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

TGF-β blockade drives a transitional effector phenotype in T cells reversing SIV latency and decreasing SIV reservoirs in vivo

HIV-1 persistence during ART is due to the establishment of long-lived viral reservoirs in resting immune cells. Using an NHP model of barcoded SIVmac239 intravenous infection and therapeutic dosing of anti-TGFBR1 inhibitor galunisertib (LY2157299), we confirm the latency reversal properties of in vivo TGF-β blockade, decrease viral reservoirs and stimulate immune responses. Treatment of eight female, SIV-infected macaques on ART with four 2-weeks cycles of galunisertib leads to viral reactivation as indicated by plasma viral load and immunoPET/CT with a 64Cu-DOTA-F(ab')2-p7D3-probe. Post-galunisertib, lymph nodes, gut and PBMC exhibit lower cell-associated (CA-)SIV DNA and lower intact pro-virus (PBMC). Galunisertib does not lead to systemic increase in inflammatory cytokines. High-dimensional cytometry, bulk, and single-cell (sc)RNAseq reveal a galunisertib-driven shift toward an effector phenotype in T and NK cells characterized by a progressive downregulation in TCF1. In summary, we demonstrate that galunisertib, a clinical stage TGF-β inhibitor, reverses SIV latency and decreases SIV reservoirs by driving T cells toward an effector phenotype, enhancing immune responses in vivo in absence of toxicity.

Defining the role of natural killer cells in COVID-19

Natural killer (NK) cells are critical effectors of antiviral immunity. Researchers have therefore sought to characterize the NK cell response to coronavirus disease 2019 (COVID-19) and the virus that causes it, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The NK cells of patients with severe COVID-19 undergo extensive phenotypic and functional changes. For example, the NK cells from critically ill patients with COVID-19 are highly activated and exhausted, with poor cytotoxic function and cytokine production upon stimulation. The NK cell response to SARS-CoV-2 is also modulated by changes induced in virally infected cells, including the ability of a viral peptide to bind HLA-E, preventing NK cells from receiving inhibitory signals, and the downregulation of major histocompatibility complex class I and ligands for the activating receptor NKG2D. These changes have important implications for the ability of infected cells to escape NK cell killing. The implications of these findings for antibody-dependent NK cell activity in COVID-19 are also reviewed. Despite these advances in the understanding of the NK cell response to SARS-CoV-2, there remain critical gaps in our current understanding and a wealth of avenues for future research on this topic.

Porcine Circovirus 2 Increases the Frequency of Transforming Growth Factor-β via the C35, S36 and V39 Amino Acids of the ORF4

Porcine circovirus 2 (PCV2) is one of the most important endemic swine pathogens, inducing immunosuppression in pigs and predisposing them to secondary bacterial or viral infections. Our previous studies show that PCV2 infection stimulated pig intestinal epithelial cells (IPEC-J2) to produce the secretory transforming growth factor-β (TGF-β), which, in turn, caused CD4⁺ T cells to differentiate into regulatory T cells (T_regs). This may be one of the key mechanisms by which PCV2 induces immunosuppression. Here, we attempt to identify the viral proteins that affect the TGF-β secretion, as well as the key amino acids that are primarily responsible for this occurrence. The three amino acids C35, S36 and V39 of the ORF4 protein are the key sites at which PCV2 induces a large amount of TGF-β production in IPEC-J2 and influences the frequency of T_regs. This may elucidate the regulatory effect of PCV2 on the T_regs differentiation from the perspective of virus structure and intestinal epithelial cell interaction, laying a theoretical foundation for improving the molecular mechanism of PCV2-induced intestinal mucosal immunosuppression in piglets.

Transforming Growth Factor β Signaling Promotes HIV-1 Infection in Activated and Resting Memory CD4+ T Cells

