Syphilis Infection Differentially Regulates the Phenotype and Function of γδ T Cells in HIV-1-Infected Patients Depends on the HIV-1 Disease Stage

Serofast status in syphilis: Pathogenesis to therapeutics

Syphilis, a sexually transmitted infection caused by Treponema pallidum, has been experiencing a rise in prevalence in recent years. "Syphilis serofast" describes a unique serological reaction in patients with syphilis whose clinical symptoms have resolved following consistent anti-syphilitic therapy, but the non-Treponema pallidum antigen serologic test is still positive. Syphilis serofast is a risk factor for syphilis recurrence, neurosyphilis, and multisystem involvement. Considering the current lack of comprehensive knowledge about the epidemiological characteristics, pathogenesis, and therapies of syphilis serofast, we conducted an online search of research relating to syphilis serofast over the last twenty years. Previous research has shown that the pathogenesis of syphilis serofast is mainly related to clinical factors, immune factors, syphilis subtypes, and T.pallidum membrane protein repeat gene antigen. There are two distinct viewpoints on the treatment of serofast: no excessive treatment and active treatment. In addition, serofast patients also showed two clinical outcomes: syphilis recurrence and persistent serofast status. This article systematically reviews the related factors, treatment, and clinical outcomes of syphilis serofast, provides a theoretical basis for its research, diagnosis, and treatment, and helps clinicians develop a follow-up treatment management plan for syphilis serofast.

Changing roles of CD3 + CD8 low T cells in combating HIV-1 infection

BACKGROUND

Cluster of differentiation 8 (CD8 T) cells play critical roles in eradicating human immunodeficiency virus (HIV)-1 infection, but little is known about the effects of T cells expressing CD8 at low levels (CD8 low ) or high levels (CD8 high ) on HIV-1 replication inhibition after HIV-1 invasion into individual.

METHODS

Nineteen patients who had been acutely infected with HIV-1 (AHI) and 20 patients with chronic infection (CHI) for ≥2 years were enrolled in this study to investigate the dynamics of the quantity, activation, and immune responses of CD3 + CD8 low T cells and their counterpart CD3 + CD8 high T cells at different stages of HIV-1 infection.

RESULTS

Compared with healthy donors, CD3 + CD8 low T cells expanded in HIV-1-infected individuals at different stages of infection. As HIV-1 infection progressed, CD3 + CD8 low T cells gradually decreased. Simultaneously, CD3 + CD8 high T cells was significantly reduced in the first month of AHI and then increased gradually as HIV-1 infection progressed. The classical activation of CD3 + CD8 low T cells was highest in the first month of AHI and then reduced as HIV-1 infection progressed and entered the chronic stage. Meanwhile, activated CD38 - HLA-DR + CD8 low T cells did not increase in the first month of AHI, and the number of these cells was inversely associated with viral load ( r = -0.664, P = 0.004) but positively associated with the CD4 T-cell count ( r = 0.586, P = 0.014). Increased programmed cell death protein 1 (PD-1) abundance on CD3 + CD8 low T cells was observed from the 1st month of AHI but did not continue to be enhanced, while a significant T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif (ITIM) domains (TIGIT) abundance increase was observed in the 12th month of infection. Furthermore, increased PD-1 and TIGIT abundance on CD3 + CD8 low T cells was associated with a low CD4 T-cell count (PD-1: r = -0.456, P = 0.043; TIGIT: r = -0.488, P = 0.029) in CHI. Nonetheless, the nonincrease in PD-1 expression on classically activated CD3 + CD8 low T cells was inversely associated with HIV-1 viremia in the first month of AHI ( r = -0.578, P = 0.015). Notably, in the first month of AHI, few CD3 + CD8 low T cells, but comparable amounts of CD3 + CD8 high T cells, responded to Gag peptides. Then, weaker HIV-1-specific T-cell responses were induced in CD3 + CD8 low T cells than CD3 + CD8 high T cells at the 3rd and 12th months of AHI and in CHI.

