Anu Soots

Cytomegalovirus enhance expression of growth factors during the development of chronic allograft nephropathy in rats

Cytomegalovirus (CMV) accelerates chronic rejection (CRX) in a model of rat kidney allograft. In this model, the expressions of transforming growth factor beta 1 (TGF‐β), platelet‐derived growth factor (PDGF)‐AA, PDGF‐BB and connective tissue growth factor (CTGF) were investigated with and without CMV. Transplantations were performed under immunosuppression. One group of animals was infected with CMV and the other was left uninfected. The grafts were harvested on days 3–60 after transplantation. Growth factor proteins were demonstrated by immunohistochemistry, and mRNAs by in situ hybridization. A significantly more intense and earlier endothelial TGF‐β (2.4u2003±u20030.8 vs. 1.0u2003±u20030.0; Pu2003<u20030.05) and PDGF‐AA (1.8u2003±u20030.4 vs. 1.0u2003±u20030.0; Pu2003<u20030.05) expressions, confirmed by mRNA hybridization, occurred in the CMV group compared with the noninfected group. PDGF‐BB appeared in a few inflammatory cells only. In addition CTGF appeared earlier and has more intense in the CMV group (2.5u2003±u20030.6 vs. 1.2u2003±u20030.5) and the number of CTGF mRNA‐positive fibroblasts (57u2003±u20039 vs. 3u2003±u20034; Pu2003<u20030.05) was significantly higher. Thus, CMV enhanced expression of TGF‐β1, PDGF‐AA and CTGF during the development of CRX.

Time-Related Effects of Cytomegalovirus Infection on the Development of Chronic Renal Allograft Rejection in a Rat Model

Cytomegalovirus (CMV) infection is a risk factor for chronic allograft rejection. The histological findings of chronic renal allograft rejection include inflammation, vascular intimal thickening, glomerulosclerosis, tubular atrophy and fibrosis. We have developed a rat model of renal transplantation in which transplants, after an early inflammatory episode, end up with chronic rejection within 60 days. During the early phase of the process in this model, CMV increased and prolonged the inflammatory response, the expression of adhesion molecules, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and their ligands, lymphocyte function antigen-1 and very late antigen-4 in the graft. Simultaneously, the production of various growth factors, such as transforming growth factor beta, platelet-derived growth factor and connective tissue growth factor was upregulated, which induce smooth muscle cell proliferation in the vascular wall and collagen synthesis by fibroblasts. Chronic rejection developed within 20 days in CMV-infected grafts. In summary, CMV infection accelerated and enhanced the early immune response, the induction of growth factors and collagen synthesis, and the development of chronic rejection in renal allografts.

Paracrine factors from fibroblast aggregates in a fibrin-matrix carrier enhance keratinocyte viability and migration.

Efficient re-epithelialization of skin lesions is dependent on paracrine support from connective tissue fibroblasts. In deep skin defects, the supporting growth factor incentive is lacking. Current methods of keratinocyte transplantation with compromised attachment, spread, and cell proliferation warrant improvement and refinement. We describe here how human keratinocytes can be stimulated by matrix-embedded factors from a novel process of fibroblast activation: nemosis. Interestingly, the unique set of mediators released in this process also plays a key role in normal wound healing. To develop a system for targeted delivery of nemosis-derived paracrine effectors, herein designated as Finectra, we combined them with fibrin to establish a controlled-release gel. Keratinocytes seeded to cover this active matrix showed better adherence, outgrowth, and viability than did cells on control matrix. The matrix incorporating Finectra supported viability of both primary keratinocytes and green fluorescent protein (GFP)-labeled HaCaT cells, as evaluated by MTT assay and persistence of GFP-fluorescence. The fibrin-Finectra matrix promoted migration of keratinocytes to cover a larger area on the matrix, suggesting better wound coverage on transplantation. An inhibitor of EGFR/c-Met receptor tyrosine kinases abolished keratinocyte responses to fibrin-Finectra matrix. This matrix can thus deliver biologically relevant synergistic stimuli to keratinocytes and hasten re-epithelialization.

Sequential analysis of adhesion molecules and their ligands in rat renal allografts during the development of chronic rejection.

Abstract Intercellular adhesion molecule‐1 (ICAM‐1) and vascular cell adhesion molecule‐1 (VCAM‐1) are important in endothelial cell‐leukocyte interactions. In this sequential study, the expression of ICAM‐1 and VCAM‐1 and their ligands LFA‐1 and VLA‐4 as well as major histocompatibility complex class II antigens (MHC class II), and interleukin‐2‐receptor (IL‐2R) were investigated during the development of chronic renal allograft rejection in a rat model. The time‐related expression of adhesion molecules and their ligands in the graft was correlated to the chronic allograft damage index (CADI). In association with an initial short immune activation, there was a significant ICAM‐1 and VCAM‐1 induction in the vascular endothelium and the tubular epithelium. In the interstitium, there was infiltration of lymphocytes expressing ligand molecules VLA‐4 and LFA‐1, as well as activation markers MHC class II and IL‐2R. Thereafter, the expression declined together with the increase of CADI‐values. In end‐stage chronic rejection, there was practically no expression of ICAM‐1 and VCAM‐1. In the interstitium, there were only few ligand‐expressing leukocytes. In conclusion, adhesion molecules and their ligands are involved in the induction phase of the process but no longer in the later stages of chronic rejection.