Oral submucous fibrosis (OSF) is a chronic disease affecting the oral cavity and sometimes the pharynx, characterized by inflammation and fibrosis of the submucosa. Several factors are suggested to be involved in its pathogenesis, including areca nut chewing, chili consumption, nutritional deficiencies, genetic susceptibility, and autoimmunity. Areca nut contains alkaloids and tannins that may stimulate fibroblast proliferation and collagen production, stabilize collagen structure, and inhibit collagen degradation, leading to accumulation of extracellular matrix and fibrosis. OSF is considered potentially malignant, as it is strongly associated with oral cancer and shows epithelial dysplasia. The disease process may involve an altered wound healing response and dysregulation of cytokines

1. Oral Submucous
Fibrosis:
Etiopathogenesis
By
Harsh Deep Singh
Submitted to:
Department of oral pathology

3. Content
1.Introduction
2.Etiology
• Chili
• Nutritional deficiencies
• Genetic Susceptibility
• Autoimmunity
• Areca Nut
2. Pathogenesis

4. What is OSMF?
An insidious, chronic disease affecting any part of the cavity and
sometimes the pharynx. Occasionally it is preceded by and/or
associated with vesicle formation and is always associated with a
juxta-epithelial inflammatory reaction followed by fibroelastic change
of lamina propria, with epithelial atrophy leading to stiffness of the
oral mucosa and causing trismus and inability to eat

5. Etiology
Several factors such as
• Chili consumption,
•Nutritional deficiency states,
•Areca nut chewing,
•Genetic susceptibility
•Autoimmunity and
•Collagen disorders
have been suggested to be involved in the pathogenesis of this condition.
Some of these suggestions were based on ecological observations, others
were more or less speculative.

6. Chilli
•Capsaicin, which is vanillylamide of 8-methyl-6-nonenic acid, is the active ingredient
of chillies, play an etiological role in oral submucous fibrosis (Rajendran, 1994
•OSMF is found mostly among Indians and other population groups who use chilies to
spice their food.
• OSMF patients are unable to tolerate spicy food containing chilies before they
develop disease
• Histologic observations : tissue eosinophils in the biopsy specimens suggested an
allergic nature of this disease possibly due to chili intake.
•epithelial hyperplasia, presence of a chronic inflammatory cell exudate, and dense
fibrogenesis with elastic degeneration of collagen; these changes were thought to
indicate a simultaneous defense and repair mechanism, similar to the chronic
productive response.

7. Q. When are these changes present ?
A. Agent responsible for exciting an inflammatory reaction is mild and
continues to operate over a prolonged period of time
Animal experimental study
Test : capsaicin, an active principle of chilies, as a test substance has
been conducted on Wistar rats
Observation : elastic degeneration of palatal collagen, and
ultra structurally partial or complete degeneration of the
collagen into elastin like filaments, sheets, or dense
amorphous material
Inference: limited connective tissue response in an unimpaired
animal system
enhanced in protein- or vitamin-deficient animal systems
Against the hypothesis :Mexico or other South American countries where chilli
consumption is widespread, there is no report of this condition

8. Nutritional deficiencies
Observations suggesting hypothesis
• Reports of anemia, vitamin, iron and protein deficiencies among OSF patients
• A higher frequency of clinical manifestations of deficiency of vitamins A, B and C, and lower
serum vitamin levels were found in cases as compared to controls by WAHI et al.
Observations against hypothesis
•In a South African study: no difference in the prevalence of iron deficiency anemia between that
observed cases and the general population.
• Inability to tolerate spicy food, which is a normal family and community diet.
• The deficiency of these factors observed among OSF patients may be secondary
Conclusion : This functional impairment may affect normal food intake and lead to
nutritional deficiencies.

9. Genetic Susceptibility
Observation suggesting hypothesis
• Familial occurrence seen in India and South Africa .
• The occurrence of OSF among individuals without areca nut chewing habits has also been
thought to be due to genetic factors
•Polymorphism of the genes coding for TNF-α is significant risk factor for OSMF
•TNF-α is known to stimulate fibroblastic proliferation in vitro suggesting active role for TNF-
α in the pathogenesis of OSMF
• Observations suggest a possible genetic susceptibility to the action of extrageneous factors
such as areca alkaloids and tannins.

