A cysteine residue located in the transmembrane domain of CD44 is important in binding of CD44 to hyaluronic acid

In the transmembrane domain and cytoplasmic domain of human CD44 protein there are two cysteine residues. These two cysteines are conserved in all known mammalian CD44 proteins. The functions of these cysteine residues are not known. Site-specific mutagenesis was used to create CD44 mutant proteins lacking either one or both of these cysteine residues. Wild-type CD44 and mutant CD44 genes were transfected into CD44- Jurkat cells to establish stable transfectants. These transfectants were used to study whether these two cysteine residues are important in the binding of CD44(H) to fluorescein-conjugated hyaluronic acid (F-HA). Jurkat transfectant bearing wild-type CD44 did not bind F-HA, unless they were stimulated in vitro with immobilized anti-CD3 monoclonal antibody. Anti-CD3 antibody also stimulated the binding of F-HA in Jurkat CD44.C295A transfectant in which the cytoplasmic cysteine residue has been replaced with alanine. In contrast, anti-CD3 antibody failed to stimulate the binding of F-HA in Jurkat transfectant (CD44.C286A), in which the transmembrane domain cysteine 286 has been replaced with an alanine, and in Jurkat transfectant CD44.2C2A, in which both of the cysteine residues have been altered. Binding can also be induced with a monoclonal anti-CD44 antibody (F-44-10-2) in Jurkat wild-type CD44 and Jurkat CD44.C295A transfectants but not in CD44. C286A transfectant. These results provide evidence that the transmembrane domain of CD44, more specifically the cysteine residue in the transmembrane domain, is important for both activation-induced and anti-CD44 antibody-induced binding of soluble HA.     

CD44 is an independent prognostic factor in early-stage cervical cancer

Leptin and neuropeptide Y (NPY) are involved in the regulation of food intake and body weight. Both hormones act through specific receptors in the central nervous system. The objective of this study was to investigate the relation of leptin and NPY in human plasma and cerebrospinal fluid (CSF). Leptin and NPY in CSF and in serum/plasma were measured by radioimmunoassays in 35 patients. Leptin concentrations in serum were 100-200 fold higher than in CSF. There was a significant correlation between leptin levels in CSF and in serum (r=0.88, P<0.0001). Female patients had significantly higher leptin serum concentrations than males (16.6+/-10.9 microg/l vs. 6.5+/-7.3 microg/l, P=0.002). In contrast, NPY levels were only twofold higher in CSF than in plasma. There was no relation between leptin and NPY in CSF and serum/plasma, respectively. The ratio of CSF and peripheral leptin levels did not correlate with the respective albumin ratio, indicating that leptin did not merely leak into the CSF via a defective blood-CSF barrier. It is concluded that leptin uptake from the circulation into CSF is a regulated process. The NPY concentration in CSF is not directly related to leptin CSF levels.     

Pathological changes in pancreatic ducts from patients with chronic pancreatitis

The microsporidian Encephalitozoon hellem is being reported with increasing frequency in HIV-positive subjects, as an agent of disseminated microsporidiosis without involving the gastrointestinal tract. We describe a case of pulmonary microsporidiosis in a 27-year-old Italian man with AIDS who developed fever, cough, and dyspnea. A chest X-ray showed multiple bilateral pulmonary opacities and mediastinal lymph-node enlargement. Stained smears of bronchoalveolar lavage sediment showed oval structures consistent with microsporidian spores. Viral, bacterial and fungal cultures were repeatedly negative, whereas microsporidia were successfully cultured in human and bovine fibroblast cell lines. Analysis of electron micrographs indicated that the isolate belonged to the genus Encephalitozoon. Based on further immunological, biochemical and molecular studies it was characterized as E. hellem. Even though a temporary improvement with albendazole therapy was noticed, the patient deteriorated clinically and died of severe respiratory distress.     

