Neural cell adhesion molecule (N-CAM) in fetal and mature human heart

CARs and other T cell therapies for MM: The clinical experience

Harnessing the endogenous immune system to eliminate malignant cells has long been an intriguing approach. After considerable success in the treatment of B-cell acute lymphoblastic leukemia, chimeric antigen receptor (CAR)-modified T cells have entered early clinical evaluation in the field of multiple myeloma (MM). The choice of suitable non-CD19 target antigens is challenging and a variety of myeloma-associated surface molecules have been under preclinical investigation. Most recent clinical protocols have focused on targeting B-cell maturation antigen (BCMA), and early results are promising. The trials differ in receptor constructs, patient selection, dosing strategies and conditioning chemotherapy and will thus pave the way to eventually define the optimal parameters. Other sources for autologous T-cell therapy of MM include affinity-enhanced T-cell receptor-modified cells and marrow infiltrating lymphocytes. In summary, adoptive T-cell transfer for the treatment of MM is still in its infancy, but if early response rates indicate durability, will be a paradigm changing therapeutic modality for the treatment of MM.

The 140-kD isoform of CD56 (NCAM1) directs the molecular pathogenesis of ischemic cardiomyopathy

Despite recent advances in understanding the relevance of cell adhesion-related signaling in the pathogenesis of ischemic cardiomyopathy (ICM) in animal models, substantial questions remain unanswered in the human setting. We have previously shown that the neural cell adhesion molecule CD56 [neural cell adhesion molecule (NCAM1)] is specifically overexpressed in ICM; it was the aim of the current study to further elucidate the role of CD56 in the pathogenesis of human ICM. We used quantitative real-time PCR and IHC in human ICM and a rat model of coronary obstruction to demonstrate that CD56(140kD), the only extraneuronally expressed NCAM1 isoform with a cytoplasmic protein domain capable of inducing intracellular signaling, is the only up-regulated CD56 isoform in failing cardiomyocytes in human ICM in vivo. In subsequent analyses of the cellular effects of CD56(140kD) overexpression in the development of ICM using differential whole transcriptome expression analyses and functional in vitro cardiomyocyte cell culture assays, we further show that the up-regulation of CD56(140kD) is associated with profound gene expression changes, increased apoptosis, and reduced Ca(2+) signaling in failing human cardiomyocytes. Because apoptosis and Ca(2+)-related sarcomeric dysfunction are molecular hallmarks of ICM in humans, our results provide strong evidence that CD56(140kD) up-regulation plays a pivotal role in the pathogenesis of ICM and may be a target for future immunotherapeutic strategies in the treatment of this common and often fatal disease.

NCAM(CD56) and RUNX1(AML1) are up-regulated in human ischemic cardiomyopathy and a rat model of chronic cardiac ischemia

Chronic myocardial ischemia is the leading cause of impaired myocardial contractility and heart failure. To identify differentially expressed genes in human ischemic cardiomyopathy (ICM), we constructed a subtracted cDNA library using specimens of ICM compared to normal human heart. Among 100 randomly sequenced clones, seven sequences represented recently identified candidate genes for differential expression in cardiac hypertrophy. A further clone without a known hypertrophy-association coded for the adhesion molecule NCAM(CD56). RNase protection assay, immunohistochemistry, and Western blotting revealed strong overexpression of NCAM(CD56) in all hearts with ICM (n = 14) compared to normal hearts (n = 8), whereas in congestive cardiomyopathy (CCM) (n = 8), hypertrophic obstructive cardiomyopathy (n = 2), myocarditis (n = 4), and sarcoidosis (n = 2), at most slight overexpression of NCAM(CD56) was observed. NCAM(CD56) overexpression abnormally involved the whole cell membrane and the cytoplasma of cardiomyocytes only inside and adjacent to ischemia-induced cardiac scars. Normal or hypertrophic fibers at a distance from ischemic scars were devoid of NCAM overexpression. Identical alterations were observed in an experimental rat ICM model, but not in normal nor in spontaneously hypertensive rat hearts. In search of NCAM(CD56)-related transcription factors we found RUNX1(AML1) up-regulation in ICM and detected RUNX1(AML1) binding within the NCAM(CD56) promoter by electromobility shift assay. We concluded that strong overexpression of NCAM(CD56) and RUNX1(AML1) is a constant and characteristic feature of cardiomyocytes within or adjacent to scars in ICM.

