The influence of cytokines, chemokines and their receptors on HIV-1 replication in monocytes and macrophages

Decreased IL-1 β Secretion as a Potential Predictor of Tuberculosis Recurrence in Individuals Diagnosed with HIV

Background: The mechanisms of the formation of immunological competence against tuberculosis (TB), and especially those associated with HIV co-infection, remain poorly understood. However, there is an urgent need for risk recurrence predictive biomarkers, as well as for predictors of successful treatment outcomes. The goal of the study was to identify possible immunological markers of TB recurrence in individuals with HIV/TB co-infection. Methods: The plasma levels of IFN-γ, TNF-α, IL-10, and IL-1β (cytokines which play important roles in the immune activation and protection against Mycobacterium tuberculosis) were measured using ELISA EIA-BEST kits. The cytokine concentrations were determined using a standard curve obtained with the standards provided by the manufacturer of each kit. Results: A total of 211 individuals were enrolled in the study as follows: 62 patients with HIV/TB co-infection, 52 with HIV monoinfection, 52 with TB monoinfection, and 45 healthy donors. Out of the 62 patients with HIV/TB, 75.8% (47) of patients were newly diagnosed with HIV and TB, and 24.2% (15) displayed recurrent TB and were newly diagnosed with HIV. Decreased levels of IFN-γ, TNF-α, and IL-10 were observed in patients with HIV/TB when compared with HIV and TB patients. However, there was no difference in IFN-γ, TNF-α, or IL-10 secretion between both HIV/TB groups. At the same time, an almost 4-fold decrease in Il-1β levels was detected in the HIV/TB group with TB recurrence when compared with the HIV/TB group (p = 0.0001); a 2.8-fold decrease when compared with HIV patients (p = 0.001); and a 2.2-fold decrease with newly diagnosed TB patients (p = 0.001). Conclusions: Significantly decreased Il-1β levels in HIV/TB patients' cohort with secondary TB indicate that this cytokine can be a potential biomarker of TB recurrence.

Myocardial extracellular volume fraction is positively associated with activated monocyte subsets among cART-treated persons living with HIV in South Africa

BACKGROUND

Despite treatment with combination antiretroviral therapy (cART), persons living with HIV (PLWH) are at higher risk of cardiac structural abnormalities that may presage clinical heart failure, including myocardial fibrosis. This study assessed whether circulating cellular and soluble protein markers of immune activation cross-sectionally associate with myocardial fibrosis among cART-treated PLWH in South Africa.

METHODS

Participants were enrolled in Khayelitsha township near Cape Town, SA. Cardiac magnetic resonance imaging was performed. Plasma protein biomarkers were measured using enzyme-linked immunoassays and monocyte phenotypes were evaluated using flow cytometry. Associations were assessed using multivariable linear and logistic regression.

RESULTS

Among 69 cART-treated PLWH, mean (SD) age was 48 (10) years, 71% were female, and time since HIV diagnosis was 9 (6) years. Evidence of left ventricular fibrosis by late gadolinium enhancement was present in 74% of participants and mean (SD) extracellular volume fraction (ECV) was 30.9 (5.9)%. Degree of myocardial fibrosis/inflammation measured by ECV was positively associated with percentages of circulating non-classical and intermediate monocyte phenotypes reflecting inflammation and tissue injury.

CONCLUSION

These data generate hypotheses on possible immune mechanisms of HIV-associated non-ischemic myocardial disease, specifically among cART-treated PLWH in sub-Saharan Africa, where the majority of the HIV burden exists globally.

Macrophage-Derived Factors with the Potential to Contribute to Pathogenicity of HIV-1 and HIV-2: Role of CCL-2/MCP-1

Human immunodeficiency virus type 2 (HIV-2) is known to be less pathogenic than HIV-1. However, the mechanism(s) underlying the decreased HIV-2 pathogenicity is not fully understood. Herein, we report that β-chemokine CCL2 expression was increased in HIV-1-infected human monocyte-derived macrophages (MDM) but decreased in HIV-2-infected MDM when compared to uninfected MDM. Inhibition of CCL2 expression following HIV-2 infection occurred at both protein and mRNA levels. By microarray analysis, quantitative PCR, and Western blotting, we identified that Signal Transducer and Activator of Transcription 1 (STAT1), a critical transcription factor for inducing CCL2 gene expression, was also reduced in HIV-2-infected MDM. Blockade of STAT1 in HIV-infected MDM using a STAT1 inhibitor significantly reduced the production of CCL2. In contrast, transduction of STAT1-expressing pseudo-retrovirus restored CCL2 production in HIV-2-infected MDM. These findings support the concept that CCL2 inhibition in HIV-2-infected MDM is meditated by reduction of STAT1. Furthermore, we showed that STAT1 reduction in HIV-2-infected MDM was regulated by the CUL2/RBX1 ubiquitin E3 ligase complex-dependent proteasome pathway. Knockdown of CUL2 or RBX1 restored the expression of STAT1 and CCL2 in HIV-2-infected MDM. Taken together, our findings suggest that differential regulation of the STAT1-CCL2 axis may be one of the mechanisms underlying the different pathogenicity observed for HIV-1 and HIV-2.

Progress in Pathological and Therapeutic Research of HIV-Related Neuropathic Pain

HIV-related neuropathic pain (HRNP) is a neurodegeneration that gradually develops during the long-term course of acquired immune deficiency syndrome (AIDS) and manifests as abnormal sock/sleeve-like symmetrical pain and nociceptive hyperalgesia in the extremities, which seriously reduces patient quality of life. To date, the pathogenesis of HRNP is not completely clear. There is a lack of effective clinical treatment for HRNP and it is becoming a challenge and hot spot for medical research. In this study, we conducted a systematic review of the progress of HRNP research in recent years including (1) the etiology, classification and clinical symptoms of HRNP, (2) the establishment of HRNP pathological models, (3) the pathological mechanisms underlying HRNP from three aspects: molecules, signaling pathways and cells, (4) the therapeutic strategies for HRNP, and (5) the limitations of recent HRNP research and the future research directions and prospects of HRNP. This detailed review provides new and systematic insight into the pathological mechanism of HRNP, which establishes a theoretical basis for the future exploitation of novel target drugs. HIV infection, antiretroviral therapy and opioid abuse contribute to the etiology of HRNP with symmetrical pain in both hands and feet, allodynia and hyperalgesia. The pathogenesis involves changes in cytokine expression, activation of signaling pathways and neuronal cell states. The therapy for HRNP should be patient-centered, integrating pharmacologic and nonpharmacologic treatments into multimodal intervention.

HIV/Mtb Co-Infection: From the Amplification of Disease Pathogenesis to an “Emerging Syndemic”

Human immunodeficiency virus (HIV) and Mycobacterium tuberculosis (Mtb) are pathogens responsible for millions of new infections each year; together, they cause high morbidity and mortality worldwide. In addition, late-stage HIV infection increases the risk of developing tuberculosis (TB) by a factor of 20 in latently infected people, and even patients with controlled HIV infection on antiretroviral therapy (ART) have a fourfold increased risk of developing TB. Conversely, Mtb infection exacerbates HIV pathogenesis and increases the rate of AIDS progression. In this review, we discuss this reciprocal amplification of HIV/Mtb coinfection and how they influence each other’s pathogenesis. Elucidating the infectious cofactors that impact on pathogenesis may open doors for the design of new potential therapeutic strategies to control disease progression, especially in contexts where vaccines or the sterile clearance of pathogens are not effectively available.

The role of IL-1β during human immunodeficiency virus type 1 infection

Interleukin (IL)-1β is a key innate cytokine that is essential for immune activation and promoting the inflammatory process. However, abnormal elevation in IL-1β levels has been associated with unwanted clinical outcomes. IL-1β is the most extensively studied cytokine among the IL-1 family of cytokines and its role in pathology is well established. During the course of human immunodeficiency virus type 1 (HIV-1) infection, the level of this proinflammatory cytokine is increased in different anatomical compartments, particularly in lymphatic tissues, and this elevation is associated with disease progression. The aim of this review is to address the pathological roles play by IL-1β in the light of enhancing HIV-1 replication, driving immune cell depletion, and chronic immune activation. The role of IL-1β in HIV-1 transmission (sexually or vertically 'from mother-to-child') will also be discussed. Additionally, the impact of the available antiretroviral therapy regimens on the levels of IL-1β in HIV-1 treated patients is also discussed. Finally, we will provide a glance on how IL-1β could be targeted as a therapeutic strategy.

