Stromal Derived Growth Factor-1α: Another Mediator in Neural-Emerging Immune System throughTac1Expression in Bone Marrow Stromal Cells

Neurokinin receptors and their implications in various autoimmune diseases

Neurokinin receptors belong to the GPCRs family and are ubiquitously expressed throughout the nervous and immune systems. Neurokinin receptors in coordination with neurokinins playing an important role in many physiological processes, including smooth muscle contraction, secretion, proliferation, and nociception. They also contribute to various disease conditions such as inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, psoriasis, and cancer. Neurokinin receptors antagonist are potent and highly selective and showing success in treating chemotherapy-induced nausea and vomiting. In this review, discuss the various neurokinin receptor expression on immune cells and their importance in various inflammatory and autoimmune diseases and their therapeutic importance.

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The Neurokinin receptor is an important regulatory mechanism to control the neuronal and immune systems.

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Various neurokinin receptors (NK1R, NK2R, and NK3R) are expressed in neurons and cells of the immune system.

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Substance P (SP) controls the differentiation and function of immune cells.

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SP-NK1R receptor signaling shows substantial cross-talk between neuronal and immune systems in inflammation and autoimmunity.

The Role of Hormones and Trophic Factors as Components of Preservation Solutions in Protection of Renal Function before Transplantation: A Review of the Literature

Transplantation is currently a routine method for treating end-stage organ failure. In recent years, there has been some progress in the development of an optimal composition of organ preservation solutions, improving the vital functions of the organ and allowing to extend its storage period until implantation into the recipient. Optimizations are mostly based on commercial solutions, routinely used to store grafts intended for transplantation. The paper reviews hormones with a potential nephroprotective effect, which were used to modify the composition of renal perfusion and preservation solutions. Their effectiveness as ingredients of preservation solutions was analysed based on a literature review. Hormones and trophic factors are innovative preservation solution supplements. They have a pleiotropic effect and affect normal renal function. The expression of receptors for melatonin, prolactin, thyrotropin, corticotropin, prostaglandin E1 and trophic factors was confirmed in the kidneys, which suggests that they are a promising therapeutic target for renal IR (ischemia-reperfusion) injury. They can have anti-inflammatory, antioxidant and anti-apoptotic effects, limiting IR injury.

Constitutive Expression of Inducible Cyclic Adenosine Monophosphate Early Repressor (ICER) in Cycling Quiescent Hematopoietic Cells: Implications for Aging Hematopoietic Stem Cells

Despite extensive insights on the interaction between hematopoietic stem cells (HSCs) and the supporting bone marrow (BM) stroma in hematopoietic homeostasis there remains unanswered questions on HSC regulation. We report on the mechanism by which HSCs attain cycling quiescence by addressing a role for inducible cyclic AMP early repressor (ICER). ICER negatively transcriptional regulators of cAMP activators such as CREM and CREB. These activators can be induced by hematopoietic stimulators such as cytokines. We isolated subsets of hematopoietic cells from ten healthy donors: CD34⁺CD38^-/c-kit ⁺ (primitive progenitor), CD34⁺CD38⁺/c-kit^low (mature progenitor) and CD34^-CD38^+/-/c-kit^low/- (differentiated lineage-). The relative maturity of the progenitors were verified in long-term culture initiating assay. Immunoprecipitation indicated the highest level of ICER in the nuclear extracts of CD34⁺/CD38^- cells. Phospho (p)-CREM was also present suggesting a balance between ICER and p-CREM in HSC. ICER seems to be responsible for decrease in G1 transition, based on reduced Cdk4 protein, decreased proliferation and functional studies with propidium iodide. There were no marked changes in the cycling inhibitors, p15 and p-Rb, suggesting that ICER may act independently of other cycling inhibitors. The major effects of ICER were validated with BM mononuclear cells (BMNCs) in which ICER was ectopically expressed, and with BMNCs resistant to 5-fluorouracil- or cyclophosphamide. In total, this study ascribes a novel role for ICER in G1 checkpoint regulation in HSCs. These findings are relevant to gene therapy that require engineering of HSCs, age-related disorders that are associated with hematopoietic dysfunction and other hematological disorders.

