Elevated CXCL12 expression in the bone marrow of NOD mice is associated with altered T cell and stem cell trafficking and diabetes development

Bilayer lipids modulate ligand binding to atypical chemokine receptor 3

Chemokine receptors belong to the large class of G protein-coupled receptors (GPCRs) and are involved in a number of (patho)physiological processes. Previous studies highlighted the importance of membrane lipids for modulating GPCR structure and function. However, the underlying mechanisms of how lipids regulate GPCRs are often poorly understood. Here, we report that anionic lipid bilayers increase the binding affinity of the chemokine CXCL12 for the atypical chemokine receptor 3 (ACKR3) by modulating the CXCL12 binding kinetics. Notably, the anionic bilayer favors CXCL12 over the more positively charged chemokine CXCL11, which we explained by bilayer interactions orienting CXCL12 but not CXCL11 for productive ACKR3 binding. Furthermore, our data suggest a stabilization of active ACKR3 conformations in anionic bilayers. Taken together, the described regulation of chemokine selectivity of ACKR3 by the lipid bilayer proposes an extended version of the classical model of chemokine binding including the lipid environment of the receptor.

CXCL12-CXCR4 mediates CD57+ CD8+ T cell responses in the progression of type 1 diabetes

CD57+ CD8+ T cells, also referred as effector memory cells, are implicated in various conditions including tumor immunity, virus immunity, and most recently with autoimmunity. However, their roles in the progression and remission of T1D are still unclear. Here, we noted an increase in peripheral CD57+ CD8+ T cells in a T1D patient harboring an activator of transcription 3 (STAT3) mutation. Our in-depth study on the role of CD57+ CD8+ T cells within a T1D patient cohort revealed that these cells undergo significant compositional shifts during the disease's progression. Longitudinal cohort data suggested that CD57+ CD8+ T cell prevalence may be a harbinger of β-cell function decline in T1D patients. Characterized by robust cytotoxic activity, heightened production of pro-inflammatory cytokines, and increased intracellular glucose uptake, these cells may be key players in the pathophysiology of T1D. Moreover, in vitro assays showed that the CXCL12-CXCR4 axis promotes the expansion and function of CD57+ CD8+ T cells via Erk1/2 signaling. Notably, the changes of serum CXCL12 concentrations were also found in individuals during the peri-remission phase of T1D. Furthermore, treatment with the CXCR4 antagonist LY2510924 reduced the immunological infiltration of CD57+ CD8+ T cells and mitigated hyperglycemia in a STZ-induced T1D mouse model. Taken together, our work has uncovered a novel role of the CXCL12-CXCR4 axis in driving CD57+ CD8+ T cells responses in T1D, and presented a promising therapeutic strategy for delaying the onset and progression of diabetes.

Severe CD8+ T Lymphopenia in WHIM Syndrome Caused by Selective Sequestration in Primary Immune Organs

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is an ultra-rare combined primary immunodeficiency disease caused by heterozygous gain-of-function mutations in the chemokine receptor CXCR4. WHIM patients typically present with recurrent acute infections associated with myelokathexis (severe neutropenia due to bone marrow retention of mature neutrophils). Severe lymphopenia is also common, but the only associated chronic opportunistic pathogen is human papillomavirus and mechanisms are not clearly defined. In this study, we show that WHIM mutations cause more severe CD8 than CD4 lymphopenia in WHIM patients and WHIM model mice. Mechanistic studies in mice revealed selective and WHIM allele dose-dependent accumulation of mature CD8 single-positive cells in thymus in a cell-intrinsic manner due to prolonged intrathymic residence, associated with increased CD8 single-positive thymocyte chemotactic responses in vitro toward the CXCR4 ligand CXCL12. In addition, mature WHIM CD8+ T cells preferentially home to and are retained in the bone marrow in mice in a cell-intrinsic manner. Administration of the specific CXCR4 antagonist AMD3100 (plerixafor) in mice rapidly and transiently corrected T cell lymphopenia and the CD4/CD8 ratio. After lymphocytic choriomeningitis virus infection, we found no difference in memory CD8+ T cell differentiation or viral load between wild-type and WHIM model mice. Thus, lymphopenia in WHIM syndrome may involve severe CXCR4-dependent CD8+ T cell deficiency resulting in part from sequestration in the primary lymphoid organs, thymus, and bone marrow.

