HIV-1 and recombinant gp120 affect the survival and differentiation of human vessel wall-derived mesenchymal stem cells

Respiratory viruses induce the expression of type I and III IFNs in MSCs through RLR/IRF3 signaling pathways

Mesenchymal stem cells (MSCs) comprise a primitive cell population and reside in various tissues and organs. These cells exhibit immunomodulatory activity and are effective in treating respiratory viral infections. The activation of type I and III interferons, which protect cells against viral infections, can be induced after pattern recognition receptors (PRRs) recognize viral nucleic acid species. Although certain viruses can upregulate IFN-β expression in MSCs, the underlying mechanisms and responsiveness to different IFNs are unclear. We found that foreskin-derived fibroblast-like stromal cells (FDSCs), a kind of functional MSC, were permissive to IAV PR8, HCoV-229E, and EV-D68. Infection by IAV PR8 and HCoV-229E increased the expression of IFN-β and IFN-λ species in FDSCs in an IRF-3-dependent manner. RIG-I was critical for detecting IAV PR8 in FDSCs, and IAV PR8 infection induced a significant increase in the expression of interferon signaling genes (ISGs). Interestingly, only IFN-β, but not IFN-λ species, could induce the expression of ISGs, a finding supported by our observation that only IFN-β induced STAT1 and STAT2 phosphorylation in FDSCs. We also proved that treatment with IFN-β suppressed the propagation of IAV PR8 and promoted the survival of virus-infected FDSCs. Respiratory viruses could infect FDSCs and induce the expression of IFN-β and IFN-λ1, but only IFN-β could protect FDSCs against viral infection.

Consequences of HIV infection in the bone marrow niche

Dysregulation of the bone marrow niche resulting from the direct and indirect effects of HIV infection contributes to haematological abnormalities observed in HIV patients. The bone marrow niche is a complex, multicellular environment which functions primarily in the maintenance of haematopoietic stem/progenitor cells (HSPCs). These adult stem cells are responsible for replacing blood and immune cells over the course of a lifetime. Cells of the bone marrow niche support HSPCs and help to orchestrate the quiescence, self-renewal and differentiation of HSPCs through chemical and molecular signals and cell-cell interactions. This narrative review discusses the HIV-associated dysregulation of the bone marrow niche, as well as the susceptibility of HSPCs to infection by HIV.

HIV-1 Tat Protein-Mediated Inflammatory Response Inhibits the Erythroid Hematopoietic Support Function of Bone Marrow Mesenchymal Stem Cells

Although combination antiretroviral therapy is widely used to treat HIV-1 infection, anemia affects the health and quality of life in a large number of these patients. The proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs), as important support cells in the hematopoietic microenvironment, can be affected by HIV-1 Tat protein. In this study, we explored the mechanism underlying the effect of Tat protein on the hematopoietic support function of BMSCs in erythroid commitment. BMSCs were treated with Tat protein or transfected with Tat mRNA and cocultured with hematopoietic stem cells (HSCs) to detect the number of erythroid colony-forming units (CFUs) and the proportion of mature red blood cells from HSCs. Subsequently, the expression level of a series of erythroid hematopoietic support factors and inflammatory factors in BMSCs after Tat treatment were analyzed. Then, the activation effect of Tat on the mitogen-activated protein kinase/nuclear factor kappa-B (MAPK/NF-κB) pathway, which is an important inflammatory response signaling pathway, was evaluated. The results showed that the number of erythroid CFUs and the production of mature red blood cells supported by BMSCs treated with Tat protein were significantly reduced and the expression of a series of erythroid supporting factors of BMSCs were significantly decreased by Tat protein. Tat-treated BMSCs highly express a variety of inflammatory mediators. Moreover, the expression of P38, p-p38, ERK1/2, p-ERK1/2, JNK1/2, p-JNK1/2, NF-κB, and p-NF-κB was significantly upregulated by Tat protein. In conclusion, Tat protein induces the inflammatory response of BMSCs by activating the MAPK/NF-κB pathway to inhibit the erythroid hematopoietic support function of BMSCs.

