Association between -308 G/A polymorphism in TNF-α gene and lichen planus: A meta-analysis

Salivary metabolomics in patients with oral lichen planus: a preliminary study based on NMR spectroscopy

OBJECTIVES

The present preliminary study aimed to investigate the salivary metabolic profile in patients with asymptomatic oral lichen planus (OLP) using nuclear magnetic resonance (NMR) spectroscopy.

MATERIAL AND METHODS

Stimulated whole mouth saliva (SWMS) samples were collected from 15 reticular OLP female patients and 15 from age- and sex-matched controls (HCs). A total of 23 metabolites were identified and quantified. Mann-Whitney's U test was used to compare the determined concentration salivary metabolite concentrations between OLP patients and the healthy controls.

RESULTS

The concentration of acetate, methylamine, and pyruvate was elevated, whereas the concentration of tyrosine was decreased in the saliva of OLP patients compared with HCs. To identify a combination of metabolites, multivariate discrimination function analysis (DFA) was conducted. DFA analysis have shown that the most powerful discrimination between the groups was achieved when methylamine and tyrosine were considered as combined biomarkers.

CONCLUSIONS

Salivary tyrosine was of particular interest and a promising finding for the screening of OLP and its progression. Further longitudinal studies are required to establish it as a reliable salivary biomarker in OLP.

CLINICAL RELEVANCE

The salivary metabolic profiling can describe the pathologic characteristics of OLP on non-invasive saliva samples and NMR analysis. Salivary metabolites provide details to considered early detectors and to impact oral health of OLP patients.

Hallmarks of Cancer Expression in Oral Lichen Planus: A Scoping Review of Systematic Reviews and Meta-Analyses

Oral lichen planus (OLP) is a common chronic inflammatory disease of unknown etiology and likely autoimmune nature that is currently considered an oral potentially malignant disorder, implying that patients suffering from this process are at risk of developing oral cancer in their lifetime. The molecular alterations that develop in OLP and that make the affected oral epithelium predisposed to malignancy are unknown, although, as in other autoimmune diseases (ulcerative colitis, primary biliary cirrhosis, etc.), they may be linked to oncogenesis-promoting effects mediated by the inflammatory infiltrate. So far there is no in-depth knowledge on how these hallmarks of cancer are established in the cells of the oral epithelium affected by OLP. In this scoping review of systematic reviews and meta-analyses the state of evidence based knowledge in this field is presented, to point out gaps of evidence and to indicate future lines of research. MEDLINE, Embase, Cochrane Library and Dare were searched for secondary-level studies published before October 2022. The results identified 20 systematic reviews and meta-analyses critically appraising the hallmarks tumor-promoting inflammation (n = 17, 85%), sustaining proliferative signaling (n = 2, 10%), and evading growth suppressors (n = 1, 5%). No evidence was found for the other hallmarks of cancer in OLP. In conclusion, OLP malignization hypothetically derives from the aggressions of the inflammatory infiltrate and a particular type of epithelial response based on increased epithelial proliferation, evasion of growth-suppressive signals and lack of apoptosis. Future evidence-based research is required to support this hypothesis.

Association of polymorphisms in Th1/Th2-related cytokines (IFN-γ, TGFβ1, IL-1β, IL-2, IL-4, IL-18) with oral lichen planus: A pooled analysis of case–control studies

Background/purpose

Increasing evidence suggests that single-nucleotide polymorphisms (SNPs) in Th1/Th2-related cytokine genes correlated with oral lichen planus (OLP) susceptibility. However, these results were inconsistent and inconclusive. Hence, the aim of this study is to draw a more precise estimation of the genetic associations between SNPs in 6 cytokines (IFN-γ, IL-18, TGFβ1, IL-1β, IL-2, IL-4) and OLP.

Materials and methods

A systematic literature search was conducted to identify all eligible case-control studies on the association between SNPs in 6 cytokines and OLP susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) from each study were pooled to estimate the strength of the association.

