Flow cytometric analysis of peripheral blood lymphocyte immunophenotypes in persons infected with Treponema pallidum

Immunophenotypic variations in syphilis: insights from Mendelian randomization analysis

Background

Infection with Treponema pallidum instigates complex immune responses. Prior research has suggested that persistent Treponema pallidum infection can manipulate host immune responses and circumvent host defenses. However, the precise role of immune cells in Treponema pallidum infection across different stages remains a contentious issue.

Methods

Utilizing summary data from genome-wide association studies, we employed a two-sample Mendelian randomization method to investigate the association between 731 immunophenotypes and syphilis. Syphilis was categorized into early and late stages in this study to establish a more robust correlation and minimize bias in database sources.

Results

Our findings revealed that 33, 36, and 27 immunophenotypes of peripheral blood were associated with syphilis (regardless of disease stage), early syphilis and late syphilis, respectively. Subsequent analysis demonstrated significant variations between early and late syphilis in terms of immunophenotypes. Specifically, early syphilis showcased activated, secreting, and resting regulatory T cells, whereas late syphilis was characterized by resting Treg cells. More B cells subtypes emerged in late syphilis. Monocytes in early syphilis exhibited an intermediate and non-classical phenotype, transitioning to classical in late syphilis. Early syphilis featured naive T cells, effector memory T cells, and terminally differentiated T cells, while late syphilis predominantly presented terminally differentiated T cells. Immature myeloid-derived suppressor cells were evident in early syphilis, whereas the dendritic cell immunophenotype was exclusive to late syphilis.

Conclusion

Multiple immunophenotypes demonstrated associations with syphilis, showcasing substantial disparities between the early and late stages of the disease. These findings hold promise for informing immunologically oriented treatment strategies, paving the way for more effective and efficient syphilis interventions.

Prevalence of peri-implantitis in a sample of HIV-positive patients

OBJECTIVES

This study aimed to assess the prevalence of peri-implantitis in human immunodeficiency virus (HIV)-positive patients and the presence of a possible correlation between the immunological profile and serological values, of peri-implantitis, and of possible differences between all-on-4 and single crown/bridge prostheses.

SUBJECTS AND METHODS

This retrospective study included 58 adult HIV-positive patients (222 implants) with either all-in-4 prostheses or single crowns/bridges on at least one dental implant loaded for more than a year who were followed for 3 year (mean follow-up). Data pertaining to the probing pocket depth (PPD), bleeding on probing, and immunological and systemic profile were collected.

RESULTS

Patients with single crown/bridge implant rehabilitation showed higher prevalence of peri-implantitis (34%) than patients with all-on-4 rehabilitation (0%) (p = 0.012). Patients with all-on-4 rehabilitation were significantly older than those with single crowns/bridges (p = 0.004). Patients with peri-implantitis had implants for a significantly longer duration than those without (p = 0.001), implying that the probability of peri-implantitis increases as the age of implant increases.

CONCLUSIONS

The prevalence of peri-implantitis was 26% in the HIV-positive patients population. No correlation was found between patients' immunological and serological factors and peri-implantitis. The most important risk factor for peri-implantitis and mucositis was implant age.

HIV-negative Men Who Have Sex with Men have higher CD8+ T-cell Counts and Lower CD4+/CD8+ T-cell Ratios compared to HIV-negative Heterosexual Men

Background

We previously reported T-cell senescence to be similar in people with human immunodeficiency virus (PWH) with suppressed viremia (predominantly men who have sex with men [MSM]) and human immunodeficiency virus (HIV)-negative otherwise comparable controls but greater than in healthy blood donors. This led us to compare CD4⁺ and CD8⁺ T-cell counts and CD4⁺/CD8⁺ ratios between HIV-negative MSM and men who only have sex with women (MSW) and relate observed differences in behavioral factors and infectious exposures, including cytomegalovirus (CMV) infection.

Methods

In 368 HIV-negative MSM and 72 HIV-negative MSW, T lymphocyte phenotyping was performed 3 times biennially. Baseline CMV serology and sexually transmitted infection (STI) incidence and/or STI seroprevalence, sexual, and substance-use behavior data were collected during study visits.

