Myofibroblasts could be recruited in a chemokine (C-C motif) ligand 2-dependent manner in pathogenesis of oral submucous fibrosis

Areca nut-induced oral fibrosis - Reassessing the biology of oral submucous fibrosis

BACKGROUND

Oral submucous fibrosis (OSF) is a pathological condition characterized by excessive tissue healing resulting from physical, chemical, or mechanical trauma. Notably, areca nut consumption significantly contributes to the development of oral fibrosis. The current definition of OSF, recognizing its potential for malignant transformation, necessitates a more comprehensive understanding of its pathophysiology and etiology.

HIGHLIGHTS

Areca nut induces fibrotic pathways by upregulating inflammatory cytokines such as TGF-β and expressing additional cytokines. Moreover, it triggers the conversion of fibroblasts to myofibroblasts, characterized by α-SMA and γSMA expression, resulting in accelerated collagen production. Arecoline, a component of areca nut, has been shown to elevate levels of reactive oxygen species, upregulate the expression of various cytokines, and activate specific signaling pathways (MEK, COX2, PI3K), all contributing to fibrosis. Therefore, we propose redefining OSF as "Areca nut-induced oral fibrosis" (AIOF) to align with current epistemology, emphasizing its distinctive association with areca nut consumption. The refined definition enhances our ability to develop targeted interventions, thus contributing to more effective prevention and treatment strategies for oral submucous fibrosis worldwide.

CONCLUSION

Arecoline plays a crucial role as a mediator in fibrosis development, contributing to extracellular matrix accumulation in OSF. The re-evaluation of OSF as AIOF offers a more accurate representation of the condition. This nuanced perspective is essential for distinguishing AIOF from other forms of oral fibrosis and advancing our understanding of the disease's pathophysiology.

Evaluation of stromal myofibroblasts in oral submucous fibrosis and its malignant transformation: An immunohistochemical study

BACKGROUND

Oral submucous fibrosis (OSF) is a precancerous lesion, with oral squamous cell carcinoma (OSCC) being the most prevalent malignancy affecting the oral mucosa. The malignant transformation of OSF into OSCC is estimated to occur in 7-13% of cases. Myofibroblasts (MFs) play pivotal roles in both physiological and pathological processes, such as wound healing and tumorigenesis, respectively. This study aimed to explore the involvement of MFs in the progression of OSF and its malignant transformation.

MATERIALS AND METHODS

In total, 94 formalin-fixed paraffin-embedded tissue blocks were collected, including normal oral mucosa (NOM; n = 10), early-moderate OSF (EMOSF; n = 29), advanced OSF (AOSF; n = 29), paracancerous OSF (POSF; n = 21), and OSCC (n = 5) samples. Alpha-smooth muscle actin was used for the immunohistochemical identification of MFs.

RESULTS

NOM exhibited infrequent expression of MFs. A higher staining index of MFs was found in AOSF, followed by EMOSF and NOM. Additionally, a significant increase in the staining index of MFs was found from EMOSF to POSF and OSCC. The staining index of MFs in NOM, EMOSF, AOSF, POSF, and OSCC was 0.14 ± 0.2, 1.69 ± 1.4, 2.47 ± 1.2, 3.57 ± 2.6, and 8.86 ± 1.4, respectively. All results were statistically significant (P < 0.05).

CONCLUSIONS

The expression of MFs exhibited a gradual increase as the disease progressed from mild to malignant transformation, indicating the contributory role of MFs in the fibrogenesis and potential tumorigenesis associated with OSF.

Role of osteopontin in oral epithelial dysplasia, oral submucous fibrosis and oral squamous cell carcinoma

Background

Inflammatory cells and cytokines in the chronically injured mucosa promote fibrosis in the oral submucous fibrosis (OSF) fibrotic milieu. Osteopontin (OPN) is a wound-healing mediator that upregulates the inflammatory response and is involved in the malignancy and fibrosis of multiple organ systems.

Objectives

We investigated the expression of OPN in oral potentially malignant disorders (OPMDs) and oral squamous cell carcinomas (OSCCs) to determine its role in the malignant transformation and fibrosis of oral tissues. The expression of OPN in OPMDs and OSCCs was compared and correlated, and the role of OPN as a fibrotic mediator in OSF was explained.

Study Design

A total of 30 cases of normal mucosa and OPMDs (mild dysplasia, severe dysplasia, OSF and OSCCs) were studied by purposive sampling. In these groups, OPN immunoreactivity was examined and correlated with clinical findings.