Relationship Between Anemia and Systemic Inflammation in People Living With HIV and Tuberculosis: A Sub-Analysis of the CADIRIS Clinical Trial

People with HIV (PWH) are at increased risk of developing active tuberculosis (TB), and anemia is a common complication in both conditions. Anemia in TB patients has been linked to immune activation, levels of inflammatory biomarkers in blood, and risk for HIV disease progression and death. In this study we show that anemia was associated with a more pronounced inflammatory profile in HIV-TB coinfected persons in a cohort of 159 individuals with advanced HIV disease (CD4 count < 100 cells/µL) recruited as part of a randomized clinical trial (NCT00988780). A panel of plasma biomarkers was assessed on plasma obtained prior to combination antiretroviral therapy (cART) initiation. We performed a series of multidimensional analyses including clinical variables and concentrations of inflammatory biomarkers to profile systemic inflammation of PWH with and without anemia. We observed that TB participants presented with moderately lower levels of hemoglobin than non-TB participants. These participants also presented a higher Degree of Inflammatory Perturbation (DIP) score, related to increased levels of IFN-γ and TNF. The DIP was associated with TB coinfection and anemia before cART initiation. Future mechanistic studies are warranted to assess the determinants of such associations and the implications on treatment outcomes.

Dynamics of Plasmatic Levels of Pro- and Anti-Inflammatory Cytokines in HIV-Infected Individuals with M. tuberculosis Co-Infection

Tuberculosis (TB) and HIV have profound effects on the immune system, which can lead to the activation of viral replication and negatively regulate the activation of T cells. Dysregulation in the production of cytokines necessary to fight HIV and M. tuberculosis may ultimately affect the results of the treatment and be important in the pathogenesis of HIV infection and TB. This work presents the results of a study of the expression of pro- and anti-inflammatory cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10, IL-1RA) in drug-naïve patients with dual infection of HIV/TB at the late stages of HIV-infection, with newly diagnosed HIV and TB, and previously untreated HIV in the process of receiving antiretroviral (ART) and TB treatment vs. a cohort of patients with HIV monoinfection and TB monoinfection. The study revealed that during a double HIV/TB infection, both Th1 and Th2 immune responses are suppressed, and a prolonged dysregulation of the immune response and an increased severity of the disease in pulmonary/extrapulmonary tuberculosis is observed in HIV/TB co-infection. Moreover, it was revealed that a double HIV/TB infection is characterized by delayed and incomplete recovery of immune activity. High levels of IL-6 were detected in patients with HIV/TB co-infection before initiation of dual therapy (2.1-fold increase vs. HIV), which persisted even after 6 months of treatment (8.96-fold increase vs. HIV), unlike other cytokines. The persistent enhanced expression of IL-6 in patients with dual HIV/TB co-infection allows the consideration of it as a potential marker of early detection of M. tuberculosis infection in HIV-infected individuals. The results of multivariate regression analysis showed a statistical trend towards an increase in the incidence of IRIS in patients with high IL-1Ra levels (in the range of 1550–2500 pg/mL): OR = 4.3 (95%CI 3.7–14.12, p = 0.53), which also allows IL-1Ra to be considered as a potential predictive biomarker of the development of TB-IRIS and treatment outcomes.

Co-receptor signaling in the pathogenesis of neuroHIV

The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development.

Monocyte/Macrophage-Mediated Innate Immunity in HIV-1 Infection: From Early Response to Late Dysregulation and Links to Cardiovascular Diseases Onset

Although monocytes and macrophages are key mediators of the innate immune system, the focus has largely been on the role of the adaptive immune system in the context of human immunodeficiency virus (HIV) infection. Thus more attention and research work regarding the innate immune system-especially the role of monocytes and macrophages during early HIV-1 infection-is required. Blood monocytes and tissue macrophages are both susceptible targets of HIV-1 infection, and the early host response can determine whether the nature of the infection becomes pathogenic or not. For example, monocytes and macrophages can contribute to the HIV reservoir and viral persistence, and influence the initiation/extension of immune activation and chronic inflammation. Here the expansion of monocyte subsets (classical, intermediate and non-classical) provide an increased understanding of the crucial role they play in terms of chronic inflammation and also by increasing the risk of coagulation during HIV-1 infection. This review discusses the role of monocytes and macrophages during HIV-1 pathogenesis, starting from the early response to late dysregulation that occurs as a result of persistent immune activation and chronic inflammation. Such changes are also linked to downstream targets such as increased coagulation and the onset of cardiovascular diseases.

Innate Immune Response Against HIV-1

The innate immune system is comprised of both cellular and humoral players that recognise and eradicate invading pathogens. Therefore, the interplay between retroviruses and innate immunity has emerged as an important component of viral pathogenesis. HIV-1 infection in humans that results in hematologic abnormalities and immune suppression is well represented by changes in the CD4/CD8 T cell ratio and consequent cell death causing CD4 lymphopenia. The innate immune responses by mucosal barriers such as complement, DCs, macrophages, and NK cells as well as cytokine/chemokine profiles attain great importance in acute HIV-1 infection, and thus, prevent mucosal capture and transmission of HIV-1. Conversely, HIV-1 has evolved to overcome innate immune responses through RNA-mediated rapid mutations, pathogen-associated molecular patterns (PAMPs) modification, down-regulation of NK cell activity and complement receptors, resulting in increased secretion of inflammatory factors. Consequently, epithelial tissues lining up female reproductive tract express innate immune sensors including anti-microbial peptides responsible for forming primary barriers and have displayed an effective potent anti-HIV activity during phase I/II clinical trials.

Significant Induction of Soluble TNFR2 Compared with TNFR1 in Serum Samples of HIV Patients with or without Antiretroviral Medication

BACKGROUND

Tumor necrosis factor and its receptors (sTNFR1 and sTNFR2) have been implicated in many infectious diseases. Identification of the key receptor (sTNFR1 or sTNFR2) which drives the immunopathogenesis of HIV infection is crucial in developing adjunctive therapy for HIV.

OBJECTIVE

This study determined the expression levels of sTNFR1 and sTNFR2 in antiretroviral therapy (ART) - experienced and naïve HIV patients.

METHODS

A total of 40 HIV patients comprising 30 with ART and 10 without ART were enrolled from the Pantang Hospital located in the Greater Accra Region of Ghana for data and blood collection. Serum concentrations of sTNFR1 and sTNFR2 were determined by ELISA. Mann- Whitney U test was used to examine differences in serum levels of sTNFR1 and sTNFR2 between patients on ART and ART naïve patients. Wilcoxon Signed-Rank test was performed to determine the difference between sTNFR1 and sTNFR2, and Kruskal Wallis test was conducted to compare the effect of different antiretroviral drugs on the levels of sTNFR1 and sTNFR2. P< 0.05 was considered statistically significant.

RESULTS

A Wilcoxon Signed-Ranks Test indicated serum levels of sTNFR2 was statistically significantly higher than sTNFR1 (Z=-5.51; p<0.001). Levels of sTNFR1 and sTNFR2 did not differ by ART status U =91.00 (Z = -1.84), p = 0.065 and U = 131.50 (Z = -0.58, p =0.560), respectively. There were not significant differences in levels of TNFR2 H(2) = 1.86, p=0.395 and sTNFR1 (H (2) = 4.37, p=0.113 across different ART combinations.

CONCLUSION

Compared to sTNFR1, the level of sTNFR2 is significantly increased during HIV infection irrespective of ART status. The high sTNFR2 level is not associated with antiretroviral drugs and may be another potential target for therapeutic development. This is the first study of sTNFRs in African population.

The Effect of Antiretroviral Therapy on IL-6, IL-1β, TNF-α, IFN-γ Levels and their Relationship with HIV-RNA and CD4+ T Cells in HIV Patients

BACKGROUND

Serum cytokine levels over the course of HIV infection usually increase with immunosuppression and decrease after antiretroviral treatment (ART).

OBJECTIVES

The aim of the study is to compare cytokine levels between HIV-infected patients (HIP) and controls and investigate the relationship between CD4+T cell count, HIV-RNA levels, and cytokine levels.

METHODS

The study subjects comprised ART-naive HIP (n=30) with no comorbidities and age-and sex-matched healthy controls. We measured levels of IL-6, IL-1β, TNF-α, and IFN-γ in serum samples of HIP at the beginning and at month 6 of ART and in controls.