CONCLUSIONS

Our findings suggest that CD3 + CD8 low T cells play an anti-HIV role in the first month of infection due to their abundance but induce a weak HIV-1-specific immune response. Subsequently, CD3 + CD8 low T-cell number decreased gradually as infection persisted, and their anti-HIV functions were inferior to those of CD3 + CD8 high T cells.

Exposing the Great Imitator: Proposal for a Holistic Diagnosis of Oral Secondary Syphilis in People Living with HIV

Oral secondary syphilis may mimic various infectious, neoplastic, or immune-mediated processes; hence, its diagnosis may represent a challenge. Early diagnosis of syphilis, a disease that has increased in recent decades, is essential for adequate management, particularly in people living with HIV (PLWH). This study aimed to comprehensively characterize oral secondary syphilis in a group of 47 PLWH. A group of PLWH with oral secondary syphilis attending four HIV-referral centers in Mexico City was included (2004-2021). Clinical and laboratory data were retrieved, and an exhaustive oral examination was performed following the established criteria. Demographic, clinicopathological, immunohistochemical, and serological features of the patients were analyzed. Approximately 11% of PLWH with oral secondary syphilis demonstrated negative Venereal Disease Research Laboratory tests. A noticeable feature was the absence of symptoms in 95.7% of cases, despite the clinically evident appearance of the lesions. In contrast to previous results, 18% of ulcerations were detected to be deep, crateriform, and infiltrative, and 22% of the mucous patches were highly keratotic lesions. Most samples (77.3%) showed superficial lymphoplasmacytic infiltrates in the superficial lamina propria, with perivascular and perineural patterns, and immunohistochemistry was positive in 66.7% of the cases. The "great imitator" appears not only clinically but also histopathologically and immunohistochemically, where features may be comparable with those of chronic inflammatory processes, deep infections, or malignant processes. Although not recommended as a routine assay, IHC could be a critical tool, particularly in PLWH with atypical clinical features or with negative and/or dubious serology.

A Longitudinal Case Study of Concurrent Infection with Syphilis and Human Immunodeficiency Virus During the Early Phase

Due to the low incidence of concurrent human immunodeficiency virus (HIV) and syphilis infection identified during the early phase, such as window period (WP), little is known about the clinical manifestations, diagnosis, and treatment efficacy at very early stages. One longitudinal study was conducted in a 42-year-old blood donor who was concurrently infected with syphilis and HIV. This blood donor was treated with a penicillin-based regimen and early antiretroviral therapy (ART). Sequential serological and nucleic acid tests were performed and the results were comparatively analyzed. A regular male donor who had two occasions of high-risk sexual behaviors 41 and 35 days before donation donated whole blood at the Shenzhen Blood Center. ART was initiated at the 28th day after donation (DAD), and syphilis treatment was received at the 49th DAD. Microbiological analysis using a fourth-generation anti-HIV enzyme-linked immunosorbent assay (ELISA) (4th GAHE) and electro-chemiluminesent immunoassay indicated a positive signal at the 6th DAD, while a third-generation anti-HIV ELISA (3rd GAHE) showed positive at the 26th DAD. All nucleic acid testing (NAT) for HIV RNA were reactive except the minipool NAT of 6 pooled samples at 117th DAD. The HIV viral load declined more than 4-log in copies per milliliter over 3 months, until reaching nondetectable levels at 246th DAD. Nevertheless, HIV-1 DNA was still detectable at 403rd DAD. Among all methods utilized, anti-treponema pallidum ELISA detected syphilis infection at the earliest time. A successful serological response to syphilis treatment was reached around the 80th DAD. Concurrent infection with syphilis and HIV during early phases did not significantly change the sensitivity of reagents in detection nor alter the therapeutic efficacy for the treatment of both pathogens, but might result in delayed HIV serological WP.

Clinical and laboratory impact of concomitant syphilis infection during acute HIV

INTRODUCTION

Cognitive impairment has been reported in people living with HIV-1 (PLWH) with prior syphilis, while PLWH who present with incident syphilis have reduced blood CD4 T-lymphocyte and elevated HIV-1 RNA levels. However, the clinical, virological and neurocognitive effects of syphilis during acute HIV-1 (AHI) remain unknown.

