The role of cathepsin K in oral and maxillofacial disorders

LncRNA H19 promotes osteoclast differentiation by sponging miR-29c-3p to increase expression of cathepsin K

BACKGROUND

Osteoporosis is a prevalent metabolic bone disease. Osteoporotic fractures can lead to severe functional impairment and increased mortality. Long noncoding RNA H19 has emerged as a pivotal player in bone remodeling, serving both as a biomarker and a regulator. While previous research has elucidated H19's role in promoting osteogenic differentiation through diverse mechanisms, its involvement in osteoclast differentiation remains largely unknown.

METHODS

In this study, we used lentiviral vectors to stably overexpress or knockdown H19 in RAW264.7 cell lines. Quantitative reverse polymerase chain reaction, Western blot, tartrate resistant acid phosphatase staining and bone resorption assay were performed to assess the level of osteoclast differentiation and bone resorption capacity. And fluorescence in situ hybridization, dual-luciferase reporter and RNA immunoprecipitation were used to explore the specific mechanism of H19 regulating osteoclast differentiation in vitro. Then, ovariectomized osteoporosis models in wild type mice and H19 knockout mice were conducted. And micro-CT analysis, HE staining, and immunohistochemistry were performed to verify the mechanism of H19 regulating osteoclast differentiation in vivo. Bone marrow derived monocytes and bone mesenchymal stem cells were extracted from mice and assayed for osteoclastic and osteogenic-related assays, respectively.

RESULTS

In vitro, H19 promoted osteoclast differentiation and bone resorption of RAW264.7 cells, while miR-29c-3p inhibited them. Both H19 and cathepsin K were the target genes of miR-29c-3p. In vivo, H19 knockout mice have increased femur bone mineral density, decreased osteoclast formation, and reduced cathepsin K expression. MiR-29c-3p agomir could increase bone mineral density in osteoporotic mice on the premise of H19 knockout.

CONCLUSIONS

H19 upregulates cathepsin K expression through sponging miR-29c-3p, which promoting osteoclast differentiation and enhancing bone resorption. This underscores the potential of H19 and miR-29c-3p as promising biomarkers for osteoporosis.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Treatment with an inhibitor of matrix metalloproteinase 9 or cathepsin K lengthens embryonic lower jaw bone

OBJECTIVES

Skeletal malocclusions are common, and severe malocclusions are treated by invasive surgeries. Recently, jaw bone length has been shown to be developmentally controlled by osteoclasts. Our objective was to determine the effect of inhibiting osteoclast-secreted proteolytic enzymes on lower jaw bone length of avian embryos by pharmacologically inhibiting matrix metalloproteinase-9 (MMP9) or cathepsin K (CTSK).

METHODS

Quail (Coturnix coturnix japonica) embryos were given a single dose of an inhibitor of MMP9 (iMMP9), an inhibitor CTSK (iCTSK), or vehicle at a developmental stage when bone deposition is beginning to occur. At a developmental stage when the viscerocranium is largely calcified, the heads were scanned via micro-computed tomography and reproducible landmarks were placed on 3D-reconstructed skulls; the landmark coordinates were used to quantify facial bone dimensions.

RESULTS

Approximately half of the quail given either iMMP9 or iCTSK demonstrated an overt lower jaw phenotype, characterized by longer lower jaw bones and a greater lower to upper jaw ratio than control embryos. Additionally, iMMP9-treated embryos exhibited a significant change in midface length and iCTSK-treated embryos had significant change in nasal bone length.

CONCLUSION

MMP9 and CTSK play a role in osteoclast-mediated determination of lower jaw bone length. Pharmacological inhibition of MMP9 or CTSK may be a promising therapeutic alternative to surgery for treating skeletal jaw malocclusions, but more preclinical research is needed prior to clinical translation.

