H. Levesque

Localization and solubilization of hyaluronan and of the hyaluronan-binding protein hyaluronectin in human normal and arteriosclerotic arterial walls

Hyaluronectin (HN), a hyaluronan (hyaluronic acid, HA)-binding glycoprotein isolated from human brain, was studied in normal and atherosclerotic human arteries. It can be detected and assayed in tissue samples by immunohistochemistry. In addition, its high and specific affinity for HA makes it possible to develop specific histological localization of HA using HN as a probe. We tested the presence of HN and HA in human carotid artery samples from adults and newborns. In atheroma-free arterial samples HN was found in the intima, between smooth muscle cells and in the adventitial extracellular matrix. In atherosclerotic lesions, HN was strongly expressed in the diffuse thickened intima and surrounding extracellular microcrystalline calcium deposits, and very little in the lipid core. HA was found in the same locations. The similar localizations of HN and HA shown by immunohistology and demonstration of HN-HA complexes by high pressure liquid chromatography (HPLC) suggest that they are associated in vivo.

Increased Hyaluronan and Hyaluronidase Production and Hyaluronan Degradation in Injured Aorta of Insulin-Resistant Rats

Diabetic patients have a greater incidence of restenosis, which has been shown to be related to exaggerated intimal hyperplasia. Hyaluronan (HA) has been shown to be closely involved in arterial smooth muscle cell proliferation and migration, which provoke intimal hyperplasia after balloon catheter injury. Our aim was to determine the effect of fructose feeding, which produces certain characteristics of non-insulin-dependent diabetes (ie, insulin resistance, hyperinsulinemia, and hypertriglyceridemia), on production of HA and hyaluronidase and degradation of HA in rat aorta. Treated rats received fructose (25% in tap water) 12 weeks before balloon catheter injury and 14 days afterward. Fructose-fed rats had hyperinsulinemia and hypertriglyceridemia. Injury increased intima-media wet weight (7.5%) and DNA content (20%) in control rats. This increase was significantly greater in fructose-fed rats (22% for wet weight and 34% for DNA content) and was associated with greater HA and hyaluronidase production (123% and 41%, respectively) than in control rats (49% and 7%, respectively). Determination of HA molecular mass showed that balloon catheter injury increased the number of HA fragments in the aorta of control rats. Normal aorta of fructose-fed rats contained more HA fragments than that of control rats. Injury to the aorta of fructose-fed rats increased HA fragments and induced the appearance of a very-high-molecular-mass (>2000 kDa) HA. In conclusion, fructose treatment, which induced hyperinsulinemia and hypertriglyceridemia, increased HA and hyaluronidase production and HA degradation in injured aorta. This finding suggests that HA, which has been shown to play a crucial role in proliferation and migration of arterial smooth muscle cells, may be involved in the promotional effect of long-term fructose feeding on arterial wall reaction to injury.

Hyaluronan and hyaluronectin production in injured rat thoracic aorta

The aim of our study was to investigate the production of hyaluronan (HA) by the intima-media during the sclerotic response to aortic injury with a catheter balloon in the rat. In addition we analyzed, for the first time in this model, the production of a glycoprotein (hyaluronectin, HN) which binds specifically to HA. HA and HN were analyzed in control (D0), 14 (D14) and 28 (D28) days after injury using biochemical and immunohistochemical techniques. Intima-media DNA content and wet weight increased significantly on D14 and declined on D28 (but remained significantly increased in comparison to controls). HA content (median in D0 = 448 ng) increased significantly on D14 (2P < 0.04) and on D28 (2P < 0.02). HN content (median in D0 = 920 ng) increased significantly on D14 (2P < 0.05) but decreased on D28 to return to the control level. On D0 the amount of HN was about 3 times higher than that of HA (median ratio HA/HN = 0.34). The ratio remained unchanged on D14 but significantly increased on D28 (2P < 0.02). HPLC and Western blotting showed no difference between HN extracted from normal aorta and HN extracted from injured aorta at D14. Different isoforms of HN were present in both cases, ranging from 400 to 45 kDa. The HA increase on D14 and D28 was not related to a change in hyaluronidase activity of aortic tissue. Immunohistochemical analysis showed at D0 a small amount of HA around arterial smooth muscle cells (ASMC) in media, at D14 more HA was localized around and between ASMC in media and neointima but at D28 it was localized mainly near the vessel lumen. HN formed all the time (D0, D14 and D28) a continuous layer localized near the vessel lumen. In vitro studies showed that production of HA and HN was stimulated when ASMC proliferate and HA at high concentrations (1-100 micrograms/ml) reduced, in a dose dependent manner, ASMC growth. In conclusion our results show that both neointima formation in vivo and ASMC proliferation in vitro correlated with increased HA and HN production. This suggests that HA and HN are probably involved in the formation of neointima. On the other hand, the finding that HA continued to increase in the aorta when neointima decreased and that high concentrations of HA reduce ASMC proliferation in culture suggest that HA might be involved in the regression of neointima.