Expression of CD44 standard and CD44 variant 6 in human lung cancer

We immunohistochemically examined the expression of CD44 standard (CD44 st) and CD44 variant 6 (CD44 v6) in 112 cases of primary lung cancer, and their relationship to the clinical milieu, including the clinical stage. In 46 cases of squamous cell carcinoma, expression of CD44 st was observed in 45.7% of the cases, and expression of CD44 v6 was observed in 60.9%. In 43 cases of adenocarcinoma, positive staining of CD44 st and CD44 v6 was seen in 2.3% and 4.7% of the cases, respectively. None of 21 small cell carcinomas was positive for CD44 st or CD44 v6. In squamous cell carcinomas, the expression of CD44 st and CD44 v6 was observed at a rate significantly higher than in other histologic type. Most specimens positive for CD44 st stained positively for CD44 v6. Therefore, it seems likely that the CD44 expression observed in squamous cell carcinoma of the lung was a variant CD44 containing the domain encoded by variant exon 6. The expression of CD44 v6 was not related to the clinical stage. Significant association between CD44 v6 and differentiation of squamous cell carcinoma was seen; 2/7 (28.6%) for poorly differentiated, 19/31 (61.3%) for moderately differentiated, and 7/8 (87.5%) for well differentiated squamous cell carcinomas (p = 0.02 by trend test). It was previously reported that CD44 st and CD44 v6 were expressed in both normal bronchial epithelium and squamous cell metaplasia. These results suggest that the expression of CD44 v6 in squamous cell carcinoma of the lung may reflect the immunohistochemical characteristics of the tissue from which such carcinoma emerge.     

The CD44 adhesion molecule and metastasis

The family of related cell surface adhesion molecules designated CD44 are multifunctional proteins displayed by a wide variety of normal and malignant tissues. CD44 properties in vitro include hyaluronate-mediated adhesion, motility, hyaluronate degradation, self-aggregation, and adhesion to lymphoid tissue. These properties are among several that are required by invasive and metastatic tumor cells. Several in vivo experiments indicate that tumor cells transfected to overexpress specific CD44 isoforms display an enhancement in metastatic potential. Numerous CD44 isoforms exist as a result of alternative splicing, and specific isoforms enhance tumor cell metastasis more efficiently than others. This suggests that regulation of CD44 alternative splicing is an important determinant of metastatic potential. Several human tumors display specific alterations in CD44 isoform expression, and the extent of clinical disease in specific tumors correlates with the CD44 isoform expression pattern. In this review we analyze these data that suggest that CD44 plays an important role in tumor metastasis.     

Sphincter of Oddi dysfunction is associated with chronic pancreatitis

To clarify whether the content of glutathione (GSH) in the brain can be estimated by the uptake of 99mTc-meso-HMPAO, we conducted the following in vivo and in vitro experiments. METHODS: We investigated the effect of diethyl maleate (DEM) and buthionine sulfoximine (BSO) administration on the brain uptake of 99mTc-meso-HMPAO in the mouse, rat and rabbit, and the chemical specificity of in vitro interaction of 99mTc-HMPAO to GSH using measurements of octanol-extractable radioactivity as an index of remaining intact tracer. RESULTS: The uptake of 99mTc-meso-HMPAO in the mouse and rat brain were reduced together with decreased content of GSH by preloading of DEM, a GSH depletor that acts through glutathione S-transferase. Neither 99mTc-meso-HMPAO uptake nor GSH content was affected in the rabbit brain. Similarly, the uptake of 99mTc-meso-HMPAO and GSH content in the mouse brain was reduced by preinjection of BSO, a GSH depletor that acts through gamma-glutamylcysteine synthetase. In an in vitro study, 99mTc-HMPAO showed reactivity to the molecules possessing a -SH group, but were not specific to GSH. The order of 99mTc-meso-HMPAO reactivity to the mouse brain homogenate agreed with the order of GSH concentration: normal > BSO > DEM. GSH was a major contributor to the conversion reaction of 99mTc-meso-HMPAO to hydrophilic complex in mouse brain homogenate. CONCLUSION: GSH may have a major responsibility for trapping 99mTc-HMPAO in the brain, suggesting the possibility of in vivo measurement of brain GSH with 99mTc-meso-HMPAO.     