METHODS

Pre-antiretroviral therapy laboratory outcomes and neurocognitive performance in a four-test battery in the SEARCH10/RV254 AHI cohort were compared according to syphilis status, determined by serum Treponema pallidum haemagglutination (TPHA), Venereal Disease Research Laboratory (VDRL) and syphilis treatment history. Impaired cognitive performance was defined as having z-scores ≤ -1 in at least two tests or ≤ -2 in at least one test.

RESULTS

Out of 595 AHI participants (97% male, median age of 26 years and estimated duration of HIV-1 infection of 19 days), 119 (20%) had history of syphilis (TPHA-positive), of whom 51 (9%) had untreated syphilis (TPHA-positive/VDRL-positive/without prior treatment). Compared with those without syphilis (TPHA-negative), individuals with untreated syphilis had higher CD8 T-lymphocyte levels but not higher plasma HIV-1 RNA or lower CD4 T-lymphocyte levels. Taking into account estimated duration of HIV-1 infection (P < 0.001), and later Fiebig stages (III-V) (P < 0.001), those with untreated syphilis had higher CD8 T-lymphocyte levels (P = 0.049). Individuals with any syphilis (TPHA-positive), but not untreated syphilis, had higher odds of impaired cognitive performance than those without (P = 0.002).

CONCLUSIONS

During AHI, individuals with any history of syphilis (TPHA-positive) had poorer cognitive performance than those without syphilis. However, syphilis was not associated with worsened HIV disease measures as described in chronic infection.

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.

Alterations of CCR2 and CX3CR1 on Three Monocyte Subsets During HIV-1/Treponema pallidum Coinfection

HIV-1/Treponema pallidum (T. pallidum) coinfection has become a global challenge, and three monocyte subsets express varying levels of the chemokine receptors CCR2 and CX3CR1. We recently evaluated the association between monocyte subsets and regulatory T cells in HIV-infected individuals with syphilis. Currently, the dynamic changes of CCR2 and CX3CR1 on monocyte subsets during HIV-1 and syphilis coinfection have not been fully investigated. In this study, cell surface staining was used to explore CCR2 and CX3CR1 expression on three monocyte subsets during HIV-1/T. pallidum coinfection. We found that CCR2 densities on the classical monocyte subsets decreased in acute HIV-1 infected (AHI) patients, chronic HIV-1-infected individuals without antiviral therapy (ART) (CHI+ ART–), chronic HIV-1-infected individuals receiving ART (CHI+ART+), rapid plasma reagin-positive (RPR+) individuals, CHI+ ART– plus RPR+ (CHI+RPR+ ART–) individuals, and CHI+ART+ plus RPR⁺ (CHI+RPR+ART+) individuals. CX3CR1 density increased on the three monocyte subsets during HIV-1 and/or T. pallidum infection. CX3CR1 density on the intermediate and non-classical monocyte subsets in CHI+ ART– individuals was lower than that in CHI+ART+ individuals, and CX3CR1 density on the three monocyte subsets in CHI+ART+ individuals was higher than that in CHI+RPR+ART+ individuals. Our data provide new insight into the roles of CCR2 and CX3CR1 on three monocyte subsets in HIV-1 and T. pallidum pathogenesis.

Early HIV infection is associated with reduced proportions of gamma delta T subsets as well as high creatinine and urea levels

Renal dysfunctions are major predictors of co-morbidities and mortality in HIV-infected individuals. Unconventional T cells have been shown to regulate kidney functions. However, there is dearth of information on the effect of HIV-associated nephropathies on γδ and DN T cells. It is also not clear whether γδ T cell perturbations observed during the early stages of HIV infection occur before immune activation. In this study, we investigated the relationship between creatinine and urea on the number of unconventional T cells in HIV-infected individuals at the early and chronic stages of infection. Persons in the chronic stage of infection were divided into treatment naïve and exposed groups. Treatment exposed individuals were further subdivided into groups with undetectable and detectable HIV-1RNA in their blood. Creatinine and urea levels were significantly higher among persons in the early HIV infection compared with the other groups. Proportions of γδ T, γδ + CD8, γδ + CD16 cells were also significantly reduced in the early stage of HIV infection (P < .01). Markers of immune activation, CD4 + HLA-DR and CD8 + HLA-DR, were also significantly reduced during early HIV infection (P < .01). Taken together, our findings suggest that high levels of renal markers as well as reduced proportions of gamma delta T cells are associated with the early stages of HIV infection. This event likely occurs before systemic immune activation reaches peak levels. This study provides evidence for the need for early HIV infection diagnosis and treatment.