Results

A significant association of IFN-γ (874A/T) polymorphism with OLP was found (OR, 1.49; 95%CI, 1.22-1.81; P < 0.001) based on 6 eligible studies. A significant association of IL-18 (137G/C) polymorphism with OLP was found (OR, 1.64; 95%CI, 1.24-2.18; P < 0.001) based on 3 studies. A marginally significant association of TGFβ1 (509C/T) polymorphism in allele model with OLP was found (OR, 1.31; 95%CI, 1.01-1.71; P = 0.05) based on 4 studies. Nevertheless, lack of significant association of IL-1β (3954C/T), IL-2 (330T/G), IL-4 (590C/T), and IL-18 (607C/A) polymorphisms with OLP was found (P > 0.05) based on 3 studies, respectively.

Conclusion

This is the first meta-analysis to investigate the associations of 6 cytokines polymorphisms with OLP, suggesting that SNPs in IFN-γ, IL-18, and TGFβ1 may act as genetic factors for OLP risk. Further well-designed studies with larger sample size and multiple ethnicities are needed to validate these associations.

Expression and Significance of TNF-α and NF-κB/p65 in Cutaneous Lichen Planus

Purpose

The purpose of this study was to explore the expression of TNF-α and NF-κB/p65 in Lichen planus skin lesions and their correlation with the pathogenesis of Lichen planus.

Patients and Methods

The case group consisted of 30 individuals diagnosed with LP based on clinical and histopathologic examination. The control group consisted of 10 individuals from an Orthopedic Department with normal skin. TNF-α and NF-κB/p65 expression in skin tissue samples was detected by immunohistochemistry.

Results

The immunohistochemical results showed that TNF-α and NF-κB/p65 expression levels were significantly higher in LP skin lesions than normal skin tissues (P ≤ 0.05). Positive TNF-α staining mainly occurred in the cytoplasm of keratinocytes of the stratum granulosum, stratum spinosum, and stratum basale in the epidermis and lymphocytes in the superficial dermis. Positive NF-κB/p65 staining mainly occurred in the nucleus and cytoplasm of keratinocytes of the stratum spinosum and stratum basale in the epidermis and lymphocytes in the superficial dermis.

Conclusion

TNF-α and NF-κB/p65 are overexpressed in cutaneous LP. The two are positively correlated in LP, suggesting that they both play essential roles in the pathogenesis of LP.

Oral lichen planus: A disease or a spectrum of tissue reactions? Types, causes, diagnostic algorhythms, prognosis, management strategies

Oral lichen planus and lichenoid lesions comprise a group of disorders of the oral mucosa that likely represent a common reaction pattern to 1 or more unknown antigens. The coexistence of hyperkeratotic striation/reticulation, varying degrees of mucosal inflammation from mild erythema to severe widespread ulceration, and a band-like infiltrate of mononuclear inflammatory cells including activated T lymphocytes, macrophages, and dendritic cells, are considered suggestive of oral lichen planus and lichenoid lesions. Several classification systems of oral lichen planus and lichenoid lesions have been attempted, although none seem to be comprehensive. In this paper, we present a classification of oral lichen planus and lichenoid lesions that includes oral lichen planus, oral lichenoid contact lesions, oral lichenoid drug reactions, oral lichenoid lesions of graft vs. host disease, discoid lupus erythematosus, and systemic lupus erythematosus, lichen planus-like variant of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome, chronic ulcerative stomatitis, lichen planus pemphigoides, solitary fixed drug eruptions, and lichen sclerosus. We present the clinical and diagnostic aspects of oral lichen planus and lichenoid lesions, and discuss related treatment options.

Lichen planus and lichenoid dermatoses: Clinical overview and molecular basis

Deriving from the Greek word λειχήν for "tree moss" and the Latin word planus for "planar," lichen planus is a relatively uncommon and heterogeneous cutaneous disorder that typically develops in middle-aged adults. Despite the significant clinical burden associated with the disorder, little well-conducted molecular research has been undertaken, possibly because of heterogeneity impeding consistent and confident phenotyping. The multiple variants of lichenoid disease bear overlapping clinical and pathologic features despite manifesting as distinct clinical disorders. The first article in this 2-part continuing medical education series provides a comprehensive overview of the clinical and pathologic characteristics of cutaneous lichenoid dermatoses and links these manifestations to recent advances in our understanding of the underlying pathobiology of such diseases.