Serum amylase isozyme changes in chronic pancreatitis and their clinical significance

The diagnostic usefulness of serum amylase isozyme measurement was investigated in 17 cases of definite chronic pancreatitis and 13 cases of suspected chronic pancreatitis, a total of 30 cases. Six types of serum isoamylase patterns were distinguished according to the character of the two main amylase activities at the fraction of fast-gamma globulin and pre-gamma globulin. The amylase activity of the fast-gamma fraction rises in acute exacerbation, and falls in cases of chronic calcifying pancreatitis and in cases with a marked decrease in pancreatic exocrine function. Especially, a fall in fast-gamma amylase activity excellently reflects a decrease in pancreatic enzyme production. The measurement of amylase activity at the fast-gamma fraction therefore appears to be a useful method for assessing pancreatic damage. The significance of a frequent rise in pre-gamma amylase activity in chronic pancreatitis remains unknown.     

Accentuated antagonism in canine subendocardium is not altered by chronic exercise

Acetylcholine often affects cardiac action potential repolarization only during augmented adrenergic tone, i.e., the phenomenon of accentuated antagonism. Since chronic exercise involves repeated changes in autonomic outflow, we determined whether it also influenced adrenergic/cholinergic interactions in isolated canine cardiac tissue. Using standard micro-electrode techniques in thin ventricular subendocardial slices isolated from exercised (EX: 8-10 wk daily exercise) and sedentary (SED): 8-10 wk cage rest) dogs, we examined transmembrane potential responses to isoproterenol (ISO: 10(-8), 10(-7), 10(-6) M) and to ISO in the presence of ACH (10(-5) M). Control transmembrane characteristics at BCL = 500 ms were similar for EX (N = 8 dogs) and SED (N = 9 dogs). ISO (10(-6) M) decreased action potential duration at 50% repolarization (APD50): EX = -29 +/- 15 ms; SED = 11 ms and at 90% repolarization (APD90): EX = -37 +/- 17 ms; and SED = -24 +/- 14 ms (P > 0.05, EX vs SED). ACH alone did not alter APD. With ACH (10(-5) M), delta APD50 with ISO (10(-6) M) was -5 +/- ms and 0 +/- 5 ms for EX and SED, respectively; delta APD90 was -8 +/- 4 ms and -8 +/- 7 ms for EX and SED, respectively (P > 0.05, EX vs SED). Thus, ACH antagonized ISO-mediated acceleration of repolarization equally in both groups. Chronic daily exercise does not influence adrenergic/cholinergic interactions at the cellular level.     

The cytological aspects of chronic pancreatitis

Biopsy material of pancreatic tissue using light-optical radioautography and electron microscopy, and the method of high-precise radioautography also, was investigated to study up the pancreatic gland (PG) pathology in chronic pancreatitis (CHP). It was established that CHP is a chronic proliferative-destructive process causing focal generalized fibrosis of PG. All the structural components of organ, and the duct epithelium first of all, are affected in CHP. It gives reason to regard a duct system as a complex independent morphofunctional unit of PG.     

The prognostic factors of pancreatic cancer--adhesion molecule CD44

The prognosis for pancreatic cancer is extremely poor, because there are usually invasion of surrounding tissues and metastases to lymph nodes, liver or peritoneum at the time of diagnosis. Many studies from the molecular-biological stand point have demonstrated this poor prognosis. However, the mechanisms underlying these invasive and metastatic capabilities have not yet been clarified. We reviewed several reports for prognostic factors of pancreatic cancer in molecular-biological examinations, and introduced our recent study on the adhesion molecule CD44. The CD44 variant 6 (v6) molecule has been noted as a marker for tumor metastasis and prognosis in several tumors. We examined whether or not v6 is a useful marker for evaluating the prognosis of pancreatic cancer patients. In addition, we attempted to assess the clinicopathological implications for pancreatic cancer of the variant 2 (v2) isoform using a recently developed monoclonal antibody against a v2 epitope. The expression of CD44 v6 and v2 was observed only in tumor cells, if at all. The expression of CD44 v6 and v2 was correlated with decreased overall survival. A significant correlation was obtained between CD44 v2 and vessel invasion. These results suggest that CD44 v2 and CD44 v6 may be useful markers of a poor prognosis.     

