|Year : 2004 | Volume
| Issue : 2 | Page : 70-72
Role of alkaline phosphatase in fibrogenesis or fibrolysis
KL Vandana, B Savitha
Department of Periodontics, College of Dental Sciences, Davangere, India
K L Vandana
Department of Periodontics, College of Dental Sciences, Davangere - 577 004
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The enzymes alkaline phosphatase is implicated with osteogenesis and fibrogenesis by various groups of investigators. With the conflicting observations about the presence and activity of ALP in relation to areas of mineralization and conditions characterized by fibrogenesis and fibrolysis, it is felt most desirable to investigate this enzyme in relation with collagen synthesis and collagen destruction. So that it might throw some light on the possible relationship of ALP with these pathological conditions. It was concluded that ALP as a marker determined by histochemistry is more dependable and validated as the source could be confirmed. Hence for assessment of fibrogenetic activity of ALP, histochemistry is compulsory
Keywords: Alkaline phosphatase, fibrogenesis, fibrolysis, histochemistry
|How to cite this article:|
Vandana K L, Savitha B. Role of alkaline phosphatase in fibrogenesis or fibrolysis. J Oral Maxillofac Pathol 2004;8:70-2
|How to cite this URL:|
Vandana K L, Savitha B. Role of alkaline phosphatase in fibrogenesis or fibrolysis. J Oral Maxillofac Pathol [serial online] 2004 [cited 2020 Feb 19];8:70-2. Available from: http://www.jomfp.in/text.asp?2004/8/2/70/40969
| Introduction|| |
The measurement of an enzyme in a biological fluid can be used to monitor the results of pathologic changes in cells or tissues and this enzyme analysis provides valuable diagnostic and prognostic information. Of all the enzymes alkaline phosphatase is implicated with osteogenesis and fibrogenesis by various groups of investigators. Alkaline phosphatase is the name given to a group of hydrolytic enzymes, described as orthophosphoric monoester phosphohydrolases which function by liberating inorganic phosphate from phosphate ester.
An attempt to identify mRNA type of ALP in PDL tissue using bone derived tissue non-specific ALP eDNA as a hybridization probe suggested that expression of the same ALP isozyme in human periodontal ligament cell may be regulated by the same transcriptional mechanism as in bone .
With the conflicting observations about the presence and activity of ALP in relation to areas of mineralization and conditions characterized by fibrogenesis and fibrolysis, it is felt most desirable to investigate this enzyme in relation with collagen synthesis and collagen destruction. This may throw some light on the possible relationship of ALP with these pathological conditions, thereby it may add further to our understanding of disease process and carry out more meaningful and effective therapeutic procedures.
Distribution of ALP in oral tissues and its relation to fibrogenesis
ALP activity is absent in human gingival epithelium.Hence any amounts of enzyme present in the saliva of normal individuals can therefore be derived from oral bacteria and other sources. However connective tissue attachment of the gingiva contains ALP in the collagen fibers and within the cementum ALP has been found around sharpey's fibres and in the cementoblasts  . In a histologic study ALP was noticed to be present in gingival blood vessels, periostcum and periodontal fibres, and even in the gingival corium and is said to play a role in cell metabolism, deposition of enamel and dentin matrix, keratinization and calcification.
Relationship with fibroblast
The expression of membrane ALP activity on fibroblasts in inflamed gingiva, which was ultra-histochemically detected by a cerium - based - capture method is induced by micro-environmental changes associated with the loss of contact between the cells and the extraccllular collagenous matrix during inflammatory reactions  .
Tencate found that during dentinogenesis, enzyme activity occurs in the sub-odontoblastic zone of pulp tissue from which the fibers of von Korff arise. It was reported that there is as increased ALP activity during regeneration of tendon following tcnotomy due to collagen synthesis in reparative process. It is suggested that a primary influence of ALP in mucopolysaccharidc synthesis may secondarily affect collagen formation during wound healing.
ALP in periodontal diseases
The amount ofALP in the normal gingiva is slight, where as large amounts are found in the periodontal membrane which is located on the surface of the cementum, bone and the alveolar bone.
The amount of ALP is increased greatly in gingival inflammation and in diphenyl hydantoin sodium hyperplasia wherein new collagen fibers are found with production of cemental osseous lamellae for insertion of fibers. Large amount of ALP found in the granulation tissue of the lateral wall and at the bottom of the pocket in a periodontal pocket, and gingival fibers at the point of their insertion indicates a metabolic reaction of enzyme against the tissue changes caused by inflammation  . A positive correlation was found between enzyme concentration and mean percentage of bone loss suggesting bone as a source of enzyme.
ALP in mineralization and bone disease
Robinson suggested that in mineralization a possible function of ALP is to raise the local concentration of inorganic phosphate ions and thus cause precipitation of calcium phosphate, when its solubility is exceeded. ALP favours mineralization process by splitting the inhibitor inorganic pyrophosphate into two orthophosphate ions.
Intense ALP activity is observed in the areas immediately bordering newly formed bone specially in the intercellular matrix. Large quantities of ALP is secreted by osteoblasts when they are actively depositing bone matrix. Since some ALP diffuses into the blood, the blood level of ALP is usually a good indicator of the rate of bone formation  . In healthy adults, the serum ALP is derived from liver, bone and intestine, however, the bulk of the serum content of ALP in a growing individual reflects the physiologic activity of bone. The enzyme activity increases with initiation of osteogenic activity.