RESULTS

The mean age of the study subjects was 38.7 ±10.3 years, with men making up 86.7% of the study subjects (n=26). IL-6, IL-1β, and TNF-α levels were significantly higher in both ART-naive (p<0.001, p=0.002, p=0.001) and ART-experienced HIP (p<0.001) than controls. The IFN-γ level was lower in both ART-naive and ART-experienced HIP compared to controls (p=0.082 and p=0.002). There was a positive correlation between the CD4+T cell count and serum concentration of IFN- γ(r=0.320, p<0.05). While the serum IFN-γ concentration showed a negative correlation with the HIVRNA level(r=-0.412, p<0.001), the serum IL-1β, IL-6, and TNF-α concentrations showed a positive correlation with the HIV-RNA level (r=0.349, p<0.001; r:0.54, p<0.001; r:0.438, p<0.00).

CONCLUSION

Although serum concentrations of IL-6, IL-1β and TNF-α showed a significant decrease after ART, they were still significantly higher than the controls. IFN-γ responded differently to ART compared to the other cytokines, indicating that it may play a distinct and important role in the pathogenesis of HIV infection.

Loss of CXCR4 on non-classical monocytes in participants of the Women's Interagency HIV Study (WIHS) with subclinical atherosclerosis

AIMS

To test whether human immunodeficiency virus (HIV) infection and subclinical cardiovascular disease (sCVD) are associated with expression of CXCR4 and other surface markers on classical, intermediate, and non-classical monocytes in women.

METHODS AND RESULTS

sCVD was defined as presence of atherosclerotic lesions in the carotid artery in 92 participants of the Women's Interagency HIV Study (WIHS). Participants were stratified into four sets (n = 23 each) by HIV and sCVD status (HIV-/sCVD-, HIV-/sCVD+, HIV+/sCVD-, and HIV+/sCVD+) matched by age, race/ethnicity, and smoking status. Three subsets of monocytes were determined from archived peripheral blood mononuclear cells. Flow cytometry was used to count and phenotype surface markers. We tested for differences by HIV and sCVD status accounting for multiple comparisons. We found no differences in monocyte subset size among the four groups. Expression of seven surface markers differed significantly across the three monocyte subsets. CXCR4 expression [median fluorescence intensity (MFI)] in non-classical monocytes was highest among HIV-/CVD- [628, interquartile range (IQR) (295-1389)], followed by HIV+/CVD- [486, IQR (248-699)], HIV-/CVD+ (398, IQR (89-901)), and lowest in HIV+/CVD+ women [226, IQR (73-519)), P = 0.006 in ANOVA. After accounting for multiple comparison (Tukey) the difference between HIV-/CVD- vs. HIV+/CVD+ remained significant with P = 0.005 (HIV-/CVD- vs. HIV+/CVD- P = 0.04, HIV-/CVD- vs. HIV-/CVD+ P = 0.06, HIV+/CVD+ vs. HIV+/CVD- P = 0.88, HIV+/CVD+ vs. HIV-/CVD+ P = 0.81, HIV+/CVD- vs. HIV-/CVD+, P = 0.99). All pairwise comparisons with HIV-/CVD- were individually significant (P = 0.050 vs. HIV-/CVD+, P = 0.028 vs. HIV+/CVD-, P = 0.009 vs. HIV+/CVD+). CXCR4 expression on non-classical monocytes was significantly higher in CVD- (501.5, IQR (249.5-887.3)) vs. CVD+ (297, IQR (81.75-626.8) individuals (P = 0.028, n = 46 per group). CXCR4 expression on non-classical monocytes significantly correlated with cardiovascular and HIV-related risk factors including systolic blood pressure, platelet and T cell counts along with duration of antiretroviral therapy (P < 0.05). In regression analyses, adjusted for education level, study site, and injection drug use, presence of HIV infection and sCVD remained significantly associated with lower CXCR4 expression on non-classical monocytes (P = 0.003), but did not differ in classical or intermediate monocytes.

CONCLUSION

CXCR4 expression in non-classical monocytes was significantly lower among women with both HIV infection and sCVD, suggesting a potential atheroprotective role of CXCR4 in non-classical monocytes.

Interferon-γ upregulates Δ42PD1 expression on human monocytes via the PI3K/AKT pathway

BACKGROUND

We recently identified a novel alternatively spliced isoform of human programmed cell death 1 (PD-1), named Δ42PD1, which contains a 42-base-pair in-frame deletion compared with the full-length PD-1. Δ42PD1 is likely constitutively expressed on human monocytes and down-regulated in patients infected with human immunodeficiency virus type 1 (HIV-1). The mechanism underlying the regulation of Δ42PD-1 expression in monocytes remains unknown.

METHODS

By flow cytometry, we investigated the effect of Interferon-gamma (INF-γ) on the expression of Δ42PD1 in primary human monocytes as well as monocytic cell lines THP-1 and U937 cells. In addition, signaling pathway inhibitors and Δ42PD1-specific blocking antibody were used to explore the pathway involved in INF-γ-induced Δ42PD1 upregulation, and to elucidate the relationship between Δ42PD1 and TNF-α or IL-6 production by INF-γ primed monocytes in response to pre-fixed E. coli. Furthermore, we assessed T-cell proliferation, activation and cytokine production as enriched CD4⁺ T cells were co-cultured with THP-1 or U937 cells, with or without Δ42PD1-blocking antibody.

RESULTS

Treatment of human peripheral blood mononuclear cells (PBMCs) with IFN-γ resulted in an approximately 4-fold increase in the expression of Δ42PD1 on monocytes. Similarly, IFN-γ upregulates Δ42PD1 expression on human monocytic cell lines THP-1 and U937, in a time- and dose-dependent manner. IFN-γ-induced Δ42PD1 upregulation was abolished by JAK inhibitors Ruxolitinib and Tasocitinib, PI3K inhibitor LY294002, and AKT inhibitor MK-2206, respectively, but not by STAT1 inhibitor and MAPK signaling pathway inhibitors. JAK, PI3K-AKT, and MAPK signaling inhibitors abolished effectively the production of TNF-α and IL-6 in INF-γ-primed monocytes in response to pre-fixed E. coli. In contrast, Δ42PD1-specific blocking antibody did not affect the IFN-γ-induced priming effect. Furthermore, the MFI ratio of Δ42PD1 to full-length PD-1 (PD-1 Δ/F ratio) was significantly and positively correlated with TNF-α (P =  0.0289, r = 0.6038) produced by circulating CD14⁺ monocytes in response to pre-fixed E. coli. Notably, Δ42PD1 blockage significantly inhibited CD4⁺ T-cells proliferation and cytokine production in the co-culture conditions.

CONCLUSIONS

We demonstrated that IFN-γ increases Δ42PD1 expression on human monocytes via activating the PI3K/AKT signaling pathway downstream of JAKs, and that the PD-1 Δ/F ratio is a potential biomarker to predict the functional state of monocytes. Notably, we revealed the Δ42PD1 play a role in T-cell regulation, providing a novel potential approach to manipulate adaptive immune response.

Reduction in terminally differentiated T cells in virologically controlled HIV-infected aging patients on long-term antiretroviral therapy

Several studies have shown an increased accumulation of terminally differentiated T cells during HIV infection, suggestive of exhaustion/senescence, causing dysregulation of T cell homeostasis and function and rapid HIV disease progression. We have investigated whether long-term antiretroviral therapy (ART), which controls viremia and restores CD4 T cell counts, is correlated with reduction in terminally differentiated T cells, improved ratios of naïve to memory and function of T cells in 100 virologically controlled HIV-infected patients. We show that while the median frequencies of terminally differentiated CD4⁺ and CD8⁺ T cells (CD28^-, CD27^-, CD57⁺ and CD28^-CD57⁺), were higher in the virologically controlled HIV-infected patients’ cohort compared with uninfected individuals’ cohort, the frequencies of these cells significantly decreased with increasing CD4 T cell counts in HIV-infected patients. Although, the naïve CD4⁺ and CD8⁺ T cells were lower in HIV patients’ cohort than uninfected cohort, there was a significant increase in both naïve CD4⁺ and CD8⁺ T cells with increasing CD4 T cell counts in HIV-infected patients. The underlying mechanism behind this increased naïve CD4⁺ and CD8⁺ T cells in HIV-infected patients was due to an increase in recent thymic emigrants, CD4⁺CD31⁺, as compared to CD4⁺CD31^-. The CD4⁺ T cells of HIV-infected patients produced cytokines, including IL-2, IL-10 and IFN-γ comparable to uninfected individuals. In conclusion, virologically controlled HIV-infected patients on long-term ART show a significant reduction in terminally differentiated T cells, suggestive of decreased exhaustion/senescence, and improvement in the ratios of naïve to memory and function of T cells.

