Cell-type-dependent effect of transforming growth factor beta, a major cytokine in breast milk, on human immunodeficiency virus type 1 infection of mammary epithelial MCF-7 cells or macrophages

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Inhibition of miR-155 Promotes TGF-β Mediated Suppression of HIV Release in the Cervical Epithelial Cells

TGF-β has been shown to play a differential role in either restricting or aiding HIV infection in different cell types, however its role in the cervical cells is hitherto undefined. Among females, more than 80% of infections occur through heterosexual contact where cervicovaginal mucosa plays a critical role, however the early events during the establishment of infection at female genital mucosa are poorly understood. We earlier showed that increased TGF-β level has been associated with cervical viral shedding in the HIV infected women, however a causal relationship could not be examined. Therefore, here we first established an in vitro cell-associated model of HIV infection in the cervical epithelial cells (ME-180) and demonstrated that TGF-β plays an important role as a negative regulator of HIV release in the infected cervical epithelial cells. Inhibition of miR-155 upregulated TGF-β signaling and mRNA expression of host restriction factors such as APOBEC-3G, IFI-16 and IFITM-3, while decreased the HIV release in ME-180 cells. To conclude, this is the first study to decipher the complex interplay between TGF-β, miR-155 and HIV release in the cervical epithelial cells. Collectively, our data suggest the plausible role of TGF-β in promoting HIV latency in cervical epithelial cells which needs further investigations.

Levels of Total Antioxidant Capacity, sCD14, and TGF-β2 in Breast Milk Plasma of HIV-Infected and HIV-Uninfected Lactating Women

Introduction: Breast milk provides nourishment for infants and nonnutritive bioactive factors, which possess key protective and developmental benefits essential in shaping the infant immune system. However, the impact of human immunodeficiency virus (HIV) and universal antiretroviral therapy (ART) on breast milk nutritional composition and immunity status is not well documented. Objective: The study aimed to compare breast milk immune factors; total antioxidant capacity (TAC), soluble cluster of differentiation 14 (sCD14), and transcription growth factor-beta 2 (TGF-β2) levels between HIV-infected and HIV-uninfected lactating mothers and determine the association between breast milk parameters with HIV disease progression and duration of ART. Methods: Breast milk sCD14, TAC, and TGF-β2 were quantified using enzyme-linked immunosorbent assays and spectrophotometric techniques in 57 HIV-infected breast feeding mothers on option B⁺ therapy for prevention of vertical transmission of HIV and 57 HIV-uninfected mothers at 6 weeks postpartum. The plasma HIV viral load was measured on enrollment and demographic data were recorded. Results: Mean breast milk plasma TAC levels were significantly lower in HIV-infected mothers (1,250.5 ± 280.4 μmolTE/L) compared to the HIV-uninfected participants (1,915.4 ± 326 μmolTE/L; p < 0.001). Soluble CD14 levels in HIV-infected mothers were significantly higher (7,059.3 ± 1,604.7 ng/mL) compared to the HIV-uninfected group (5,670.7 ± 1,268.3 pg/mL; p < 0.001). Similarly, TGF-β2 concentration was also significantly elevated in the HIV-infected mothers (1,426.1 ± 695.4 pg/mL) compared to the HIV-uninfected counterparts (709.2 ± 196.8 pg/mL; p < 0.001). A positive correlation was observed between breast milk plasma sCD14 concentration and the plasma viral load (r = 0.576, p < 0.001), while a significant negative correlation was observed with the duration of ART (r = -0.285, p = 0.032). TAC and TGF-β2 concentrations were inversely correlated with plasma viral load levels. Conclusion: HIV-infected mothers are at risk of oxidative stress. Nutritional intervention with antioxidant rich foods is recommended for this vulnerable group during breastfeeding.

Dynamics of Transforming Growth Factor (TGF)-β Superfamily Cytokine Induction During HIV-1 Infection Are Distinct From Other Innate Cytokines

Human immunodeficiency virus type 1 (HIV-1) infection triggers rapid induction of multiple innate cytokines including type I interferons, which play important roles in viral control and disease pathogenesis. The transforming growth factor (TGF)-β superfamily is a pleiotropic innate cytokine family, some members of which (activins and bone morphogenetic proteins (BMPs)) were recently demonstrated to exert antiviral activity against Zika and hepatitis B and C viruses but are poorly studied in HIV-1 infection. Here, we show that TGF-β₁ is systemically induced with very rapid kinetics (as early as 1-4 days after viremic spread begins) in acute HIV-1 infection, likely due to release from platelets, and remains upregulated throughout infection. Contrastingly, no substantial systemic upregulation of activins A and B or BMP-2 was observed during acute infection, although plasma activin levels trended to be elevated during chronic infection. HIV-1 triggered production of type I interferons but not TGF-β superfamily cytokines from plasmacytoid dendritic cells (DCs) in vitro, putatively explaining their differing in vivo induction; whilst lipopolysaccharide (but not HIV-1) elicited activin A production from myeloid DCs. These findings underscore the need for better definition of the protective and pathogenic capacity of TGF-β superfamily cytokines, to enable appropriate modulation for therapeutic purposes.