Effects of Early and Delayed Antiretroviral Therapy on Plasma Anti-CD4 Autoreactive IgG and Its Association With CD4+ T-Cell Recovery in Acute HIV-Infected Individuals

Background

Plasma levels of anti-CD4 autoantibodies are increased in chronically HIV-infected patients and inversely correlated with CD4⁺ T-cell recovery under viral-suppressive antiretroviral therapy (ART). However, it remains unknown the effect of early ART on plasma anti-CD4 autoantibody levels in acute HIV infection (AHI).

Methods

In this cohort study, we evaluated the effect of early and delayed initiation of ART on plasma anti-CD4 autoantibody levels in AHI individuals (n = 90). Blood samples were collected from men who had sex with men (MSM) with acute infection, pre-ART, and 4, 24, 48, and 96 weeks after ART. Plasma levels of anti-CD4 immunoglobulin G (IgG) were measured by ELISA.

Results

We found that plasma anti-CD4 IgG levels were significantly increased in AHI individuals compared with healthy controls (HCs) prior to ART. Notably, early ART decreased plasma anti-CD4 IgG to the levels similar to HCs starting at 24 weeks (W). However, delayed initiation of ART did not significantly reduce plasma anti-CD4 IgG levels in AHI individuals. Moreover, the peripheral CD4⁺ T-cell counts were inversely correlated with plasma anti-CD4 IgG levels in AHI individuals at 48 and 96 W after early ART but not after delayed ART.

Conclusions

Taken together, our findings demonstrate for the first time that early ART, but not delayed initiation of ART, is effective in influencing anti-CD4 autoantibody production and recovering CD4⁺ T-cell counts in AHI individuals.

Metabolic interventions in the immune response to cancer

At the centre of the therapeutic dilemma posed by cancer is the question of how to develop more effective treatments that discriminate between normal and cancerous tissues. Decades of research have shown us that universally applicable principles are rare, but two well-accepted concepts have emerged: first, that malignant transformation goes hand in hand with distinct changes in cellular metabolism; second, that the immune system is critical for tumour control and clearance. Unifying our understanding of tumour metabolism with immune cell function may prove to be a powerful approach in the development of more effective cancer therapies. Here, we explore how nutrient availability in the tumour microenvironment shapes immune responses and identify areas of intervention to modulate the metabolic constraints placed on immune cells in this setting.

γδ T-cell responses during HIV infection and antiretroviral therapy

HIV infection is associated with a rapid and sustained inversion of the Vδ1:Vδ2 T‐cell ratio in peripheral blood. Studies of antiretroviral therapy (ART)‐treated cohorts suggest that ART is insufficient to reconstitute either the frequency or function of the γδ T‐cell subset. Recent advances are now beginning to shed light on the relationship between microbial translocation, chronic inflammation, immune ageing and γδ T‐cell immunology. Here, we review the impact of acute, chronic untreated and treated HIV infection on circulating and mucosal γδ T‐cell subsets and highlight novel approaches to harness γδ T cells as components of anti‐HIV immunotherapy.