Results

Men who have sex with men, compared with MSW, had higher CD8⁺ counts (551 vs 437 cells/mm³, P < .001), similar CD4⁺ counts (864 vs 880 cells/mm³, P = .5), and lower CD4⁺/CD8⁺ ratios (1.84 vs 2.47, P < .001). Differences were most pronounced for MSM with >10 recent sex partners and partly explained by higher CMV seroprevalence in MSM.

Conclusions

These findings suggest that factors other than HIV may, in both PWH and certain HIV-negative MSM, contribute to a low CD4⁺/CD8⁺ ratio. Whether this, like in PWH, contributes to comorbidity risk in HIV-negative MSM requires further study.

The X chromosome and sex-specific effects in infectious disease susceptibility

The X chromosome and X-linked variants have largely been ignored in genome-wide and candidate association studies of infectious diseases due to the complexity of statistical analysis of the X chromosome. This exclusion is significant, since the X chromosome contains a high density of immune-related genes and regulatory elements that are extensively involved in both the innate and adaptive immune responses. Many diseases present with a clear sex bias, and apart from the influence of sex hormones and socioeconomic and behavioural factors, the X chromosome, X-linked genes and X chromosome inactivation mechanisms contribute to this difference. Females are functional mosaics for X-linked genes due to X chromosome inactivation and this, combined with other X chromosome inactivation mechanisms such as genes that escape silencing and skewed inactivation, could contribute to an immunological advantage for females in many infections. In this review, we discuss the involvement of the X chromosome and X inactivation in immunity and address its role in sexual dimorphism of infectious diseases using tuberculosis susceptibility as an example, in which male sex bias is clear, yet not fully explored.

Sex differences in immune responses to infectious diseases

PURPOSE

The influence of sex hormones is recognized to account for the susceptibility and distinct outcomes of diverse infectious diseases.

METHODS

This review discusses several variables including differences in behavior and exposure to pathogens, genetic, and immunological factors.

CONCLUSION

Understanding sex-based differences in immunity during different infectious diseases is crucial in order to provide optimal disease management for both sexes.

Immune evasion and recognition of the syphilis spirochete in blood and skin of secondary syphilis patients: two immunologically distinct compartments

BACKGROUND

The clinical syndrome associated with secondary syphilis (SS) reflects the propensity of Treponema pallidum (Tp) to escape immune recognition while simultaneously inducing inflammation.

METHODS

To better understand the duality of immune evasion and immune recognition in human syphilis, herein we used a combination of flow cytometry, immunohistochemistry (IHC), and transcriptional profiling to study the immune response in the blood and skin of 27 HIV(-) SS patients in relation to spirochetal burdens. Ex vivo opsonophagocytosis assays using human syphilitic sera (HSS) were performed to model spirochete-monocyte/macrophage interactions in vivo.

RESULTS

Despite the presence of low-level spirochetemia, as well as immunophenotypic changes suggestive of monocyte activation, we did not detect systemic cytokine production. SS subjects had substantial decreases in circulating DCs and in IFNγ-producing and cytotoxic NK-cells, along with an emergent CD56-/CD16+ NK-cell subset in blood. Skin lesions, which had visible Tp by IHC and substantial amounts of Tp-DNA, had large numbers of macrophages (CD68+), a relative increase in CD8+ T-cells over CD4+ T-cells and were enriched for CD56+ NK-cells. Skin lesions contained transcripts for cytokines (IFN-γ, TNF-α), chemokines (CCL2, CXCL10), macrophage and DC activation markers (CD40, CD86), Fc-mediated phagocytosis receptors (FcγRI, FcγR3), IFN-β and effector molecules associated with CD8 and NK-cell cytotoxic responses. While HSS promoted uptake of Tp in conjunction with monocyte activation, most spirochetes were not internalized.

