Modulation of Human Mesenchymal Stem Cell Immunogenicity through Forced Expression of Human Cytomegalovirus US Proteins

BACKGROUND: Mesenchymal stem cells (MSC) are promising candidates for cell therapy, as they migrate to areas of injury, differentiate into a broad range of specialized cells, and have immunomodulatory properties. However, MSC are not invisible to the recipient's immune system, and upon in vivo administration, allogeneic MSC are able to trigger immune responses, resulting in rejection of the transplanted cells, precluding their full therapeutic potential. Human cytomegalovirus (HCMV) has developed several strategies to evade cytotoxic T lymphocyte (CTL) and Natural Killer (NK) cell recognition. Our goal is to exploit HCMV immunological evasion strategies to reduce MSC immunogenicity. METHODOLOGY/PRINCIPAL FINDINGS: We genetically engineered human MSC to express HCMV proteins known to downregulate HLA-I expression, and investigated whether modified MSC were protected from CTL and NK attack. Flow cytometric analysis showed that amongst the US proteins tested, US6 and US11 efficiently reduced MSC HLA-I expression, and mixed lymphocyte reaction demonstrated a corresponding decrease in human and sheep mononuclear cell proliferation. NK killing assays showed that the decrease in HLA-I expression did not result in increased NK cytotoxicity, and that at certain NK∶MSC ratios, US11 conferred protection from NK cytotoxic effects. Transplantation of MSC-US6 or MSC-US11 into pre-immune fetal sheep resulted in increased liver engraftment when compared to control MSC, as demonstrated by qPCR and immunofluorescence analyses. CONCLUSIONS AND SIGNIFICANCE: These data demonstrate that engineering MSC to express US6 and US11 can be used as a means of decreasing recognition of MSC by the immune system, allowing higher levels of engraftment in an allogeneic transplantation setting. Since one of the major factors responsible for the failure of allogeneic-donor MSC to engraft is the mismatch of HLA-I molecules between the donor and the recipient, MSC-US6 and MSC-US11 could constitute an off-the-shelf product to overcome donor-recipient HLA-I mismatch

Molecular imaging of the initial inflammatory response in atherosclerosis : implications for early detection of disease

Background- We hypothesized that molecular imaging of endothelial cell adhesion molecule expression could noninvasively evaluate prelesion atherogenic phenotype. METHODS AND RESULTS: Mice deficient for the LDL-receptor and the Apobec-1 editing peptide (DKO mice) were studied as an age-dependent model of atherosclerosis. At 10, 20, and 40 weeks of age, ultrasound molecular imaging of the proximal thoracic aorta was performed with contrast agents targeted to P-selectin and VCAM-1. Atherosclerotic lesion severity and content were assessed by ultrahigh frequency ultrasound, histology, and immunohistochemistry. In wild-type mice at all ages, there was neither aortic thickening nor targeted tracer signal enhancement. In DKO mice, lesions progressed from sparse mild intimal thickening at 10 weeks to widespread severe lesions with luminal encroachment at 40 weeks. Molecular imaging for P-selectin and VCAM-1 demonstrated selective signal enhancement (P>0.01 versus nontargeted agent) at all ages for DKO mice. P-selectin and VCAM-1 signal in DKO mice were greater by 3-fold at 10 weeks, 4- to 6-fold at 20 weeks, and 9- to 10-fold at 40 weeks compared to wild-type mice. En face microscopy demonstrated preferential attachment of targeted microbubbles to regions of lesion formation. CONCLUSIONS: Noninvasive ultrasound molecular imaging of endothelial activation can detect lesion-prone vascular phenotype before the appearance of obstructive atherosclerotic lesions

Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio as biomarkers in axial spondyloarthritis: Observational studies from the program to understand the longterm outcomes in spondyloarthritis registry

Objectives:This study was conducted to assess the utility of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in predicting radiographic sacroiliitis and active disease in axial spondyloarthritis (SpA) and to explore the association between use of a tumor necrosis factor inhibitor (TNFi) and these laboratory values compared with traditional inflammatory markers. Methods:Observational data from the Program to Understand the Longterm Outcomes in Spondyloarthritis (PULSAR) registry were analyzed. We generated receiver operating characteristic curves to calculate laboratory cutoff values; we used these values in multivariable logistic regression models to identify associations with radiographically confirmed sacroiliitis and active disease. We also used logistic regression to determine the likelihood of elevated laboratory values after initiation of TNFi. Results:Most study participants (n = 354) were White, male, and HLA-B27 positive. NLR (odds ratio [OR] 1.459, P = 0.034), PLR (OR 4.842, P \u3c 0.001), erythrocyte sedimentation rate (OR 4.397, P \u3c 0.001), and C-reactive protein (CRP) level (OR 2.911, P = 0.001) were independent predictors of radiographic sacroiliitis. Models that included PLR with traditional biomarkers performed better than those with traditional biomarkers alone. NLR (OR 6.931, P = 0.002) and CRP (OR 2.678, P = 0.004) were predictors of active disease, but the model that included both NLR and CRP performed better than CRP alone. TNFi use reduced the odds of elevated NLR (OR 0.172, P \u3c 0.001), PLR (OR 0.073, P \u3c 0.001), erythrocyte sedimentation rate (OR 0.319, P \u3c 0.001), and CRP (OR 0.407, P \u3c 0.001), but models that included NLR or PLR and traditional biomarkers performed best. Conclusions:These findings demonstrate an association between NLR and PLR and sacroiliitis and disease activity, with NLR and PLR showing response after TNFi treatment and adding useful clinical information to established biomarkers, thus perhaps assisting in management of axial SpA