Modulation of OPRM1 Alternative Splicing by Morphine and HIV-1 Nef

Clinically used opioids, such as morphine, activate the mu opioid receptor (MOR) encoded by Opioid Receptor Mu 1 (OPRM1) gene. Examination of the opioid receptor genes showed that the human OPRM1 pre-mRNA undergoes extensive alternative splicing events and capable of expressing 21 isoforms. However, characterization of OPRM1 signaling is generalized, and only one isoform (MOR-1) has been extensively studied. Compounding this issue is the increasing significance of intravenous drug abuse in HIV neuropathogenesis. Here, we investigated the molecular impact of morphine and HIV-1 on regulation of OPRM1 pre-mRNA splicing in in vitro and in vivo models. Our results suggested that morphine treatment specifically induces the alternative splicing of MOR-1X isoform among the other isoforms analyzed in neuronal cells. Interestingly, alternative splicing and expression of MOR-1X isoform was also induced in postmortem brain tissues obtained from people with HIV (PWH). Additionally, treatment of control rats with morphine induced alternative splicing of MOR-1X in the brain regions involved in the reward pathways. More interestingly, HIV-1 transgenic (HIV-1Tg) rats, showed an additive induction of MOR-1X isoform with the exposure to morphine. To further assess the possible role of HIV secretory proteins in alternative splicing of OPRM1 gene, we analyzed the impact of HIV-1 Tat, gp120 and Nef proteins on alternative splicing of MOR-1X isoform. While the Tat and gp120 had no visible effects, treatment of neurons with Nef induced MOR-1X alternative splicing that was comparable to treatment with morphine. Altogether, our results suggest that HIV-1 may alter MOR isoform expression with Nef protein by amplifying the rate of MOR-1X alternative splicing induced by morphine.

Mesenchymal Stromal Cells: a Possible Reservoir for HIV-1?

The introduction of antiretroviral therapy (ART) and highly active antiretroviral therapy (HAART) has transformed human immunodeficiency virus (HIV)-1 into a chronic, well-managed disease. However, these therapies do not eliminate all infected cells from the body despite suppressing viral load. Viral rebound is largely due to the presence of cellular reservoirs which support long-term persistence of HIV-1. A thorough understanding of the HIV-1 reservoir will facilitate the development of new strategies leading to its detection, reduction, and elimination, ultimately leading to curative therapies for HIV-1. Although immune cells derived from lymphoid and myeloid progenitors have been thoroughly studied as HIV-1 reservoirs, few studies have examined whether mesenchymal stromal/stem cells (MSCs) can assume this function. In this review, we evaluate published studies which have assessed whether MSCs contribute to the HIV-1 reservoir. MSCs have been found to express the receptors and co-receptors required for HIV-1 entry, albeit at levels of expression and receptor localisation that vary considerably between studies. Exposure to HIV-1 and HIV-1 proteins alters MSC properties in vitro, including their proliferation capacity and differentiation potential. However, in vitro and in vivo experiments investigating whether MSCs can become infected with and harbour latent integrated proviral DNA are lacking. In conclusion, MSCs appear to have the potential to contribute to the HIV-1 reservoir. However, further studies are needed using techniques such as those used to prove that cluster of differentiation (CD)4⁺ T cells constitute an HIV-1 reservoir before a reservoir function can definitively be ascribed to MSCs.

Parvovirus B19 affects thrombopoietin and IL-11 gene expression in human bone marrow mesenchymal stem cells

Aim: Human bone marrow mesenchymal stem cells (hBMSCs) may be infected by parvovirus B19 (B19V). hBMSCs support bone marrow hematopoiesis by producing stromal cells, secretion of cytokines and growth factors, etc. Because of the lifetime persistent infection of the virus in healthy individual’s bone marrow, this study aims to evaluate B19V effects on hBMSCs gene expression of some crucial hematopoietic cytokines. Materials & methods: hBMSCs were transfected with pHI0 plasmid containing the B19V genome. The quantitative mRNA expression of target genes was evaluated 24 h after transfection. Results: Our findings demonstrated a significant increase in expression levels of IL-11 and TPO (p < 0.05). Conclusion: We concluded that alteration in the gene expressions in B19V-infected hBMSCs might have significant effects on the bone marrow microenvironment as well as hematopoiesis.

Sleep disruption and duration are associated with variants in genes involved in energy homeostasis in adults with HIV/AIDS

OBJECTIVE

To determine whether selected genes and plasma markers involved in energy homeostasis are associated with sleep disruption or duration in adults with HIV/AIDS.

METHODS

A sample of 289 adults with HIV/AIDS wore a wrist actigraph for 72 h to estimate total sleep time (TST) and wake after sleep onset (WASO). Twenty-three single nucleotide polymorphisms (SNP) spanning 5 energy homeostasis genes (adiponectin [ADIPOQ], ghrelin [GHRL], leptin [LEP], peroxisome proliferator-activated receptor-alpha [PPARA], and -gamma [PPARG]) were genotyped using a custom array. Plasma markers of energy homeostasis (adiponectin, ghrelin, leptin) were measured by commercial multiplex assay.