Inhibition of arterial cells proliferation in vivo in injured arteries by hyaluronan fragments

It has been demonstrated previously that administration of high levels of high molecular mass hyaluronan (hyaluronic acid, HA) to rats was able to reduce in a significant way neointima formation in the injured arteries. In the present study, our aim was to verify whether small forms of HA (4-16 saccharides) are still able to reduce the proliferative response of ASMC to aortic injury. Treated rats received a total of 8 injections of a fixed dose of HA fragments (27 mg/kg rat contained in a volume of 550 microl). Two injections were given on the day of balloon catheter injury (BCI): one, intravenous, 10 min before BCI and one, subcutaneous, immediately after the BCI. The others injections (subcutaneous) were at 2, 4, 6, 8, 10 and 12 days after BCI. Control rats received an equivalent volume of the dissolving buffer containing only hyaluronidase, which has been destroyed before injection to rats. Neointima formation was analysed 14 days after the BCI. Intima-media wet weight and DNA content were significantly reduced in rats receiving HA fragments in comparison to controls (2P=0.01 for wet weight and 0.03 for DNA). This finding was confirmed by the histomorphometric study which showed that both neointima area and the ratio neointima/neointima+media were significantly decreased in treated rats (2P=0.03 for intima area and 0.049 for the ratio). Our data showed thus and for the first time that administration of HA fragments with a very low molecular mass (4-16 saccharides) reduces the proliferative reaction of aorta to injury in vivo. In conclusion, HA fragments, which are components with an excellent safety profile, may offer hope for the prevention of restenosis after angioplasty.

Effect of aging on neointima formation and hyaluronan, hyaluronidase and hyaluronectin production in injured rat aorta

Few studies have examined the effect of aging on arterial wall response to injury, and the results are discordant. Moreover, the effect of aging on hyaluronan synthesis in injured vessels is unknown. The aim of this present study was to determine the effect of aging on neointima formation and hyaluronan (HA), hyaluronidase and hyaluronectin production in injured rat aorta. Aorta was analysed in sham-operated rats (group D0) and 14 (D14) and 28 (D28) days after injury using biochemical and immunohistochemical techniques. Uninjured aorta of old rats was more thickened than that of young rats; it showed a decreased number of arterial smooth muscle cells (ASMC) and was characterized by HA accumulation in the intima and increased hyaluronidase activity. Intima-media wet weight was significantly increased in young rats at D14 and D28 but remained unchanged in old rats. DNA content was significantly enhanced at D14 in both young and old rats. DNA decreased slightly in young rats at D28 but significantly in old rats to return to control level. HA content and hyaluronidase activity in the intima-media were markedly increased in young rats at D14 (+148% and +116% respectively) but slightly in old rats (+23% and +15% respectively). Both HA and hyaluronidase activity continued to increase at D28, but remained more produced in young rats. The immunohistochemical analysis showed the formation of a thickened neointima in young rats, which was associated with strong expression of HA and HN. Neointima of old rats was reduced; it also showed strong expression of HA and HN but their distributions were different from those observed in neointima of young rats. In conclusion, aorta of old rats showed an increased amount of HA in the intima and elevated activity of hyaluronidase. Injury induced formation of a significant neointima in young rats but not in old rats. This was correlated with more HA and hyaluronidase production in injured aorta of young rats. As HA is considered to increase extracellular matrix space and to promote ASMC proliferation and migration, our findings suggest that HA may be implicated in intima thickening with age and after injury.