Cilengitide inhibits osteoclast adhesion through blocking the αvβ3-mediated FAK/Src signaling pathway

The remodeling of actin cytoskeleton of osteoclasts on the bone matrix is essential for osteoclastic resorption activity. A specific regulator of the osteoclast cytoskeleton, integrin αvβ3, is known to provide a key role in the degradation of mineralized bone matrixes. Cilengitide is a potent inhibitor of integrins and is capable of affecting αvβ3 receptors, and has anti-tumor and anti-angiogenic and apoptosis-inducing effects. However, its function on osteoclasts is not fully understood. Here, the cilengitide role on nuclear factor κB ligand-receptor activator (RANKL)-induced osteoclasts was explored. Cells were cultured with varying concentrations of cilengitide (0,0.002,0.2 and 20 μM) for 7 days, followed by detected via Cell Counting Kit-8, staining for tartrate resistant acid phosphatase (TRAP), F-actin ring formation, bone resorption assays, adhesion assays, immunoblotting assays, and real-time fluorescent quantitative PCR. Results demonstrated that cilengitide effectively restrained the functionality and formation of osteoclasts in a concentration-dependent manner, without causing any cytotoxic effects. Mechanistically, cilengitide inhibited osteoclast-relevant genes expression; meanwhile, cilengitide downregulated the expression of key signaling molecules associated with the osteoclast cytoskeleton, including focal adhesion kinase (FAK), integrin αvβ3 and c-Src. Therefore, this results have confirmed that cilengitide regulates osteoclast activity by blocking the integrin αvβ3 signal pathway resulting in diminished adhesion and bone resorption of osteoclasts.

Surgical treatment of pycnodysostosis associated with pathological tibial fracture : Case report and review of the literature

BACKGROUND

Pycnodysostosis is a rare autosomal recessive lysosomal disorder of bone characterized by diffuse skeletal condensation with thickening of the cortex and narrowing of the medullary canal.

CASE PRESENTATION

We present the case of a 4-year-old girl diagnosed with pycnodysostosis and associated pathological tibial fracture. The tibia had an absence of medullary canal. Surgery included reduction and reaming of the canal with placement of a 5 mm diameter telescopic growing nail.

CONCLUSION

The presentation of pycnodysostosis as tibial fracture is rare and there is limited literature on its management. We showed its approach focusing mainly on the management of the absent medullary canal.

A multifunctional drug consisting of tetracycline conjugated with odanacatib for efficient periodontitis therapy

The treatment of periodontitis can be very challenging due to its complex etiologies. A new pharmacologic strategy entitled “host-modulation therapy,” has been introduced to improve periodontal treatment outcomes. Supposedly, a multifunctional drug with the potential for bacterial infection prevention, host-response modulation and bone healing promotion would be a promising option for periodontitis therapy, but related studies remain substantially lacking. In this study, we successfully conjugated tetracycline with odanacatib (a selective inhibitor of cathepsin K) to construct a multifunctional drug (TC-ODN). We discovered that TC-ODN could promote macrophages polarizing toward anti-inflammatory phenotype and promote osteogenesis of PDLSCs under inflammatory microenvironment. In vivo, TC-ODN could be absorbed and distributed specifically to the bone after systemic administration, and accumulation of TC-ODN increased bone mineral density in ovariectomized rats. Importantly, periodontal administration of TC-ODN could successfully promote bone healing in periodontitis rats with alveolar bone loss. The findings in our study uncovered the excellent biocompatibility and multifunction of TC-ODN, including bone-targeted accumulation, immunoregulation, anti-inflammatory activity and promotion of bone healing, which might contribute to the clinical treatment of periodontitis.

Modulation of Cystatin C in Human Macrophages Improves Anti-Mycobacterial Immune Responses to Mycobacterium tuberculosis Infection and Coinfection With HIV

Tuberculosis owes its resurgence as a major global health threat mostly to the emergence of drug resistance and coinfection with HIV. The synergy between HIV and Mycobacterium tuberculosis (Mtb) modifies the host immune environment to enhance both viral and bacterial replication and spread. In the lung immune context, both pathogens infect macrophages, establishing favorable intracellular niches. Both manipulate the endocytic pathway in order to avoid destruction. Relevant players of the endocytic pathway to control pathogens include endolysosomal proteases, cathepsins, and their natural inhibitors, cystatins. Here, a mapping of the human macrophage transcriptome for type I and II cystatins during Mtb, HIV, or Mtb-HIV infection displayed different profiles of gene expression, revealing cystatin C as a potential target to control mycobacterial infection as well as HIV coinfection. We found that cystatin C silencing in macrophages significantly improves the intracellular killing of Mtb, which was concomitant with an increased general proteolytic activity of cathepsins. In addition, downmodulation of cystatin C led to an improved expression of the human leukocyte antigen (HLA) class II in macrophages and an increased CD4⁺ T-lymphocyte proliferation along with enhanced IFN-γ secretion. Overall, our results suggest that the targeting of cystatin C in human macrophages represents a promising approach to improve the control of mycobacterial infections including multidrug-resistant (MDR) TB.