Poly (I:C) and LPS induce distinct immune responses by ovarian stromal fibroblasts

Despite its anatomical location, the ovary is a site of pathogen exposure in the human female reproductive tract (FRT). However, the role of ovarian stromal fibroblasts in immune protection is unclear. We generated a population of ovarian stromal fibroblasts derived from normal human ovaries that expressed the pattern recognition receptors TLR3, TLR4, RIG-I, & MDA5. Poly (I:C) and LPS, respective mimics of viral and bacterial infections, selectively upregulated antiviral gene expression and secretion of chemokines and antimicrobials. Poly (I:C) exclusively stimulated the expression of interferon (IFN) β, IFNλ1, and the IFN-stimulated gene OAS2. Poly (I:C) also significantly increased secretion of elafin, CCL20, and RANTES, but had no effect on SDF-1α. In contrast, LPS had no effect on IFN or ISG expression but significantly increased secretion of RANTES and SDF-1α. Secretions from poly (I:C)-treated fibroblasts had both greater anti-HIV activity and induced higher levels of CD4 + T cell chemotaxis than those from LPS-treated cells. Our studies demonstrate a potential key role for ovarian fibroblasts in innate immune protection against incoming pathogens in the normal ovary.

Protein phosphatase, Mg2+/Mn2+-dependent 1A controls the innate antiviral and antibacterial response of macrophages during HIV-1 and Mycobacterium tuberculosis infection

Co-infection with HIV-1 and Mycobacterium tuberculosis (Mtb) is a major public health issue. While some research has described how each pathogen accelerates the course of infection of the other pathogen by compromising the immune system, very little is known about the molecular biology of HIV-1/Mtb co-infection at the host cell level. This is somewhat surprising, as both pathogens are known to replicate and persist in macrophages. We here identify Protein Phosphatase, Mg²⁺/Mn²⁺-dependent 1A (PPM1A) as a molecular link between Mtb infection and increased HIV-1 susceptibility of macrophages. We demonstrate that both Mtb and HIV-1 infection induce the expression of PPM1A in primary human monocyte/macrophages and THP-1 cells. Genetic manipulation studies revealed that increased PPMA1 expression rendered THP-1 cells highly susceptible to HIV-1 infection, while depletion of PPM1A rendered them relatively resistant to HIV-1 infection. At the same time, increased PPM1A expression abrogated the ability of THP-1 cells to respond to relevant bacterial stimuli with a proper cytokine/chemokine secretion response, blocked their chemotactic response and impaired their ability to phagocytose bacteria. These data suggest that PPM1A, which had previously been shown to play a role in the antiviral response to Herpes Simplex virus infection, also governs the antibacterial response of macrophages to bacteria, or at least to Mtb infection. PPM1A thus seems to play a central role in the innate immune response of macrophages, implying that host directed therapies targeting PPM1A could be highly beneficial, in particular for HIV/Mtb co-infected patients.

CD4 regulatory T cells augment HIV-1 expression of polarized M1 and M2 monocyte derived macrophages

Previous in vitro studies have shown that the HIV-1 virus can alter the cytokine/chemokine profile of polarized macrophages which may lead to their increased susceptibility to viral infection. Here, we found that M2 monocyte derived macrophages (MDM) were significantly more permissive to productive infection by R5-tropic HIV-1 strains, including transmitted founder (T/F) viruses, than M1 MDM. Previous in vitro studies by our lab showed that regulatory T cells (Tregs) suppress HIV-1 infection in non-Treg CD4 T cells. Here, we investigated potential inhibitory effects of Tregs on HIV-1 infection of polarized MDM. We found that Tregs significantly increased HIV-1 infection in M1 and M2 MDM via a mechanism that was cell contact dependent. These findings suggest a potential role for Tregs in HIV-1 infection of tissue resident macrophages of M1 and M2 phenotype, which may contribute to the establishment and pathogenesis of HIV-1 disease.

Increase in HIV Receptors/Co-receptors/α-defensins in Inflamed Human Gingiva

Transmission of HIV-1 through the oral cavity is considered to be a rare event. To identify factors in resistance/susceptibility to oral HIV-1 infection, we analyzed expression in human gingiva of HIV-1 receptors Langerin, DC-SIGN, MR, and GalCer, HIV-1 co-receptors CCCR5, CXCR4, and anti-microbial protein α-defensin-1. Our results show that healthy gingiva is infiltrated with cells expressing all HIV-1 receptors tested; however, there are very few CCR5+ cells and a complete absence of CXCR4+ cells in the lamina propria. In chronic periodontitis (CP), DC-SIGN, MR, CXCR4, and CCR5 increase, but this was accompanied by a ten-fold increase in α-defensin-1 mRNA. The CCR5+ cells were revealed to be T-cells, macrophages, and dermal dendritic cells. Moreover, epithelial expression of GalCer and CXCR4 together was not apical and showed no trend with underlying inflammation. Thus, low expression of HIV-1 co-receptors in health and high expression of α-defensin during CP may comprise endogenous factors that provide protection from oral HIV-1 infection.

HIV-infected CD4+ T Cells Use T-bet-dependent Pathway for Production of IL-10 Upon Antigen Recognition

Interleukin (IL)-10 has been implicated in persistence of pathogens in a number of chronic infections. Infected CD4+ cells upon reactivation with HIV antigens were also shown to produce IL-10, which might contribute to their persistence. Hence, it is crucial to determine mechanisms regulating IL-10 production after activation with HIV antigens for devising effective blocking strategies. In this study, ERK-, T-bet- and FoxP3-dependent pathways were evaluated for their possible roles in IL-10 production by infected CD4+ cells after reactivation with HIV Env. Intracellular and secreted IL-10 levels were determined by flow cytometry and Bioplex assay after treating PBMCs with PD98059, tipifarnib and cyclosporin A for blocking of ERK-, T-bet-and FoxP3-dependent pathways, respectively. Baseline levels of T-bet, pERK were higher in P24+ CD4+ cells as compared to uninfected CD4+ cells, which increased further after activation with Env. Inhibition of T-bet resulted in 2.3-fold reduction of IL-10 expression whereas ERK and FoxP3 inhibition failed to cause suppression of IL-10 expression. Conversely, IL-10 secreted by PBMCs was inhibited maximally after ERK inhibition suggesting its role in regulation of cytokine secretory pathway. IFN-γ was found to be suppressed after treatment with inhibitors of all these pathways. Thus, the study highlighted need for IL-10 blockade along with the use of antigens for therapeutic vaccinations or latency reversal and identified the T-bet-dependent pathway as an important pathway regulating IL-10 production by infected CD4+ cells. However, simultaneous blockade of IFN-γ precludes use of inhibitor of this pathway as an IL-10 blocking strategy.

Subtypes of depressive symptoms and inflammatory biomarkers: An exploratory study on a sample of HIV-positive patients

Depressive symptoms cause major impairment and may accelerate HIV progression despite the use of antiretroviral medication. The somatic symptoms criteria for HIV infection and depression partially overlap, which can make differential diagnosis challenging. Because of chronic inflammation caused by HIV infection, HIV-positive patients may develop somatic and affective-cognitive symptoms of depression. Inflammation-related depression is primarily characterized with severe somatic symptoms such as fatigue and sleep disturbance. This study sought to explore the patterns of somatic and cognitive-affective depressive symptoms that characterize HIV-positive patients. Our specific aims were (1) to identify subtypes of depressive symptoms in a sample of HIV-positive patients; and (2) to test the subtypes' difference on inflammatory and HIV disease progression biomarkers. HIV-positive men and women (N=102) with and without depressive symptoms were randomly selected from an Italian HIV clinic. Depressive symptoms (PHQ-9), viral load (VL), CD4+, Il-6, TNF-α, and monocytes were assessed. The three subtypes formed using Latent Class Analysis (LCA) identified patients with (1) severe cognitive-affective and somatic depressive symptoms; (2) severe/moderate somatic symptoms; and (3) absent or low depressive symptoms. The subtype with severe/moderate somatic symptoms was characterized with elevated levels of Il-6 and monocytes. No difference on HIV progression biomarkers was found. The subtypes of depressive symptoms might help differentiating depressive symptoms from HIV- and inflammatory-related somatic symptoms. When present, cognitive-affective and/or somatic symptoms cause significant impairment to patients' lives and thus warrant further assessment and treatment.