RESULTS

After adjusting for demographic and clinical characteristics (race/ethnicity, gender, CD4 cell count, waist circumference, medications), both WASO and TST were associated with SNPs in ADIPOQ (rs182052), LEP (rs10244329, rs3828942), PPARA (rs135551, rs4253655), and PPARG (rs709151). Additional SNPs in ADIPOQ were associated with WASO (rs1501299, rs3821799, rs6773957) and TST (rs2241766). TST was also associated with SNPs in GHRL (rs26802), LEP (rs11760956), PPARA (rs135547, rs8138102, rs4253776), and PPARG (rs12490265, rs796313). Many covariate-adjusted associations involved a significant interaction with markers of HIV (viral load, years since diagnosis). Among plasma markers, higher adiponectin was associated with less WASO, higher ghrelin and glucose levels with shorter TST, and higher leptin with longer TST.

CONCLUSIONS

Replication of SNPs in all five genes and three plasma markers of energy homeostasis were associated with objective sleep measures. HIV disease influenced many of the associations. Findings strengthen evidence for associations between energy homeostasis genetics and poor sleep, and provide direction for pharmacological intervention research.

HIV glycoprotein gp120 enhances mesenchymal stem cell migration by upregulating CXCR4 expression

BACKGROUND

HIV infection and/or the direct pathogenic effects of circulating HIV proteins impairs the physiological function of mesenchymal stem cells (MSCs), and contribute to the pathogenesis of age-related clinical comorbidities in people living with HIV. The SDF-1/CXCR4 pathway is vital for modulating MSC proliferation, migration and differentiation. HIV glycoprotein gp120 inhibits SDF-1 induced chemotaxis by downregulating the expression and function of CXCR4 in monocytes, B and T cells. The influence of gp120 on CXCR4 expression and migration in MSCs is unknown.

METHODS

We investigated CXCR4 expression and SDF-1/CXCR4-mediated MSC migration in response to gp120, and its effect on downstream signaling pathways: focal adhesion kinase (FAK)/Paxillin and extracellular signal-regulated kinase (ERK).

RESULTS

Gp120 upregulated MSC CXCR4 expression. This potentiated the effects of SDF-1 in inducing chemotaxis; FAK/Paxillin and ERK pathways were over-activated, thereby facilitating actin stress fiber reorganization. CXCR4 blockage or depletion abrogated the observed effects.

CONCLUSION

Gp120 from both T- and M- tropic HIV strains upregulated CXCR4 expression in MSCs, resulting in enhanced MSC chemotaxis in response to SDF-1.

GENERAL SIGNIFICANCE

HIV infection and its proteins are known to disrupt physiological differentiation of MSC; increased gp120-driven migration amplifies the total MSC population destined for ineffective and inappropriate differentiation, thus contributing to the pathogenesis of HIV-related comorbidities. Additionally, given that MSCs are permissive to HIV infection, initial cellular priming by gp120 results in increased expression of CXCR4 and could lead to co-receptor switching and cell tropism changes in chronic HIV infection and may have implications against CCR5-knockout based HIV cure strategies.

miR-191 promotes tumorigenesis of human colorectal cancer through targeting C/EBPβ

MicroRNA-191 (miR-191), a small non-coding RNA, is involved in disease development and cancer diagnosis and prognosis. However, how miR-191 functions in colorectal cancer remains largely unclear. In this study, we show that miR-191 is highly expressed in colon tumor tissues, and that inhibition of miR-191 leads to decreased cell growth, proliferation and tumorigenicity in a xenograft model. Overexpression of miR-191 in colorectal cancer cell lines alters cell cycle progression and cell resistance to 5-Fu induced cell apoptosis. Mechanistic studies demonstrated that miR-191 directly binds to the 3′UTR of the C/EBPβ mRNA and mediates a decrease in the mRNA and protein expression of C/EBPβ. We further showed that C/EBPβ induces growth arrest in a colorectal cancer cell line and that its expression is negatively correlated with the miR-191 level in patient samples. Our findings suggest that miR-191 may be a potential gene therapy target for the treatment of colorectal cancer.