Results

In mild dysplasia, OPN expression was restricted to the basal cell layer with moderate staining intensity. In severe dysplasia, it was extremely intense and extended throughout the epithelium. In the OSF, OPN expression was moderate in the perinuclear areas of the basal cell layer. The expression of OPN was very strong in OSCC. A flow diagram explaining the profibrotic role of OPN in OSF has been provided.

Conclusion

A positive role of OPN in both pathogenesis and malignant transformation of OPMDs and OSCC has been demonstrated.

Molecular pathways of oral submucous fibrosis and its progression to malignancy

OBJECTIVE

The review aims to comprehend various factors engaged in the alteration of molecular events resulting in Oral submucous fibrosis (OSMF) and its malignant transformation.

DESIGN

Literature pertinent to pathways involved in OSMF were explored in databases such as PubMed, Scopus and Google Scholar. The relevant literature was reviewed and critically appraised in this narrative review.

RESULTS

Areca nut components influence myriad of cellular molecules such as cytokines, growth factors, myofibroblasts, non-coding RNAs and alter their expression. These aberrantly expressed molecules drive the progression of OSMF from localized inflammation to fibrosis of buccal mucosa. The oral tissue suffers from oxidative stress, hypoxia, autophagy, aberration of cell cycle and DNA damage. Apoptosis of epithelial layer results in its atrophy facilitating deeper penetration of areca nut elements. With the advance of disease, epithelial-mesenchymal transition eventuates and promotes dysplasia. The jeopardized expression of various cellular molecules, suppressed apoptosis, along with increased genetic alterations and neovascularization favors the malignant transformation.

CONCLUSION

OSMF is a progressive disorder with complex mechanism of pathogenesis initiated by inflammation of oral mucosa. Continuous habit of areca nut chewing and the resulting insult to the tissues prevents healing process and is destined to debilitating disease which affects the quality of life with a higher probability of progression to malignancy.

CC group of chemokines and associated gene expression of transcription factors: Deciphering immuno-pathogenetic aspect of oral submucous fibrosis

BACKGROUND

Oral submucous fibrosis (OSMF) is a chronic disease with significantly increasing malignant transformation rate. To date the pathogenesis of OSMF has been considered to be associated with areca nut constituents and their action on fibroblasts. However, fibrosis is also associated with immunological factors such as chemokines. In-depth analysis of such factors is the need of the hour in OSMF to better understand the pathogenesis so that effective therapeutic strategies can be developed in the future.

MATERIALS AND METHOD

Clinically diagnosed cases of OSMF (n=21) and healthy individuals (n=10) were enrolled in the present study. Chemokines such as CCL2, CCL3, CCL4, CCL5, CCL11, CCL17, CCL28, CXCL1, CXCL5, CXCL8, CXCL9, CXCL10, and CXCL11 were assessed using the chemokine bead array in conjunction with the flow cytometry, along with real-time PCR (RT-PCR). The transcription factors CREB, NF-κB and NFAT5 were also studied for their expressions. The analysis of pg/ml (picogram/milliliter) values was done by using LEGENDplex™ Data Analysis Software.

RESULTS

The results obtained demonstrated early phase transient increase in CXCL-11, CCL20, CXCL9, CCL3, CCL2, CXCL10 and CXCL8. However, the expression of CCL3, CXCL10 and CXCL8 was higher in the late stage as compared to the early stage. The relative gene expression of CREB, NF-κB, NFAT5 were upregulated in the late stage of OSMF when compared to normal.

CONCLUSION

Distinctive sets of chemokine expression during the early and late stages of OSMF suggest a unique pattern of disease progression playing an important role in the pathogenesis.

Expression profiles of tRNA-derived small RNA and their potential roles in oral submucous fibrosis

BACKGROUND

Although transfer RNA (tRNA) has been found to be the main source of a rich class of noncoding RNA, the tRNA-derived small RNA (tsRNA) has been proved to play an irreplaceable role in the human body, and its dynamic imbalance could affect the progress of the disease. However, the research on tsRNA in oral submucous fibrosis (OSF) is still scarce.

METHODS

We sequenced the OSF and validated it by PCR. We found that there were significant differences in their expression levels in OSF. Furthermore, bioinformatic analysis was performed to explore the roles of these fragments in oral submucous fibrosis.