Association between TNFα - 308 G/A polymorphism and oral lichen planus (OLP): a meta-analysis

OBJECTIVES

To determine whether Tumor Necrosis Factor alpha (TNFα) -308 G/A polymorphism is associated with oral lichen planus (OLP).

MATERIAL AND METHODS

A systematic electronic search of the literature was conducted to identify all published studies on the association between TNFα -308 G/A polymorphism and OLP. All case-control studies evaluating the TNFα -308 G/A polymorphisms in OLP were selected. A meta-analysis of the studies that fulfilled the inclusion criteria was performed. Odds ratios (OR) with 95% confidence intervals (CI) were also calculated.

RESULTS

Seven studies comprising 450 OLP cases and 867 controls were included in the meta-analysis. In the pooled analysis, TNFα -308 G/A polymorphism was associated with OLP with random effects and OR of 2.33 (95%CI=1.07-5.11; p=0.03), assuming a dominant mode of inheritance (AA+GA vs. GG). In the subgroup analysis by ethnicity, TNFα -308 G/A was associated with a significantly increased odds ratio of OLP in mixed ethnicity (OR=5.22; 95%CI=1.93-14.15; p=0.001), but not in Asians (OR=1.57; 95%CI=0.54-4.54; p=0.41) or Caucasians (OR=1.45; 95%CI=0.19-11.22; p=0.72). For subgroup analysis based on HCV (hepatitis C virus) infection status, significant increased risk of OLP was found among patients with mixed HCV infection status (OR=3.77; 95%CI=1.07-13.2; p=0.038), but not in patients without HCV infection (OR=2.09; 95%CI=0.63-6.91; p=0.22) and patients with HCV infection (OR=0.48; 95%CI=0.13-1.69; p=0.25).

CONCLUSION

Our results suggest that -308 G/A polymorphism in TNFα is a potential genetic marker for OLP.

The measurement of serum TNF-α levels in patients with lichen planus

BACKGROUND

Lichen planus is a common mucocutaneous inflammatory skin disease with a multifactorial etiology. Cytokines play a key role in lichen planus pathogenesis. This study investigates the relationship between disease severity and levels of tumor necrosis factor-α (TNF-α), which is considered a primary cytokine that initiates cytotoxicity.

MATERIAL AND METHODS

Serum TNF-α levels were compared between a patient group (n = 34) and a control group (n = 20). TNF-α serum levels were measured using human TNF-α Enzyme-Linked Immunosorbent Assay (ELISA) test kits, and the two groups were statistically compared to each other.

RESULTS

Mean serum TNF-α levels were found to be significantly higher in the patient group than in the control group (p < 0.005). However, no significant association was observed between TNF-α levels and oral mucosal involvement (p > 0.005). No relationship was detected between TNF-α levels and patients' sex.

CONCLUSION

It is thought that TNF-α, a proinflammatory cytokine, may play an important role in the pathogenesis of lichen planus. TNF-α may be a simple and effective predictor to illustrate the inflammatory status in patients with lichen planus.

Association of genetic polymorphisms in interferon-γ, interleukin-6 and transforming growth factor-β1 gene with oral lichen planus susceptibility

BACKGROUND

Oral lichen planus (OLP) is a premalignant mucocutaneous disease in which genetic factors and immune responses play a major role. Cytokines play an important role in the pathogenesis and disease progression of OLP. The aim of this study was to investigate the impact of gene polymorphisms of T helper cell subtype Th1 and Th2 cytokines, interferon-gamma (IFN-γ), interleukin-6 (IL-6) and transforming growth factor (TGF)-β1 on OLP susceptibility in a Saudi cohort.