Expression profiling of human milk derived exosomal microRNAs and their targets in HIV-1 infected mothers

Despite the use of antiretroviral therapy (ART) in HIV-1 infected mothers approximately 5% of new HIV-1 infections still occur in breastfed infants annually, which warrants for the development of novel strategies to prevent new HIV-1 infections in infants. Human milk (HM) exosomes are highly enriched in microRNAs (miRNAs), which play an important role in neonatal immunity. Furthermore, HM exosomes from healthy donors are known to inhibit HIV-1 infection and transmission; however, the effect of HIV-1 on HM exosomal miRNA signatures remains unknown. In this study, we used nCounter NanoString technology and investigated miRNAs expression profiles in first week postpartum HM exosomes from HIV-1 infected and uninfected control mothers (n = 36). Our results indicated that HIV-1 perturbed the differential expression patterns of 19 miRNAs (13 upregulated and 6 downregulated) in HIV-1 infected women compared to healthy controls. DIANA-miR functional pathway analyses revealed that multiple biological pathways are involved including cell cycle, pathways in cancer, TGF-β signaling, FoxO signaling, fatty acid biosynthesis, p53 signaling and apoptosis. Moreover, the receiver operating characteristics (ROC) curve analyses of miR-630 and miR-378g yielded areas under the ROC curves of 0.82 (95% CI 0.67 to 0.82) and 0.83 (95% CI 0.67 to 0.83), respectively highlighting their potential to serve as biomarkers to identify HIV-1 infection in women. These data may contribute to the development of new therapeutic strategies in prevention of mother-to-child transmission (MTCT) of HIV-1.

TGF-β1 increases viral burden and promotes HIV-1 latency in primary differentiated human bronchial epithelial cells

Combination antiretroviral therapy (cART) has increased the life expectancy of HIV patients. However, the incidence of non-AIDS associated lung comorbidities, such as COPD and asthma, and that of opportunistic lung infections have become more common among this population. HIV proteins secreted by the anatomical HIV reservoirs can have both autocrine and paracrine effects contributing to the HIV-associated comorbidities. HIV has been recovered from cell-free bronchoalveolar lavage fluid, alveolar macrophages, and intrapulmonary lymphocytes. We have recently shown that ex-vivo cultured primary bronchial epithelial cells and the bronchial brushings from human subjects express canonical HIV receptors CD4, CCR5 and CXCR4 and can be infected with HIV. Together these studies suggest that the lung tissue can serve as an important reservoir for HIV. In this report, we show that TGF-β1 promotes HIV latency by upregulating a transcriptional repressor BLIMP-1. Furthermore, we identify miR-9-5p as an important intermediate in TGF-β-mediated BLIMP-1 upregulation and consequent HIV latency. The transcriptionally suppressed HIV can be reactivated by common latency reactivating agents. Together our data suggest that in patients with chronic airway diseases, TGF-β can elevate the HIV viral reservoir load that could further exacerbate the HIV associated lung comorbidities.

HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood-brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level.

Placental Hofbauer cells limit HIV-1 replication and potentially offset mother to child transmission (MTCT) by induction of immunoregulatory cytokines

Background

Despite readily detectable levels of the HIV-1 (co)-receptors CD4, CCR5 and DC-SIGN on placental macrophages (Hofbauer Cells [HCs]), the rate of HIV-1 infection in utero in the absence of interventions is only 7% of exposed infants. Here, we examine the replication kinetics of human HCs to the primary isolate HIV-1_BaL. We also determined the infectivity of HIV-1-exposed HCs by co-culturing with isolated cord and peripheral blood mononuclear cells [CBMCs, PBMCs]. To understand the limiting nature of HCs to HIV-1 replication, we examined the effect of endogenously secreted cytokines on replication kinetics.