Exploring Computational Data Amplification and Imputation for the Discovery of Type 1 Diabetes (T1D) Biomarkers from Limited Human Datasets

Background: Type 1 diabetes (T1D) is a devastating disease with serious health complications. Early T1D biomarkers that could enable timely detection and prevention before the onset of clinical symptoms are paramount but currently unavailable. Despite their promise, omics approaches have so far failed to deliver such biomarkers, likely due to the fragmented nature of information obtained through the single omics approach. We recently demonstrated the utility of parallel multi-omics for the identification of T1D biomarker signatures. Our studies also identified challenges. Methods: Here, we evaluated a novel computational approach of data imputation and amplification as one way to overcome challenges associated with the relatively small number of subjects in these studies. Results: Using proprietary algorithms, we amplified our quadra-omics (proteomics, metabolomics, lipidomics, and transcriptomics) dataset from nine subjects a thousand-fold and analyzed the data using Ingenuity Pathway Analysis (IPA) software to assess the change in its analytical capabilities and biomarker prediction power in the amplified datasets compared to the original. These studies showed the ability to identify an increased number of T1D-relevant pathways and biomarkers in such computationally amplified datasets, especially, at imputation ratios close to the “golden ratio” of 38.2%:61.8%. Specifically, the Canonical Pathway and Diseases and Functions modules identified higher numbers of inflammatory pathways and functions relevant to autoimmune T1D, including novel ones not identified in the original data. The Biomarker Prediction module also predicted in the amplified data several unique biomarker candidates with direct links to T1D pathogenesis. Conclusions: These preliminary findings indicate that such large-scale data imputation and amplification approaches are useful in facilitating the discovery of candidate integrated biomarker signatures of T1D or other diseases by increasing the predictive range of existing data mining tools, especially when the size of the input data is inherently limited.

Stem Cell Transplantation in the Treatment of Type 1 Diabetes Mellitus: From Insulin Replacement to Beta-Cell Replacement

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that attacks pancreatic β-cells, leading to the destruction of insulitis-related islet β-cells. Islet β-cell transplantation has been proven as a curative measure in T1DM. However, a logarithmic increase in the global population with diabetes, limited donor supply, and the need for lifelong immunosuppression restrict the widespread use of β-cell transplantation. Numerous therapeutic approaches have been taken to search for substitutes of β-cells, among which stem cell transplantation is one of the most promising alternatives. Stem cells have demonstrated the potential efficacy to treat T1DM by reconstitution of immunotolerance and preservation of islet β-cell function in recent research. cGMP-grade stem cell products have been used in human clinical trials, showing that stem cell transplantation has beneficial effects on T1DM, with no obvious adverse reactions. To better achieve remission of T1DM by stem cell transplantation, in this work, we explain the progression of stem cell transplantation such as mesenchymal stem cells (MSCs), human embryonic stem cells (hESCs), and bone marrow hematopoietic stem cells (BM-HSCs) to restore the immunotolerance and preserve the islet β-cell function of T1DM in recent years. This review article provides evidence of the clinical applications of stem cell therapy in the treatment of T1DM.

SDF-1 inhibits the dedifferentiation of islet β cells in hyperglycaemia by up-regulating FoxO1 via binding to CXCR4

Islet β cell dedifferentiation is one of the most important mechanisms in the occurrence and development of diabetes. We studied the possible effects of chemokine stromal cell-derived factor-1 (SDF-1) in the dedifferentiation of islet β cells. It was noted that the number of dedifferentiated islet β cells and the expression of SDF-1 in pancreatic tissues significantly increased with diabetes. In islet β cell experiments, inhibition of SDF-1 expression resulted in an increase in the number of dedifferentiated cells, while overexpression of SDF-1 resulted in a decrease. This seemed to be contradicted by the effect of diabetes on the expression of SDF-1 in pancreatic tissue, but it was concluded that this may be related to the loss of SDF-1 activity. SDF-1 binds to CXCR4 to form a complex, which activates and phosphorylates AKT, subsequently increases the expression of forkhead box O1 (FOXO1), and inhibits the dedifferentiation of islet β cells. This suggests that SDF-1 may be a novel target in the treatment of diabetes.

Polyfunctionality of the CXCR4/CXCL12 axis in health and disease: Implications for therapeutic interventions in cancer and immune-mediated diseases

Historically the chemokine receptor CXCR4 and its canonical ligand CXCL12 are associated with the bone marrow niche and hematopoiesis. However, CXCL12 exhibits broad tissue expression including brain, thymus, heart, lung, liver, kidney, spleen, and bone marrow. CXCR4 can be considered as a node which is integrating and transducing inputs from a range of ligand-receptor interactions into a responsive and divergent network of intracellular signaling pathways that impact multiple cellular processes such as proliferation, migration, and stress resistance. Dysregulation of the CXCR4/CXCL12 axis and consequent fundamental cellular processes, are associated with a panoply of disease. This review frames the polyfunctionality of the receptor at a molecular, physiological, and pathophysiological levels. Transitioning our perspective of this axis from a single gene/protein:single function model to a polyfunctional signaling cascade highlights the potential for finer therapeutic intervention and cautions against a reductionist approach.

