanisms behind the frequency of T cell subset changes and the associations between these subsets during syphilitic infection remain unclear. Herein, we used a cell-staining method and flow cytometry to explore changes in T cell subpopulations and potential contribution of apoptosis and pyroptosis that triggered therein. We investigated caspase-1-mediated pyroptosis and caspase-3-mediated apoptosis of CD4⁺ and CD8⁺ T cells, the major effector lymphocytes with pivotal roles in the pathogenesis of infectious diseases. We found that the levels of caspase-1 and caspase-3 increased in both the circulation and intracellularly in CD4⁺ and CD8⁺ T cells. Caspase-1 showed a continual increase from early latent stage infection through to phase 2 disease, whereas caspase-3 increased through to phase 1 disease but declined during phase 2. In addition, serum levels and intracellular expression of caspase-1 and caspase-3 were positively correlated. Overall, this study increases our understanding of how syphilitic infection influences CD4⁺ and CD8⁺ T-cell turnover, which may help with designing novel and effective strategies to control syphilis infection and prevent its transmission.