Anna Engström-Laurent

Hyaluronan in joint disease

Engström‐Laurent A (University of Umeå, Umeå, Sweden). Hyaluronan in joint disease (Minisymposium: Hyaluronan). J Intern Med 1997; 242: 57–60.

Localization of hyaluronan in various muscular tissues

SummaryThe histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analysed in various types of muscles in the rat by use of a hyaluronan-binding protein (HABP) and the avidin-biotin/peroxidase complex staining procedure. Microwave-aided fixation was used to retain the extracellular location of the glycosaminoglycan. In skeletal muscles, HYA was detected in the connective tissue sheath surrounding the muscles (epimysium), in the septa subdividing the muscle fibre bundles (perimysium) and in the connective tissue surrounding each muscle fibre (endomysium). HYA was heterogeneously distributed in all striated muscles. In skeletal muscles with small fibre dimensions (e.g., the lateral rectus muscle of the eye and the middle ear muscles), HYA was predominantly accumulated around the individual muscle fibres. Perivascular and perineural connective tissue formations were distinctly HYA-positive. In cardiac muscles, HYA was randomly distributed around the branching and interconnecting muscle fibres. In comparison, smooth muscle tissue was devoid of HYA.

Localization and quantity of hyaluronan in urogenital organs of male and female rats

The histochemical distribution of hyaluronan was analysed in various urogenital organs of male and female (non-pregnant and pregnant) rats by use of a hyaluronan-binding protein and avidin biotin/peroxidase staining. Microwave-aided fixation was used to preserve the extracellular location of hyaluronan. The concentrations of hyaluronan in the different tissues were measured with a highly sensitive radio-assay. Hyaluronan accumulated predominantly in the connective tissue around smooth muscle fibres and in the subepithelial lamina propria. Abundant hyaluronan also occurred in perivascular and perineural connective tissue. In the female urogenital organs, hyaluronan content was high in the vagina and urinary bladder, and highest in the vagina during pregnancy. In the uterus, the surface epithelium of the endometrium stained intensely. In the ovary, the zona pellucida of the oocyte and the theca interna cell layer of the follicles and the follicular fluid of mature follicles exhibited prominent staining. The corpus luteum was devoid of hyaluronan, whereas enlarged corpora lutea of pregnancy exhibited weak, patchy staining. In male urogenital organs, staining for hyaluronan was absent from the testis and epididymis, whereas the erectile connective tissue of the penis stained intensely. The hyaluronan concentrations were high in penile tissue and urinary bladder, while testis, epididymis and the ductus deferens contained only little hyaluronan.

THE ROLE OF LIVER AND KIDNEYS IN THE REMOVAL OF CIRCULATING HYALURONAN. AN EXPERIMENTAL STUDY IN THE RAT

The concentration of circulating hyaluronan was determined in rats after either the liver or the kidneys had been excluded from the systemic circulation. Both conditions caused an increase of the serum levels of hyaluronan. However, the rate of increase was more rapid in the animals with ligated hepatic vessels compared to those with ligated renal vessels. This in vivo investigation indicates that in the rat both kidney and liver systems are important for the removal of hyaluronan from the blood.

Serum hyaluronan and aminoterminal propeptide of type III procollagen in primary biliary cirrhosis : relation to clinical symptoms, liver histopathology and outcome

Abstract. Hyaluronan (HA) and aminoterminal propeptide of type III procollagen (PIIINP), two biochemical connective tissue markers, were determined in 76 patients with primary biliary cirrhosis (PBC). The HA and PIIINP concentrations were significantly increased compared with controls (P < 0.001). Both HA and PIIINP levels correlated significantly with conventional liver‐function tests. All patients with stage IV PBC showed increased concentrations of both these variables. However, HA was a better marker with regard to prediction of development of cirrhosis as well as prediction of symptoms. Furthermore, HA also showed a negative correlation with time of survival (P < 0.05). The present data indicate that HA is a more sensitive marker of liver damage in PBC than PIIINP.

Loss of hyaluronan in the basement membrane zone of the skin correlates to the degree of stiff hands in diabetic patients.

Glycosaminoglycans are important components of all extracellular matrices. One of the glycosaminoglycans is hyaluronan, which is ubiquitously distributed throughout the connective tissue. Hyaluronan is especially abundant in the skin, in which it is of both structural and functional importance. This study describes the localization and distribution of hyaluronan in the skin of healthy individuals and of 23 patients with insulin-dependent diabetes mellitus and various degrees of limited joint mobility. In normal skin, hyaluronan staining was seen in all layers but most prominently in the papillary dermis and the basement membrane zone. In the skin from diabetic patients with normal or only moderately restricted mobility of the hands (limited joint mobility grades 0 and 1), the distribution of hyaluronan was similar to that of normal skin. In the skin of patients with severe restriction in joint mobility (limited joint mobility grade 2) the staining pattern was significantly different with weak hyaluronan staining in the papillary dermis and the basement membrane zone almost devoid of hyaluronan. Moreover, an increased epidermal thickness in the latter patients was evident as well as a pronounced hyaluronan staining compared with normal epidermis.