Intérêt de l’imagerie par résonance magnétique nucléaire au cours de l’atteinte cardiaque du syndrome de Churg-Strauss. Trois observations et revue de la littérature

PURPOSE The reported prevalence of cardiac complications is variable in patients with Churg-Strauss syndrome (15-92%) and depends on diagnostic tools. Diagnosis at early stage of heart involvement is crucial, resulting in appropriate management. METHODS We report three patients who developed cardiac manifestations, revealing Churg-Strauss syndrome. The diagnosis of cardiac involvement was obtained using cardiac magnetic resonance imaging (MRI). RESULTS Two patients were males and the remaining one was a female. Presenting clinical manifestations were: cardiac failure (n=1) and retrosternal pain (n=2). Laboratory findings disclosed: high blood count of eosinophils (range: 6000-11,000/mm(3)); antineutrophil cytoplasmic antibodies were positive in a single patient. Cardiac MRI demonstrated: (1) late gadolinium enhancement (n=3), involving mainly the apical and mid-cavity left ventricular segments; (2) impaired left ventricular function (n=2), mean left ventricular ejection fraction being: 51%; and (3) pericardial effusion (n=3). Outcome was favourable after institution of combined therapy with prednisone and cyclophosphamide (n=2); one patient also underwent plasma exchanges. CONCLUSION Our case series underlines that MRI is a helpful tool in the diagnosis of Churg-Strauss syndrome-related cardiac complications. We further suggest that clinical assessment of patients with Churg-Strauss syndrome should include cardiac MRI, in order to detect cardiac involvement at an early stage; indeed, because cardiac manifestations are predictive factors of poor prognosis, diagnosis at early stages of cardiac involvement may result in improvement of patients management.

The fibroproliferative response of arterial smooth muscle cells to balloon catheter injury is associated with increased hyluronidase production and hyaluronan degradation

Hyaluronan (HA) is a glycosaminoglycan found in greatest amounts in the extra-cellular matrix of loose connective tissue. HA has been shown to be closely involved in arterial smooth muscle cell (ASMC) proliferation and migration. No studies have examined the degradation of HA in the vessel wall during proliferation of ASMC. The aim of our study was to determine whether HA degradation was modulated in the injured rat aorta with a catheter balloon. To evaluate HA degradation we quantified the activity of the enzyme which degrades HA (hyaluronidase) and determined HA molecular mass in the aorta. Aorta was analyzed in sham operated aorta (D0) and 14 (D14) days after injury. Intima-media wet weight and DNA content, a parameters reflecting ASMC response to injury, were significantly increased at D14 (+35.5 and +40.8%). HA increased at D14 (+87%) and was mainly expressed in the neointima. Hyaluronidase activity also increased in the aorta at D14 (+25.5%). In the normal aorta, HA was mainly present in a high molecular mass form (2000 kDa). Two low molecular mass HA were also detected (29 and <20 kDa). At D14, the form of 2000 kDa was dramatically increased in comparison to that in normal aorta. In addition, the injured aorta contained a large number of low molecular mass form of HA. To know whether hyaluronidase production in the injured aorta was associated with appearance of new isoforms, we determined the molecular mass of this enzyme. Only one form of hyaluronidase (78 kDa) was present in both groups (D0 and D14). In conclusion, the proliferative response of ASMC to injury in the rat was found to be associated with increased HA degradation.