Understanding the facilitator of HIV-1 infection and subsequent latency establishment may aid the discovery of potential therapeutic targets. Here, we report the elevation of plasma transforming growth factor β (TGF-β) during acute HIV-1 infection among men who have sex with men (MSM). Using a serum-free in vitro system, we further delineated the role of TGF-β signaling in mediating HIV-1 infection of activated and resting memory CD4+ T cells. TGF-β could upregulate both the frequency and expression of the HIV-1 coreceptor CCR5, thereby augmenting CCR5-tropic viral infection of resting and activated memory CD4+ T cells via Smad3 activation. The production of live HIV-1JR-FL upon infection and reactivation was increased in TGF-β-treated resting memory CD4+ T cells without increasing CD4 expression or inducing T cell activation. The expression of CCR7, a central memory T cell marker that serves as a chemokine receptor to facilitate T cell trafficking into lymphoid organs, was also elevated on TGF-β-treated resting and activated memory CD4+ T cells. Moreover, the expression of CXCR3, a chemokine receptor recently reported to facilitate CCR5-tropic HIV-1 infection, was increased on resting and activated memory CD4+ T cells upon TGF-β treatment. These findings were coherent with the observation that ex vivo CCR5 and CXCR3 expression on total resting and resting memory CD4+ T cells in combination antiretroviral therapy (cART)-naive and cART-treated patients were higher than in healthy individuals. Overall, the study demonstrated that TGF-β upregulation induced by acute HIV-1 infection might promote latency reservoir establishment by increasing infected resting memory CD4+ T cells and lymphoid organ homing of infected central memory CD4+ T cells. Therefore, TGF-β blockade may serve as a potential supplementary regimen for HIV-1 functional cure by reducing viral latency. IMPORTANCE Incomplete eradication of HIV-1 latency reservoirs remains the major hurdle in achieving a complete HIV/AIDS cure. Dissecting the facilitator of latency reservoir establishment may aid the discovery of druggable targets for HIV-1 cure. This study showed that the T cell immunomodulatory cytokine TGF-β was upregulated during the acute phase of infection. Using an in vitro serum-free system, we specifically delineated that TGF-β promoted HIV-1 infection of both resting and activated memory CD4+ T cells via the induction of host CCR5 coreceptor. Moreover, TGF-β-upregulated CCR7 or CXCR3 might promote HIV-1 latent infection by facilitating lymphoid homing or IP-10-mediated viral entry and DNA integration, respectively. Infected resting and central memory CD4+ T cells are important latency reservoirs. Increased infection of these cells mediated by TGF-β will promote latency reservoir establishment during early infection. This study, therefore, highlighted the potential use of TGF-β blockade as a supplementary regimen with cART in acute patients to reduce viral latency.

Roles of TGF-β1 in Viral Infection during Pregnancy: Research Update and Perspectives

Transforming growth factor-beta 1 (TGF-β1) is a pleiotropic growth factor playing various roles in the human body including cell growth and development. More functions of TGF-β1 have been discovered, especially its roles in viral infection. TGF-β1 is abundant at the maternal-fetal interface during pregnancy and plays an important function in immune tolerance, an essential key factor for pregnancy success. It plays some critical roles in viral infection in pregnancy, such as its effects on the infection and replication of human cytomegalovirus in syncytiotrophoblasts. Interestingly, its role in the enhancement of Zika virus (ZIKV) infection and replication in first-trimester trophoblasts has recently been reported. The above up-to-date findings have opened one of the promising approaches to studying the mechanisms of viral infection during pregnancy with links to corresponding congenital syndromes. In this article, we review our current and recent advances in understanding the roles of TGF-β1 in viral infection. Our discussion focuses on viral infection during pregnancy, especially in the first trimester. We highlight the mutual roles of viral infection and TGF-β1 in specific contexts and possible functions of the Smad pathway in viral infection, with a special note on ZIKV infection. In addition, we discuss promising approaches to performing further studies on this topic.

SMAD2/3 Phosphorylation Is Downregulated in T Cells in HIV-Infected Patients

Persistent inflammation contributes to the exhaustion of immune system and non-AIDS-defining events in HIV-infected patients. Transforming growth factor β (TGF-β) is generally considered an anti-inflammatory cytokine. It is unclear that why high-level TGF-β coexists with chronic inflammation during HIV infection. In this study, it was found that HIV-infected patients had lower proportion of phosphorylated SMAD2/3-positive cells among total CD3⁺ T cells and subsets of CD3⁺CD8⁺ and CD3⁺CD8^- T cells when compared with health subjects. The findings implied that phosphorylation of SMAD2/3 is inhibited in HIV-infected patients, and that disturbance of TGF-β/SMAD2/3 signaling pathway may be involved in HIV-related chronic inflammation.