Results

HCs have reduced ability to replicate HIV-1 in vitro (p < 0.01) and to transmit virus to CBMCs and PBMCs (p < 0.001 for both) compared to standard infections of MDMs. HCs were shown to release HIV-1 particles at levels comparable to MDMs, however exhibit significant decreases in viral transcription (gag and env), which may account for lower levels of HIV-1 replication. Un-stimulated HCs constitutively express significantly higher levels of regulatory cytokines, IL-10 and TGF-β, compared to MDMs (p < 0.01), which may contribute to immunoregulatory predominance at the placenta and possibly account for down-regulation of HIV-1 replication and infectivity by HCs. We further demonstrate that these regulatory cytokines inhibit HIV-1 replication within HCs in vitro.

Conclusion

HCs have reduced ability to replicate and disseminate R5-tropic HIV-1_BaLin vitro and potentially offset mother to child transmission (MTCT) of HIV-1 by the induction of immunoregulatory cytokines. Despite the potential for migration and infectivity, HCs are not present in the neighboring fetal circulation. These results implicate HCs as important mediators of protection at the feto-maternal interface during ongoing HIV-1 exposure.

Arc of a vicious circle: pathways activated by Mycobacterium tuberculosis that target the HIV-1 long terminal repeat

In this review, we examine how a subset of signal transduction cascades initiated by Mycobacterium tuberculosis (Mtb) infection modulates transcription mediated by the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR). We describe two distinct phases of signaling that target transcription factors known to bind the HIV-1 LTR, and thus drive viral transcription and replication, in cells of the Mtb-infected host. First, Mtb-derived molecules, including cell wall components and DNA, interact with a number of host pattern recognition receptors. Second, cytokines and chemokines secreted in response to Mtb infection initiate signal transduction cascades through their cognate receptors. Given the variation in cell wall components among distinct clinical Mtb strains, the initial pattern recognition receptor interaction leading to direct LTR activation and differential cytokine and chemokine production is likely to be an important aspect of Mtb strain-specific regulation of HIV-1 transcription and replication. Improved understanding of these molecular mechanisms in the context of bacterial and host genetics should provide key insights into the accelerated viral replication and disease progression characteristic of HIV/TB coinfection.

APOBEC3 proteins expressed in mammary epithelial cells are packaged into retroviruses and can restrict transmission of milk-borne virions

Viruses, including retroviruses like human immunodeficiency virus (HIV) and mouse mammary tumor virus (MMTV), are transmitted from mother to infants through milk. Lymphoid cells and antibodies are thought to provide mammary gland and milk-borne immunity. In contrast, little is known about the role of mammary epithelial cells (MECs). The APOBEC3 family of retroviral restriction factors is highly expressed in macrophages and lymphoid and dendritic cells. We now show that APOBEC3 proteins are also expressed in mouse and human MECs. Lymphoid cell-expressed APOBEC3 restricts in vivo spread of MMTV to lymphoid and mammary tissue. In contrast, mammary gland-expressed APOBEC3 is packaged into MMTV virions and decreases the infectivity of milk-borne viruses. Moreover, APOBEC3G and other APOBEC3 genes are expressed in human mammary cells and have the potential to restrict viruses produced in this cell type. These data point to a role for APOBEC3 proteins in limiting infectivity of milk-transmitted viruses.

A quantitative study of NF-kappaB activation by H2O2: relevance in inflammation and synergy with TNF-alpha

Although the germicide role of H(2)O(2) released during inflammation is well established, a hypothetical regulatory function, either promoting or inhibiting inflammation, is still controversial. In particular, after 15 years of highly contradictory results it remains uncertain whether H(2)O(2) by itself activates NF-kappaB or if it stimulates or inhibits the activation of NF-kappaB by proinflammatory mediators. We investigated the role of H(2)O(2) in NF-kappaB activation using, for the first time, a calibrated and controlled method of H(2)O(2) delivery--the steady-state titration--in which cells are exposed to constant, low, and known concentrations of H(2)O(2). This technique contrasts with previously applied techniques, which disrupt cellular redox homeostasis and/or introduce uncertainties in the actual H(2)O(2) concentration to which cells are exposed. In both MCF-7 and HeLa cells, H(2)O(2) at extracellular concentrations up to 25 microM did not induce significantly per se NF-kappaB translocation to the nucleus, but it stimulated the translocation induced by TNF-alpha. For higher H(2)O(2) doses this stimulatory role shifts to an inhibition, which may explain published contradictory results. The stimulatory role was confirmed by the observation that 12.5 microM H(2)O(2), a concentration found during inflammation, increased the expression of several proinflammatory NF-kappaB-dependent genes induced by TNF-alpha (e.g., IL-8, MCP-1, TLR2, and TNF-alpha). The same low H(2)O(2) concentration also induced the anti-inflammatory gene coding for heme oxygenase-1 (HO-1) and IL-6. We propose that H(2)O(2) has a fine-tuning regulatory role, comprising both a proinflammatory control loop that increases pathogen removal and an anti-inflammatory control loop, which avoids an exacerbated harmful inflammatory response.

