Short-term function and immune-protection of microencapsulated adult porcine islets with alginate incorporating CXCL12 in healthy and diabetic non-human primates without systemic immune suppression: A pilot study.

Replacement of insulin-producing pancreatic beta-cells by islet transplantation offers a functional cure for type-1 diabetes (T1D). We recently demonstrated that a clinical grade alginate micro-encapsulant incorporating the immune-repellent chemokine and pro-survival factor CXCL12 could protect and sustain the integrity and function of autologous islets in healthy non-human primates (NHPs) without systemic immune suppression. In this pilot study, we examined the impact of the CXCL12 micro encapsulant on the function and inflammatory and immune responses of xenogeneic islets transplanted into the omental tissue bilayer sac (OB; n = 4) and diabetic (n = 1) NHPs. Changes in the expression of cytokines after implantation were limited to 2-6-fold changes in blood, most of which did not persist over the first 4 weeks after implantation. Flow cytometry of PBMCs following transplantation showed minimal changes in IFNγ or TNFα expression on xenoantigen-specific CD4+  or CD8+  T cells compared to unstimulated cells, and these occurred mainly in the first 4 weeks. Microbeads were readily retrievable for assessment at day 90 and day 180 and at retrieval were without microscopic signs of degradation or foreign body responses (FBR). In vitro and immunohistochemistry studies of explanted microbeads indicated the presence of functional xenogeneic islets at day 30 post transplantation in all biopsied NHPs. These results from a small pilot study revealed that CXCL12-microencapsulated xenogeneic islets abrogate inflammatory and adaptive immune responses to the xenograft. This work paves the way toward future larger scale studies of the transplantation of alginate microbeads with CXCL12 and porcine or human stem cell-derived beta cells or allogeneic islets into diabetic NHPs without systemic immunosuppression.

Plasma osteopontin relates to myocardial fibrosis and steatosis and to immune activation among women with HIV.

OBJECTIVE: Women with HIV (WWH) have heightened heart failure risk. Plasma OPN (osteopontin) is a powerful predictor of heart failure outcomes in the general population. Limited data exist on relationships between plasma OPN and surrogates of HIV-associated heart failure risk. DESIGN: Prospective, cross-sectional. METHODS: We analyzed relationships between plasma OPN and cardiac structure/function (assessed using cardiovascular magnetic resonance imaging) and immune activation (biomarkers and flow cytometry) among 20 WWH and 14 women without HIV (WWOH). RESULTS: Plasma OPN did not differ between groups. Among WWH, plasma OPN related directly to the markers of cardiac fibrosis, growth differentiation factor-15 (ρ = 0.51, P = 0.02) and soluble interleukin 1 receptor-like 1 (ρ = 0.45, P = 0.0459). Among WWH (but not among WWOH or the whole group), plasma OPN related directly to both myocardial fibrosis (ρ = 0.49, P = 0.03) and myocardial steatosis (ρ = 0.46, P = 0.0487). Among the whole group and WWH (and not among WWOH), plasma OPN related directly to the surface expression of C-X3-C motif chemokine receptor 1 (CX3CR1) on nonclassical (CD14-CD16+) monocytes (whole group: ρ = 0.36, P = 0.04; WWH: ρ = 0.46, P = 0.04). Further, among WWH and WWOH (and not among the whole group), plasma OPN related directly to the surface expression of CC motif chemokine receptor 2 (CCR2) on inflammatory (CD14+CD16+) monocytes (WWH: ρ = 0.54, P = 0.01; WWOH: ρ = 0.60, P = 0.03), and in WWH, this held even after controlling for HIV-specific parameters. CONCLUSION: Among WWH, plasma OPN, a powerful predictor of heart failure outcomes, related to myocardial fibrosis and steatosis and the expression of CCR2 and CX3CR1 on select monocyte subpopulations. OPN may play a role in heart failure pathogenesis among WWH. CLINICALTRIALSGOV REGISTRATION: NCT02874703.

Cardiac strain is lower among women with HIV in relation to monocyte activation.

BACKGROUND: Women with HIV (WWH) face heightened risks of heart failure; however, insights on immune/inflammatory pathways potentially contributing to left ventricular (LV) systolic dysfunction among WWH remain limited. SETTING: Massachusetts General Hospital, Boston, Massachusetts. METHODS: Global longitudinal strain (GLS) is a sensitive measure of LV systolic function, with lower cardiac strain predicting incident heart failure and adverse heart failure outcomes. We analyzed relationships between GLS (cardiovascular magnetic resonance imaging) and monocyte activation (flow cytometry) among 20 WWH and 14 women without HIV. RESULTS: WWH had lower GLS compared to women without HIV (WWH vs. women without HIV: 19.4±3.0 vs. 23.1±1.9%, P<0.0001). Among the whole group, HIV status was an independent predictor of lower GLS. Among WWH (but not among women without HIV), lower GLS related to a higher density of expression of HLA-DR on the surface of CD14+CD16+ monocytes (ρ = -0.45, P = 0.0475). Further, among WWH, inflammatory monocyte activation predicted lower GLS, even after controlling for CD4+ T-cell count and HIV viral load. CONCLUSIONS: Additional studies among WWH are needed to examine the role of inflammatory monocyte activation in the pathogenesis of lower GLS and to determine whether targeting this immune pathway may mitigate risks of heart failure and/or adverse heart failure outcomes. TRIAL REGISTRATION: Clinical trials.gov registration: NCT02874703.