Fibrocytes Differ from Macrophages but Can Be Infected with HIV-1

Fibrocytes (fibroblastic leukocytes) are recently identified as unique hematopoietic cells with features of both macrophages and fibroblasts. Fibrocytes are known to contribute to the remodeling or fibrosis of various injured tissues. However, their role in viral infection is not fully understood. In this study, we show that differentiated fibrocytes are phenotypically distinguishable from macrophages but can be infected with HIV-1. Importantly, fibrocytes exhibited persistently infected cell-like phenotypes, the degree of which was more apparent than macrophages. The infected fibrocytes produced replication-competent HIV-1, but expressed HIV-1 mRNA at low levels and strongly resisted HIV-1-induced cell death, which enabled them to support an extremely long-term HIV-1 production at low but steady levels. More importantly, our results suggested that fibrocytes were susceptible to HIV-1 regardless of their differentiation state, in contrast to the fact that monocytes become susceptible to HIV-1 after the differentiation into macrophages. Our findings indicate that fibrocytes are the previously unreported HIV-1 host cells, and they suggest the importance of considering fibrocytes as one of the long-lived persistently infected cells for curing HIV-1.

Twelve-Month Antiretroviral Therapy Suppresses Plasma and Genital Viral Loads but Fails to Alter Genital Levels of Cytokines, in a Cohort of HIV-Infected Rwandan Women

Background

Genital viral load (GVL) is the main determinant of sexual transmission of human immune-deficiency virus (HIV). The effect of antiretroviral therapy (ART) on local cervico-vaginal immunological factors associated with GVL is poorly described. We aimed to identify the risk factors of detectable GVL, and the impact of ART on HIV genital shedding and its correlates in a cohort of HIV-infected women, attending HIV care in Kigali, Rwanda.

Materials and Methods

All participants were evaluated for GVL, plasma viral load (PVL), CD4 count, various sexually-transmitted infections (STIs) at baseline and at month 12. Genital concentration of 19 cytokines and mRNA expression of APOBEC3G and BST2, two host HIV restriction factors, were evaluated at baseline in all participants. Cytokine levels were re-assessed at month 12 only in participants eligible for ART at baseline. Risk factors of GVL ≥40copies/mL at baseline and month 12 were assessed using logistic regression. Effect of 12-month ART on various local and systemic immunological parameters was examined using a paired t-test and McNemar as appropriate.

Results

96 of the 247 women enrolled in the study were eligible for ART. After 12 months of ART, PVL and GVL decreased to undetectable level in respectively 74 and 88% of treated participants. ART did not affect cytokine levels. HIV genital shedding occurred only when PVL was detectable. At baseline, GVL was independently associated with IL-1β after controlling for PVL, age and N. gonorrhea infection (95% CI 1.32-2.15) and at month 12 with MIP-1β (95% CI 0.96-21.32) after controlling for baseline GVL, PVL and month 12 IL-8.

Conclusion

Suppressive ART does not necessarily reduce genital level of immune activation. Minimizing all conditions favoring genital inflammation, including active detection and treatment of STIs, might reduce the risk of HIV transmission as supplement to the provision of potent ART.

Tuberculosis and HIV Coinfection

Tuberculosis (TB) and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) constitute the main burden of infectious disease in resource-limited countries. In the individual host, the two pathogens, Mycobacterium tuberculosis and HIV, potentiate one another, accelerating the deterioration of immunological functions. In high-burden settings, HIV coinfection is the most important risk factor for developing active TB, which increases the susceptibility to primary infection or reinfection and also the risk of TB reactivation for patients with latent TB. M. tuberculosis infection also has a negative impact on the immune response to HIV, accelerating the progression from HIV infection to AIDS. The clinical management of HIV-associated TB includes the integration of effective anti-TB treatment, use of concurrent antiretroviral therapy (ART), prevention of HIV-related comorbidities, management of drug cytotoxicity, and prevention/treatment of immune reconstitution inflammatory syndrome (IRIS).

Interactions between HIV-1 and mucosal cells in the female reproductive tract

Worldwide, the heterosexual route is the prevalent mode of HIV-1 transmission, and the female reproductive tract accounts for approximately 40% of all HIV-1 transmissions. HIV-1 infection in the female reproductive tract involves three major events: entry through the mucosal epithelium, productive infection in subepithelial mononuclear cells, and delivery to lymph nodes to initiate systemic infection. Here, we provide a focused review of the interaction between HIV-1 and mucosal epithelial cells, lymphocytes, macrophages, and dendritic cells in female genital mucosa. Increased understanding of these interactions could illuminate new approaches for interdicting HIV-1 heterosexual transmission.

Temporal association between incident tuberculosis and poor virological outcomes in a South African antiretroviral treatment service

Introduction:

The temporal relationship between incident tuberculosis (TB) and virological outcomes during antiretroviral therapy (ART) is poorly defined. This was studied in a cohort in Cape Town, South Africa.

Methods:

Data regarding TB diagnoses, ART regimens, and 4-monthly updated viral load (VL) and CD4 count measurements were extracted from a prospectively maintained database. Rates of virological breakthrough (VL > 1000 copies/mL) and failure (VL > 1000 copies/mL on serial measurements) following initial VL suppression were calculated. Poisson models were used to calculate incidence rate ratios (IRRs) and identify risk factors for these virological outcomes.

Results:

Incident TB was diagnosed in 391 (28.5%) of 1370 patients during a median of 5.2 years follow-up. Five hundred seventy-eight episodes of virological breakthrough and 231 episodes of virological failure occurred, giving rates of 10.0 episodes per 100 person-years and 4.0 episodes per 100 person-years, respectively. In multivariate analyses adjusted for baseline and time-updated risk factors, TB was an independent risk factor for adverse virological outcomes. These associations were strongly time dependent; the 6-month period following diagnosis of incident TB was associated with a substantially increased risk of virological breakthrough (IRR: 2.3, 95% confidence interval: 1.7 to 3.2) and failure (IRR: 2.6, 95% confidence interval: 1.6 to 4.3) compared with time without a TB diagnosis. Person-time preceding TB diagnosis or more than 6 months after a TB diagnosis was not associated with poor virological outcomes.

Conclusions:

Incident TB during ART was strongly associated with poor virological outcomes during the 6-month period following TB diagnosis. Although underlying mechanisms remain to be defined, patients with incident TB may benefit from virological monitoring and treatment adherence support.

The CD8-derived chemokine XCL1/lymphotactin is a conformation-dependent, broad-spectrum inhibitor of HIV-1

CD8+ T cells play a key role in the in vivo control of HIV-1 replication via their cytolytic activity as well as their ability to secrete non-lytic soluble suppressive factors. Although the chemokines that naturally bind CCR5 (CCL3/MIP-1α, CCL4/MIP- 1β, CCL5/RANTES) are major components of the CD8-derived anti-HIV activity, evidence indicates the existence of additional, still undefined, CD8-derived HIV-suppressive factors. Here, we report the characterization of a novel anti-HIV chemokine, XCL1/lymphotactin, a member of the C-chemokine family that is produced primarily by activated CD8+ T cells and behaves as a metamorphic protein, interconverting between two structurally distinct conformations (classic and alternative). We found that XCL1 inhibits a broad spectrum of HIV-1 isolates, irrespective of their coreceptor-usage phenotype. Experiments with stabilized variants of XCL1 demonstrated that HIV-1 inhibition requires access to the alternative, all-β conformation, which interacts with proteoglycans but does not bind/activate the specific XCR1 receptor, while the classic XCL1 conformation is inactive. HIV-1 inhibition by XCL1 was shown to occur at an early stage of infection, via blockade of viral attachment and entry into host cells. Analogous to the recently described anti-HIV effect of the CXC chemokine CXCL4/PF4, XCL1-mediated inhibition is associated with direct interaction of the chemokine with the HIV-1 envelope. These results may open new perspectives for understanding the mechanisms of HIV-1 control and reveal new molecular targets for the design of effective therapeutic and preventive strategies against HIV-1.

Although HIV, the causative agent of AIDS, establishes a lifelong infection that cannot be eradicated even with effective treatment, the host immune system has the ability to contain its replication for many years in which the disease remains asymptomatic. Key players in HIV control are CD8+ T cells, specialized immune cells that can not only destroy infected cells, but also secrete soluble factors that suppress the virus without killing infected cells. CD8+ T cells produce multiple HIV-suppressive factors, including certain chemokines (soluble proteins that attract immune cells), which block the virus even before it can gain access to its target cells. In the present study, we characterize a new anti-HIV chemokine, XCL1 or lymphotactin, which is primarily produced by CD8+ T cells. A unique feature of XCL1 is that, unlike other antiviral chemokines, it has a very broad spectrum of activity against different variants of HIV-1 and directly binds the virus outer coat, rather than blocking specific receptors on the target cell. Also unique is that fact that XCL1 adopts two possible conformations, and only one of them is capable of HIV inhibition. These findings may open new avenues for the design of effective drugs or vaccines against HIV.