Hematopoietic Stem Cells in Type 1 Diabetes

Despite the increasing knowledge of pathophysiological mechanisms underlying the onset of type 1 diabetes (T1D), the quest for therapeutic options capable of delaying/reverting the diseases is still ongoing. Among all strategies currently tested in T1D, the use of hematopoietic stem cell (HSC)-based approaches and of teplizumab, showed the most encouraging results. Few clinical trials have already demonstrated the beneficial effects of HSCs in T1D, while the durability of the effect is yet to be established. Investigators are also trying to understand whether the use of selected and better-characterized HSCs subsets may provide more benefits with less risks. Interestingly, ex vivo manipulated HSCs showed promising results in murine models and the recent introduction of the humanized mouse models accelerated the translational potentials of such studies and their final road to clinic. Indeed, immunomodulatory as well as trafficking abilities can be enhanced in genetically modulated HSCs and genetically engineered HSCs may be viewed as a novel "biologic" therapy, to be further tested and explored in T1D and in other autoimmune/immune-related disorders.

AMD3465 (hexahydrobromide) rescues the MG63 osteoblasts against the apoptosis induced by high glucose

Diabetic osteoporosis (DOP) is a serious complication of diabetes, which brings a heavy burden to patients' families and society. The SDF-1/CXCR4 signal pathway may be a target to prevent articular cartilage degeneration. In this study, we studied the effects of high glucose (20 mmol/L) and CXCR4 antagonist AMD3465 (10 μmol/L) on the apoptosis and gene expression of osteoblast-like cells MG63 to determine a new treatment for DOP. CCK8 and clone formation assays confirmed that AMD3465 resisted the decrease of proliferation caused by high glucose. According to the results of scratch and transwell analysis, AMD3465 could remedy the decrease of cell migration and invasion induced by high glucose. The results of flow cytometry analysis and double staining with Hoechst and PI showed AMD3465 corrected the apoptosis induced by high glucose. In addition, high glucose regulated the expression of cell cycle- and apoptosis-related proteins, while AMD3465 blocked the regulation of high glucose. Furthermore, high glucose enhanced the expression levels of SDF-1 and CXCR4 in MG63 cells, as well as the release of MMP1, 3, 9 and 13. AMD3465 inhibited the release of MMPs. The results showed that AMD3465 resisted the apoptosis of MG63 cells induced by high glucose, provided a new strategy for the therapy of DOP.

CXCL12/CXCR4 signal transduction in diseases and its molecular approaches in targeted-therapy

Chemokines are small molecules called "chemotactic cytokines" and regulate many processes like leukocyte trafficking, homing of immune cells, maturation, cytoskeletal rearrangement, physiology, migration during development, and host immune responses. These proteins bind to their corresponding 7-membrane G-protein-coupled receptors. Chemokines and their receptors are anti-inflammatory factors in autoimmune conditions, so consider as potential targets for neutralization in such diseases. They also express by cancer cells and function as angiogenic factors, and/or survival/growth factors that enhance tumor angiogenesis and development. Among chemokines, the CXCL12/CXCR4 axis has significantly been studied in numerous cancers and autoimmune diseases. CXCL12 is a homeostatic chemokine, which is acts as an anti-inflammatory chemokine during autoimmune inflammatory responses. In cancer cells, CXCL12 acts as an angiogenic, proliferative agent and regulates tumor cell apoptosis as well. CXCR4 has a role in leukocyte chemotaxis in inflammatory situations in numerous autoimmune diseases, as well as the high levels of CXCR4, observed in different types of human cancers. These findings suggest CXCL12/CXCR4 as a potential therapeutic target for therapy of autoimmune diseases and open a new approach to targeted-therapy of cancers by neutralizing CXCL12 and CXCR4. In this paper, we reviewed the current understanding of the role of the CXCL12/CXCR4 axis in disease pathology and cancer biology, and discuss its therapeutic implications in cancer and diseases.

CXCR4, but not CXCR3, drives CD8+ T-cell entry into and migration through the murine bone marrow

The BM serves as a blood-forming organ, but also supports the maintenance and immune surveillance function of many T cells. Yet, in contrast to other organs, little is known about the molecular mechanisms that drive T-cell migration to and localization inside the BM. As BM accumulates many CXCR3-expressing memory CD8⁺ T cells, we tested the involvement of this chemokine receptor, but found that CXCR3 is not required for BM entry. In contrast, we could demonstrate that CXCR4, which is highly expressed on both naive and memory CD8⁺ T cells in BM, is critically important for homing of all CD8⁺ T-cell subsets to the BM in mice. Upon entry into the BM parenchyma, both naïve and memory CD8⁺ T cells locate close to sinusoidal vessels. Intravital imaging experiments revealed that CD8 T cells are surprisingly immobile and we found that they interact with ICAM-1+VCAM-1+BP-1+ perivascular stromal cells. These cells are the major source of CXCL12, but also express key survival factors and maintenance cytokines IL-7 and IL-15. We therefore conclude that CXCR4 is not only crucial for entry of CD8⁺ T cells into the BM, but also controls their subsequent localization toward BM niches that support their survival.