[Activation of mir-30a-wnt/β-catenin signaling pathway upregulates cathepsin K expression to promote cementogenic differentiation of periodontal ligament stem cells]

OBJECTIVE

To explore the role of cathepsin K (CTSK) regulated by mir-30a-wnt/β-catenin signaling pathway in cementogenic differentiation of periodontal ligament stem cells (PDLSCs).

METHODS

Human PDLSCs isolated by limiting dilution culture were induced by enamel matrix protein derivative (EMD) for differentiation into cementoblast-like cells. MicroRNA chip technique was employed to screen the differentially expressed microRNAs in the cells during induced differentiation. The effect of inhibiting miR-30a on CTSK expression in the induced cells was examined using RT-PCR and Western blotting. Ceramic scaffolds coated with PDLSCs treated with EMD and transfected with the miR-30a inhibitor or a lentiviral vector for CTSK overexpression were prepared and implanted subcutaneously in nude mice, and 8 weeks later the cellular expressions of cementoblast markers CAP and CEMP-1 were detected with immunohistochemistry to verify whether CTSK participate in cementogenic differentiation of PDLSCs. The role of wnt signaling pathway in miR-30a-mediated regulation of CTSK expression was explored by examining CTSK protein expressions after blocking wnt signaling in PDLSCs.

RESULTS

In PDLSCs with EMD-induced differentiation into cementoblast-like cells, multiple microRNAs exhibited differential expressions; and among them, miR-30a was specifically and significantly up-regulated (P < 0.05). Up-regulation of miR-30a obviously increased the expression of CTSK (P < 0.05) and promoted PDLSCs to form cementum-like tissues with high expressions of CAP and CEMP-1. The regulatory effect of miR-30a on CTSK expression was obviously attenuated after inhibiting wnt/β-catenin signaling pathway.

CONCLUSION

EMD induces cementogenic differentiation of PDLSCs possibly by up-regulating the expression of miR-30a, which further activates the wnt/β-catenin signaling pathway to enhance the expression of CTSK.

Cathepsins and Their Endogenous Inhibitors in Host Defense During Mycobacterium tuberculosis and HIV Infection

The moment a very old bacterial pathogen met a young virus from the 80's defined the beginning of a tragic syndemic for humanity. Such is the case for the causative agent of tuberculosis and the human immunodeficiency virus (HIV). Syndemic is by definition a convergence of more than one disease resulting in magnification of their burden. Both pathogens work synergistically contributing to speed up the replication of each other. Mycobacterium tuberculosis (Mtb) and HIV infections are in the 21st century among the leaders of morbidity and mortality of humankind. There is an urgent need for development of new approaches for prevention, better diagnosis, and new therapies for both infections. Moreover, these approaches should consider Mtb and HIV as a co-infection, rather than just as separate problems, to prevent further aggravation of the HIV-TB syndemic. Both pathogens manipulate the host immune responses to establish chronic infections in intracellular niches of their host cells. This includes manipulation of host relevant antimicrobial proteases such as cathepsins or their endogenous inhibitors. Here we discuss recent understanding on how Mtb and HIV interact with cathepsins and their inhibitors in their multifactorial functions during the pathogenesis of both infections. Particularly we will address the role on pathogen transmission, during establishment of intracellular chronic niches and in granuloma clinical outcome and tuberculosis diagnosis. This area of research will open new avenues for the design of innovative therapies and diagnostic interventions so urgently needed to fight this threat to humanity.