Immunological Changes in Monocyte Subsets and Their Association With Foxp3+ Regulatory T Cells in HIV-1-Infected Individuals With Syphilis: A Brief Research Report

The incidence of syphilis has increased dramatically in men who have sex with men (MSM), especially those with HIV-1 infection. Treponema pallidum and HIV-1 are bidirectionally synergistic, accelerating disease progression reciprocally in co-infected individuals. We have shown that monocytes have different effects on T helper cells at different stages of HIV-1 infection. However, the immunological changes in the three monocyte subsets and in regulatory T cells (Tregs), and the associations between these cell types during syphilis infection among HIV-1-infected MSM remain unclear. Herein, we used cell staining methods to explore changes in monocyte subsets and Tregs and any associations between these cells. We found that the frequency of classical monocytes was higher in the rapid plasma reagin (RPR⁺) group than in the healthy controls (HCs) and the chronic HIV-1 infection (CHI) plus RPR⁺ (CHI&RPR⁺) group. The frequencies of Foxp3⁺CD25⁺CD45RA⁺ and Foxp3⁺Helios⁺CD45RA⁺ Tregs were significantly higher in the RPR⁺, CHI, and CHI&RPR⁺ groups than in HCs, whereas the frequency of CD45RA⁺ Tregs was lower in the CHI&RPR⁺ group than in CHI group. The frequencies of Foxp3⁺CD25⁺CD45RO⁺ and Foxp3⁺Helios⁺CD45RO⁺ Tregs were lower in the RPR⁺, CHI, and CHI&RPR⁺ groups than in HCs. The frequency of intermediate monocytes was inversely correlated with the frequency of CD45RA⁺ Tregs and positively correlated with the frequency of CD45RO⁺ Tregs. These results demonstrate for the first time that intermediate monocytes control the differentiation of Treg subsets in Treponema pallidum/HIV-1 co-infections. These findings provide new insights into an immunological mechanism involving monocytes/Tregs in HIV-infected individuals with syphilis.

KIR3DL1-Negative CD8 T Cells and KIR3DL1-Negative Natural Killer Cells Contribute to the Advantageous Control of Early Human Immunodeficiency Virus Type 1 Infection in HLA-B Bw4 Homozygous Individuals

Bw4 homozygosity in human leukocyte antigen class B alleles has been associated with a delayed acquired immunodeficiency syndrome (AIDS) development and better control of human immunodeficiency virus type 1 (HIV-1) viral load (VL) than Bw6 homozygosity. Efficient CD8 T cell and natural killer (NK) cell functions have been described to restrain HIV-1 replication. However, the role of KIR3DL1 expression on these cells was not assessed in Bw4-homozygous participants infected with HIV-1 CRF01_A/E subtype, currently the most prevalent subtype in China. Here, we found that the frequency of KIR3DL1-expressing CD8 T cells of individuals homozygous for Bw6 [1.53% (0–4.56%)] was associated with a higher VL set point (Spearman r_s = 0.59, P = 0.019), but this frequency of KIR3DL1⁺CD8⁺ T cells [1.37% (0.04–6.14%)] was inversely correlated with CD4 T-cell count in individuals homozygous for Bw4 (r_s = −0.59, P = 0.011). Moreover, CD69 and Ki67 were more frequently expressed in KIR3DL1⁻CD8⁺ T cells in individuals homozygous for Bw4 than Bw6 (P = 0.046 for CD69; P = 0.044 for Ki67), although these molecules were less frequently expressed in KIR3DL1⁺CD8⁺ T cells than in KIR3DL1⁻CD8⁺ T cells in both groups (all P < 0.05). KIR3DL1⁻CD8⁺ T cells have stronger p24-specific CD8⁺ T-cell responses secreting IFN-γ and CD107a than KIR3DL1⁺CD8⁺ T cells in both groups (all P < 0.05). Thus, KIR3DL1 expression on CD8 T cells were associated with the loss of multiple functions. Interestingly, CD69⁺NK cells lacking KIR3DL1 expression were inversely correlated with HIV-1 VL set point in Bw4-homozygous individuals (r_s = −0.52, P = 0.035). Therefore, KIR3DL1⁻CD8⁺ T cells with strong early activation and proliferation may, together with KIR3DL1⁻CD69⁺NK cells, play a protective role during acute/early HIV infection in individuals homozygous for Bw4. These findings highlight the superior functions of KIR3DL1⁻CD8⁺ T cells and KIR3DL1⁻CD69⁺NK cells being a potential factor contributing to delayed disease progression in the early stages of HIV-1 infection.