Common Polymorphisms Linked to Obesity and Cardiovascular Disease in Europeans and Asians are Associated with Type 2 Diabetes in Mexican Mestizos

Background and objectives: Type 2 diabetes (T2D) is a major problem of public health in Mexico. We investigated the influence of five polymorphisms, previously associated with obesity and cardiovascular disease in Europeans and Asians, on T2D in Mexican Mestizos. Materials and Methods: A total of 1358 subjects from 30 to 85 years old were genotyped for five loci: CXCL12 rs501120; CDNK2A/B rs1333049; HNF-1α rs2259816; FTO rs9939609; and LEP rs7799039. We used logistic regressions to test the effect of each locus on T2D in two case⁻control groups with obesity and without obesity. Also, linear regression models on glucose and glycated hemoglobin (HbA1c) were carried out on the whole sample, adjusted by age, gender, and body mass index. Results: The CXCL12 rs501120 C allele (OR = 1.96, p = 0.02), the FTO rs9939609 A allele (OR = 2.20, p = 0.04) and the LEP rs7799039 A allele (OR = 0.6, p = 0.03) were significantly associated with T2D in obesity case⁻control group. No significant association was found in the non-obesity case⁻control group. The linear regression model showed that CDNK2A/B rs1333049 C allele (β = 0.4, p = 0.03) and FTO rs9939609 A allele (β = 0.5, p = 0.03), were significantly associated with HbA1c, but no association was found among the loci with the glucose levels. Conclusions: Polymorphisms previously linked with obesity and cardiovascular events were also associated with T2D and high levels of HbA1c. Furthermore, we must point at the fact that this is the first report where polymorphisms CXCL12 rs501120 and LEP rs7799039 are associated with T2D in subjects with obesity.

The Role of the CXCL12/CXCR4/ACKR3 Axis in Autoimmune Diseases

Chemokine receptors are members of the G protein-coupled receptor superfamily. These receptors are intimately involved in cell movement, and thus play a critical role in several physiological and pathological situations that require the precise regulation of cell positioning. CXCR4 is one of the most studied chemokine receptors and is involved in many functions beyond leukocyte recruitment. During embryogenesis, it plays essential roles in vascular development, hematopoiesis, cardiogenesis, and nervous system organization. It has been also implicated in tumor progression and autoimmune diseases and, together with CD4, is one of the co-receptors used by the HIV-1 virus to infect immune cells. In contrast to other chemokine receptors that are characterized by ligand promiscuity, CXCR4 has a unique ligand-stromal cell-derived factor-1 (SDF1, CXCL12). However, this ligand also binds ACKR3, an atypical chemokine receptor that modulates CXCR4 functions and is overexpressed in multiple cancer types. The CXCL12/CXCR4/ACKR3 axis constitutes a potential therapeutic target for a wide variety of inflammatory diseases, not only by interfering with cell migration but also by modulating immune responses. Thus far, only one antagonist directed against the ligand-binding site of CXCR4, AMD3100, has demonstrated clinical relevance. Here, we review the role of this ligand and its receptors in different autoimmune diseases.

SDF-1 Is an Autocrine Insulin-Desensitizing Factor in Adipocytes

Insulin desensitization occurs not only under the obese diabetic condition but also in the fasting state. However, little is known about the common secretory factor(s) that are regulated under these two insulin-desensitized conditions. Here, using database analysis and in vitro and in vivo experiments, we identified stromal derived factor-1 (SDF-1) as an insulin-desensitizing factor in adipocytes, overexpressed in both fasting and obese adipose tissues. Exogenously added SDF-1 induced extracellular signal-regulated kinase signal, which phosphorylated and degraded IRS-1 protein in adipocytes, decreasing insulin-mediated signaling and glucose uptake. In contrast, knockdown of endogenous SDF-1 or inhibition of its receptor in adipocytes markedly increased IRS-1 protein levels and enhanced insulin sensitivity, indicating the autocrine action of SDF-1. In agreement with these findings, adipocyte-specific ablation of SDF-1 enhanced insulin sensitivity in adipose tissues and in the whole body. These results point to a novel regulatory mechanism of insulin sensitivity mediated by adipose autocrine SDF-1 action and provide a new insight into the process of insulin desensitization in adipocytes.

Targeting the 5T4 oncofetal glycoprotein with an antibody drug conjugate (A1mcMMAF) improves survival in patient-derived xenograft models of acute lymphoblastic leukemia