The bone marrow niche in support of breast cancer dormancy

Despite the success in detecting breast cancer (BC) early and, with aggressive therapeutic intervention, BC remains a clinical problem. The bone marrow (BM) is a favorable metastatic site for breast cancer cells (BCCs). In BM, the survival of BCCs is partly achieved by the supporting microenvironment, including the presence of immune suppressive cells such as mesenchymal stem cells (MSCs). The heterogeneity of BCCs brings up the question of how each subset interacts with the BM microenvironment. The cancer stem cells (CSCs) survive in the BM as cycling quiescence cells and, forming gap junctional intercellular communication (GJIC) with the hematopoietic supporting stromal cells and MSCs. This type of communication has been identified close to the endosteum. Additionally, dormancy can occur by soluble mediators such as cytokines and also by the exchange of exosomes. These latter mechanisms are reviewed in the context of metastasis of BC to the BM for transition as dormant cells. The article also discusses how immune cells such as macrophages and regulatory T-cells facilitate BC dormancy. The challenges of studying BC dormancy in 2-dimensional (2-D) system are also incorporated by proposing 3-D system by engineering methods to recapitulate the BM microenvironment.

Effect of truncated neurokinin-1 receptor expression changes on the interaction between human breast cancer and bone marrow-derived mesenchymal stem cells

Previous studies in breast cancer cell lines showed that truncated neurokinin receptor-1 (NK1R-Tr) was able to promote malignant transformation of breast cells, and NK1R-Tr may contribute to tumor progression and promote distant metastasis in human breast cancer. A co-culture model of breast cancer and bone marrow-derived human mesenchymal stem (HMSC-bm) cells showed that HMSC-bm inhibited the growth of breast cancer cells and entered the bone marrow at early stages. Down-regulation of NK1R-Tr may be a key factor in maintaining the quiescent phenotype of breast cancer cells among bone marrow stroma. Stromal-derived factor (SDF)-1α expression was negatively correlated with NK1R-Tr expression in breast cancer cells. Secretion of SDF-1α by HMSC-bm may maintain the quiescent phenotype of breast cancer cells among bone marrow stroma by down-regulating NK1R-Tr expression. Transforming growth factor (TGF)-β1 expression was positively associated with NK1R-Tr expression in breast cancer cells. In a co-culture system, MDA-MB-231-TGF-β1I (TGF-β genes were suppressed using specific shRNA) cells were able to attach to HMSC-bm quickly, indicating that TGF-β1 was also a key factor for maintaining the quiescent phenotype of breast cancer cells in bone marrow stroma. However, the detailed mechanism still remained unclear and could involve other molecules, in addition to NK1R-Tr.

The joint association of REST and NFKB1 polymorphisms on the risk of colorectal cancer

Due to the high morbidity and mortality of colorectal cancer (CRC), this study aims to determine the joint association of RE-1-silencing transcription factor (REST) and nuclear factor-κB 1 (NFKB1) genes with CRC in a population-based study. A well-matched case-control study including 390 controls and 388 patients with CRC was enrolled in China. The selected single nucleotide polymorphisms (SNPs) in the REST and NFKB1 genes were genotyped by Illumina SnapShot Chip. After adjustment for important covariates, the associations of SNPs and joint association of REST and NFKB1 with CRC were evaluated by multiple logistic regression models. The subjects with the rs2228991 AA genotype of the REST gene had a decreased risk for CRC (OR = 0.38; 95%CI: 0.19-0.74), compared with the GG genotype. There were no significant associations between three SNPs in the NFKB1 gene, their haplotype and CRC risk. However, a significant combined effect of rs3774959 and rs3774964 in the NFKB1 gene with rs2228991 in the REST gene on CRC risk was observed. In conclusion, the present study found that mutation in the REST gene rather than the NFKB1 gene was associated with the risk of CRC. Furthermore, significant REST-NFKB1 joint association was observed for CRC, colon cancer and rectal cancer risk.

Stem Cell Transplantation for Hematological Malignancies: Prospects for Personalized Medicine and Co-therapy with Mesenchymal Stem Cells

Bone marrow transplantation is a form of cell therapy that has been in practice for decades for the treatment of hematological disorders and solid tumors. Immunosuppressive therapy has been a mainstay for treatment, but the severity of the adverse effects has made it an undesirable choice. Mesenchymal stem cells (MSCs), which reside in the vascular regions of the bone marrow, have been shown to serve as cellular support for the hematopoietic stem cell (HSC) niche. Furthermore, the immune suppressive properties of MSCs have been explored in the treatment of inflammatory and autoimmune disorders. Thus, co-therapy with MSCs has been shown to facilitate engraftment of hematopoietic cells by suppressive graft versus host disease (GvHD). Although the mechanism by which MSCs suppress GvHD is unclear, the experimental evidence suggests that this partly occurs by modulation of immune response such as the induction of regulatory T cells. This paper discusses the role of MSCs as co-therapy for the future of stem cell transplantation, with the overarching theme of personalized medicine for cell-based health interventions.