METHODS

Forty two unrelated patients with OLP and 195 healthy controls were genotyped for IFN-γ (874A/T), IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms.

RESULTS

The frequency of genotype AT of IFN-γ (874A/T) was significantly higher while genotype AA was lower in OLP patients as compared to controls (P < 0.05). The frequency of T containing genotypes (AT + TT) was also higher in OLP patients as compared to that in controls (P = 0.003). The frequencies of allele T was higher while that of allele A lower in patients than the controls however the difference was not statistically significant (P = 0.07). There was no significant difference in the frequencies of alleles and genotypes of IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms between patient and control groups. These results indicated that genotype AT of IFN-γ (874A/T) polymorphism is associated with OLP risk and genotype AA is protective to OLP. On the other hand the polymorphisms IL-6 (174G/C) and TGF-β1 (509C/T) may not be associated with OLP risk in our population.

CONCLUSION

It is concluded that IFN-γ (874A/T) polymorphism is associated with the susceptibility of OLP, however further studies with large sample size involving different ethnic populations should be conducted to strengthen our results.

Clinical characteristics and analysis of familial oral lichen planus in eight Chinese families

Oral lichen planus (OLP) is one of the most common oral mucosa diseases; however, familial OLP is uncommon. The present study reported and analyzed patients with familial OLP (n=18) in eight different Chinese families between January 1, 2012 and December 31, 2013. Parameters analyzed include gender, age at diagnosis, lesion distribution and lesion type. The follow-up period for each patient was a minimum of 1 year. In this survey, 18/88 individuals in the eight families were affected. Females were more frequently affected, and the female to male ratio for familial OLP (2.2:1) was higher compared with that previously reported for nonfamilial OLP (1.4:1). The age at diagnosis, lesion distribution and lesion type showed consistency with reports concerning nonfamilial OLP, with the exception of family VI, in which 4/5 children had OLP/LP lesions and were of an early age at diagnosis. There were two families in which three generations had been affected by OLP. In addition, it appeared that patients of the same generation in the same family were of a similar age at diagnosis. No malignant or premalignant lesion was identified in the 18 individuals diagnosed with OLP from the eight families. The present study supports the hypothesis that genetic predisposition may serve a role in the etiology of OLP.

Mucosal Lesions in an Allergy Practice

The diagnosis and treatment of mucosal disease with an allergic pathogenesis are challenging. Oral allergy is often a hypersensitivity reaction with variable symptoms and physical exam findings. Clinical diagnosis requires a history of prior allergen exposure, a delay from exposure to clinical findings, and improvement following allergen removal. The past decades have seen great contributions to the field of oral allergy. The aim of this review is to provide an approach to the diagnosis and treatment of oral dermatologic disease with a focus on diseases with an investigated allergic pathogenesis.

Activation of myeloid dendritic cells, effector cells and regulatory T cells in lichen planus

Background

Lichen planus (LP) is a chronic mucocutaneous inflammatory disease. Evaluating the balance between regulatory T cells and effector T cells could be useful for monitoring the proinflammatory profile of LP. Therefore, this study aimed to assess populations of dendritic cells (DCs) and regulatory and effector T cells in peripheral blood samples collected from patients with LP to evaluate the polyfunctionality of T cells upon toll-like receptor (TLR) activation.

Methods

Peripheral blood mononuclear cells collected from 18 patients with LP and 22 healthy control subjects were stimulated with agonists of TLR4, TLR7, TLR7/TLR8 or TLR9. Frequencies of circulating IFN-α⁺ plasmacytoid DCs (pDCs); TNF-α⁺ myeloid DCs (mDCs); regulatory T cells (Tregs); and IL-17-, IL-10-, IL-22-, TNF-, and IFN-γ-secreting T cells were assessed via flow cytometry.