Outcome in childhood acute lymphoblastic leukemia is prognosticated from levels of minimal residual disease after remission induction therapy. Higher levels of minimal residual disease are associated with inferior results even with intensification of therapy, thus suggesting that identification and targeting of minimal residual disease cells could be a therapeutic strategy. Here we identify high expression of 5T4 in subclonal populations of patient-derived xenografts from patients with high, post-induction levels of minimal residual disease. 5T4-positive cells showed preferential ability to overcome the NOD-scidIL2Rγ^null mouse xenograft barrier, migrated in vitro on a CXCL12 gradient, preferentially localized to bone marrow in vivo and displayed the ability to reconstitute the original clonal composition on limited dilution engraftment. Treatment with A1mcMMAF (a 5T4-antibody drug conjugate) significantly improved survival without overt toxicity in mice engrafted with a 5T4-positive acute lymphoblastic leukemia cell line. Mice engrafted with 5T4-positive patient-derived xenograft cells were treated with combination chemotherapy or dexamethasone alone and then given A1mcMMAF in the minimal residual disease setting. Combination chemotherapy was toxic to NOD-scidIL2Rγ^null mice. While dexamethasone or A1mcMMAF alone improved outcomes, the sequential administration of dexamethasone and A1mcMMAF significantly improved survival (P=0.0006) over either monotherapy. These data show that specifically targeting minimal residual disease cells improved outcomes and support further investigation of A1mcMMAF in patients with high-risk B-cell precursor acute lymphoblastic leukemia identified by 5T4 expression at diagnosis.

CXCR4 antagonist AMD3100 ameliorates thyroid damage in autoimmune thyroiditis in NOD.H‑2h⁴ mice

CXC chemokine ligand 12 (CXCL12) and its receptor, CXC chemokine receptor 4 (CXCR4), are upregulated in mice with autoimmune thyroid diseases. However, whether this interaction is involved in the pathophysiology of autoimmune thyroiditis (AIT) remains to be elucidated. In the present study, the effects of the CXCR4 antagonist, AMD3100, in an iodine‑induced autoimmune thyroiditis model were investigated. NOD.H‑2h4 mice were randomly separated into a control, AIT and AIT+AMD3100 groups. The mice were fed with 0.05% sodium iodide water for 8 weeks to induce AIT. The AMD3100‑treated mice were administered with the CXCR4 antagonist at a dose of 10 mg/kg intraperitoneally three times a week during the experimental period. The percentages of CD19+interleukin (IL)10+ B cells and CD4+IL10+ T cells, and the mRNA expression levels of IL10 in the splenocytes were reduced in the AIT group, compared with the control group, however, they increased following AMD3100 treatment, compared with the untreated AIT group. The percentages of CD4+ T cells, CD8+ T cells, CD19+ B cells and CD8+ interferon (IFN)γ+ T cells, and the mRNA expression levels of IFNγ increased in the AIT group, compared with the control group, however, these were reduced in the AMD3100 group, compared with the AIT group. The AMD3100‑treated mice also had lower serum thyroglobulin antibody titers and reduced lymphocytic infiltration in the thyroid, compared with the untreated AIT mice. These results suggested that inhibition of this chemokine axis may offer potential as a therapeutic target for the treatment of AIT.

The Importance of the CXCL12/CXCR4 Axis in Therapeutic Approaches to Diabetes Mellitus Attenuation

The pleiotropic chemokine (C–X–C motif) ligand 12 (CXCL12) has emerged as a crucial player in several diseases. The role of CXCL12 in diabetes promotion and progression remains elusive due to its multiple functions and the overwhelming complexity of diabetes. Diabetes is a metabolic disorder resulting from a failure in glucose regulation due to β-cell loss and/or dysfunction. In view of its ability to stimulate the regeneration, proliferation, and survival of β-cells, as well as its capacity to sustain local immune-isolation, CXCL12 has been considered in approaches aimed at attenuating type 1 diabetes. However, a note of caution emerges from examinations of the involvement of CXCL12 in the development of diabetes and its complications, as research data indicate that CXCL12 displays effects that range from protective to detrimental. Therefore, as a beneficial effect of CXCL12 in one process could have deleterious consequences in another, a more complete understanding of CXCL12 effects, in particular its functioning in the cellular microenvironment, is essential before CXCL12 can be considered in therapies for diabetes treatment.

CXCR4 antagonist AMD3100 redistributes leukocytes from primary immune organs to secondary immune organs, lung, and blood in mice

AMD3100 (plerixafor), is a specific CXCR4 antagonist approved by the FDA for mobilizing hematopoietic stem cells from bone marrow to blood for transplantation in cancer. AMD3100 also mobilizes most mature leukocyte subsets to blood; however, their source and trafficking potential have not been fully delineated. Here, we show that a single injection of AMD3100 10 mg/kg into C57Bl/6 mice rapidly mobilizes (peak ∼ 2.5 h) the same leukocyte subsets to blood as in humans. Using this model, we found that AMD3100 mobilization of neutrophils, lymphocytes, and monocytes to blood is not reduced by splenectomy or by blockade of lymphocyte egress from lymph node with FTY720, but is coupled to (i) reduced content of each of these cell types in the bone marrow; (ii) reduced T-cell numbers in thymuses; (iii) increased lymphocytes in lymph nodes; and (iv) increased neutrophil and monocyte content in the lung. Direct intrathymic labeling showed that AMD3100 selectively mobilizes naïve thymic CD4(+) and CD8(+) T cells to blood. Finally, AMD3100-induced neutrophil mobilization to blood did not reduce neutrophil trafficking to thioglycollate-inflamed peritoneum. Thus, AMD3100 redistributes lymphocytes, monocytes, and neutrophils from primary immune organs to secondary immune organs, peripheral tissues, and blood, without compromising neutrophil trafficking to inflamed sites.