Mesenchymal Stromal Cells and Viral Infection

Mesenchymal Stromal Cells (MSCs) are a subset of nonhematopoietic adult stem cells, readily isolated from various tissues and easily culture-expanded ex vivo. Intensive studies of the immune modulation and tissue regeneration over the past few years have demonstrated the great potential of MSCs for the prevention and treatment of steroid-resistant acute graft-versus-host disease (GvHD), immune-related disorders, and viral diseases. In immunocompromised individuals, the immunomodulatory activities of MSCs have raised safety concerns regarding the greater risk of primary viral infection and viral reactivation, which is a major cause of mortality after allogeneic transplantation. Moreover, high susceptibilities of MSCs to viral infections in vitro could reflect the destructive outcomes that might impair the clinical efficacy of MSCs infusion. However, the interplay between MSCs and virus is like a double-edge sword, and it also provides beneficial effects such as allowing the proliferation and function of antiviral specific effector cells instead of suppressing them, serving as an ideal tool for study of viral pathogenesis, and protecting hosts against viral challenge by using the antimicrobial activity. Here, we therefore review favorable and unfavorable consequences of MSCs and virus interaction with the highlight of safety and efficacy for applying MSCs as cell therapy.

IFI16 Expression Is Related to Selected Transcription Factors during B-Cell Differentiation

The interferon-inducible DNA sensor IFI16 is involved in the modulation of cellular survival, proliferation, and differentiation. In the hematopoietic system, IFI16 is consistently expressed in the CD34+ stem cells and in peripheral blood lymphocytes; however, little is known regarding its regulation during maturation of B- and T-cells. We explored the role of IFI16 in normal B-cell subsets by analysing its expression and relationship with the major transcription factors involved in germinal center (GC) development and plasma-cell (PC) maturation. IFI16 mRNA was differentially expressed in B-cell subsets with significant decrease in IFI16 mRNA in GC and PCs with respect to naïve and memory subsets. IFI16 mRNA expression is inversely correlated with a few master regulators of B-cell differentiation such as BCL6, XBP1, POU2AF1, and BLIMP1. In contrast, IFI16 expression positively correlated with STAT3, REL, SPIB, RELA, RELB, IRF4, STAT5B, and STAT5A. ARACNE algorithm indicated a direct regulation of IFI16 by BCL6, STAT5B, and RELB, whereas the relationship between IFI16 and the other factors is modulated by intermediate factors. In addition, analysis of the CD40 signaling pathway showed that IFI16 gene expression directly correlated with NF-κB activation, indicating that IFI16 could be considered an upstream modulator of NF-κB in human B-cells.

Functional RIG-I-like receptors control the survival of mesenchymal stem cells

Because of their potent regenerative and immunomodulatory properties, mesenchymal stem cells (MSCs) have promising therapeutic benefits in clinical treatment of inflammatory and infectious diseases. Recent studies suggest that many biological activities of MSCs are largely determined by pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs). However, the role of PRRs in regulating the survival of MSCs remains unknown. In the present study, we examined the viability of MSCs after stimulation of distinct PRRs. Activation of TLRs by direct addition with their respective ligands showed no significant effect on the survival of MSCs, whereas transfection with double-stranded RNA (dsRNA) resulted in marked cell death in MSCs. Transfection of dsRNA upregulated cytosolic retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), including RIG-I and melanoma differentiation-associated antigen 5 (MDA5). Moreover, transfection of dsRNA activated downstream transcription factors interferon regulatory factor 3 (IRF3) and nuclear factor κB (NF-κB), as well as induced the expression of interferon-β (IFN-β) and pro-inflammatory cytokine interleukin 6 (IL-6) via RLR signaling. Furthermore, we found that transfection of dsRNA triggered both extrinsic and intrinsic apoptotic responses via RLRs. However, ectopic expression of RIG-I or MDA5 was not sufficient to induce apoptosis of MSCs without dsRNA transfection. Our study also revealed that IκB kinase α/β (IKKα/β) was required for RLR-mediated apoptosis in MSCs, while TANK-binding kinase 1 (TBK1)/IKKɛ served a pro-survival role. Moreover, neither overexpression of B-cell lymphoma 2 (Bcl2) nor neutralizing autocrined IFN-β reduced RLR-mediated apoptosis. In addition, autophagy was induced upon activation of RLRs, however, blocking autophagy did not rescue MSCs from the dsRNA-induced cell death. To the best of our knowledge, this is the first study to explore the role of RLRs in controlling the survival of MSCs, which may provide a clue to understand the pathogenesis of viral infection in MSCs.