Overexpression of neural cell adhesion molecule in Chagas' myocarditis

The expression of the neural cell adhesion molecule (NCAM) was studied in normal human myocardium and in Chagas' disease myocarditis. We found that NCAM is expressed in the conduction system as well as the myocardium in the fetal heart, but its expression is restricted to the conduction system and absent in the adult myocardium. Chagas' disease is an American endemic disease caused by the Trypanosoma cruzi parasite, which produces myocarditis and a blockade of the conduction system, resulting in cardiac dysfunction. We studied the expression of NCAM in paraffin-embedded human heart tissues from 34 autopsies of patients with Chagas' myocarditis and from murine and canine experimental acute Chagas' myocarditis, using a polyclonal anti-NCAM antibody and immunohistochemistry. Our results show a dramatic upregulation of NCAM expression in the intercalated discs of cardiomyocytes in acute and chronic Chagas' myocarditis. Surprisingly, the NCAM signal was detected in intracellular nests of amastigote forms of the parasite, within infected cardiomyocytes of human and experimental Chagas' myocarditis. In contrast, cardiac cell-cell adhesion proteins, N-cadherin and beta-catenin, were found in intercalated discs distorted by the infection but absent from the amastigote nests. Proteins reactive to several antibodies against NCAM were detected by Western immunoblotting in cultured T cruzi parasites and in trypomastigote forms of T cruzi extracted from the blood of infected mice. The upregulation of NCAM in Chagas' myocarditis and the expression of NCAM or a NCAM-like protein by T cruzi suggest that NCAM may act as a receptor for tissue targeting and cellular invasion by T cruzi in Chagas' disease.

Reexpression of the neural cell adhesion molecule (NCAM) on cardiac myocytes in aging rat heart

The neural cell adhesion molecules, NCAM, is present in several non-neuronal tissues including heart. Using biochemical methods it has been recently shown that NCAM is expressed on cardiac myocytes in early development. During postnatal development NCAM expression is down-regulated and is restricted to neural components of rat heart. However, in the aged rat heart NCAM expression is increased compared to young adult rats. In the present immunohistochemical study the localization of NCAM in different regions of aging rat heart was investigated. Cardiac myocytes expressed NCAM in newborn rat heart whereas NCAM was absent from myocytes in young adult heart. In aged rat heart, NCAM was reexpressed on cardiac myocytes in the ventricles. Thus, NCAM reexpression may be an element in regenerative processes or alternatively a marker of degenerating or dying myocytes.

Expression of polysialylated N-CAM during rat heart development

Developmental patterns of immunoreactivity for the neural cell adhesion molecule (N-CAM) and alpha 2.8-linked polysialic acid (PSA) were identified in embryonic and postnatal rat heart by immunocytochemistry and immunoblotting. Polyclonal antibodies against N-CAM and a monoclonal antibody which recognises only polymers of PSA with a chain length greater than eight units were used. Gold- and alkaline-phosphatase-labelled antibodies were used for detection. The N-CAM polypeptide isoform pattern seen by immunoblotting after endoneuraminidase treatment changed as development progressed. During embryonic development a 160-kDa polypeptide isoform was predominant. Around birth, 130-, 160- and 170-kDa polypeptide isoforms were found. The expression of the 130- and 170-kDa isoforms diminished until finally, in the adult, weak immunoreactivity for bands of 120-, 130- and 160-kDa was seen. In general the extent and intensity of PSA and N-CAM immunostaining in rat heart increased until birth and declined thereafter. Early in development prominent immunostaining for PSA and N-CAM was seen in the epicardium while later in development this area was only weakly stained. Initially myocardial cells, endocardial cells and some cells in the atrioventricular cushions were immunoreactive for both PSA and N-CAM. Later in development N-CAM immunostaining was more prominent than PSA immunoreactivity, reflecting a decrease in N-CAM polysialylation, which was also seen by immunoblotting. During innervation of the heart, nerve fibres were strongly immunostained for PSA and N-CAM, and this was the only immunostaining seen in adult heart.