10. Autoimmunity
Reasons for investigating as an autoimmune disorders included
1. Slight female predilection
2. Occurrence in middle age group
3. Presence of circulating immune complexes
4. Immunoglobin contents
5. Detection of various autoantibodies in patients sera
Observation suggesting hypothesis
•Similarities of this condition with other collagen disorders, namely scleroderma, having an
autoimmune pathogenesis.
• Antibodies which showed increased frequency were anti gastric-parietal cell (GPCA),
anti thyroid microsomal, anti-nuclear (ANA), anti reticulin and anti smooth muscle
(SMA) antibodies
• Increased levels of immune complexes and serum levels of IgG, IgA. And IgM when
compared with control groups

11. Areca Nut
Areca nut (often erroneously referred to as betel nut) is the endosperm
of the fruit of the Areca catechu tree.
Contents
Areca nut contains
1. Tannins
• gallotannic acid
• D-Catechol are important
2. Alkaloids
• arecoline is the most abundant
• arecaidine
• guvacine
• isoguvacine
• arecolidine
• guvacoline are also present in small quantities. Other substances comprise fats,
carbohydrates, proteins, and mineral matter

12. Areca Nut Preparations
• In India areca nut is chewed by itself
• in the form of various areca nut preparations such as
1. scented supari
2. mawa
3. Manipuri tobacco,
4. pan masala
5. betel quid, either with or without tobacco

13. Epidemiologic studies
Ecological Observations
•The occurrence of OSMF in an area or population in which areca nut chewing is
popular, compared to its rarity in populations or areas where areca nut chewing is
unknown or less common
• South Africa: common among women of Indian origin and rare among blacks
Dose-response relationship
The relationship between the degree of exposure and the risk of a disease is an important
criterion for causal inference
The relative risk increased with the duration as well as the frequency of the areca nut
chewing habit.*

14. Regional variations
Frequency of OSMF and arecoline content of the areca nut varies from place to place in India
and perhaps this may have some influence on the prevalence rates.
Clinical Study
Pune, Maharashtra Ernakulum, Kerala
Areca nut
preparation
67% chewed only areca nut 77% chewed areca nut as an ingredient
of betel quid with tobacco
Area affected this condition affected the posterior one-
third of the buccal mucosa, soft palate,
the uvula, and retromolar areas
significantly more often than in
Ernakulum
tongue, floor of the mouth and the
hard palate were not involved in
Pune
Explanation when individuals chew areca nut without
tobacco, as in Pune, they generally
swallow the juice, thus exposing the
posterior part of the oral mucosa (to
areca nut contents much more than the
anterior parts
areca nut is chewed in betel quid
with tobacco, therefore the quid
and the juice are held for a longer
time and are spat out when they
become bland. This results in a
more generalized contact of the
quid with the oral mucosa, perhaps
leading to its generalized
involvement in OSF

15. Animal experiments and tissue-culture studies
• In animal models the submucosal collagen showed altered staining similar
to that seen in human OSF only in two rats, and therefore the investigators
opined it was improbable that arecoline per se played any part in the
causation of human OSF. They pointed out, however, that tissue changes
brought about in animal systems by a test substance cannot be identically
correlated to those in man.
•Tissue culture experiments using human fibroblasts suggested
demonstrated that ethanolic extracts of three varieties of areca nut
stimulated collagen synthesis to the extent of 170% over that in control
cultures
•Interestingly, it was suggested that the addition of slaked lime to areca nut
in pan (betel quid) hydrolyses arecoline to arecaidine . This means that the
hydrolysis of arecoline could occur in the saliva as well as in fibroblasts. It
was suggested that the inflamed oral mucosa has enhanced permeability to
arecoline and arecaidine

16. Pathogenesis
• Fibrosis and hyalisation of sub epithelial tissues account for most
of the clinical features
•Increased collagen synthesis or reduced collagen degradation are
possible mechanism in the development of the disease
• Numerous biological pathways are involved in the above
processes and the normal regulatory mechanisms are either down
regulated or up regulated at different stages of disease

17. Areca alkaloids causing fibroblast proliferation and increased
collagen synthesis
•In vitro studies on human fibroblast using areca extracts or chemically
purified arecolin suggest the theory of fibroblastic proliferation and
increased collagen formation that is also demonstrable histologically in
human OSMF tissue
• Concentration dependent stimulation of collagen synthesis when fibroblast
were exposed to both arecoline and arecaidine. The stimulation was always
greater with arecaidine
•There is a correlation between the hydrolysis rates of different esters and the
extent to which they stimulate collagen synthesis , suggest that hydrolysis of
arecoline in arecaidine is necessary before fibroblast stimulation. This suggest
that arecaidine is the active metabolite for fibroblats prolliferation

18. Flow chart : Role of areca nut in oralsubmucous fibrosis (Ghom & Mhaske,
2008)
Areca nut
Fibroblast
prolieration
Alkaloids
Arecoline etc
trauma Flavanoids copper
chewing tanins, catechins
inflammation
Growth factors
Stabilization cross linking
Increased collagen synthesis Decreased phagocytosis
Collagen accumulation
OSMF

19. Stabilization of collagen structure by tannins(and
catachins polyphenols)
Treatment of reconstituted collagen fibrils and pieces of rat dermis with crude
extracts of nut or purified tannins from areca nut increased their resistance to both
human and bacterial collagenase
Possible mechanisms
•by reduced degradation of collagen by forming a more stable collagen
structure
•tannin present in areca nut reduces collagen degradation by inhibiting
collagenase
•It was postulated that the reason for high level of collagen production in
OSMF because these fibroblast are a subset with increased potential among
heterogenetic fibroblast