CONCLUSIONS

Our findings support the importance of macrophage driven opsonophagocytosis and cell mediated immunity in treponemal clearance, while suggesting that the balance between phagocytic uptake and evasion is influenced by the relative burdens of bacteria in blood and skin and the presence of Tp subpopulations with differential capacities for binding opsonic antibodies. They also bring to light the extent of the systemic innate and adaptive immunologic abnormalities that define the secondary stage of the disease, which in the skin of patients trends towards a T-cell cytolytic response.

Gender specific differences in the immune response to infection

There are many instances where males and females differ in the susceptibility to infections. The reason for these differences in susceptibility is multifactorial. The primary cause is thought to be due to differences induced by sex hormones and their effects on gene expression as well as the immune system, but may also be due to innate physiological differences between males and females. This review summarizes gender specific differences seen in infections caused by bacteria, fungi, parasites and viruses. Ultimately, gender specific differences appear to be dependent on the microbe causing the infection, as not every infection with a specific microbial type results in increased susceptibility of one gender over the other. This suggests that there is an interaction between gender specific immune differences and the specific immune response to individual microbes.

Syphilis in the United States: an update for clinicians with an emphasis on HIV coinfection

Diagnosis and treatment of syphilis are challenging because of its variable clinical presentation and course and the lack of definitive tests of cure after treatment. This review of the most recent literature on the epidemiology, clinical manifestations, current diagnosis, and treatment of syphilis is focused toward clinicians who treat patients with this disease. Syphilis coinfection with human immunodeficiency virus is emphasized because it is increasingly common in the United States and affects the initial presentation, disease course, diagnosis, and treatment of syphilis. Of particular consequence is the effect of human immunodeficiency virus on the clinical diagnosis, prevalence, and course of neurosyphilis, one of the most serious consequences of syphilis infection.

Syphilis and human immunodeficiency virus (HIV)-1 coinfection: influence on CD4 T-cell count, HIV-1 viral load, and treatment response

OBJECTIVES

To assess the effect of human immunodeficiency virus (HIV)-1 and syphilis coinfection on HIV-ribonucleic acid (RNA) viral load, CD4 cell count, and the response in rapid plasmin reagin (RPR) to treatment of the syphilis infection.

STUDY DESIGN

Cases of syphilis diagnosed during 1 year in HIV-infected patients in Copenhagen were included. HIV-RNA, CD4 cell counts, and RPR-serology were measured before, during, and after syphilis.

RESULTS

Forty-one patients were included. CD4 cell count decreased significantly during infection in patients with primary and secondary stages of syphilis (mean 106 cells/mm, P = 0.03). Treatment of syphilis was associated with an increase in the CD4 cell count and a decrease in HIV-RNA in the overall group (mean 66 cells/mm and -0.261 RNA log10 copies/ml, P = 0.02 and 0.04). The serological response rates for 15 patients treated with penicillin and 25 treated with doxycycline were the same.

CONCLUSION

Syphilis was associated with a decrease in CD4 cell counts and an increase in HIV-RNA levels that both improved after treatment of syphilis.

Flow cytometry study of lymphocyte subsets in malnourished and well-nourished children with bacterial infections

Protein-energy malnutrition is the primary cause of immune deficiency in children across the world. It has been related to changes in peripheral T-lymphocyte subsets. The aim of the present study was to evaluate the effects of infection and malnutrition on the proportion of peripheral-lymphocyte subsets in well-nourished non-bacterium-infected (WN), well-nourished bacterium-infected (WNI), and malnourished bacterium-infected (MNI) children by flow cytometry. A prospectively monitored cohort of 15 MNI, 12 WNI, and 17 WN children was studied. All the children were 3 years old or younger and had only bacterial infections. Results showed a significant decrease in the proportion of T CD3(+) (P < 0.05 for relative and P < 0.03 for absolute values), CD4(+) (P < 0.01 for relative and absolute values), and CD8(+) (P < 0.05 for relative values) lymphocyte subsets in WNI children compared to the results seen with WN children. Additionally, B lymphocytes in MNI children showed significant lower values (CD20(+) P < 0.02 for relative and P < 0.05 for absolute values) in relation to the results seen with WNI children. These results suggest that the decreased proportions of T-lymphocyte subsets observed in WNI children were associated with infection diseases and that the incapacity to increase the proportion of B lymphocyte was associated with malnutrition. This low proportion of B lymphocytes may be associated with the mechanisms involved in the immunodeficiency of malnourished children.