Effect of pancreatic ductal and parenchymal changes on exocrine function in chronic pancreatitis

The effect of pancreatic ductal and parenchymal changes on exocrine pancreatic function was analyzed prospectively in 75 patients with chronic pancreatitis (CP). Endoscopic retrograde pancreatography (ERP), computed tomography (CT), and serum pancreolauryl test (PLT) were performed to evaluate the degree of ductal, parenchymal, and functional changes, respectively. Results were evaluated by stepwise multivariate logistic regression and are expressed as the odds ratio (OR). A strong association was found between the degree of ductal changes in ERP and the degree of exocrine functional impairment (OR = 5.8). However, the association between the degree of parenchymal changes in CT and the degree of pancreatic dysfunction was weaker and was clearly confounded by the degree of ductal changes. On the basis of these findings, we suggest that the development of exocrine pancreatic functional impairment in patients with CP depends primarily on the degree of ductal changes, while parenchymal abnormalities play a less important role.     

Structural variability of CD44v molecules and reliability of immunodetection of CD44 isoforms using mAbs specific for CD44 variant exon products

CD44 can be considered structurally and functionally one of the most variable surface molecules. Alternative splicing of variant exons as well as posttranslational modifications of the molecule (differences in glycosylation) generate a rich repertoire of CD44 isoforms (CD44v), some of which seem to play a key role in tumor growth and progression. Immunodetection of CD44 isoforms in vivo, using mAbs specific for CD44 variant exon products, is largely used to identify those CD44 molecules involved in tumor growth and progression and to interfere with CD44-mediated processes. In the present work we demonstrate that the immunoreactivity of some mAbs directed to CD44 exon-specific epitopes can be impaired by the structural variability of the molecule. Our findings demonstrate that (1) specific exon assortment and/or posttranslational modifications of CD44v molecules can mask CD44 exon-specific epitopes; (2) glycosaminoglycan side chains, carried by some CD44v isoforms of high molecular weight, may play a critical role in determining the exact conformation of the molecule, which is necessary for the detection of CD44 variant epitopes by specific mAbs; and (3) in a panel of stable transfectants expressing CD44 N-glycosylation site-specific mutants, generated in the constant region of CD44 extracellular domain, asparagine-isoleucine substitution is sufficient per se to impair the immunoreactivity of several mAbs to pan-CD44. Thus, conformational changes due to the alternative splicing of CD44 variant exons and/or posttranslational modifications of the molecule (different degree of glycosylation), which are cell type-specific, are likely to generate CD44 variants that elude immunodetection. These findings strongly suggest that immunohistochemical analysis of CD44 expression in vitro and in vivo, using mAbs specific for CD44 variant exon epitopes, can potentially be impaired by a large number of false negative results.     

The prognostic value of CD44 isoform expression in endometrial cancer

Elite sport requires high training volumes. However, little is known about the relationship between training volume and performance development. This relationship appears to have an inverted U-shape. Short-term overtraining or overreaching is probably associated with insufficient metabolic recovery, resulting in a decline in ATP levels. Systemic overtraining or staleness is attributed to failure of the hypothalamus to cope with the total amount of stress. Clinically, a parasympathetic and sympathetic form has been distinguished. It is assumed that these two forms express different stages of staleness. No specific, simple, and reliable parameters are known to diagnose overreaching and overtraining in the earliest stage.     

The diagnosis of chronic cholecystitis and pancreatitis

Results are submitted of ultrasonic monitoring of gallbladder, pancreas and duodenum during the I, II, III phases of digestion in 186 patients who ranged from 30 to 60 years old. The form was studied of the gallbladder as was its size and location together with the volume, thickness of walls, presence of deformities; echogenicity of pancreas, outline, state of the main duct. Interdigestive duodenal motility and intracavitary pressure were recorded. Relationship has been established of the gallbladder and pancreas contraction phases to the condition of the intracavitary pressure in the duodenum.     