Paget's disease consists of irregular bone resumption followed by replacement with a poorly mineralized ostcoid matrix, hence serum ALP level have been used as an indication of the success of therapy in the treatment of Paget's disease.
Further, Woodward and Dean suggested that ALP is produced by bone as an essential agent for growth and repair. It is produced in large amounts whenever bone is formed or an attempt at new bone formation is being made. 'Thus in hyper parathyroidism new bone is not being formed, because calcium and phosphorous are being lost rapidly from body yet the bones produce large amounts of ALP in the unsuccessful attempt to conserve phosphorus and the serum ALP is correspondingly elevated.
Various studies have shown ALP to be involved in phosphate theory of calcification, differentiation of both osteoblasts and chondroblasts from their mesenchymal origin, formation of fibrous protein and the pre-osseous matrix of bone, the formation of mucopolysaccharides of the ground substance, transphosphorylation of some phosphate receptors in the matrix, removal of inorganic phosphates that may poison the bone crystal growth.
Method of identification of ALP
A new chemiluminescent assay for the enzyme ALP was developed that is capable of quantifying the enzyme in sub-microlitres volumes ofGCF and serum.
The chemiluminescent upon reaction with ALP undergoes dephosphorylation in a two stage reaction that culminates in the production of a glow of light, which is measured by luminometer for over a 15 sec period  .
ALP in GCF
ALP is an enzyme that is broadly distributed, in mammalian tissues, but bacteria can also contribute to the pool of this enzyme. Concentration of ALP in GCF is the best indication of active disease. The mean ALP activity in GCF was 20 times that of plasma. Through experiments its been shown that ALP is produced at a constant rate by a local source, possibly a tissue component, and enters the periodontal pocket independently of GCF which dilutes it. G.J. Harrap attempted to clarify the likely source of the enzyme and concluded that bacteria make an important contribution.
Using chemiluminescent assay, GCF ALP levels in health and in the presence of gingivitis showed that there was a site specific pattern of ALP concentrations with higher enzyme concentrations around the upper and lower anterior teeth. Patients with gingivitis demonstrated a higher GCF ALP levels for a gingival index of 1 than of 0. In more advanced stages of the disease, the associated pathogenic flora, osteoblast and fibroblast activities contribute to overall GCF ALP levels  . Enzyme levels show a high correlation with GCF volume but appear independent of rate of fluid flow.
ALP as a diagnostic marker
Detection of ALP has a potential for diagnosing currently progressing or recently active attachment loss.
Koichi Nakashima collected crevicular samples to establish a possible relationship between crevicular biochemical parameter to attachment loss and it was concluded that total amounts of PGE 2 (prostaglandin E 2 ), COL (collegenase), ALP, a 2M (a-2 mactoglobulin), OC (osteocalcin) and AEL (antigenic and functional elastase) showed significant diagnostic values (sensitivity 80%, specificity 91%) over the other 11 markers, Chapple ILC  reported that the identification of low GCF level of ALP using chemiluminescent assay lead to the initial diagnosis of hypophosphatasia. Nakashima reported that on comparison, OC, PGE, and ALP showed a positive correlations with each other, both when expressed as total amounts and concentrations and thus these can be considered potential markers of periodontitis. Salivary ALP level and serum ALP level was estimated by numerous authors, but attempts were not made to correlate serum and salivary ALP levels in the same individual. Hence a study was carried on to compare the same.
A study was conducted by Devanath KR and Vandana KL (1980) to establish the relationship of ALP in various periodontal lesions associated either with synthesis or collagen destruction. This study included 60 patients belonging to the age group of 17 - 55 years from Department of Periodontics, Bapuji Dental College and Hospital. Davangere, Karnataka, India. The patients were divided into 3 groups; Groups I controls, Group 11 patients with gingival enlargement, Group III also divided into 3 subgroups A. B and C included patients with chronic gingivitis, chronic generalized periodontitis and Juvenile periodontitis respectively. From each patients samples of saliva and serum were collected for estimation of ALP activity, which was done by Kind and King method. Analysis of serum and salivary ALP in the f brotic group, i.e. chronic inflammatory tihrotic gingival enlargement [16.5 K.A.U ± 3.826] and [5.1 K.A.U.± 2.1] and phenytoin induced gingival enlargement [15.78 K.A.U. ± 4.1] and [4.78 K.A.U.] shows increased serum and salivary ALP levels compared to control group.
Analysis of serum and salivary ALP in the fibrolytic (Troup i.e. Chronic gingivitis [7.98 K.A.U. and 3.0 K.A.U.], Chronic generalized periodontitis. [9.44 K.A.U. and 3.0 K.A.U.], juvenile periodontitis. [13.79 K.A.U. and 3.87 K.A.U.] showed similar serum and salivary ALP levels as in the control group except for slightly higher serum ALP level in chronic generalized periodontitis cases.
However in juvenile periodontitis cases, scrum ALP levels were increased when compared to control group. It was concluded that there is a positive relationship between ALP and librogenesis, but the biochemical mechanism ofaction of ALP still remains unclear.
| Conclusion|| |
ALP as marker determined by histochemistry is more dependable and validated as the source could be confirmed. The serum or salivary ALP levels would be more generalized expression of source of ALP. Hence for assessment of fibrogenetic activity of ALP, histochemistry is compulsory.
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