Immuno-metabolic control of the balance between Th17-polarized and regulatory T-cells during HIV infection

Th17-polarized CD4⁺ effector T-cells together with their immunosuppressive regulatory T-cell (Treg) counterparts, with transcriptional profiles governed by the lineage transcription factors RORγt/RORC2 and FOXP3, respectively, are important gatekeepers at mucosal interfaces. Alterations in the Th17/Treg ratios, due to the rapid depletion of Th17 cells and increased Treg frequencies, are a hallmark of both HIV and SIV infections and a marker of disease progression. The shift in Th17/Treg balance, in favor of increased Treg frequencies, contributes to gut mucosal permeability, immune dysfunction, and microbial translocation, subsequently leading to chronic immune activation/inflammation and disease progression. Of particular interest, Th17 cells and Tregs share developmental routes, with changes in the Th17 versus Treg fate decision influencing the pro-inflammatory versus anti-inflammatory responses. The differentiation and function of Th17 cells and Tregs rely on independent yet complementary metabolic pathways. Several pathways have been described in the literature to be involved in Th17 versus Treg polarization, including 1) the activity of ectonucleotidases CD39/CD73; 2) the increase in TGF-β1 production; 3) a hypoxic environment, and subsequent upregulation in hypoxia-inducible factor-1α (HIF-1α); 4) the increased mTOR activity and glycolysis induction; 5) the lipid metabolism, including fatty acid synthesis, fatty acids oxidation, cholesterol synthesis, and lipid storage, which are regulated by the AMPK, mevalonate and PPARγ pathways; and 6) the tryptophan catabolism. These metabolic pathways are understudied in the context of HIV-1 infection. The purpose of this review is to summarize the current knowledge on metabolic pathways that are dysregulated during HIV-1 infection and their impact on Th17/Treg balance.

Increased serum lipofuscin associated with leukocyte telomere shortening in veterans: a possible role for sulfur mustard exposure in delayed-onset accelerated cellular senescence

BACKGROUND

Sulfur mustard (SM) is a toxic gas that causes chronic inflammation and oxidative stress leading to cell senescence. This study aimed to evaluate two indicators of biological aging (i.e., serum lipofuscin level and leukocyte telomere length) and assess their relationship based on the severity of SM exposure in the long term.

METHODS

The study was performed on two groups of male participants. 1) SM-exposed group (exposed to SM once in 1987), 73 volunteers. 2) Non-exposed group, 16 healthy volunteers. The SM-exposed group was categorized into three subgroups based on the severity of SM exposure and body damage (asymptom, mild, and severe). The blood sample was prepared from members of each group. The serum lipofuscin, TGF-β, malondialdehyde (MDA), c-reactive protein (CRP), and leukocyte telomere length (TL) were measured in all participants.

RESULTS

The MDA level was increased in the SM-exposed group (mean = 39.6 µM, SD = 16.5) compared to the non-exposed group (mean = 21.1 µM, SD = 10.3) (P < 0.05). The CRP level was also increased in the SM-exposed group (mean = 5.12 mg/l, SD = 3.36) compared to the non-exposed group (mean = 3.51 mg/l, SD = 1.21), while the TGF-β level was decreased (P < 0.05) in the SM-exposed group (mean = 52.6 pg/ml, SD = 18.7) compared to the non-exposed group (mean = 68.9 pg/ml, SD = 13.8). The relative TL was shorter in the SM-exposed group (mean = 0.40, SD = 0.28) than in the non-exposed group (mean = 2.25, SD = 1.41) (P < 0.05). The lipofuscin level was higher in the total SM-exposed group (mean = 1.44 ng/ml, SD = 0.685) than in the non-exposed group (mean = 0.88 ng/ml, SD = 0.449) (P < 0.05). The MDA and CRP levels were increased in the SM-exposed subgroups of asymptom, mild, and severe than the non-exposed group, while TGF-β level and TL were decreased in those subgroups. The lipofuscin level was higher in the SM-exposed subgroups of mild and severe than in the non-exposed group. The regression analysis determined a negative correlation between lipofuscin level and TL. The lipofuscin/TL ratio was higher in the total SM-exposed group (mean = 6.36, SD = 5.342) than in the non-exposed group (mean = 0.51, SD=0.389). This ratio was also higher in the SM-exposed subgroups of asymptom, mild, and severe than in the non-exposed group. The lipofuscin/TL ratio did not differ between mild and severe subgroups.

CONCLUSION

The delayed toxicity of SM is associated with chronic oxidative stress, continuous inflammatory stimulation, increased lipofuscin, and telomere shortening. Future studies are needed to verify the suitability of serum lipofuscin to telomere length ratio in determining the severity of SM toxicity.

The mechanism of action of a novel neuroprotective low molecular weight dextran sulphate: New platform therapy for neurodegenerative diseases like Amyotrophic Lateral Sclerosis

Background: Acute and chronic neurodegenerative diseases represent an immense socioeconomic burden that drives the need for new disease modifying drugs. Common pathogenic mechanisms in these diseases are evident, suggesting that a platform neuroprotective therapy may offer effective treatments. Here we present evidence for the mode of pharmacological action of a novel neuroprotective low molecular weight dextran sulphate drug called ILB^®. The working hypothesis was that ILB^® acts via the activation of heparin-binding growth factors (HBGF).