Results

The frequencies of regulatory CD4⁺ and CD8⁺CD25⁺Foxp3⁺CD127^low/− T cells and TNF-α⁺ mDCs were induced following activation with TLR4, TLR7 and TLR8 agonists in the LP group. Moreover, increased baseline frequencies of CD4⁺IL-10⁺ T cells and CD8⁺IL-22⁺ or IFN-γ⁺T cells were found. In the LP group, TLR4 activation induced an increased frequency of CD4⁺IFN-γ⁺ T cells, while TLR7/8 and staphylococcal enterotoxin B (SEB) activation induced an increased frequency of CD8⁺ IL-22⁺ T cells. An increased frequency of polyfunctional CD4⁺ T cells that simultaneously secreted 3 of the evaluated cytokines (not including IL-10) was verified upon TLR7/8/9 activation, while polyfunctional CD8⁺ T cells were already detectable at baseline.

Conclusions

TLR-mediated activation of the innate immune response induced the production of proinflammatory mDCs, Tregs and polyfunctional T cells in patients with LP. Therefore, TLR activation has an adjuvant role in inducing both innate and adaptive immune responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0938-1) contains supplementary material, which is available to authorized users.

Oral lichen planus

Lichen planus is an inflammatory mucocutaneous disease that can affect the skin, hair, nails, and mucosal surfaces. Mucosal sites of involvement include oral, genital, ocular, otic, esophageal, and, less commonly, bladder, nasal, laryngeal, and anal surfaces. Oral lichen planus is a mucosal variant of lichen planus, which tends to affect women more often than men, with a typically more chronic course and potential for significant morbidity. Treatment can be challenging, and there is potentially a low risk of malignant transformation; however, therapeutic benefits can be obtained with various topical and systemic medications. Clinical monitoring is recommended to ensure symptomatic control. Increasing awareness and recognition of this entity have continued to fuel advances in therapy and in our understanding of the disease.

Role of distinct CD4(+) T helper subset in pathogenesis of oral lichen planus

Oral lichen planus (OLP) is one of the most common chronic inflammatory oral mucosal diseases with T-cell-mediated immune pathogenesis. In subepithelial and lamina propria of OLP local lesions, the presence of CD4(+) T helper (CD4(+) Th) cells appeared as the major lymphocytes. These CD4(+) T lymphocytes can differentiate into distinct Th cell types such as Th1, Th2, Treg, Th17, Th22, Th9, and Tfh within the context of certain cytokines environment. Growing evidence indicated that Th1/Th2 imbalance may greatly participate into the cytokine network of OLP immunopathology. In addition, Th1/Th2 imbalance can be regulated by the Treg subset and also greatly influenced by the emerging novel CD4(+) Th subset Th17. Furthermore, the presence of novel subsets Th22, Th9 and Tfh in OLP patients is yet to be clarified. All these Th subsets and their specific cytokines may play a critical role in determining the character, extent and duration of immune responses in OLP pathogenesis. Therefore, we review the roles of distinct CD4(+) Th subsets and their signature cytokines in determining disease severity and susceptibility of OLP and also reveal the novel therapeutic strategies based on T lymphocytes subsets in OLP treatment.

TNF-α, TNF-β and IL-10 gene polymorphism and association with oral lichen planus risk in Saudi patients

Objectives

Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease. Cytokines play an important role in the pathogenesis and disease progression of OLP. Various reports have implicated cytokine gene polymorphisms in susceptibility to develop some immune mediated conditions including OLP. The purpose of this study was to investigate the association of tumor necrosis factor (TNF)-α, TNF-β and interleukin (IL)-10 gene polymorphisms with the OLP risk.

Material and Methods

Forty two unrelated patients with OLP and 211 healthy volunteers were genotyped for TNF-α (-308 G/A), TNF-β (+252A/G), IL-10 (-1082G/A), IL-10 (-819C/T), and IL-10 (-592C/A) polymorphisms.