Stem cell mobilizers targeting chemokine receptor CXCR4: renoprotective application in acute kidney injury

We have discovered a novel series of quinazoline-based CXCR4 antagonists. Of these, compound 19 mobilized CXCR4(+) cell types, including hematopoietic stem cells and endothelial progenitor cells, more efficiently than the marketed 1 (AMD3100) with subcutaneous administration at the same dose (6 mg/kg) in mice. This series of compounds thus provides a set of valuable tools to study diseases mediated by the CXCR4/SDF-1 axis, including myocardial infarction, ischemic stroke, and cancer metastasis. More importantly, treatment with compound 19 significantly lowered levels of blood urea nitrogen and serum creatinine in rats with renal ischemia-reperfusion injury, providing evidence for its therapeutic potential in preventing ischemic acute kidney injury. CXCR4 antagonists such as 19 might also be useful to increase circulating levels of adult stem cells, thereby exerting beneficial effects on damaged and/or inflamed tissues in diseases that currently are not treated by standard approaches.

CXCR4 expression on pathogenic T cells facilitates their bone marrow infiltration in a mouse model of aplastic anemia

Aplastic anemia (AA) is a disease characterized by T-cell-mediated destruction of bone marrow (BM) hematopoietic stem and progenitor cells. Physiologically, T cells migrate to the BM in response to chemokines, such as SDF-1α, the ligand for CXCR4. However, how T cells traffic to the BM in AA is poorly understood. CXCR4 is aberrantly expressed in immune-mediated diseases and its regulation by nuclear factor-κB (NF-κB) in cancer models is well documented. In this study, we show that CXCR4 is highly expressed on BM-infiltrating CD4(+) and CD8(+) T cells in a mouse model of AA. Inhibiting CXCR4 in AA mice, using CXCR4(-/-) splenocytes or AMD3100, significantly reduced BM infiltration of T cells. We also report that NF-κB occupancy at the CXCR4 promoter is enhanced in BM-infiltrating CD8(+) T cells of AA mice. Moreover, inhibiting NF-κB signaling in AA mice using Bay11 or dehydroxymethylepoxyquinomicin, or transferring p50(-/-) splenocytes, decreased CXCR4 expression on CD8(+) T cells, significantly reduced BM infiltration of T cells, and strongly attenuated disease symptoms. Remarkably, therapeutic administration of Bay11 significantly extended survival of AA mice. Overall, we demonstrate that CXCR4 mediates migration of pathogenic T cells to the BM in AA mice, and inhibiting NF-κB signaling may represent a novel therapeutic approach to treating AA.

Synergistic vasculogenic effects of AMD3100 and stromal-cell-derived factor-1α in vasa nervorum of the sciatic nerve of mice with diabetic peripheral neuropathy

Autologous endothelial progenitor cell (EPC) transplantation has been suggested as a potential therapeutic approach in diabetic neuropathy (DN). However, such treatment might be limited by safety concerns regarding possible unwanted proliferation or differentiation of the transplanted stem cells. An alternative approach is the stimulation of endogenous bone-marrow-derived EPC (BM-EPC) recruitment into ischemic lesions by the administration of stem cell mobilization agents or chemokines. We first tested the EPC mobilization effect of vascular endothelial growth factor (VEGF) and AMD3100 in a mouse model of diabetes and found that AMD3100 was effective as an EPC mobilization agent, whereas VEGF did not increase circulating EPCs in these animals. Because recent studies have suggested that deceased local expression of stromal-cell-derived factor (SDF)-1α in diabetes is the main cause of defective EPC migration, AMD3100 was administrated systemically to stimulate EPC mobilization and SDF-1α was injected locally to enhance its migration into the streptozotocin-induced DN mice model. This combined therapy increased local expression levels of vasculogenesis-associated factors and newly formed endothelial cells in the sciatic nerve, resulting in the restoration of the sciatic vasa nervorum. The treatment also improved the impaired conduction velocity of the sciatic nerve in DN mice. Thus, AMD3100 might be an effective EPC mobilization agent in diabetes, with local SDF-1α injection synergistically increasing vascularity in diabetic nerves. This represents a novel potential therapeutic option for DN patients.