Methods: Pre-clinical and clinical (healthy people and patients with ALS) in vitro and in vivo studies evaluated the mode of action of ILB^®. In vitro binding studies, functional assays and gene expression analyses were followed by the assessment of the drug effects in an animal model of severe traumatic brain injury (sTBI) using gene expression studies followed by functional analysis. Clinical data, to assess the hypothesized mode of action, are also presented from early phase clinical trials.

Results: ILB^® lengthened APTT time, acted as a competitive inhibitor for HGF-Glypican-3 binding, effected pulse release of heparin-binding growth factors (HBGF) into the circulation and modulated growth factor signaling pathways. Gene expression analysis demonstrated substantial similarities in the functional dysregulation induced by sTBI and various human neurodegenerative conditions and supported a cascading effect of ILB^® on growth factor activation, followed by gene expression changes with profound beneficial effect on molecular and cellular functions affected by these diseases. The transcriptional signature of ILB^® relevant to cell survival, inflammation, glutamate signaling, metabolism and synaptogenesis, are consistent with the activation of neuroprotective growth factors as was the ability of ILB^® to elevate circulating levels of HGF in animal models and humans.

Conclusion: ILB^® releases, redistributes and modulates the bioactivity of HBGF that target disease compromised nervous tissues to initiate a cascade of transcriptional, metabolic and immunological effects that control glutamate toxicity, normalize tissue bioenergetics, and resolve inflammation to improve tissue function. This unique mechanism of action mobilizes and modulates naturally occurring tissue repair mechanisms to restore cellular homeostasis and function. The identified pharmacological impact of ILB^® supports the potential to treat various acute and chronic neurodegenerative disease, including sTBI and ALS.

CMV and EBV Co-Infection in HIV-Infected Children: Infection Rates and Analysis of Differential Expression of Cytokines in HIV Mono- and HIV-CMV-EBV Co-Infected Groups

(1) Background: CMV and EBV co-infections can affect the HIV disease progression by modulating the immune system. The disease dynamics can differ in HIV-positive adults and children. In Pakistan, HIV is rapidly expanding, especially in children; however, the prevalence of CMV and EBV co-infection and the effect on immune modulation in HIV-positive children are not known. This study aimed to bridge this gap by estimating the rate of active CMV and EBV co-infection in HIV-positive children, followed by the analysis of differential expression of cytokines in HIV mono- and HIV/CMV/EBV co-infected children. (2) Methods: DNA samples from 319 HIV-positive children, previously recruited as part of a study to investigate the HIV outbreak in Larkana, Pakistan, in 2019, were screened for CMV and EBV through qPCR. Subsequently, differences in HIV viral loads and CD4 counts were analyzed between the HIV mono- and HIV/CMV/EBV co-infected groups. The RNA samples were used to determine the differential expression of both pro- and anti-inflammatory cytokines in the mono- and co-infected groups using RT-qPCR, while unpaired T-test and Pearson correlation test were applied to, respectively, analyze the differential cytokine expression and correlation between cytokine in the two groups. (3) Results: Of 319 samples, the rate of active EBV and CMV co-infection in HIV-positive children was observed in 79.9% and 38.9%, respectively. A significant difference was observed in HIV viral load between HIV mono- and co-infected groups. IFN-γ expression was found to be lower in the HIV mono-infected group, while higher in all other three co-infected groups. Meanwhile, mRNA expression of TGF-β1 was found to be lower in HIV mono- and HIV–CMV–EBV co-infected groups, while higher in HIV–CMV and HIV–EBV co-infected groups. IFN-γ and IL-2 exhibited a significant positive correlation in all except HIV–CMV co-infected group. (4) Conclusions: The study suggests that the presence of EBV/CMV co-infection can affect the HIV viral loads and expression of certain cytokines (IFN-γ and TGF-β1), which may affect the HIV disease dynamics in infected children.

CD160 Promotes NK Cell Functions by Upregulating Glucose Metabolism and Negatively Correlates With HIV Disease Progression

Natural killer (NK) cells are crucial for immune responses to viral infections. CD160 is an important NK cell activating receptor, with unknown function in HIV infection. Here, we found that CD160 expression was reduced on NK cells from HIV-infected individuals and its expression was negatively correlated with HIV disease progression. Further, GLUT1 expression and glucose uptake were higher in CD160+ NK cells, and the results of RNA-seq and flow cytometry demonstrated that CD160 positively regulated glucose metabolism through the PI3K/AKT/mTOR/s6k signaling pathway, thereby enhancing NK cell function. Moreover, we determined that reduced CD160 expression on NK cells could be attributed to the higher plasma levels of TGF-β1 in HIV-infected individuals. Overall, these results highlight the vital role of CD160 in HIV disease progression and regulation of glucose metabolism, indicating a potential target for HIV immunotherapy.