Immunophenotypes, Apoptosis, and Expression of Fas and Bcl-2 From Peripheral Blood Lymphocytes in Patients With Secondary Early Syphilis

OBJECTIVES

Whether syphilis influences lymphocyte apoptosis has not been reported so far.

GOAL

The goals of this study were to determine whether syphilis influences lymphocyte apoptosis and to investigate the molecular mechanism of apoptosis.

STUDY DESIGN

Peripheral blood lymphocyte (PBL) immunophenotypes, apoptosis, and expression of Fas (CD95) and Bcl-2 were detected by flow cytometry in 33 patients with secondary early syphilis and 30 healthy subjects.

RESULTS

Compared with the control subjects, the percentage of CD4 T cells and the ratio of CD4:CD8 were significantly decreased, and that of CD8 T cells and the apoptotic rates of PBLs and CD4 T cells were obviously increased in syphilitic patients. Fas overexpression and Bcl-2 downexpression in the syphilitic group were observed in PBLs and CD4 cells but not in CD8 and CD19 cells.

CONCLUSIONS

The increased apoptosis of PBLs and CD4 T cells by Fas-mediated death pathway and downexpression of Bcl-2 protein could account for immune dysfunction in secondary early syphilis, which is responsible for the incomplete clearance of Treponema pallidum from the lesions and the chronic infection.

A simplified approach to determining P-glycoprotein expression in peripheral blood mononuclear cell subsets

P-glycoprotein (P-gp), encoded by the MDR-1 (multidrug resistance) gene mediates the cellular efflux of several therapeutic agents with the potential of treatment failure. The differential expression of P-gp in many localised tissues and cells of the hematopoietic system implies diverse physiological and pharmacological roles. The exact function of P-gp involved in multidrug resistance remains unclear owing to the numerous discrepancies between different laboratories. The ability to characterise accurately P-gp expression has important clinical implications. However, a complete consensus recommendation regarding methods of P-gp detection has been difficult to reach. With the advancement in immune technology and new commercially available antibodies, we describe a simplified direct immunofluorescent assay capable of detecting surface P-gp expression in peripheral blood mononuclear cells (PBMCs) and subpopulations of lymphocytes in vivo by dual colour flow cytometry. Results were expressed as mean increase in fluorescence (MI) compared to isotypically matched controls. Using this assay, differential basal P-gp expression was found to exist in the following significant hierarchy CD56+ (MI=0.684+/-0.273; n=15)>CD8+ (MI=0.312+/-0.117; n=15)>CD4+ (MI=0.194+/-0.086; n=15). This method is rapid and reproducible and has potential use for in vitro and in vivo application.

Laboratory diagnosis and interpretation of tests for syphilis

The lack of a method for demonstrating the presence of Treponema pallidum by growth necessitates the use of alternative methods. Traditionally, these methods are divided into direct detection methods (animal inoculation, dark-field microscopy, etc.) and serologic tests for the presence of patient antibody against T. pallidum. Serologic methods are further divided into two classes. One class, the nontreponemal tests, detects antibodies to lipoidal antigens present in either the host or T. pallidum; examples are the Venereal Disease Research Laboratory and rapid plasma reagin and tests. Reactivity in these tests generally indicates host tissue damage that may not be specific for syphilis. Because these tests are easy and inexpensive to perform, they are commonly used for screening, and with proper clinical signs they are suggestive of syphilis. The other class of test, the treponemal tests, uses specific treponemal antigens. Confirmation of infection requires a reactive treponemal test. Examples of the treponemal tests are the microhemagglutination assay for antibodies to T. pallidum and the fluorescent treponemal antibody absorption test. These tests are more expensive and complicated to perform than the nontreponemal tests. On the horizon are a number of direct antigen, enzyme-linked immunosorbent assay, and PCR techniques. Several of these techniques have shown promise in clinical trials for the diagnosis of congenital syphilis and neurosyphilis that are presently difficult to diagnose.