Charles K. Moore

Stretch-induced membrane type matrix metalloproteinase and tissue plasminogen activator in cardiac fibroblast cells

In the normal heart, cardiomyocytes are surrounded by extracellular matrix (ECM) and latent matrix metalloproteinases (MMPs), which are produced primarily by cardiac fibroblasts. An activator of latent MMPs might be induced by ischemic conditions or pressure‐induced stretching. To test the hypothesis that an activator of latent MMP is induced in the ischemic heart during transformation of a compensatory hypertrophic response to a decompensatory failing response in cardiac fibroblast cells, we stretched the human cardiac fibroblasts at 25 cycles/min in serum‐free or 5% serum culture condition. The membrane type (MT)‐MMP activity in stretched cells was measured by zymography and immuno‐blot analyses using MT‐MMP‐2 antibody. The MT‐MMP activity was further characterized by transverse‐urea gradient (TUG)‐zymography. The results suggested that stretch induced a membrane MMP in the fibroblasts that was similar to the MT‐MMP induced in ischemic heart. Furthermore, we observed that membrane MMP has distinct mobility in TUG‐zymography. To localize the MT‐MMP and tissue plasminogen activator (tPA) of latent MMPs, the membrane and cytosol were separated by a method employing a detergent and sedimentation. The MT‐MMP and tPA activities of cytosol and membrane fractions were measured by gelatin‐ and plasminogen‐zymography, respectively. Differential‐display mRNA analysis was performed on control and stretched cells. In situ immuno‐labelling was performed to localize the MT‐MMP. The results indicate that induction of MT‐MMP occurred in the membrane fractions. The secretion of tPA was elevated in the stretched cells. The MT‐MMP activity was inhibited by prior incubation with an antibody generated to membrane MMP. The tPA activity was inhibited by using tPA antibody. These results suggest that, under stretched conditions, neutral transmembrane matrix proteinases are induced in the cardiac fibroblasts. This may lead to activation of adverse ECM remodeling, cardiac dilatation, and failure. J. Cell. Physiol. 176:374–382, 1998.

Cardiac allograft rejection correlates with increased expressions of Toll-like receptors 2 and 4 and allograft inflammatory factor 1.

BACKGROUND Evidence suggests that injury-induced activation of the recipients innate immune response determines the outcome of allograft transplantation. The mechanism responsible for the induction of such innate immune response is not clear yet. We hypothesized that in cardiac transplantation settings, the initial myocardial ischemia and postischemia graft reperfusion may release allograft inflammatory factor (AIF) 1, causing Toll-like receptor (TLR)-mediated activation of macrophages and dendritic cells, leading to the production of cytokines and the activation of adaptive alloimmunity. Therefore, our goal was to validate the presence of these biomarkers in the peripheral blood and biopsy specimens of patients presenting allograft rejection. METHODS We studied 90 peripheral blood and 30 endomyocardial biopsy specimens from patients who had undergone cardiac transplantation. Specimens were tested by quantitative reverse-transcription polymerase chain reaction to determine TLR-2 and -4 and AIF-1 expression levels, correlating with clinical rejection grades. The group differences for mRNA transcript levels between the rejection grades were determined by 1-way analysis of variance. The level of significance was set at P < .05 for comparison between the groups. RESULTS The mean ± SEM level of TLR-2 mRNA expression was increased 1.7-fold in monocytes (P < .05) and 4.2-fold in biopsy samples from groups with grade 3A compared with grade 1A or grade 0 rejection (P < .0001). AIF-1 expression was increased 2.4-fold in monocytes (P < .05) and 4.2-fold in biopsy samples comparing grade 3A versus 1A rejections. The TLR-4 mRNA expression was also increased in the group with 3A rejections; however, the difference was only significant in biopsy specimens (P < .0001). CONCLUSIONS Our data demonstrated that expression profiles of AIF-1 and TLR-2 correlated with biopsy-proven allograft rejection in both peripheral blood and local tissue, suggesting their potential as diagnostic biomarkers for early detection of allograft rejection.

Tamponade Precedes Diagnosis of Systemic Lupus Erythematosus

The most common cardiovascular manifestation of Systemic Lupus Erythematosus is pericardial disease. Tamponade in SLE is rarely described. The patient discussed in this case report presented with symptoms of heart failure. Physical exam, laboratory testing, echocardiography, and right heart catheterization revealed multiple morbid conditions including tamponade. The diagnoses satisfied four criteria for the classification of SLE. This case emphasizes the importance of a thorough physical exam in guiding diagnostic and therapeutic measures.