HIV-Mycobacterium tuberculosis co-infection: a 'danger-couple model' of disease pathogenesis

Tuberculosis (TB) and human immunodeficiency virus (HIV) infection interfere and impact the pathogenesis phenomena of each other. Owing to atypical clinical presentations and diagnostic complications, HIV/TB co-infection continues to be a menace for healthcare providers. Although the increased access to highly active antiretroviral therapy (HAART) has led to a reduction in HIV-associated opportunistic infections and mortality, the concurrent management of HIV/TB co-infection remains a challenge owing to adverse effects, complex drug interactions, overlapping toxicities and tuberculosis -associated immune reconstitution inflammatory syndrome. Several hypotheses have been put forward for the exacerbation of tuberculosis by HIV and vice versa supported by immunological studies. Discussion on the mechanisms produced by infectious cofactors with impact on disease pathology could shed light on how to design potential interventions that could decelerate disease progression. With no vaccine for HIV and lack of an effective vaccine for tuberculosis, it is essential to design strategies against HIV-TB co-infection.

Cystic echinococcosis in South Africa: the worst yet to come?

A considerable number of cases of cystic echinococcosis (CE) are reported from South Africa, but the exact epidemiology remains unknown. In addition, southern Africa is one of the global regions worst afflicted by an excessively high HIV- and TB co-endemicity. As deductable from anecdotal observation, the immune modulation caused by all three diseases seems to affect the clinical courses of all of them. Due to the ongoing high HIV and TB infection rates and the long latency period of CE, South Africa may experience increasing numbers of CE with potentially unusual and severe clinical courses due to concomitant immune suppression. The extent of the problem and the additional complexity of appropriate patient care remain to be recognized.

Design, syntheses, and characterization of pharmacophore based chemokine receptor CCR5 antagonists as anti prostate cancer agents

Accumulating evidence has shown multiple roles that chemokine receptor CCR5 may play to promote the progression of several types of cancer. The mechanism of such promotion is believed to involve chronic inflammation that creates a microenvironment which enhances tumor survival. Therefore, blocking CCR5 function with an antagonist may provide a novel treatment of cancers such as prostate cancer. Currently, several CCR5 antagonists are available, but all have been optimized for their inhibitory activity on HIV-1 cellular membrane invasion process rather than inhibition on cytoplasmic signaling pathways. Thus, there is need to develop CCR5 antagonists focusing on blockage of CCR5 downstream signaling and inhibition of CCR5 related prostate cancer proliferation and progression. In this report, a pharmacophore analysis was conducted based on docking studies of several known CCR5 antagonists in a CCR5 homology model. A unique structural skeleton for CCR5 antagonist was constructed and functionalized, resulting in a new series of small molecules to be synthesized and characterized. A combination of CCR5 calcium flux inhibition, anti prostate cancer cell proliferation, basal cytotoxicity, and in vivo animal model studies were applied to screen the newly synthesized compounds. Results from this study provided a potential lead compound for future CCR5 antagonist development focusing on prostate cancer therapy.

Efficient influenza A virus replication in the respiratory tract requires signals from TLR7 and RIG-I

Induction of a proinflammatory response is the hallmark of host innate defense against invading pathogens. Host recognition of influenza A virus (IAV) infection relies on pattern-recognition receptors, including Toll-like receptor 7 (TLR7) and retinoic acid inducible gene-1 (RIG-I) for the activation of innate-immune responses. Here, we show that following a physiological low dose of IAV infection, viral sensing by either TLR7 or RIG-I induces a proinflammatory program that promotes viral replication. Transfer of bronchoalveolar lavage from infected wild-type mice into the airway of mice deficient in TLR7 and RIG-I pathways was sufficient to restore viral replication efficiency. Comparison of IAV-infected cells revealed that inflammatory mediators elicited by TLR7 and RIG-I signaling recruit viral target cells to the airway, thereby enhancing viral load within the respiratory tract. Our data suggest that IAV uses physiological levels of inflammatory responses for its replicative advantage and highlight the complex interplay between viruses and the host innate-immune responses.

A multi-targeted drug candidate with dual anti-HIV and anti-HSV activity

Human immunodeficiency virus (HIV) infection is often accompanied by infection with other pathogens, in particular herpes simplex virus type 2 (HSV-2). The resulting coinfection is involved in a vicious circle of mutual facilitations. Therefore, an important task is to develop a compound that is highly potent against both viruses to suppress their transmission and replication. Here, we report on the discovery of such a compound, designated PMEO-DAPym. We compared its properties with those of the structurally related and clinically used acyclic nucleoside phosphonates (ANPs) tenofovir and adefovir. We demonstrated the potent anti-HIV and -HSV activity of this drug in a diverse set of clinically relevant in vitro, ex vivo, and in vivo systems including (i) CD4⁺ T-lymphocyte (CEM) cell cultures, (ii) embryonic lung (HEL) cell cultures, (iii) organotypic epithelial raft cultures of primary human keratinocytes (PHKs), (iv) primary human monocyte/macrophage (M/M) cell cultures, (v) human ex vivo lymphoid tissue, and (vi) athymic nude mice. Upon conversion to its diphosphate metabolite, PMEO-DAPym markedly inhibits both HIV-1 reverse transcriptase (RT) and HSV DNA polymerase. However, in striking contrast to tenofovir and adefovir, it also acts as an efficient immunomodulator, inducing β-chemokines in PBMC cultures, in particular the CCR5 agonists MIP-1β, MIP-1α and RANTES but not the CXCR4 agonist SDF-1, without the need to be intracellularly metabolized. Such specific β-chemokine upregulation required new mRNA synthesis. The upregulation of β-chemokines was shown to be associated with a pronounced downmodulation of the HIV-1 coreceptor CCR5 which may result in prevention of HIV entry. PMEO-DAPym belongs conceptually to a new class of efficient multitargeted antivirals for concomitant dual-viral (HSV/HIV) infection therapy through inhibition of virus-specific pathways (i.e. the viral polymerases) and HIV transmission prevention through interference with host pathways (i.e. CCR5 receptor down regulation).

To contain the HIV-1 epidemic, it is necessary to develop antivirals that prevent HIV-1 transmission. It is well known that HIV infection might be accompanied by other pathogens, which often are engaged with HIV-1 in a vicious circle of mutual facilitation. One of the most common of these pathogens is herpes simplex virus (HSV) type 2. Since there is an urgent need for a next generation antivirals that are multi-targeted, we can now report on the development of the first antiviral of this new generation that efficiently suppresses both HIV-1 and HSV-2. We found that the dual-targeted antiviral drug affects several targets for viral replication. It uniquely combines in one molecule three important abilities: (i) to efficiently suppress HSV-encoded DNA polymerase, (ii) to efficiently suppress HIV-1-encoded reverse transcriptase, and (iii) to stimulate secretion of CC-chemokines that downregulate the HIV-1 coreceptor CCR5. The compound suppresses both viruses in a wide-range of in vitro, ex vivo, and in vivo experimental models. The ability of one molecule to suppress HIV-1 and HSV-2 by combining direct activity against their two key enzymes and indirect immunomodulatory effects is unique in the antiviral field.

Heme oxygenase-1 induction alters chemokine regulation and ameliorates human immunodeficiency virus-type-1 infection in lipopolysaccharide-stimulated macrophages

We have elucidated a putative mechanism for the host resistance against HIV-1 infection of primary human monocyte-derived macrophages (MDM) stimulated with lipopolysaccharide (LPS). We show that LPS-activated MDM both inhibited HIV-1 entry into the cells and were refractory to post-entry productive viral replication. LPS-treated cells were virtually negative for mature virions as revealed by transmission electron microscopy. LPS activation of MDM markedly enhanced the expression of heme oxygenase-1 (HO-1), a potent inducible cytoprotective enzyme. Increased HO-1 expression was accompanied by elevated production of macrophage inflammatory chemokines (MIP1α and MIP1β) by LPS-activated MDM, significantly decreased surface chemokine receptor-5 (CCR-5) expression, and substantially reduced virus replication. Treatment of cells with HO-1 inhibitor SnPP IX (tin protoporphyrin IX) attenuated the LPS-mediated responses, HIV-1 replication and secretion of MIP1α, MIP1β, and LD78β chemokines with little change in surface CCR-5 expression. These results identify a novel role for HO-1 in the modulation of host immune response against HIV infection of MDM.