Growth factor PDGF-BB stimulates cultured cardiomyocytes to synthesize the extracellular matrix component hyaluronan

Background Hyaluronan (HA) is a glycosaminoglycan located in the interstitial space which is essential for both structural and cell regulatory functions in connective tissue. We have previously shown that HA synthesis is up-regulated in a rat model of experimental cardiac hypertrophy and that cardiac tissue utilizes two different HA synthases in the hypertrophic process. Cardiomyocytes and fibroblasts are two major cell types in heart tissue. The fibroblasts are known to produce HA, but it has been unclear if cardiomyocytes share the same feature, and whether or not the different HA synthases are activated in the different cell types. Methodology/Principal Findings This study shows, for the first time that cardiomyocytes can produce HA. Cardiomyocytes (HL-1) and fibroblasts (NIH 3T3) were cultivated in absence or presence of the growth factors FGF2, PDGF-BB and TGFB2. HA concentration was quantified by ELISA, and the size of HA was estimated using dynamic light scattering. Cardiomyocytes synthesized HA but only when stimulated by PDGF-BB, whereas fibroblasts synthesized HA without addition of growth factors as well as when stimulated by any of the three growth factors. When fibroblasts were stimulated by the growth factors, reverse dose dependence was observed, where the highest dose induced the least amount of HA. With the exception of TGFB2, a trend of reverse dose dependence of HA size was also observed. Conclusions/Significance Co-cultivation of cardiomyocytes and fibroblasts (80%/20%) increased HA concentration far more that can be explained by HA synthesis by the two cell types separately, revealing a crosstalk between cardiomyocytes and fibroblasts that induces HA synthesis. We conclude that dynamic changes of the myocardium, such as in cardiac hypertrophy, do not depend on the cardiomyocyte alone, but are achieved when both cardiomyocytes and fibroblasts are present.

Progression of Bone Marrow Fibrosis in Patients with Essential Thrombocythemia and Polycythemia Vera During Anagrelide Treatment

Anagrelide is a second-line option for reduction of thrombocythemia in patients with chronic myeloproliferative disorders (CMPDs). A multicenter, open, phase II study of anagrelide treatment in 60 patients during 2 yr was performed by the Swedish Myeloproliferative Disorder Study Group. Adequate bone marrow biopsies were obtained from 53 of the CMPD patients [36 essential thrombocythemia (ET), 16 polycythemia vera (PV), 1 chronic idiopathic myelofibrosis (CIMF)] before treatment and compared with biopsies from 30 healthy volunteers and 34 patients with acute myeloid leukemia (AML). Higher reticulin and hyaluronan (HYA) scores were found before anagrelide therapy in the CMPD patients than in the normal controls (p<0.001 and p<0.001, respectively) and AML patients (p<0.001 and p=0.011, respectively). At the end of the study 30 CMPD patients were still on anagrelide treatment and in 19 of these patients, all diagnosed as ET (n=16) or PV (n=3), pretreatment bone marrow biopsies were compared with follow-up samples. After 2 yr of anagrelide therapy the reticulin and HYA scores were significantly higher than before treatment (p=0.02 and p=0.002, respectively). The cellularity was significantly higher (p=0.014), although the number of megakaryocytes did not change significantly. The increase of reticulin and HYA in the bone marrow after 2 yr of treatment with anagrelide indicated progression of fibrosis. Although anagrelide is a valuable drug for reduction of platelet levels, it seems unable to stop progression of bone marrow fibrosis and hypercellularity in ET and PV.

Localisation and distribution of hyaluronan in normal bone marrow matrix: a novel method to evaluate impending fibrosis?

Abstract: Bone marrow trephine biopsies from 30 healthy volunteers, 10 men and 20 women aged 18–60 yr were obtained for identification and localisation of hyaluronan (HYA). Fixation, decalcification and embedding were performed by two different methods, with identical results in both. For comparison bone marrow trephine biopsies from three patients with different haematological diseases and known fibrosis were studied. All bone marrow specimens were also stained for reticulin grading. HYA was found in the bone marrow specimens from healthy individuals in a pattern that was concordant with the reticulin staining, the common way of visualising bone marrow fibrosis. In bone marrow from the patients with known fibrosis the HYA and reticulin staining were both more intense and abundant. Interestingly, HYA was also found intracellularly in eosinophilic cells in normal bone marrow. HYA is a polysaccharide unique both in structural and biological properties, and in excess it may predict bone marrow fibrosis.

Temporal correlation between transcriptional changes and increased synthesis of hyaluronan in experimental cardiac hypertrophy.

The role of hyaluronan in cardiac growth has become evident, previously shown by increased myocardial levels of hyaluronan in a rat model of cardiac hypertrophy. To further investigate the role of hyaluronan and regulation of its synthesis in cardiac hypertrophy, quantitative measurements of myocardial hyaluronan concentration was correlated to gene transcription in hypertrophic cardiac tissue. Factor analysis was used to study this correlation over time. A subset of differentially expressed genes was identified with a transcriptional regulation correlating to the increased synthesis of hyaluronan, suggesting a common regulatory pathway. Four transcription factors, Myc, Fos, Junb and Egr1, were also up-regulated. Furthermore, the Ace gene was up-regulated, representing increase of angiotensin II, an inducer of these transcription factors and fetal genes in cardiac hypertrophy. This demonstrates a coordinated synthesis of hyaluronan and pro-hypertrophic gene expression, regulated by immediate early genes, with angiotensin II as a possible mediator.