Results

The frequencies of allele A and genotype GA of TNF-α (-308G/A) were significantly higher while allele G and GG genotypes were lower in OLP patients as compared to the controls (P<0.001). The frequency of GA genotype of TNF-β (+252A/G) was significantly higher in patients than in controls while the AA genotype was completely absent in OLP patients. These results indicated that allele A and genotype GA of TNF-α (-308G/A) as well as the GA genotype of TNF-β (+252A/G) polymorphisms are associated with OLP risk. The frequencies of alleles and genotypes of -1082G/A, -819C/T and -592C/A polymorphisms in IL-10 gene did not differ significantly between OLP patients and controls (P>0.05). However, haplotype ATA extracted from 1082G/A, -819C/T, -592C/A polymorphisms of IL-10 were more prevalent in OLP patients when compared to controls indicating its possible association with OLP susceptibility.

Conclusion

It is concluded that TNF-α (-308G/A), TNF-β (+252A/G) and IL-10 (-1082G/A, -819C/T and -592C/A) polymorphisms are associated with the susceptibility of OLP, thus giving additional support for the genetic basis of this disease.

The association between tumor necrosis factor-α-308 G/A polymorphism and risk for vitiligo: a meta-analysis

BACKGROUND

The contribution of tumor necrosis factor-α (TNF-α)-308 G/A gene polymorphism (rs1800629) to risk for vitiligo is subject to controversy.

OBJECTIVES

The fundamental purpose of the present meta-analysis was to investigate large-scale evidence to determine the overall association between TNF-α-308 G/A polymorphism and susceptibility to vitiligo.

METHODS

A literature search of the PubMed, EMBASE, Web of Science, and China National Knowledge Infrastructure (CNKI) databases was conducted to identify all studies referring to an association between TNF-α-308 G/A polymorphism and vitiligo published to June 1, 2014. The principal outcome measure for evaluating the strength of the association was the crude odds ratio (OR) along with the corresponding 95% confidence interval (CI). Data were extracted, and statistical analyses were implemented using stata Version 12.0.

RESULTS

Data for a total of 1505 vitiligo cases and 2253 controls from five case-control studies concentrating on the association between TNF-α-308 G/A polymorphism and vitiligo were included in this meta-analysis. Combined analysis revealed there to be no association between this polymorphism and susceptibility to vitiligo in five genetic models under random-effects models. A subgroup analysis by clinical type also demonstrated the absence of any association between TNF-α-308 G/A polymorphism and generalized vitiligo. However, a significant association was detected in the miscellaneous subgroup under the dominant model (fixed-effects model: OR 5.69, 95% CI 4.70-6.88; P = 0.000) and overdominant model (random-effects model: OR 5.24, 95% CI 2.26-12.17; P = 0.000).

CONCLUSIONS

This meta-analysis indicates that TNF-α-308 G/A polymorphism is not a genetic risk factor for vitiligo.

Associations between TNF-α-308A/G polymorphism and susceptibility with dermatomyositis: a meta-analysis

Background

Some surveys had inspected the effects of the tumor necrosis factor-α (TNF-α)-308A/G polymorphism on susceptibility to dermatomyositis (DM), and showed mixed results. To briefly review these consequences, a comprehensive meta-analysis was carried out to estimate the relationship between them much more accurately.

Methods

Relevant documents dated to February 2014 were acquired from the PUBMED, MEDLINE, and EMBASE databases. The number of the genotypes and/or alleles for the TNF-α-308A/G in the DM and control subjects was extracted and statistical analysis was conducted using STATA 11.2 software. Summary odds ratios (ORs) with their 95% confidence intervals (95% CIs) were used to calculate the risk of DM with TNF-α-308A/G. Stratified analysis based on ethnicity and control population source was also performed.

Results

555 patients with DM and 1005 controls from eight published investigations were finally involved in this meta-analysis. Combined analysis revealed that the overall ORs for the TNF-α-308A allele were 2.041 (95% CIs 1.528–2.725, P<0.0001) in DM. Stratification by ethnicity indicated the TNF-α-308A allele polymorphism was found to be significantly associated with DM in Europeans (OR = 1.977, 95% CI 1.413–2.765, P<0.0001). The only study conducted on TNF-α-308A/G polymorphism in Asians could not be used in ethnicity-stratified meta-analysis. Meta-analysis of the AA+AG vs. GG (dominant model) and AA vs. GG (additive model) of this polymorphism revealed a significant association with DM in overall populations and Europeans.