Pycnodysostosis: a case report and literature review concerning oral and maxillofacial complications and their management

OBJECTIVE

There is a lack of knowledge regarding pycnodysostosis (PYCD), which is commonly misdiagnosed as other, similar malformations. This study aims to report a patient with PYCD and conjointly present a comprehensive literature review regarding oral complications after oral surgery procedures.

STUDY DESIGN

This study aims to report a noteworthy case of a 40-year-old woman with PYCD who suffered from a midface defect after iatrogenic fracture during extraction of the upper right molars. A comprehensive electronic search was carried out in January 2020 for detection and analysis of the most commonly encountered dentoalveolar PYCD-related complications. The study was granted an exemption from the local institutional review board.

RESULTS

The electronic search yielded 35 articles reporting 41 PYCD cases with 62 various reported dentoalveolar complications. The survey reported a prevalence of osteomyelitis (n = 39) followed by pathologic fracture (n = 17), iatrogenic fracture (n = 5), and oronasal communication (n = 1).

CONCLUSIONS

This study advocates handling patients with PYCD with care through the use of extensive clinical and radiographic examinations, giving priority to any conservative treatment modalities, atraumatic surgical procedures, prophylactic antibiotic prescriptions, and a regular follow-up schedule to tackle any anticipated complications.

Differentiated Immunohistochemical Expression of Osteoclastogenic Markers in Radicular Cyst, Odontogenic Keratocyst, and Ameloblastoma

The aim of this study was to investigate the osteoclastogenesis process by means of immunohistochemical markers for receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), interleukin-6 (IL-6), and cathepsin K (CTSK) antigens in osteolytic lesions of maxillary bones. The sample consisted of 23 radicular cysts (RC), 25 odontogenic keratocysts (OKC), and 25 ameloblastomas (AM). RANKL was statistically higher in RC (49.6±15.2/53.7±18) and OKC (48.6±15.1/51.4±16.8) when compared with AM (37.2±12.5/36.4±13) in the epithelium and connective tissue. OPG was lower in OKC (34.8±18.5) only in connective tissue when compared with RC (44.5±11.2). The expression of RANKL was statistically higher than OPG in RC (epithelium and connective tissue) and OKC (connective tissue). For IL-6, a statistical difference was observed only in the connective tissue between groups, with higher expression in RC (48.2±15) and lower in OKC (22±11.9). The expression of IL-6 was correlated with the intensity of the inflammatory infiltrate. CTSK was statistically higher in AM (34±19) and OKC (29±13.8) compared with RC (19±10.5). According to the results of the present research the bone resorption in cysts and odontogenic tumors occurs through different mechanisms. The ostoclastogenic process in lesions with aggressive clinical behavior, as AM and OKC, seems to be associated with the expression of CTSK. In contrast, lesions with inflammatory etiology, as RC, the expression of IL-6 seems to have an important role in the bone resorption process. The highest expression of RANKL under the expression of OPG also seems to contribute to the growth mechanism of RC and OKC.

Gan-Lu-Yin (Kanroin), Traditional Chinese Herbal Extracts, Reduces Osteoclast Differentiation In Vitro and Prevents Alveolar Bone Resorption in Rat Experimental Periodontitis

Gan-Lu-Yin (GLY), a traditional Chinese herbal medicine, shows therapeutic effects on periodontitis, but that mechanism is not well known. This study aims to clarify the precise mechanism by investigating the inhibitory effects of GLY extracts on osteoclastogenesis in vitro and on bone resorption in periodontitis in vivo. RAW264.7 cells are cultured with soluble receptor activator of nuclear factor-kappa B (sRANKL) and GLY extracts (0.01–1.0 mg/mL), and stained for tartrate-resistant acid phosphatase (TRAP) to evaluate osteoclast differentiation. Experimental periodontitis is induced by placing a nylon ligature around the second maxillary molar in rats, and rats are administered GLY extracts (60 mg/kg) daily for 20 days. Their maxillae are collected on day 4 and 20, and the levels of alveolar bone resorption and osteoclast differentiation are estimated using micro-computed tomography (CT) and histological analysis, respectively. In RAW264.7 cells, GLY extracts significantly inhibit sRANKL-induced osteoclast differentiation at a concentration of more than 0.05 mg/mL. In experimental periodontitis, administering GLY extracts significantly decreases the number of TRAP-positive osteoclasts in the alveolar bone on day 4, and significantly inhibits the ligature-induced bone resorption on day 20. These results show that GLY extracts suppress bone resorption by inhibiting osteoclast differentiation in experimental periodontitis, suggesting that GLY extracts are potentially useful for oral care in periodontitis.