20. Copper in nut and fibrosis
•The copper content of areca nut is high and the levels of soluble
copper in saliva may rise in volunteers who chew areca quid.
• The enzyme lysyl oxidase is found to be up regulated in OSMF .
This is a copper dependent enzyme and plays a key role in collagen
synthesis and its cross linkage
• The fibroblast in OSMF have not only increased lysyl oxidase
activities but also specific growth characteristics. This was
evident with reported cell doubling time of 3.2 days for OSMF
and 3.6 days for normal fibroblast

21. Upregulation of cyclo-oxygenase (Cox-2)
•It is known that OSMF is associated with inflammatory changes
in at least some stages of the disease. Prostaglandins is one of
the main inflammatory mediators and its production is controlled
by various enzymes such cyclooxygenase (COX)
Experimental Finding
• Immunochemistry : increased expression of the enzyme COX-2
in moderate fibrosis and this disappeared in advanced fibrosis
• Compatible with the histology of the disease as there is lack of
disease in advanced disease.

22. Fibrigenetic cytokines
• Changes in cytokines secretion in OSF has been investigated.
Endothelin and tgf β-1 estimated by radioimmunoassay and ELISA
respectively were increased in OSF fibroblast compared to
fibroblast of normal individuals. Therefore it has been postulated
that external stimuli such as areca nut may induce the
development of the disease by increased levels of cytokines in
the lamina propria
• It has been shown that there has been increased expression of
fibrogenic cytokines namely TGF-β, PGDF and bFGF in OSF tissues
compared to normal
•These observation suggest that disease process in OSMF may be
an altered version of wound healing as our recent finding show
that the expression of various ECM molecules are similar to those
seen in maturation of granulation tissue

23. Genetic polymorphism predisposing to OSMF
•Polymorphism of the genes coding for TNF-α has been
reported as a significant risk factor for OSMF
•TNF-α is known to stimulate fibroblastic proliferation in vitro
providing evidence for an active role for TNF-α in the
pathogenesis of OSMF

24. Inhibition of collagen phagocytosis
• Degradation of collagen by fibroblast phagocytosis is an important
pathway of physiological remodeling of extracellular matrix (ECM) in
connective tissue. OSMF shows a gross imbalance in ECM remodeling
• Reduction of phagocytic cell was strongly related to arecoline levels in
fibroblast culture
• Dose- dependent enhancement of phagocytic cells when the cultures
were treated with corticosteroids

25. Stabilization of extracellular matrix
• Increased and continuous deposition of extracellular matrix may take place as a result of
disruption of the equilibrium between matrix metalloprotinases (MMPs) and tissue inhibitors of
matrix metalloproteinase (TIMP)
• Although the main pathological change present in OSMF appears to be markedly increased
production of extracellular matrix (ECM), there is little information on actual remodeling of
connective tissue with the progression of the disease
• The patterns of expression of several molecules were investigated in various phases of the
disease. It was apparent that the expression of teascin disappeared when the lesion advanced
from early to intermediate phase
• Heparin sulphate proteologlycans, fibronectin type III collagen and elastin appeared in the
early and intermediate phases but there was complete replacement by collagen type I when the
lesion progressed to an advanced phase. The pattern of expression of most of these molecules
followed a similar pattern to the organization of granulation tissue

26. Collagen related genes
• Collagen related genes play an important role in homeostasis of
collagen in the body. As OSMF is a disease with disregulation of collagen
metabolism,
• There is evidence to suggest that collagen related genes are altered
due to ingredients in quid. The genes Col1A2, Col3A1, Col6A3 and
Col7A1 have been identified as definite TGF-β targets and induced in
fibroblast at early stages of the disease
• The transcriptional activation of procollagen genes by TGF-β suggest
that it may contribute to increased collagen levels in OSMF

27. Precancerous nature and malignant transformation
• Pindborg in 1972 put forward five criteria to prove that disease is
precancerous
1. High occurrence of OSMF in in oral cancer patients
2. Higher incidence of SCC in patients with OSMF
3. Histological diagnosis of cancer without any clinical suspicion in OSMF
4. High frequency of epithelial dysplasia
5. Higher prevalence of leukoplakia among OSMF cases
• Recently, the carcinogenicity of areca nut without tobacco was identified
• The strong association of areca nut with OSMF , its dose dependent effects
and confirmation of OSMF as potentially malignant disease leading to oral
cancer provided further evidence for this assertion

28. References
Oral submucous fibrosis: Review on aetiology and pathogenesis
Tilakaratne, W.M. et al.
Oral Oncology , Volume 42 , Issue 6 , 561 - 568

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