FoxP3+ CD8 T-cells in acute HIV infection and following early antiretroviral therapy initiation

Objectives

Besides CD4 regulatory T-cells (Tregs), immunosuppressor FoxP3+ CD8 T-cells are emerging as an important subset of Tregs, which contribute to immune dysfunction and disease progression in HIV infection. However, FoxP3+ CD8 T-cell dynamics in acute HIV infection and following early antiretroviral therapy (ART) initiation remain understudied.

Methods

Subsets of FoxP3+ CD8 T-cells were characterized both prospectively and cross-sectionally in PBMCs from untreated acute (n=26) and chronic (n=10) HIV-infected individuals, early ART-treated in acute infection (n=10, median of ART initiation: 5.5 months post-infection), ART-treated in chronic infection (n=10), elite controllers (n=18), and HIV-uninfected controls (n=21).

Results

Acute and chronic infection were associated with increased total, effector memory, and terminally differentiated FoxP3+ CD8 T-cells, while early ART normalized only the frequencies of total FoxP3+ CD8 T-cells. We observed an increase in FoxP3+ CD8 T-cell immune activation (HLADR+/CD38+), senescence (CD57+/CD28-), and PD-1 expression during acute and chronic infection, which were not normalized by early ART. FoxP3+ CD8 T-cells in untreated participants expressed higher levels of immunosuppressive LAP(TGF-β1) and CD39 than uninfected controls, whereas early ART did not affect their expression. The expression of gut-homing markers CCR9 and Integrin-β7 by total FoxP3+ CD8 T-cells and CD39+ and LAP(TGF-β1)+ FoxP3+ CD8 T-cells increased in untreated individuals and remained higher than in uninfected controls despite early ART. Elite controllers share most of the FoxP3+ CD8 T-cell characteristics in uninfected individuals.

Conclusions

Although early ART normalized total FoxP3+ CD8 T-cells frequencies, it did not affect the persistent elevation of the gut-homing potential of CD39+ and LAP(TGF-β1)+ FoxP3+ CD8 T-cell, which may contribute to immune dysfunction.

The Role of Neuroinflammatory Mediators in the Pathogenesis of Traumatic Brain Injury: A Narrative Review

Traumatic brain injury (TBI) is a debilitating acquired neurological disorder that afflicts nearly 74 million people worldwide annually. TBI has been classified as more than just a single insult because of its associated risk toward various long-term neurological and neurodegenerative disorders. This risk may be triggered by a series of postinjury secondary molecular and cellular pathology, which may be dependent on the severity of the TBI. Among the secondary injury mechanisms, neuroinflammation may be the most crucial as it may exacerbate brain damage and lead to fatal consequences when prolonged. This Review aimed to elucidate the influence of neuroinflammatory mediators on the TBI functional and pathological outcomes, particularly focusing on inflammatory cytokines which were associated with neuronal dysfunctions in the acute and chronic stages of TBI. These cytokines include interleukins (IL) such as IL-1(beta)β, IL-4, IL-6, IL8, IL-10, IL-18, IL-33 and tumor necrosis factor alpha (TNF-α), which have been extensively studied. Apart from these, IL-2, interferon gamma (IFN-γ), and transforming growth factor-beta (TGF-β) may also play a significant role in the pathogenesis of TBI. These neuroinflammatory mediators may trigger a series of pathological events such as cell death, microglial suppression, and increased catecholaminergic activity. Interestingly, in the acute phase of TBI, most of these mediators may also play a neuroprotective role by displaying anti-inflammatory properties, which may convert to a pro-inflammatory action in the chronic stages post TBI. Early identification and treatment of these mediators may help the development of more effective treatment options for TBI.

The multi-faceted roles of TGF-β in regulation of immunity to infection

Transforming Growth Factor-β is a potent regulator of the immune system, acting at every stage from thymic differentiation, population of the periphery, control of responsiveness, tissue repair and generation of memory. It is therefore a central player in the immune response to infectious pathogens, but its contribution is often clouded by multiple roles acting on different cells in time and space. Hence, context is all-important in understanding when TGF-β is beneficial or detrimental to the outcome of infection. In this review, a full range of infectious agents from viruses to helminth parasites are explored within this framework, drawing contrasts and general conclusions about the importance of TGF-β in these diseases.