Genetic study of eight Egyptian patients with pycnodysostosis: identification of novel CTSK mutations and founder effect

This is the first Egyptian study with detailed clinical and orodental evaluation of eight patients with pycnodysostosis and identification of four mutations in CTSK gene with two novel ones and a founder effect.

INTRODUCTION

Pycnodysostosis is a rare autosomal recessive skeletal dysplasia due to mutations in the CTSK gene encoding for cathepsin K, a lysosomal cysteine protease.

METHODS

We report on the clinical, orodental, radiological, and molecular findings of eight patients, from seven unrelated Egyptian families with pycnodysostosis.

RESULTS

All patients were offspring of consanguineous parents and presented with the typical clinical picture of the disorder including short stature, delayed closure of fontanels, hypoplastic premaxilla, obtuse mandibular angle, and drum stick terminal phalanges with dysplastic nails. Their radiological findings showed increased bone density, acro-osteolysis, and open cranial sutures. Mutational analysis of CTSK gene revealed four distinct homozygous missense mutations including two novel ones, c.164A>C (p. K55T) and c.433G>A (p.V145M). The c.164A>C (p. K55T) mutation was recurrent in three unrelated patients who also shared similar haplotype, suggesting a founder effect.

CONCLUSION

Our findings expand the mutational spectrum of CTSK gene and emphasize the importance of full clinical examination of all body systems including thorough orodental evaluation in patients with pycnodysostosis.

Cathepsin K associates with lymph node metastasis and poor prognosis in oral squamous cell carcinoma

Background

Lymph node metastasis (LNM) is a major determinant of prognosis and treatment planning of oral squamous cell carcinoma (OSCC). Cysteine cathepsins constitute a family of proteolytic enzymes with known role in the degradation of the extracellular matrix. Involvement in pathological processes, such as inflammation and cancer progression, has been proved. The aim of the study was to discover the clinicopathological and prognostic implications of cathepsin K (CTSK) expression in oral squamous cell carcinoma.

Methods

Eighty-three patients with primary OSCC, treated surgically between 1996 and 2000, were included. Gene expression data were acquired from a previously reported study. Human papilloma virus (HPV) status was previously determined by an algorithm for HPV-16. CTSK Protein expression was semi-quantitatively determined by immunohistochemistry in tumor and stromal cells. Expression data were correlated with various clinicopathological variables.

Results

Elevated gene and protein expression of CTSK were strongly associated to LNM and perineural invasion (p < 0.01). Logistic regression analysis highlighted increased CTSK protein expression in tumor cells as the most significant independent factor of lymphatic metastasis (OR = 7.65, CI:2.31–23.31, p = 0.001). Survival analysis demonstrated CTSK protein expression in both stromal and tumor cells as significant indicators of poor 5-year disease specific survival (HR = 2.40, CI:1.05–5.50, p = 0.038 for stromal cells; HR = 2.79, CI:1.02–7.64, p = 0.045 for tumor cells).

Conclusion

Upregulation of CTSK seems to be associated with high incidence of lymphatic spread and poor survival in OSCC. CTSK could therefore serve as a predictive biomarker for OSCC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4315-8) contains supplementary material, which is available to authorized users.

Clinical and radiographic features of pycnodysostosis: A case report

Pycnodysostosis is a rare disorder that was first described in 1962; however, it was only in 1996 that the defective gene was discovered, which led to a better understanding of this disease. This study reports and discuss a case of pycnodysostosis. In addition, a search of articles published in PubMed-Medline was performed. The case was a 13-year-old girl who was referred to a private clinic for dental treatment. Clinical examination showed midface hypoplasia, prominent cheeks, a high nasal bridge, beaked nose, spoon-shaped fingers, frontal bossing, open fontanelles and dental alterations, findings compatible with pycnodysostosis. Patients with this disease also suffer from fractures because of bone hardness with almost no elasticity, a fact that requires special care particularly in the case of children and adolescents. The diagnosis of pycnodysostosis is made based on clinical and radiographic findings. Clinicians should be aware of this disorder to provide adequate dental treatment.