RESULTS

Of 126 tsRNAs in OSF were dysregulated, including 73 upregulated tsRNAs and 53 downregulated tsRNAs. The downregulated tiRNA-Val-CAC-002, tRF-Asn-GTT-005, tRF-Trp-CCA-007 and upregulated tRF-Gly-TCC-016, tRF-Pro-TGG-009 showed significant differences by qRT-PCR validation, which were consistent with the results of RNA sequencing. Gene ontology and pathway analysis revealed that tRF-Gly-TCC-016 would possibly promote the formation and progress of OSF through cytokine-cytokine receptor interaction and cAMP signal pathway, while tiRNA-Val-CAC-002 could be primarily concerned with the transition from OSF to oral squamous cell carcinoma (OSCC).

CONCLUSION

tRNA-derived fragments are dysregulated and could be involved in the pathogenesis of oral submucous fibrosis. tRF-Gly-TCC-016 and tiRNA-Val-CAC-002 may be new regulatory molecules that could affect the process of OSF by regulating signal pathways through interacting with multiple genes.

Emerging role of cellular senescence in the pathogenesis of oral submucous fibrosis and its malignant transformation

Senescence is a common denominator in wound healing, fibrosis, and cancer. Although, senescence is transiently antifibrotic, when prolonged, promotes fibrosis and malignant transformation. Eligible studies indexed in MEDLINE, Embase and Web of Science were searched to understand the role of cellular senescence in the pathogenesis of oral submucous fibrosis (OSF) and its malignant transformation. The senescence-associated secretory phenotype (SASP) components like IL-1, IL-6, and GRO-α induce double-strand DNA breaks in keratinocytes and drive genetic instability. SASP derived from myofibroblasts induces epithelial-mesenchymal transition in OSF and facilitates cancer progression. The use of senolytics has been shown to eliminate senescent cells from the areas of fibrosis, thereby preventing malignancy. Naturally occurring agents such as apigenin and kaempferol inhibit SASP. Mechanistic insight into the emerging role of senescence in the pathogenesis of OSF and modalities to inhibit senescence-associated antiapoptotic pathways as a supplementary therapy to prevent malignant transformation of OSF is underlined.

Localized peripheral autonomous neuropathy and dysfunctional myoepithelial cells: A novel hypothesis for xerostomia in oral submucous fibrosis

Oral submucous fibrosis (OSMF) is a potentially malignant disorder of the oral cavity characterized by submucosal deposition of dense collagen bundles leading to limited mouth opening. Besides, patients also complain about the burning sensation in the oral cavity and xerostomia. These symptoms have a major impact on the functional and psychological domains of oral health-related quality of life. However, the pathogenesis of xerostomia in OSMF is not yet well established. In our routine histopathology practice, we observed fibrosis surrounding minor salivary glands, distended acini, obliteration of acinar lumen and loss of interstitial spaces. Based on these features, we hypothesized that fibrosis in OSMF drives localized peripheral autonomous neuropathy in minor salivary glands, which leads to dysfunctional myoepithelial cells. These dysfunctional myoepithelial cells will unable to contract and expel saliva out of the salivary secretary unit, thus leading to xerostomia. In the present paper, experiments are recommended to prove this hypothesis, which can be exploited in the future for the development of appropriate drugs.

Antifibrogenic effects of C-C chemokine receptor type 2 antagonist in a bleomycin-induced scleroderma model

There have been several studies on the role of the monocyte chemotactic protein-1/C-C chemokine receptor type 2 (CCR2) signalling pathway in fibrotic diseases, which identified the blockade of this pathway as a potential therapeutic target for treating fibrosis. We examined the efficacy of CCR2 antagonist (RS-504393) in a mouse model of scleroderma induced by bleomycin. RS-504393 was administered via intradermal injection 6 hours prior to bleomycin injection, in the same sites. Histopathological examination showed that RS-504393 treatment suppressed dermal fibrosis and decreased dermal thickness. The numbers of mast cells and myofibroblasts in the skin of RS-504393-treated mice were significantly lower compared with those in PBS-treated mice. Moreover, the amount of collagen in the skin of RS-504393-treated mice was significantly lower compared with that in the PBS-treated mice. Additionally, mRNA levels of TGF-β1 and collagen I alpha 1 in sclerotic skin were significantly decreased by RS-504393, and semiquantitative histopathological scoring of the lungs showed inhibition of fibrosis in RS-504393-treated mice. The amount of collagen in the lung of the RS-504393-treated mice was lower compared with that in the PBS-treated mice. These data suggest that CCR2 antagonist RS-504393 may be a therapeutic agent for human scleroderma.