Communication of substance P, calcitonin-gene-related neuropeptides and chemokine receptor 4 (CXCR4) in cord blood hematopoietic stem cells

BACKGROUND

Modulation of the expression of CXCR4 as a critical adhesion molecule on cord blood (CB) CD34+ cells could overcome delay following cord blood transplantation. Identification of beneficial effects of growth factors including cytokines and neuropeptides on CXCR4 expression would enable our understanding of this complicated network. Therefore, we aimed to assess the role of substance P (SP) and Calcitonin gene related peptide (CGRP) on CXCR4 levels.

MATERIAL AND METHODS

CD34+cells purified from CB were cultured in a serum-free liquid culture system. Different concentrations of SP and CGRP were used in combination with cytokine cocktail. Expression of CXCR4 at protein and genomic levels was assessed by flow cytometry and real time RT-PCR.

RESULTS

Our results indicate increased CXCR4+ CD34+ cells after 7 days cultivation with SP and/or CGRP. Increased gene expression of the CXCR4 molecule was observed at 10(-9) M either SP or CGRP individually, by day 11 as compared to control group.

CONCLUSIONS

Our study indicates that SP and CGRP induce CXCR4 protein expression in short term culture, and stimulate its expression. Consequently, the increased expression of CXCR4 could improve engraftment of CB CD34+ cells.

Effects of neuropeptide substance P on the expression of adhesion molecules in cord blood hematopoietic stem cells

Modulation of adhesion molecules expression on the surface of cord blood (CB) CD34(+) cells may assist in overcoming the delay in cord blood engraftment. Likewise, utilization of diverse growth factors such as neuropeptides could also be helpful. Therefore, we aimed to assess the role of Substance P (SP) along with a cytokine cocktail on CB CD34(+) adhesion molecule expression. CB CD34(+) cells were cultured in a serum-free media containing different concentrations of SP in combination with a cytokine cocktail (SCF, FL, TPO, IL-3, and IL-6). Expression of adhesion molecules CXCR4, CD44, CD49e, and CD62L was analyzed after 7 and/or 11 days of cell cultivation. Additionally, the colonogenic capacity of cells was analyzed by colony formation unit assay. Our results show an enhanced percentage of CD34(+)cells with CXCR4, CD44, and CD62L on day 7, as compared with control. Furthermore, an increase in frequency was observed for CD49e(+) CD34(+)cells by day 7 in both test and control groups compared with day 0. Colonogenic assays show occurrence of more total colony formation and immature progenitor cells in SP-treated cells. Our study indicates that SP could act as an effective modulator for expression of cell adhesion molecules.

Mesenchymal stem cells protect breast cancer cells through regulatory T cells: role of mesenchymal stem cell-derived TGF-beta

Mesenchymal stem cells (MSCs) have been shown to support breast cancer growth. Because MSCs also increase the frequency of regulatory T cells (T(regs)), this study tested the hypothesis that human MSCs, via Tregs, protect breast cancer cells (BCCs) from immune clearance MSCs suppressed the proliferation of PBMCs when the latter were exposed to gamma-irradiated BCCs. Similarly, MSCs showed significant inhibition of PBMC migration toward BCCs and a corresponding decrease in CXCL12. MSCs also inhibited NK cell and CTL functions, which correlated with reduced numbers of CD8(+) and CD56(+) cells compared with parallel cultures without MSCs. The reduced NK and CTL activities correlated with a decrease in intracellular and secreted granzyme B. To explain these immunosuppressive findings, we compared T(reg) levels after coculture with MSCs and found an approximately 2-fold increase in T(regs), with associated decreases in antitumor Th1 cytokines and increases in Th2 cytokines. MSC-derived TGF-beta1 was largely responsible for the increase in T(regs) based on knockdown studies. In the presence of T(reg) depletion, PBMC proliferation and effector functions were partially restored. Together, these studies show an MSC-mediated increase in T(regs) in cocultures of PBMCs and BCCs. The results could be explained, in part, by the increase in Th2-type cytokines and MSC-generated TGF-beta1. These findings demonstrate immune protection by MSCs to BCCs. The reduction in immune cell proliferation and recruitment mediated by MSCs has implications for treatment of breast cancer with chemotherapy.