Cellular pharmacology and potency of HIV-1 nucleoside analogs in primary human macrophages

Understanding the cellular pharmacology of antiretroviral agents in macrophages and subsequent correlation with antiviral potency provides a sentinel foundation for definition of the dynamics between antiretroviral agents and viral reservoirs across multiple cell types, with the goal of eradication of HIV-1 from these cells. Various clinically relevant nucleoside antiviral agents, and the integrase inhibitor raltegravir, were selected for this study. The intracellular concentrations of the active metabolites of the nucleoside analogs were found to be 5- to 140-fold lower in macrophages than in lymphocytes, and their antiviral potency was significantly lower in macrophages constitutively activated with macrophage colony-stimulating factor (M-CSF) during acute infection than in resting macrophages (EC(50), 0.4 to 9.42 μM versus 0.03 to 0.4 μM, respectively). Although tenofovir-treated cells displayed significantly lower intracellular drug levels than cells treated with its prodrug, tenofovir disoproxil fumarate, the levels of tenofovir-diphosphate for tenofovir-treated cells were similar in lymphocytes and macrophages. Raltegravir also displayed significantly lower intracellular concentrations in macrophages than in lymphocytes, independent of the activation state, but had similar potencies in resting and activated macrophages. These data underscore the importance of delivering adequate levels of drug to macrophages to reduce and eradicate HIV-1 infection.

The Impact of Macrophage Nucleotide Pools on HIV-1 Reverse Transcription, Viral Replication, and the Development of Novel Antiviral Agents

Macrophages are ubiquitous and represent a significant viral reservoir for HIV-1. Macrophages are nondividing, terminally differentiated cells, which have a unique cellular microenvironment relative to actively dividing T lymphocytes, all of which can impact HIV-1 infection/replication, design of inhibitors targeting viral replication in these cells, emergence of mutations within the HIV-1 genome, and disease progression. Scarce dNTPs drive rNTP incorporation into the proviral DNA in macrophages but not lymphocytes. Furthermore, the efficacy of a ribose-based inhibitor that potently inhibits HIV-1 replication in macrophages, has prompted a reconsideration of the previously accepted dogma that 2′-deoxy-based inhibitors demonstrate effective inhibition of HIV-1 replication. Additionally, higher levels of dUTP and rNTP incorporation in macrophages, and lack of repair mechanisms relative to lymphocytes, provide a further mechanistic understanding required to develop targeted inhibition of viral replication in macrophages. Together, the concentrations of dNTPs and rNTPs within macrophages comprise a distinctive cellular environment that directly impacts HIV-1 replication in macrophages and provides unique insight into novel therapeutic mechanisms that could be exploited to eliminate virus from these cells.

The potential role of anibamine, a natural product CCR5 antagonist, and its analogues as leads toward development of anti-ovarian cancer agents

Chemokines and their receptors play important roles in the development of primary tumors and their metastases. Particularly CC chemokine receptor 5 (CCR5) and its ligand CC chemokine ligand 5 (CCL5/RANTES) seem to be critical in proliferation and invasion of ovarian cancer, the leading cause of death from gynecological malignancies in the United States. Anibamine, the first natural product CCR5 antagonist, and its analogues were examined for their effects on proliferation of the OVCAR-3 ovarian cancer cells in order to validate their candidacy as leads to develop novel anti-ovarian cancer agents. Acting as CCR5 antagonists, anibamine and its analogues significantly suppressed CCL5-induced intracellular Ca(2+) flux. The compounds also inhibited the proliferation of OVCAR-3 at micromolar to submicromolar range. Moreover, anibamine and several analogues did not show significant cytotoxicity in NIH 3T3 cells at concentrations up to 20μM. Based on these results, anibamine and one of its synthetic analogues were defined as potential leads to develop novel agents against ovarian cancer.

Immune activation in the pathogenesis of treated chronic HIV disease: a workshop summary

With the advent of highly effective antiretroviral therapy (ART), infection with human immunodeficiency virus (HIV) has become a chronic disease rather than a death sentence. Nevertheless, effectively treated individuals have a higher than normal risk for developing noninfectious comorbidities, including cardiovascular and renal disease. Although traditional risk factors of aging as well as treatment toxicity contribute to this risk, many investigators consider chronic HIV-associated inflammation a significant factor in such end-organ disease. Despite effective viral suppression, chronic inflammation persists at levels higher than in uninfected people, yet the stimuli for the inflammation and the mechanism by which inflammation persists and promotes disease pathology remain incompletely understood. This critical gap in scientific understanding complicates and hampers effective decision making about appropriate medical intervention. To better understand the mechanism(s) of chronic immune activation in treated HIV disease, three questions need answers: (1) what is the cause of persistent immune activation during treated HIV infection, (2) what are the best surrogate markers of chronic immune activation in this setting, and (3) what therapeutic intervention(s) could prevent or reverse this process? The NIH sponsored and convened a meeting to discuss the state of knowledge concerning these questions and the best course for developing effective therapeutic strategies. This report summarizes the findings of that NIH meeting.

Molecular mechanisms of HIV-1 infection in neonatal target cells

HIV-1-infected neonates and infants have a higher viral load and progress to symptomatic AIDS more rapidly than their own infected mothers, as well as other infected adults, with differences in clinical manifestations, recurrent bacterial infections and CNS disorders. Two major reasons have been attributed to this differential HIV pathogenesis and disease; the relative immaturity of the neonate’s immune system and it’s inability to contain the highly replicating and mutating HIV-1, and the more efficient replication of HIV-1 in neonatal cells than in adult target cells. In this context, it has been demonstrated that HIV-1 replicates more efficiently in neonatal (cord) blood monocytes/macrophages and T lymphocytes – including naive and memory T lymphocytes – compared with adult blood cells. We have also determined the mechanisms of the differential HIV-1 replication in cord versus adult blood monocytes/macrophages and T lymphocytes (naive and memory), finding that it was influenced at the level of HIV-1 gene expression. The increased HIV-1 gene expression in neonatal versus adult target cells was regulated by differential expression of host factors, transcription factors (NF-κB, E2F, HAT-1, TFIIE, Cdk9 and Cyclin T1), signal transducers (STAT3 and STAT5A) and cytokines (IL-1β, IL-6 and IL-10). We also showed that nuclear extracts from cord cells interacted with HIV-1 long terminal repeat cis-acting sequences, including NF-κB, NFAT, AP1 and NF-IL6, to a greater extent when compared with adult peripheral blood mononuclear cell nuclear extracts. Additionally, shRNA of retroviral origin for STAT3 and IL-6 downregulated both their own gene expression as well as that of HIV-1, indicating that these factors influenced the differential expression of HIV-1 genes in cord cells compared with adult cells. In addition, HIV-1 integration plays an important role in differential HIV-1 replication and gene expression in neonatal versus adult cells by integrating into more actively transcribed genes in neonates compared with adults. We characterized 468 HIV-1 integration sites within cord and adult blood T lymphocytes and monocytes/macrophages, including genes coding for cellular components, and those involved with maintenance of the intracellular environment, enzyme regulation, cellular metabolism, catalytic activity and cation transport, as well as several potential transcription factor binding sites at the sites of integration. Additionally, the genes at the integration sites, transcription factors and transcription binding sites were expressed at higher levels in cord than adult target cells. In summary, the increased HIV-1 gene expression and replication in neonatal target cells due to differential expression of host factors all contribute to an increased viral load and faster disease progression in neonates and infants when compared with similar situations in adult patients. Based on these findings, it may be possible to identify new viral and host targets for use in developing strategies for the treatment and prevention of HIV-1.

Variable effect of co-infection on the HIV infectivity: within-host dynamics and epidemiological significance

Background

Recent studies have implicated viral characteristics in accounting for the variation in the HIV set-point viral load (spVL) observed among individuals. These studies have suggested that the spVL might be a heritable factor. The spVL, however, is not in an absolute equilibrium state; it is frequently perturbed by immune activations generated by co-infections, resulting in a significant amplification of the HIV viral load (VL). Here, we postulated that if the HIV replication capacity were an important determinant of the spVL, it would also determine the effect of co-infection on the VL. Then, we hypothesized that viral factors contribute to the variation of the effect of co-infection and introduce variation among individuals.

Methods

We developed a within-host deterministic differential equation model to describe the dynamics of HIV and malaria infections, and evaluated the effect of variations in the viral replicative capacity on the VL burden generated by co-infection. These variations were then evaluated at population level by implementing a between-host model in which the relationship between VL and the probability of HIV transmission per sexual contact was used as the within-host and between-host interface.

Results

Our within-host results indicated that the combination of parameters generating low spVL were unable to produce a substantial increase in the VL in response to co-infection. Conversely, larger spVL were associated with substantially larger increments in the VL. In accordance, the between-host model indicated that co-infection had a negligible impact in populations where the virus had low replicative capacity, reflected in low spVL. Similarly, the impact of co-infection increased as the spVL of the population increased.