Treg cells in pancreatic lymph nodes: the possible role in diabetogenesis and β cell regeneration in a T1D model

Previously, we established a model in which physiologically adequate function of the autologous β cells was recovered in non-obese diabetic (NOD) mice after the onset of hyperglycemia by rendering them hemopoietic chimera. These mice were termed antea-diabetic. In the current study, we addressed the role of T regulatory (Treg) cells in the mechanisms mediating the restoration of euglycemia in the antea-diabetic NOD model. The data generated in this study demonstrated that the numbers of Treg cells were decreased in unmanipulated NOD mice, with the most profound deficiency detected in the pancreatic lymph nodes (PLNs). The impaired retention of the Treg cells in the PLNs correlated with the locally compromised profile of the chemokines involved in their trafficking, with the most prominent decrease observed in SDF-1. The amelioration of autoimmunity and restoration of euglycemia observed in the antea-diabetic mice was associated with restoration of the Treg cell population in the PLNs. These data indicate that the function of the SDF-1/CXCR4 axis and the retention of Treg cells in the PLNs have a potential role in diabetogenesis and in the amelioration of autoimmunity and β cell regeneration in the antea-diabetic model. We have demonstrated in the antea-diabetic mouse model that lifelong recovery of the β cells has a strong correlation with normalization of the Treg cell population in the PLNs. This finding offers new opportunities for testing the immunomodulatory regimens that promote accumulation of Treg cells in the PLNs as a therapeutic approach for type 1 diabetes (T1D).

CXCL12/CXCR4 axis plays pivotal roles in the organ-specific metastasis of pancreatic adenocarcinoma: A clinical study

Pancreatic cancer is one of the most lethal types of cancer, and curative resection is only applicable to potentially limited cases due to early metastasis and local invasion. This study reports the influence of CXCL12 and its receptor CXCR4 on the progression of pancreatic cancer and highlights the correlation between the CXCL12/CXCR4 axis and the organ-specific metastasis of pancreatic adenocarcinoma (PAC). A total of 34 patients with pancreatic cancer participated in the current study. The expression of CXCL12 and CXCR4 in cancerous tissues, paracancerous tissues, normal pancreas and lymph nodes surrounding the pancreas were investigated using immunohistochemistry and RT-PCR; furthermore, their relationship with clinicopathological factors was explored (PV9000 method). The positive rate of CXCL12 protein was 13.3% (4/30), the positive rate of CXCR4 protein was 80% (24/30) in tumor tissues. Additionally, a significant correlation between the expression pattern of the CXCL12/CXCR4 axis with lymph node metastasis was identified (P<0.05), excluding gender, age, tumor node metastasis (TNM) stage and differentiation (all P>0.05). Also, the positive rate of CXCL12 protein was 50% (15/30), the positive rate of CXCR4 protein was 73.3% (22/30) in the lymphocytes in lymph nodes surrounding the pancreas. Furthermore, we found that CXCL12 and CXCR4 expression in paratumorous vessels and neural tissue were significantly strongly positive. The paratumorous vessels and neural tissue with positive CXCL12 and CXCR4 expression were invaded by CXCL12-positive pancreatic cancer cells. The chemotactic interaction between CXCR4 and its ligand CXCL12 may be a critical event during the progression of pancreatic cancer. The CXCL12/CXCR4 axis plays an important role in the progression and organ-specific metastasis of pancreatic adenocarcinoma.

Immunological applications of stem cells in type 1 diabetes

Current approaches aiming to cure type 1 diabetes (T1D) have made a negligible number of patients insulin-independent. In this review, we revisit the role of stem cell (SC)-based applications in curing T1D. The optimal therapeutic approach for T1D should ideally preserve the remaining β-cells, restore β-cell function, and protect the replaced insulin-producing cells from autoimmunity. SCs possess immunological and regenerative properties that could be harnessed to improve the treatment of T1D; indeed, SCs may reestablish peripheral tolerance toward β-cells through reshaping of the immune response and inhibition of autoreactive T-cell function. Furthermore, SC-derived insulin-producing cells are capable of engrafting and reversing hyperglycemia in mice. Bone marrow mesenchymal SCs display a hypoimmunogenic phenotype as well as a broad range of immunomodulatory capabilities, they have been shown to cure newly diabetic nonobese diabetic (NOD) mice, and they are currently undergoing evaluation in two clinical trials. Cord blood SCs have been shown to facilitate the generation of regulatory T cells, thereby reverting hyperglycemia in NOD mice. T1D patients treated with cord blood SCs also did not show any adverse reaction in the absence of major effects on glycometabolic control. Although hematopoietic SCs rarely revert hyperglycemia in NOD mice, they exhibit profound immunomodulatory properties in humans; newly hyperglycemic T1D patients have been successfully reverted to normoglycemia with autologous nonmyeloablative hematopoietic SC transplantation. Finally, embryonic SCs also offer exciting prospects because they are able to generate glucose-responsive insulin-producing cells. Easy enthusiasm should be mitigated mainly because of the potential oncogenicity of SCs.