Advances in understanding the molecular basis of clonal hematopoiesis.

Hematopoietic stem cells (HSCs) are polyfunctional, regenerating all blood cells via hematopoiesis throughout life. Clonal hematopoiesis (CH) is said to occur when a substantial proportion of mature blood cells is derived from a single dominant HSC lineage, usually because these HSCs have somatic mutations that confer a fitness and expansion advantage. CH strongly associates with aging and enrichment in some diseases irrespective of age, emerging as an independent causal risk factor for hematologic malignancies, cardiovascular disease, adverse disease outcomes, and all-cause mortality. Defining the molecular mechanisms underlying CH will thus provide a framework to develop interventions for healthy aging and disease treatment. Here, we review the most recent advances in understanding the molecular basis of CH in health and disease.

Metabolomic and transcriptomic analyses of the anti-rheumatoid arthritis potential of xylopic acid in a bioinspired lipoprotein nanoformulation.

Xylopic acid (XA), a diterpene kaurene and the major active ingredient of the African spice Xylopia aethiopica (Annonaceae), is reported to possess anti-inflammatory and analgesic properties. Here, we investigated the therapeutic potential of XA for rheumatoid arthritis (RA), a debilitating autoimmune inflammatory disease characterized by joint damage, in the complete Freund's adjuvant (CFA)-induced arthritis model in rats. We synthesized bioinspired reconstituted high-density lipoprotein (rHDL) nanoparticles loaded with purified XA crystals (rHDL/XA) that passively accumulate in inflamed joints of CFA-induced arthritic rats. Treatment with rHDL/XA minimized mononuclear cell infiltration of CFA-induced arthritic sites and ameliorated disease burden. Metabolomic and transcriptomic analyses revealed that the major molecular pathways perturbed following CFA-induced arthritis correlated with amino acid and lipid metabolism, which were restored to normal states by rHDL/XA treatment. This work demonstrates the anti-RA potential of XA in a nanoformulation and uncovers its underlying therapeutic mechanisms at the transcript and metabolite levels.

Genomic Instability in Multiple Myeloma.

Genomic instability (GIN), an increased tendency to acquire genomic alterations, is a cancer hallmark. However, its frequency, underlying causes, and disease relevance vary across different cancers. Multiple myeloma (MM), a plasma cell malignancy, evolves through premalignant phases characterized by genomic abnormalities. Next-generation sequencing (NGS) methods are deconstructing the genomic landscape of MM across the continuum of its development, inextricably linking malignant transformation and disease progression with increasing acquisition of genomic alterations, and illuminating the mechanisms that generate these alterations. Although GIN drives disease evolution, it also creates vulnerabilities such as dependencies on 'superfluous' repair mechanisms and the induction of tumor-specific antigens that can be targeted. We review the mechanisms of GIN in MM, the associated vulnerabilities, and therapeutic targeting strategies.

Alginate-microencapsulation of human stem cell-derived ß cells with CXCL12 prolongs their survival and function in immunocompetent mice without systemic immunosuppression.

Pancreatic ß-cell replacement by islet transplantation for the treatment of type 1 diabetes (T1D) is currently limited by donor tissue scarcity and the requirement for lifelong immunosuppression. The advent of in vitro differentiation protocols for generating functional ß-like cells from human pluripotent stem cells, also referred to as SC-ß cells, could eliminate these obstacles. To avoid the need for immunosuppression, alginate-microencapsulation is widely investigated as a safe path to ß-cell replacement. Nonetheless, inflammatory foreign body responses leading to pericapsular fibrotic overgrowth often causes microencapsulated islet-cell death and graft failure. Here we used a novel approach to evade the pericapsular fibrotic response to alginate-microencapsulated SC-ß cells; an immunomodulatory chemokine, CXCL12, was incorporated into clinical grade sodium alginate to microencapsulate SC-ß cells. CXCL12 enhanced glucose-stimulated insulin secretion activity of SC-ß cells and induced expression of genes associated with ß-cell function in vitro. SC-ß cells co-encapsulated with CXCL12 showed enhanced insulin secretion in diabetic mice and accelerated the normalization of hyperglycemia. Additionally, SC-ß cells co-encapsulated with CXCL12 evaded the pericapsular fibrotic response, resulting in long-term functional competence and glycemic correction (>150 days) without systemic immunosuppression in immunocompetent C57BL/6 mice. These findings lay the groundwork for further preclinical translation of this approach into large animal models of T1D.

Harnessing CXCL12 signaling to protect and preserve functional ß-cell mass and for cell replacement in type 1 diabetes.

