The American journal of pathology
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Fibrotic obliteration of the small airways leading to progressive airflow obstruction, termed bronchiolitis obliterans syndrome (BOS), is the major cause of poor outcomes after lung transplantation. We recently demonstrated that a donor-derived population of multipotent mesenchymal stem cells (MSCs) can be isolated from the bronchoalveolar lavage (BAL) fluid of human lung transplant recipients. Herein, we study the organ specificity of these cells and investigate the role of local mesenchymal progenitors in fibrogenesis after lung transplantation. ⋯ MSCs isolated from patients with BOS demonstrated increased expression of α-SMA and collagen I when compared with non-BOS controls, consistent with a stable in vivo fibrotic phenotype. FOXF1 mRNA expression in the BAL cell pellet correlated with the number of MSCs in the BAL fluid, and myofibroblasts present in the fibrotic lesions expressed FOXF1 by in situ hybridization. These data suggest a key role for local tissue-specific, organ-resident, mesenchymal precursors in the fibrogenic processes in human adult lungs.
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Evidence is emerging for differential pathogenicity among Borrelia burgdorferi genotypes in the United States. By using two linked genotyping systems, ribosomal RNA intergenic spacer type (RST) and outer surface protein C (OspC), we studied the inflammatory potential of B. burgdorferi genotypes in cells and patients with erythema migrans or Lyme arthritis. When macrophages were stimulated with 10 isolates of each RST1, RST2, or RST3 strain, RST1 (OspC type A)-stimulated cells expressed significantly higher levels of IL-6, IL-8, chemokine ligand (CCL) 3, CCL4, tumor necrosis factor, and IL-1β, factors associated with innate immune responses. ⋯ Similarly, serum samples from patients with erythema migrans who were infected with the RST1 genotype had significantly higher levels of almost all of these mediators, including exceptionally high levels of IFN-γ-inducible chemokines, CCL2, CXCL9, and CXCL10; and this pronounced inflammatory response was associated with more symptomatic infection. Differences among genotypes were not as great in patients with Lyme arthritis, but those infected with RST1 strains more often had antibiotic-refractory arthritis. Thus, the B. burgdorferi RST1 (OspC type A) genotype, followed by the RST3 (OspC type I) genotype, causes greater inflammation and more severe disease, establishing a link between spirochetal virulence and host inflammation.
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Clinical evidence accumulated from hemophilic patients during prophylaxis with recombinant activated factor VII (rFVIIa) suggests that the duration of the hemostatic action of rFVIIa exceeds its predicted plasma half-life. Mechanisms involved in this outcome have not been elucidated. We have investigated in vitro the redistribution of rFVIIa in platelets from healthy donors, patients with FVII deficiency, and one patient with Bernard-Soulier syndrome. ⋯ Perfusion studies revealed that the presence of 30% of platelets containing FVIIa improved platelet aggregate formation and enhanced fibrin generation (P < 0.01 versus control). Our results indicate that, at therapeutic concentrations, rFVIIa can be internalized into platelets, where it is protected from physiological clearance mechanisms and can still promote hemostatic activity. Redistribution of rFVIIa into platelets may explain the prolonged prophylactic effectiveness of rFVIIa in hemophilia.
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Ubiquitin C-terminal hydrolase L1 (UCH-L1), a key protease of the ubiquitin-proteasome system (UPS), is associated with neurodegenerative diseases and cancer. Recently, de novo expression of UCH-L1 was described in podocytes in patients with membranous nephropathy (MN), in which UCH-L1 expression correlated with increased ubiquitin content. The objective of the present study was to investigate the role of UCH-L1 in ubiquitin homeostasis and proteasomal degradation in a rat model of MN. ⋯ Stable UCH-L1 overexpression in cultured podocytes resulted in accumulation of monoubiquitin and polyubiquitin proteins. In contrast, stable knock-down of UCH-L1 reduced monoubiquitin and polyubiquitin proteins and significantly increased proteasomal activity, indicating that the observed effects in rat MN also occurred in cultured podocytes. These data demonstrate that UCH-L1 activity results in polyubiquitin accumulation, proteasome inhibition, and disease aggravation in experimental models of MN.