Conclusion

Our results indicated that variations in the viral replicative capacity would influence the effect of co-infection on the VL. Therefore, viral factors could play an important role driving several virus-related processes such as the increment of the VL induced by co-infections. These results raise the possibility that biological differences could alter the effect of co-infection and underscore the importance of identifying these factors for the implementation of control interventions focused on co-infection.

Tuberculosis and HIV co-infection

Tuberculosis (TB) and HIV co-infections place an immense burden on health care systems and pose particular diagnostic and therapeutic challenges. Infection with HIV is the most powerful known risk factor predisposing for Mycobacterium tuberculosis infection and progression to active disease, which increases the risk of latent TB reactivation 20-fold. TB is also the most common cause of AIDS-related death. Thus, M. tuberculosis and HIV act in synergy, accelerating the decline of immunological functions and leading to subsequent death if untreated. The mechanisms behind the breakdown of the immune defense of the co-infected individual are not well known. The aim of this review is to highlight immunological events that may accelerate the development of one of the two diseases in the presence of the co-infecting organism. We also review possible animal models for studies of the interaction of the two pathogens, and describe gaps in knowledge and needs for future studies to develop preventive measures against the two diseases.

In utero activation of fetal memory T cells alters host regulatory gene expression and affects HIV susceptibility

In utero priming to malaria antigens renders cord blood mononuclear cells (CBMC) more susceptible to productive HIV infection in vitro in the absence of exogenous stimulation. This provides a unique model to better understand mechanisms affecting lymphocyte susceptibility to HIV infection in vivo. Effector memory CD3(+)CD4(+) T cells (T(EM)) were the exclusive initial targets of HIV with rapid spread to central memory cells. HIV susceptibility correlated with increased expression of CD25 and HLA-DR on T(EM). Virus entered all samples equally, however gag/pol RNA was only detected in HIV susceptible samples, suggesting regulation of proviral gene transcription. Targeted analysis of human genes in memory T cells showed greater expression of IFNG, NFATc1, IRF1, FOS, and PPIA and decreased expression YY1 and TFCP2 in HIV susceptible samples. Thus fetal priming to exogenous antigens enhances specific proviral gene transcription pathways in effector memory cells that may increase risk of vertical transmission of HIV.

Modulatory effects of the CCR5 antagonist maraviroc on microglial pro-inflammatory activation elicited by gp120

Despite important clinical benefits of the highly active antiretroviral therapy, neurological disorders affect approximately 50% of AIDS patients. In the brain, infected microglia release pro-inflammatory mediators as well as human immunodeficiency virus type 1 (HIV-1) proteins, like the envelope protein gp120, that sustain inflammation and mediate neuronal damage. Gp120 allows the virus entry in the host cells via binding to the CD4 receptor together with a specific co-receptor (CCR5/CXCR4). The antiretroviral drug maraviroc is a CCR5 receptor antagonist, approved for the treatment of HIV-experienced patients. By interfering with a chemokine receptor, highly expressed in microglia, maraviroc has the potential to modulate their activation during HIV-1 infection. To test this hypothesis, primary cultures of rat cortical microglia were activated by gp120. Gp120(CN54) , a protein derived by macrophage (M)-tropic viruses, showed strong pro-inflammatory action, thus it was used to test the effects of maraviroc. The latter displayed opposite effects, depending on whether or not interferon-γ (IFNγ) was also present in the system. IFNγ significantly enhanced gp120 proinflammatory activity, possibly via up-regulation of CCR5 receptor expression. In this experimental paradigm, maraviroc significantly increased microglial activation, thus suggesting that its chronic use can exacerbate neuronal pathology, especially in HIV-experienced patients with higher cerebral IFNγ levels.

Enhanced HIV-1 replication in ex vivo ectocervical tissues from post-menopausal women correlates with increased inflammatory responses

Knowledge about early innate immune responses at the mucosal surfaces of the female genital tract is important in understanding the pathogenesis of heterosexual transmission of human immunodeficiency virus type-1 (HIV-1). As estradiol decreases inflammatory responses, we postulated that an estradiol-deficient state such as post-menopause could enhance expression of inflammatory factors that stimulate HIV-1 replication. We compare HIV-1 integration, transcription, and viral p24 release levels among ectocervical tissues obtained from pre- and post-menopausal donors. We detected enhanced HIV-1 p24 release levels in post- compared with pre-menopausal tissues (P<0.0001), but saw no difference in HIV-1 integration. Overall, 100% of post-menopausal tissues exhibited levels of HIV-1 transcription above background compared with only 60% of pre-menopausal tissues. Increased HIV-1 transcription was associated with enhanced interleukin (IL)-1β, IL-6, monocyte chemotactic protein-1, growth-regulated oncogene-α, and interferon-γ-inducible protein-10 expression. Neutralization and nuclear factor-κB-targeting small-interfering RNA experiments both decreased HIV-1 transcription, suggesting that the early inflammatory response may facilitate HIV-1 replication in ex vivo ectocervical tissues from post-menopausal women.

The natural product CCR5 antagonist anibamine and its analogs as anti-prostate cancer agents

Prostate cancer is a leading cause of death among males in the United States. As the chemokine receptor CCR5 is over-expressed in more aggressive forms of prostate cancer, and is also a critical receptor in inflammation, chemokine receptor CCR5 antagonists could potentially act as anti-prostate cancer agents. Anibamine, a natural product CCR5 antagonist, provides a unique molecular scaffold for the generation of novel analogs with possible anti-prostate cancer activity. A series of analogs of anibamine were designed, synthesized and tested against several prostate cancer cell lines. The analogs all acted as CCR5 antagonists at micromolar range affinity to the receptor while their anti-proliferative activity varied depending on the cell line type and their chemical structural properties. Further basal cytotoxicity characterization on these compounds indicated some of them may be suitable for in vivo studies.

Stromal down-regulation of macrophage CD4/CCR5 expression and NF-κB activation mediates HIV-1 non-permissiveness in intestinal macrophages

Tissue macrophages are derived exclusively from blood monocytes, which as monocyte-derived macrophages support HIV-1 replication. However, among human tissue macrophages only intestinal macrophages are non-permissive to HIV-1, suggesting that the unique microenvironment in human intestinal mucosa renders lamina propria macrophages non-permissive to HIV-1. We investigated this hypothesis using blood monocytes and intestinal extracellular matrix (stroma)-conditioned media (S-CM) to model the exposure of newly recruited monocytes and resident macrophages to lamina propria stroma, where the cells take up residence in the intestinal mucosa. Exposure of monocytes to S-CM blocked up-regulation of CD4 and CCR5 expression during monocyte differentiation into macrophages and inhibited productive HIV-1 infection in differentiated macrophages. Importantly, exposure of monocyte-derived macrophages simultaneously to S-CM and HIV-1 also inhibited viral replication, and sorted CD4⁺ intestinal macrophages, a proportion of which expressed CCR5⁺, did not support HIV-1 replication, indicating that the non-permissiveness to HIV-1 was not due to reduced receptor expression alone. Consistent with this conclusion, S-CM also potently inhibited replication of HIV-1 pseudotyped with vesicular stomatitis virus glycoprotein, which provides CD4/CCR5-independent entry. Neutralization of TGF-β in S-CM and recombinant TGF-β studies showed that stromal TGF-β inhibited macrophage nuclear translocation of NF-κB and HIV-1 replication. Thus, the profound inability of intestinal macrophages to support productive HIV-1 infection is likely the consequence of microenvironmental down-regulation of macrophage HIV-1 receptor/coreceptor expression and NF-κB activation.

Human intestinal macrophages, unlike lymphoid tissue macrophages, brain microglia and genital (vaginal) macrophages, are profoundly incapable of supporting productive HIV-1 infection. Intriguingly, all macrophages are derived exclusively from blood monocytes, which are HIV-1 permissive after differentiation into monocyte-derived macrophages. Therefore, the unique non-permissiveness of intestinal macrophages to HIV-1 must be conferred by the intestinal mucosal microenvironment. Here we report that intestinal stroma potently blocked up-regulation of HIV-1 receptor/coreceptor CD4 and CCR5 expression during monocyte differentiation into macrophages and macrophage nuclear translocation of NF-κB, which is a critical requirement for HIV-1 transcription. These two mechanisms work collaboratively to render intestinal macrophages non-permissive to HIV-1. Harnessing this natural antiviral defense may provide a novel strategy to exploit for the prevention of infection in HIV-1 permissive cells.