CD8+CD103+ T cells analogous to intestinal intraepithelial lymphocytes infiltrate the pancreas in chronic pancreatitis

OBJECTIVE: Chronic pancreatitis is a painful chronic inflammatory disease of the exocrine pancreas that is associated with the replacement of functional parenchyma by extended fibrosis and with a massive infiltration of T lymphocytes. However, to date further characterization of infiltrating T cells in chronic pancreatitis has not been undertaken. METHODS: Using the novel method of multiepitope imaging with fluorochrome-tagged specific monoclonal antibodies, which allows the simultaneous localization and characterization of T cells in tissues, we analyzed the distribution and phenotypes of T cells infiltrating the pancreas in chronic pancreatitis. RESULTS: The mean CD4:CD8 ratio in 10 cases of chronic pancreatitis was 2.4:1. In order of decreasing frequency, the following markers were observed: CD45RO, CD18, TCRgammadelta, and CD103. The lymphocytes, especially of the CD4+ subset, were found mainly in the fibrous stroma, but T cells were also observed periductally. A T-cell subset bearing the phenotype CD8+CD103+, analogous to intestinal intraepithelial lymphocytes, was found intracalating between the cells of the ductal epithelium. CONCLUSIONS: Phenotyping of the T lymphocytes in chronic pancreatitis supports the concept of the involvement of cell-mediated cytotoxicity in the pathogenesis of this disease. In addition, intraepithelial lymphocytes were found interspersed between the ductal epithelial cells, pointing to a role of this T-cell subset as a first-line defense against deleterious epithelial events in chronic pancreatitis.     

Functional activation of lymphocyte CD44 in peripheral blood is a marker of autoimmune disease activity

Interactions between complementary receptors on leukocytes and endothelial cells play a central role in regulating extravasation from the blood and thereby affect both normal and pathologic inflammatory responses. CD44 on lymphocytes that has been "activated" to bind its principal ligand hyaluronate (HA) on endothelium can mediate the primary adhesion (rolling) of lymphocytes to vascular endothelial cells under conditions of physiologic shear stress, and this interaction is used for activated T cell extravasation into an inflamed site in vivo in mice (DeGrendele, H.C., P. Estess, L.J. Picker, and M.H. Siegelman. 1996. J. Exp. Med. 183:1119-1130. DeGrendele, H.D., P. Estess, and M.H. Siegelman. 1997. Science. 278:672-675. DeGrendele, H.C., P. Estess, and M.H. Siegelman. 1997. J. Immunol. 159: 2549-2553). Here, we have investigated the role of lymphocyte-borne-activated CD44 in the human and show that CD44-dependent primary adhesion is induced in human peripheral blood T cells through T cell receptor triggering. In addition, lymphocytes capable of CD44/HA-dependent rolling interactions can be found resident within inflamed tonsils. In analysis of peripheral bloods of patients from a pediatric rheumatology clinic, examining systemic lupus erythematosus, and a group of chronic arthropathies, expression of CD44-dependent primary adhesion strongly correlates with concurrent symptomatic disease, with 85% of samples from clinically active patients showing elevated levels of rolling activity (compared with only 4% of inactive patients). These rolling interactions are predominantly mediated by T cells. The results suggest that circulating T lymphocytes bearing activated CD44 are elevated under conditions of chronic inflammation and that these may represent a pathogenically important subpopulation of activated circulating cells that may provide a reliable marker for autoimmune or chronic inflammatory disease activity.     

Physical association between CD155 and CD44 in human monocytes

Regulation of CD44-mediated binding to hyaluronan is critical in normal and diseased immune cell function. In earlier work by others (Shepley and Racaniello, J. Virol., 68, 1301 1309), anti-CD44 mAb blocked poliovirus binding to CD155 (the poliovirus receptor) in HeLa cells, suggesting that CD155 and CD44 may be physically associated. Here, we present evidence that CD155 and CD44 are physically associated in human monocytes. In co-modulation experiments in U937 monocytic cells, CD155 and CD44 reciprocally co-modulated. In primary human monocytes, CD 155 syn-capped with CD44. In immunofluorescence flow cytometric experiments, anti CD44 mAb inhibited up to 94% of binding by anti-CD155 mAb which blocks poliovirus binding to CD155. This inhibition was specific for CD155. Culturing monocytes increased the extent of inhibition. In addition, mAb against PRR2, a novel molecule that is related to CD 155, was inhibited by anti-CD44 in a dose-dependent manner, but not by anti-CD14. These data support the interpretation that CD155 (and related proteins) are physically associated with CD44 on monocyte cell surfaces. Although the current study does not address functional significance, we speculate that this interaction may have a role in regulating monocyte CD44 ligand binding which may be critical in pathological processes such as tumor metastasis and arthritis.