Key words:Pycnodysostosis, developmental bone disease, imaging diagnosis.

The Immune Response in Periodontal Tissues

The uniqueness of periodontal diseases is caused by several factors. This group of diseases is caused by numerous bacterial species formed in the dental biofilm, and one cannot distinguish the specific pathogen that is responsible for the disease initiation or progress (though Gram-negative anaerobic rods are associated with the advanced form of the disease). The disease is both infectious and inflammatory in its nature, and in the state of health there is always a subclinical level of inflammatory response, caused by the so-called harmless bacteria. Negligence in oral hygiene may result in maturation of the biofilm and trigger host response, manifesting clinically as gingivitis or-later and in susceptible subjects-as periodontitis. The article presents the contemporary knowledge of the inflammatory reaction occurring in tissues surrounding the tooth during periodontal inflammation. The most important mechanisms are described, together with implications for clinicists.

Cathepsin K modulates invasion, migration and adhesion of oral squamous cell carcinomas in vitro

OBJECTIVE

Cathepsin K was initially discovered as an osteoclast-specific cysteine proteinase, but the enzyme is also expressed in various cancers including oral squamous cell carcinomas. This study aimed to clarify the function of cathepsin K in oral squamous cell carcinomas.

MATERIALS AND METHODS

Expression levels of cathepsin K were examined in six types of cell carcinomas. Carcinomas overexpressing cathepsin K were constructed. Effects of cathepsin K overexpression and treatment with odanacatib, a specific cathepsin K inhibitor, on cell invasion, migration and adhesion were analysed.

RESULTS

Different levels of cathepsin K were expressed in carcinomas. Cathepsin K was predominantly localised in lysosomes. Cathepsin K overexpression impaired the proliferation of carcinomas. Invasion analysis showed that cathepsin K overexpression enhanced invasion and migration of carcinomas, whereas inhibition of cathepsin K by odanacatib caused the opposite effects in carcinomas. Cathepsin K overexpression also increased cell adhesion and slightly increased surface expression of the adhesion receptor CD29/integrin β₁ .

CONCLUSIONS

The enhanced invasion of carcinomas resulting from cathepsin K overexpression is probably due to the increased cell migration and adhesion. Thus, cathepsin K is implicated not only in protein degradation but also in invasion, migration and adhesion of oral squamous cell carcinomas.

Cathepsin K expression is increased in oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is an idiopathic T-cell-mediated mucosal inflammatory disease. Cathepsin K (Cat K) is one of the lysosomal cysteine proteases. It is involved in many pathological conditions, including osteoporosis and cancer. The expression and role of Cat K in OLP are unknown.

METHODS

Twenty-five oral mucosal specimens diagnosed histopathologically as OLP and fourteen healthy controls (HC) were used to study the immunohistochemical (IHC) expression of Cat K. Colocalization of Cat K with CD1a, Melan-A, CD68, CD45, mast cell tryptase (MCT), and Toll-like receptors (TLRs) 4 and 9 were studied using double IHC and/or immunofluorescence (IF) staining. Expression of Cat K was also evaluated in OLP tissue samples before and after topical tacrolimus treatment.

RESULTS

Cat K was expressed in a higher percentage of cells in the epithelial zone, and the staining intensity was stronger in the stroma in OLP compared to controls (P < 0.001). In OLP, Cat K was present mostly in melanocytes and macrophages and sporadically in basal keratinocytes, endothelial cells, and extracellularly. Cat K was found also in some fibroblasts in HC and OLP samples. Coexpression of Cat K and TLRs 4 and 9 was seen in some dendritic cells (presumably melanocytes) and macrophages. In OLP, tacrolimus treatment reduced the expression of Cat K in the epithelium but increased it in the stroma.

CONCLUSIONS

These results suggest that Cat K is involved in the pathogenesis of OLP. Cat K possibly takes part in the modulation of matrix molecules and cellular receptors.