Conclusions

Our meta-analysis demonstrated that the TNF-α-308A/G polymorphism in the TNF gene might contribute to DM susceptibility, especially in European population. However, further studies with large sample sizes and among different ethnicity populations should be required to verify the association.

Inflammation-related cytokines in oral lichen planus: an overview

Cytokines are powerful mediators which play a central role in both innate and adapted immune responses. Aberrant productions of cytokines may lead to the onset of immune deficiency, allergy or autoimmunity, which are involved in the mechanisms of various immune-mediated inflammatory diseases. Oral lichen planus (OLP) is a chronic inflammation disease affecting the oral mucosa with unknown aetiology. Previous studies have described the abnormal expression patterns of various inflammation-related cytokines, such as IL-1, 2, 4, 5, 6, 8, 10, 12, 17, 18, TGF-β, IFN-γ and TNF-α, in lesions, saliva, serum and peripheral blood mononuclear cells from patients with OLP, which may reflect the immune dysregulation status and emerge as central players in the immunopathogenesis of OLP. Besides, the gene polymorphisms of several cytokines such as IFN-γ, TNF-α, IL-4, IL-10 have been found to be involved in the susceptibility of OLP. In this review, we gave a brief introduction of the characteristics and biological functions of these inflammation-related cytokines and summarized for the first time the current knowledge on the involvement of inflammation-related cytokines in OLP. Further research on the exact roles of these cytokines will aid the understanding of the pathogenesis and the identification of novel therapeutic approaches of OLP.

The association between tumor necrosis factor alpha promoter polymorphisms and ankylosing spondylitis: a meta-analysis

BACKGROUND

Studies investigating the association between tumor necrosis factor (TNF)-alpha promoter polymorphisms and ankylosing spondylitis have reported conflicting results. We here performed a meta-analysis based on the evidence currently available from the literature to make a more precise estimation of this relationship.

METHODS

We performed a systematic search of the National Library of Medline and Embase databases before January 2013. This meta-analysis included 14 case-control studies, which included 1607 ankylosing spondylitis cases and 1910 controls.

RESULTS

The combined results based on all studies showed that ankylosing spondylitis cases had a significantly lower frequency of -308GA [OR (codominant model)=0.81, 95% CI=0.66, 0.99, P=0.04], -857CT [OR (codominant model)=0.55, 95% CI=0.32, 0.94, P=0.03], -863AA [OR (codominant model)=0.11, 95% CI=0.01, 0.94, P=0.04], -863CA [OR (codominant model)=0.32, 95% CI=0.18, 0.58, P<0.001], and -1031TC [OR (codominant model)=0.44, 95% CI=0.25, 0.77, P=0.004] genotype. However, ankylosing spondylitis cases had a significantly higher frequency of -238AA [OR (recessive model)=7.43, 95% CI=3.66, 15.05, P<0.001] and -850TT [OR (recessive model)=2.49, 95% CI=1.16, 5.34, P=0.02; OR (codominant model)=2.83, 95% CI=1.28, 6.25, P=0.01] genotype. In the subgroup analysis by race, we found that ankylosing spondylitis cases had a significantly higher frequency of -238AA [OR (recessive model)=7.43, 95% CI=3.66, 15.05, P<0.001] genotype in Caucasians and lower frequency of -857CT [OR (codominant model)=0.53, 95% CI=0.30, 0.94, P=0.03] in Asians.

CONCLUSIONS

Our meta-analysis suggests that TNF-alpha promoter polymorphisms at positions -238, -308, -850, -857, -863 and -1031 could have a small influence on ankylosing spondylitis susceptibility. But there is a lack of association of the TNF-alpha-376G/A and -646G/A polymorphisms with ankylosing spondylitis.