Vascular dysfunction in diabetes: The endothelial progenitor cells as new therapeutic strategy

The vascular endothelium is a critical determinant of diabetes-associated vascular complications, and improving endothelial function is an important target for therapy. Diabetes mellitus contributes to endothelial cell injury and dysfunction. Endothelial progenitor cells (EPCs) play a critical role in maintaining endothelial function and might affect the progression of vascular disease. EPCs are essential to blood vessel formation, can differentiate into mature endothelial cells, and promote the repair of damaged endothelium. In diabetes, the circulating EPC count is low and their functionality is impaired. The mechanisms that underlie this reduced count and impaired functionality are poorly understood. Knowledge of the status of EPCs is critical for assessing the health of the vascular system, and interventions that increase the number of EPCs and restore their angiogenic activity in diabetes may prove to be particularly beneficial. The present review outlines current thinking on EPCs’ therapeutic potential in endothelial dysfunction in diabetes, as well as evidence-based perspectives regarding their use for vascular regenerative medicine.

Interference with islet-specific homing of autoreactive T cells: an emerging therapeutic strategy for type 1 diabetes

Pathogenesis of type 1 diabetes involves the activation of autoimmune T cells, consequent homing of activated lymphocytes to the pancreatic islets and ensuing destruction of insulin-producing b cells. Interaction between activated lymphocytes and endothelial cells in the islets is the hallmark of the homing process. Initial adhesion, firm adhesion and diapedesis of lymphocytes are the three crucial steps involved in the homing process. Cell-surface receptors including integrins, selectins and hyaluronate receptor CD44 mediate the initial steps of homing. Diapedesis relies on a series of proteolytic events mediated by matrix metalloproteinases. Here, molecular mechanisms governing transendothelial migration of the diabetogenic effector cells are discussed and resulting pharmacological strategies are considered.

The CXCR4-CXCL12 pathway facilitates the progression of pancreatic cancer via induction of angiogenesis and lymphangiogenesis

BACKGROUND

This study reports the influence of CXCL12 and its receptor CXCR4 on the progression of pancreatic cancer and illuminates the correlation between the CXCL12/CXCR4 axis and the angiogenesis and lymphangiogenesis of pancreatic adenocarcinoma (PAC).

METHODS

A total of 30 patients with pancreatic cancer participated in the current study. The expression of CXCL12 and CXCR4 in cancerous tissues, paracancerous tissues, normal pancreas, and lymph nodes surrounding the pancreas were investigated using real-time PCR and immunohistochemistry, respectively. In addition, we assessed microvessel density (MVD) and microlymphatic vessel density (MLVD) in tumor tissues using immunohistochemistry.

RESULTS

CXCL12 expression in tumor tissues was significantly lower than that of paracancerous tissues, normal pancreas, and lymph nodes. In contrast, CXCR4 expression in cancerous tissues was considerably higher than that of normal pancreas. Additionally, a significant correlation between the expression pattern of the CXCL12/CXCR4 axis and clinicopathologic features, such as lymph node metastasis, was identified. Furthermore, we found that CXCL12 expression was significantly associated with MVD but not significantly associated with MLVD, while CXCR4 expression was significantly associated with MLVD but not significantly associated with MVD.

CONCLUSIONS

The chemotactic interaction between CXCR4 and its ligand CXCL12 may be a critical event during the progression of pancreatic cancer. The underlying mechanism may be the induction of angiogenesis and lymphangiogenesis regulated by the interaction of CXCL12 and CXCR4.

A case of WHIM syndrome associated with diabetes and hypothyroidism

The WHIM syndrome is a rare immunological disorder characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. We hypothesized that immunological or genetic mechanisms may link WHIM syndrome and type 1 diabetes. We report that the young girl with WHIM syndrome developed diabetes and transient hypothyroidism. A nonsense mutation (C-->T) truncating the CXC chemokine receptor 4 (CXCR4) C-terminal cytoplasmic tail domain occurred at nucleotide position 1000(R334X) of the CXCR4 gene in one allele of the patient was identified, and the person was diagnosed as having WHIM syndrome. Recent observation suggested that the CXCR4, a G-protein-coupled receptor with a unique ligand, CXCL12, might be involved in the pathogenesis for type 1 diabetes. Taken into consideration the concurrent prevalence of the two disorders and the speculated common pathogenesis associated with the CXCR4, our patient may enable us to understand the genetic damage related to accelerated apoptosis.

Differentiation, expansion, and homeostasis of autoreactive T cells in type 1 diabetes mellitus

Autoreactive T cells play a major role in the pathogenesis of type 1 diabetes mellitus (T1DM) and are considered a major target of immunomodulatory strategies aimed at preventing or delaying the disease onset. However, the T-cell response against insulin-producing beta cells is still poorly understood. T cells potentially able to recognize and destroy beta cells are present in most individuals, but only in a few do they differentiate into pathogenic effectors. Recent and novel findings in T-cell biology on the dynamics of T-cell activation and memory maintenance are shedding new light on the general mechanisms of the T-cell response. In this article, we discuss how new discoveries about T-cell differentiation, expansion, and homeostasis could help to clarify mechanisms of autoimmunity that lead to T1DM.