Tachykinins and Neurokinin Receptors in Bone Marrow Functions: Neural-Hematopoietic Link

After many decades of neuropeptide research, advances in the field of tachykinins have considerably increased and shown their implications in several physiological processes. In this review we focus on the role of the tachykinins in the regulation of hematopoietic functions. Evidence has shown that neural control of this process is emerging as a significant category in hematopoietic modulation. In the context of this regulation, we discuss the existence of a complex network involving the neurokinin receptors, tachykinins and cytokines. This network is tightly regulated by each of its components.

Blood-forming stem cells are nervous: direct and indirect regulation of immature human CD34+ cells by the nervous system

The nervous system regulates immunity through hormonal and neuronal routes as part of host defense and repair mechanism. Here, we review the emerging evidence for regulation of human hematopoietic stem and progenitor cells (HSPC) by the nervous system both directly and indirectly via their bone marrow (BM) niche-supporting stromal cells. Functional expression of several neurotransmitter receptors was demonstrated on HSPC, mainly on the more primitive CD34(+)/CD38(-/low) fraction. The myeloid cytokines, G-CSF and GM-CSF, dynamically upregulate neuronal receptor expression on human HSPC. This is followed by an increased response to neurotransmitters, leading to enhanced proliferation and motility of human CD34(+) progenitors, repopulation of the murine BM and their egress to the circulation. Importantly, recent observations showed rapid mobilization of human HSPC to high SDF-1 expressing ischemic tissues of stroke individuals followed by neoangiogenesis, neurological and functional recovery. Along with decreased levels of circulating immature CD34(+) cells and SDF-1 blood levels found in patients with early-stage Alzheimer's disease, these findings suggest a possible involvement of human HSPC in brain homeostasis and thus their potential clinical applications in neuropathology.

An in vitro method to study the effects of hematopoietic regulators during immune and blood cell development

In adults, hematopoiesis occurs in bone marrow (BM) through a complex process with differentiation of hematopoietic stem cells (HSCs) to immune and blood cells. Human HSCs and their progenitors express CD34. Methods on hematopoietic regulation are presented to show the effects of the chemokine, stromal-derived growth factor (SDF)-1I and the neuropeptide, substance P (SP). SDF-1I production in BM stroma causes interactions with HSCs, thereby retaining the HSCs in regions close to the endosteum, at low oxygen. Small changes in SDF-1I levels stimulate HSC functions through direct and indirect mechanisms. The indirect method occurs by SP production, which stimulates CD34+ cells, supported by ligand-binding studies, long-term culture-initiating cell assays for HSC functions, and clonogenic assays for myeloid progenitors. These methods can be applied to study other hematopoietic regulators.

‘Sensing’ autoimmunity in type 1 diabetes

Type 1 diabetes (T1D) results from autoimmune-mediated loss of insulin-producing beta-cells. Recent findings suggest that the events controlling T1D development are not only immunological, but also neuronal in nature. In the non-obese diabetic (NOD) mouse model of T1D, a mutant sensory neuron channel, TRPV1, initiates chronic, progressive beta-cell stress, inducing islet cell inflammation. This novel mechanism of organ-specific damage requires a permissive, autoimmune-prone host, but ascribes tissue specificity to the local secretory dysfunction of sensory afferent neurons. In NOD mice, normalizing this neuronal function by administration of the neurotransmitter substance P clears islet cell inflammation, reduces insulin resistance and restores normoglycemia. Here, we discuss this neuro-immuno-endocrine model, its implications and the involvement of sensory neurons in other autoimmune disorders. These developments might provide novel neuronal-based therapeutic interventions, particularly in diabetes.