Article originalIntérêt de l’imagerie par résonance magnétique nucléaire au cours de l’atteinte cardiaque du syndrome de Churg-Strauss. Trois observations et revue de la littératureUsefulness of magnetic resonance imaging in Churg-Strauss syndrome related cardiac involvement. A case series of three patients and literature review

PURPOSE The reported prevalence of cardiac complications is variable in patients with Churg-Strauss syndrome (15-92%) and depends on diagnostic tools. Diagnosis at early stage of heart involvement is crucial, resulting in appropriate management. METHODS We report three patients who developed cardiac manifestations, revealing Churg-Strauss syndrome. The diagnosis of cardiac involvement was obtained using cardiac magnetic resonance imaging (MRI). RESULTS Two patients were males and the remaining one was a female. Presenting clinical manifestations were: cardiac failure (n=1) and retrosternal pain (n=2). Laboratory findings disclosed: high blood count of eosinophils (range: 6000-11,000/mm(3)); antineutrophil cytoplasmic antibodies were positive in a single patient. Cardiac MRI demonstrated: (1) late gadolinium enhancement (n=3), involving mainly the apical and mid-cavity left ventricular segments; (2) impaired left ventricular function (n=2), mean left ventricular ejection fraction being: 51%; and (3) pericardial effusion (n=3). Outcome was favourable after institution of combined therapy with prednisone and cyclophosphamide (n=2); one patient also underwent plasma exchanges. CONCLUSION Our case series underlines that MRI is a helpful tool in the diagnosis of Churg-Strauss syndrome-related cardiac complications. We further suggest that clinical assessment of patients with Churg-Strauss syndrome should include cardiac MRI, in order to detect cardiac involvement at an early stage; indeed, because cardiac manifestations are predictive factors of poor prognosis, diagnosis at early stages of cardiac involvement may result in improvement of patients management.

Effects of Diabetes and Insulin Treatment of Diabetic Rats on Hyaluronan and Hyaluronectin Production in Injured Aorta

The present study was conducted to determine the effect of diabetes with and without insulin treatment on the production of hyaluronen (HA) and distribution of hyaluronectin (HN) in the rat aorta 14 days after injury with a catheter balloon. Injury increased intima-media wet weight (+11%) and DNA content (+37.5%). This increase was slightly enhanced in untreated diabetic rats (+14.7% for wet weight and +48.9% for DNA content) and was significantly greater in diabetic rats treated with insulin (+28.9% for wet weight and +54% for DNA content). HA content increase in the injured aorta of nondiabetic rats (+43.6%) was similar in untreated diabetic (+44.7%) and more pronounced in diabetic rats treated with insulin (+91.3%). HA was markedly expressed in the neointima of nondiabetic rats, particularly near the lumen of the aorta. In untreated diabetic rats, HA was present throughout the neointima and not mainly close to the lumen. HA staining in the neointima of diabetic rats treated with insulin was similar to that in nondiabetic rats. HN was strongly expressed throughout the neointima of all groups. Injury enhanced the production of a high molecular mass HN (>400 kDa); this was not observed either in untreated or in insulin-treated diabetic rats. In conclusion, insulin treatment promoted the proliferative response of aorta to injury and this was associated mainly with increased HA production. This finding suggests that HA, which has been shown to play a crucial role in smooth muscle cell proliferation and migration, may be involved in the promoting effect of insulin treatment on arterial wall reaction to injury.

La tuberculose péritonéale : une entité toujours présente. À propos de quatre observations

INTRODUCTION Tuberculous peritonitis, a major problem in developing country, occurs preferentially in immigrant population and in patients with acquired immune deficiency syndrome (AIDS). Although rare in France, it did not disappear and epidemiological, clinical and therapeutic approach deserve to be reminded. EXEGESIS We reported 4 patients (immigrants in two cases), occurred in caucasian and African persons (one with AIDS). Disease was characterized by fever, abdominal pain, anorexia, weight loss and ascites. Biological and radiological were unconclusive. Cell count analysis from ascitic fluid show a lymphocytic predominance with negative direct smear for Ziehl-Neelsen strain. Tuberculous peritonitis was established with combined visual and histological diagnosic laparoscopic examination. CONCLUSION These observations have the interest to underline that tuberculous peritonitis must be evoked in case of lymphocytic ascitis. We believe an aggressive diagnostic approach, particulary with peritoneal biopsy, is warranted for the diagnosis of tuberculous peritonitis. Validity of PCR amplification is ascitic fluid still needs to be established.