Bone-derived mesenchymal stromal cells from HIV transgenic mice exhibit altered proliferation, differentiation capacity and paracrine functions along with impaired therapeutic potential in kidney injury

Mesenchymal stem cells (MSCs) secrete paracrine factors that could be cytoprotective and serve roles in immunoregulation during tissue injury. Although MSCs express HIV receptors, and co-receptors, and are susceptible to HIV infection, whether HIV-1 may affect biological properties of MSCs needs more study. We evaluated cellular proliferation, differentiation and paracrine functions of MSCs isolated from compact bones of healthy control mice and Tg26 HIV-1 transgenic mice. The ability of MSCs to protect against cisplatin toxicity was studied in cultured renal tubular cells as well as in intact mice. We successfully isolated MSCs from healthy mice and Tg26 HIV-1 transgenic mice and found the latter expressed viral Nef, Vpu, NL4-3 and Vif genes. The proliferation and differentiation of Tg26 HIV-1 MSCs was inferior to MSCs from healthy mice. Moreover, transplantation of Tg26 HIV-1 MSCs less effectively improved outcomes compared with healthy MSCs in mice with acute kidney injury. Also, Tg26 HIV-1 MSCs secreted multiple cytokines, but at significantly lower levels than healthy MSCs, which resulted in failure of conditioned medium from these MSCs to protect cultured renal tubular cells from cisplatin toxicity. Therefore, HIV-1 had adverse biological effects on MSCs extending to their proliferation, differentiation, function, and therapeutic potential. These findings will help in advancing mechanistical insight in renal injury and repair in the setting of HIV-1 infection.

Effects of human immunodeficiency virus on the erythrocyte and megakaryocyte lineages

Anaemia and thrombocytopenia are haematological disorders that can be detected in many human immunodeficiency virus (HIV)-positive patients during the development of HIV infection. The progressive decline of erythrocytes and platelets plays an important role both in HIV disease progression and in the clinical and therapeutic management of HIV-positive patients. HIV-dependent impairment of the megakaryocyte and erythrocyte lineages is multifactorial and particularly affects survival, proliferation and differentiation of bone marrow (BM) CD34+ haematopoietic progenitor cells, the activity of BM stromal cells and the regulation of cytokine networks. In this review, we analyse the major HIV-related mechanisms that are involved in the genesis and development of the anaemia and thrombocytopenia observed in HIV positive patients.

Analysis of the effects of HIV-1 Tat on the survival and differentiation of vessel wall-derived mesenchymal stem cells

HIV infection is an independent risk factor for atherosclerosis development and cardiovascular damage. As vessel wall mesenchymal stem cells (MSCs) are involved in the regulation of vessel structure homeostasis, we investigated the role of Tat, a key factor in HIV replication and pathogenesis, in MSC survival and differentiation. The survival of subconfluent MSCs was impaired when Tat was added at high concentrations (200-1,000 ng/ml), whereas lower Tat concentrations (1-100 ng/ml) did not promote apoptosis. Tat enhanced the differentiation of MSC toward adipogenesis by the transcription and activity upregulation of PPARγ. This Tat-related modulation of adipogenesis was tackled by treatment with antagonists of Tat-specific receptors such as SU5416 and RGD Fc. In contrast, Tat inhibited the differentiation of MSCs to endothelial cells by downregulating the expression of VEGF-induced endothelial markers such as Flt-1, KDR, and vWF. The treatment of MSCs with Tat-derived peptides corresponding to the cysteine-rich, basic, and RGD domains indicated that these Tat regions are involved in the inhibition of endothelial marker expression. The Tat-related impairment of MSC survival and differentiation might play an important role in vessel damage and formation of the atherosclerotic lesions observed in HIV-infected patients.

Sarcomas as a mise en abyme of mesenchymal stem cells: exploiting interrelationships for cell mediated anticancer therapy

Mise en abyme meaning "placed into abyss or infinite recurrence" is an apt paradigm for the relentless growth of sarcoma cells. Its alternative meaning, "self-reflexive embedding" fits the central role attributed to cancer stem cells (CSCs). Diversely sourced and defined, mesenchymal stem cells (MSCs) may be the cells of sarcoma origin, evolve a CSC phenotype and/or contribute to tumor growth through inherent qualities for homing, neovascularization, paracrine cross-feeding, microvesicle secretion, cell fusion, entosis and immune modulation. Exploiting these qualities, MSC expressing modified forms of the TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) are being developed to complement more conventional radiation and chemotherapy.