Synergy between the RE-1 Silencer of Transcription and NFκB in the Repression of the Neurotransmitter Gene TAC1 in Human Mesenchymal Stem Cells

The RE-1 silencer of transcription (REST) is a transcriptional regulator that represses neuron-specific genes in non-neuronal tissues by remodeling chromatin structure. We have utilized human mesenchymal stem cells (MSCs) as a research tool to understand the molecular mechanisms that regulate a neurogenic program of differentiation in non-neuronal tissue. MSCs are mesoderm-derived cells that generate specialized cells such as stroma, fat, bone, and cartilage. We have reported previously the transdifferentiation of MSCs into functional neuronal cells (Cho, K. J., Trzaska, K. A., Greco, S. J., McArdle, J., Wang, F. S., Ye, J.-H., and Rameshwar, P. (2005) Stem Cells 23, 383-391). Expression of the neurotransmitter gene TAC1 was detected only in neuronal cells and thus served as a model to study transcriptional regulation of neuron-specific genes in undifferentiated MSCs. Bone marrow stromal cells are known to transiently express TAC1 following stimulation with the microenvironmental factor interleukin-1alpha. We thus compared the effects of interleukin-1alpha stimulation and neuronal induction of MSCs on TAC1 regulation. Transcription factor mapping of the 5'-flanking region of the TAC1 promoter predicted two REST-binding sites adjacent to one NFkappaB site within exon 1. Chromatin immunoprecipitation, mutagenesis, and loss-of-function studies showed that both transcription factors synergistically mediated repression of TAC1 in the neurogenic and microenvironmental models. Together, the results support the novel finding of synergism between REST and NFkappaB in the suppression of TAC1 in non-neuronal cells.

The CXCR4-SDF1alpha axis is a critical mediator of rhabdomyosarcoma metastatic signaling induced by bone marrow stroma

Rhabdomyosarcoma (RMS) is the most common malignant soft-tissue tumor of childhood. Nearly 15% of children present with metastatic disease, frequently involving the lungs and bone marrow. The prognosis for patients with metastatic RMS is dismal, with an estimated 3-year overall survival of 30%. Stromal-cell derived factor 1-alpha (SDF1alpha, CXCL12) is a chemokine that plays a crucial role in the metastatic attraction of tumor cells expressing its receptor, CXCR4. We investigated the role of the bone marrow microenvironment on RMS signaling through the CXCR4/SDF1alpha pathway in cell lines and primary tumors. Conditioned media (CM) isolated from cultured patient-derived bone marrow stromal cells (BMS) induced migration and proliferation in multiple RMS cell lines. CXCR4 was expressed in RMS cell lines and primary tumors, with higher expression in alveolar subtype RMS. Further, SDF1alpha was secreted by all BMS cultures and potently induced the migration and proliferation of RMS cells. Small molecule or blocking antibody-mediated inhibition of CXCR4 or SDF1alpha suppressed RMS cell migration towards BMS-CM, confirming the activity of this axis. Our study provides strong evidence for the involvement of the bone marrow microenvironment and CXCR4/SDF1alpha signaling in metastasis of RMS. These results form the basis for future studies to delineate the mechanisms of bone marrow metastasis in RMS.

Nuclear Factor-κB Accounts for the Repressor Effects of High Stromal Cell–Derived Factor-1α Levels onTac1Expression in Nontumorigenic Breast Cells

Stromal cell-derived factor-1alpha (SDF-1alpha) is a CXC chemokine that interacts with CXCR4 receptor. Tac1 encodes peptides belonging to the tachykinins, including substance P. SDF-1alpha production is decreased in Tac1 knockdown breast cancer cells and is also reduced in these cancer cells following contact with bone marrow stroma when Tac1 expression is increased. Here, we report on the effects of relatively high and low SDF-1alpha levels on Tac1 expression in nontumorigenic breast cells MCF12A. Reporter gene assays, Northern analyses, and ELISA for substance P showed increased Tac1 expression at 20 and 50 ng/mL SDF-1alpha and reduced expression at 100 ng/mL. Omission of the untranslated region showed a dose-dependent effect of SDF-1alpha on reporter gene activity, suggesting that receptor desensitization cannot account for the suppressive effects at 100 ng/mL SDF-1alpha. Tac1 expression at high SDF-1alpha involves an intracellular signaling pathway that incorporates the activation of phosphatidylinositol 3-kinase-phosphoinositide-dependent kinase-1-AKT-nuclear factor-kappaB (NF-kappaB). The major repressive effect occurs via NF-kappaB located within exon 1. In summary, NF-kappaB is involved in the repression of Tac1 at higher levels of SDF-1alpha in MCF12A. These results are relevant to dysfunction of Tac1 in breast cancer cells and also provide insights on the behavior of breast cancer cells as they traverse across gradient changes of SDF-1alpha.