Interleukin-15 but not interleukin-7 abrogates vaccine-induced decrease in virus level in simian immunodeficiency virus mac251-infected macaques

The loss of CD4(+) T cells and the impairment of CD8(+) T cell function in HIV infection suggest that pharmacological treatment with IL-7 and IL-15, cytokines that increase the homeostatic proliferation of T cells and improve effector function, may be beneficial. However, these cytokines could also have a detrimental effect in HIV-1-infected individuals, because both cytokines increase HIV replication in vitro. We assessed the impact of IL-7 and IL-15 treatment on viral replication and the immunogenicity of live poxvirus vaccines in SIV(mac251)-infected macaques (Macaca mulatta). Neither cytokine augmented the frequency of vaccine-expanded CD4(+) or CD8(+) memory T cells, clonal recruitment to the SIV-specific CD8(+) T cell pool, or CD8(+) T cell function. Vaccination alone transiently decreased the viral set point following antiretroviral therapy suspension. IL-15 induced massive proliferation of CD4(+) effector T cells and abrogated the ability of vaccination to decrease set point viremia. In contrast, IL-7 neither augmented nor decreased the vaccine effect and was associated with a decrease in TGF-beta expression. These results underscore the importance of testing immunomodulatory approaches in vivo to assess potential risks and benefits for HIV-1-infected individuals.

PRO 2000 elicits a decline in genital tract immune mediators without compromising intrinsic antimicrobial activity

OBJECTIVE

Vaginal microbicides should protect against infection without disrupting the mucosal environment or its mediators of host defense. The objective of this study was to examine the effect of 14 daily applications of 0.5% PRO 2000 or placebo gel on mediators of mucosal immunity and intrinsic antimicrobial activity.

DESIGN AND METHODS

A randomized, prospective, double-blind, placebo-controlled study was conducted among 24 healthy, abstinent women. Levels of cytokines, chemokines, defensins, and other protective factors and intrinsic antimicrobial activity were determined in cervicovaginal lavage samples collected on study days 0, 7, 14, and 21.

RESULTS

No increase in pro-inflammatory cytokines was observed. Rather cytokines and protective factors including interleukin (IL)-1 receptor antagonist, immunoglobulins and human beta-defensin 2 were lower in the drug compared with the placebo group. All of the mediators returned towards baseline on day 21. Women who were cycling had lower levels of most proteins on study days 7 and/or 14 compared with women on oral contraceptives; however, the magnitude of decline was greater in women who received PRO 2000 compared with placebo gel. The reduction in protective factors was not associated with a loss in the intrinsic anti-viral (HIV or herpes simplex virus) activity or anti-bacterial activity (Escherichia coli or Staphylococcus aureus).

CONCLUSION

In contrast to experience with nonoxynol-9, PRO 2000 did not trigger an inflammatory response in cervicovaginal secretions. There was a modest reduction in mucosal immune mediators, but this loss was not associated with a reduction in intrinsic antimicrobial activity.

Norepinephrine inhibits human immunodeficiency virus type-1 infection through the NF-κB inactivation

Exercise or acute stress can exert significant effects on immune system as well as cardiovascular and respiratory systems through catecholamines. In this study, we investigated effects of norepinephrine (NE), a catecholamine neurotransmitter on human immunodeficiency virus type-1 (HIV-1) infection. NE inhibited in vitro HIV-1 infection of peripheral blood mononuclear cells (PBMC) from healthy donors and ex vivo HIV-1 replication in patients' PBMC. In transient expression assays, NE downregulated HIV-1 long terminal repeat, but site-directed mutagenesis on NF-kappaB-binding sites or cotreatment with H89 (a protein kinase A inhibitor) abrogated the NE-mediated effect. Gel-shift assays showed suppression of NF-kappaB activity in NE-treated cells. NE increased cytoplasmic levels of IkappaB-alpha, a natural inhibitor of NF-kappaB. Thus, NE apparently inhibits HIV-1 infection, at least in part through NF-kappaB inactivation.