Type 1 diabetes (T1D) is a complex multifactorial disease characterized by autoimmune destruction of insulin-producing pancreatic ß cells. Our understanding of the pathogenic mechanisms and natural history of T1D has evolved significantly over the past two decades; we can efficiently predict high-risk individuals, early diagnose the disease and stage progression. Fortuitously, novel in vitro differentiation protocols for generating functional ß-like cells from human pluripotent stem cells have been developed. These advances provide a definitive roadmap to implement realistic preventive and ß-cell replacement therapies in T1D. Immunoprotection and preservation of functional ß-cell mass are a sine qua non for the success of these interventions. The chemokine, stromal cell-derived factor-1alpha, known as CXCL12-α, is an attractive therapeutic target molecule in this context. CXCL12-α signaling promotes ß-cell development, survival and regeneration and can mediate local immunomodulation in the pancreatic islets. Interestingly, CXCL12-α is robustly expressed in maturing insulin-producing ß cells and in adult ß cells during periods of injury and regeneration. However, under normal physiological settings, CXCL12-α is repressed in terminally differentiated mature ß cells and islets. Here, we provide a comprehensive overview of the role of CXCL12-α signaling in ß-cell biology, physiology and immune regulation. We discuss CXCL12-α signaling mechanisms that could be harnessed to modulate ß-cell autoimmunity, protect and preserve functional ß-cell mass and for cell replacement therapy in T1D.

A Cyclin-Dependent Kinase Inhibitor, Dinaciclib, Impairs Homologous Recombination and Sensitizes Multiple Myeloma Cells to PARP Inhibition.

PARP1/2 are required for single-strand break repair, and their inhibition causes DNA replication fork collapse and double-strand break (DSB) formation. These DSBs are primarily repaired via homologous recombination (HR), a high-fidelity repair pathway. Should HR be deficient, DSBs may be repaired via error-prone nonhomologous end-joining mechanisms, or may persist, ultimately resulting in cell death. The combined disruption of PARP and HR activities thus produces synthetic lethality. Multiple myeloma cells are characterized by chromosomal instability and pervasive DNA damage, implicating aberrant DNA repair. Cyclin-dependent kinases (CDK), upstream modulators of HR, are dysregulated in multiple myeloma. Here, we show that a CDK inhibitor, dinaciclib, impairs HR repair and sensitizes multiple myeloma cells to the PARP1/2 inhibitor ABT-888. Dinaciclib abolishes ABT-888-induced BRCA1 and RAD51 foci and potentiates DNA damage, indicated by increased γH2AX foci. Dinaciclib treatment reduces expression of HR repair genes, including Rad51, and blocks BRCA1 phosphorylation, a modification required for HR repair, thus inhibiting HR repair of chromosome DSBs. Cotreatment with dinaciclib and ABT-888 in vitro resulted in synthetic lethality of multiple myeloma cells, but not normal CD19(+) B cells, and slowed growth of multiple myeloma xenografts in SCID mice almost two-fold. These findings support combining dinaciclib with PARP inhibitors for multiple myeloma therapy. Mol Cancer Ther; 15(2); 241-50. ©2015 AACR.

A Small-Molecule Inhibitor of RAD51 Reduces Homologous Recombination and Sensitizes Multiple Myeloma Cells to Doxorubicin.

We previously reported high expression of RAD51 and increased homologous recombination (HR) rates in multiple myeloma (MM) cells, and showed that genomic instability and disease progression are commensurate with HR levels. Moreover, high RAD51 expression in vivo is associated with chemoresistance and poor patient survival. Doxorubicin (DOX) is one of the most widely used drug treatments in MM chemotherapy. DOX is cytotoxic because it induces DNA double-strand breaks, which can be repaired by RAD51-mediated HR; activation of this pathway thus contributes to resistance. To investigate the role of RAD51 in MM drug resistance, we assessed the ability of B02, a small-molecule inhibitor of RAD51, to enhance DOX sensitivity of MM cells. Combining low-toxicity doses of DOX and B02 resulted in significant synthetic lethality, observed as increased apoptosis and reduced viability compared to either agent alone, or to the product of their individual effects. In contrast, the combination did not produce significant synergy against normal human CD19(+) B cells from peripheral blood. DOX induced RAD51 at both mRNA and protein levels, while arresting cells in S and G2. DOX treatment also increased the number of RAD51 foci, a marker of HR repair, so that the fraction of cells with ≥5 foci rose fourfold, whereas γH2AX foci rose far less, implying that most new breaks are repaired. When B02 treatment preceded DOX exposure, the induction of RAD51 foci was severely blunted, whereas, γH2AX foci rose significantly relative to basal levels or either agent alone. In MM cells carrying a chromosomally integrated reporter of HR repair, DOX increased HR events while B02 inhibition of RAD51 blocked the HR response. These studies demonstrate the crucial role of RAD51 in protecting MM cells from genotoxic agents such as DOX, and suggest that specific inhibition of RAD51 may be an effective means to block DNA repair in MM cells and thus to enhance the efficacy of chemotherapy.