Oral lichen planus (OLP) is a chronic immunological, inflammatory disease of the oral mucosa, of still unknown etiology. Cell-mediated immunity triggered by endogenous and exogenous factors holds a special place in the pathogenesis of OLP, especially in individuals with a genetic predisposition to disease. The disease may occur along with skin changes, in case of which it is referred to as skin lichen planus (LP). Oral changes can occur at the same time as skin lesions, but in 30 to 70% of cases they occur separately (1). LP has been associated with a number of autoimmune disorders, but it remains unclear whether patients with LP are more likely to develop other autoimmune diseases or the diseases are related etiologically (2). Cutaneous LP may also occur in some autoimmune diseases, such as Sjögren's syndrome (SS), rheumatoid arthritis (RA), sarcoidosis, autoimmune hepatitis and vitiligo (3). The occurrence of OLP can also be enhanced by psychological distress, stress and anxiety (4).
Pathogenetic mechanisms of OLP formation imply an autoimmune reaction in which T lymphocytes invade antigenically altered basal keratinocytes. The target antigen that triggers the reaction has not yet been detected. In susceptible patients, basal keratinocytes present antigen permanently, leading to chronicity and their direct cell-mediated damage (5). The inflammatory infiltrate in OLP is composed of lymphocytes and a small number of macrophages. T lymphocytes dominate over B lymphocytes, and CD4 + T (helper) cells are more common than CD8 + T cells (cytotoxic / suppressor) (6).Autoimmune disease (AID) is a pathological condition triggered by an autoimmune process (7). The etiology of AID is multifaceted. It is caused by impaired neuroendocrine - humoral regulation of immunity in genetically predisposed individuals exposed to the provocative action of external factors. Epidemiological studies have shown that genetic factors determine the preference for AID, as indicated by family relatedness and more frequent diseases of identical and fraternal twins. According to Roitt, organ specific diseases are distinguished from a wide range of AIDs versus organ nonspecific or multisystemic diseases (8).
The importance of the autoimmune reaction in the etiopathogenesis of OLP is based on studies that have observed some changes in the population of T lymphocytes in the peripheral blood of patients, including decreased CD4 + and CD45RA + lymphocytes. The finding of suppressed spontaneous lymphocyte proliferation in peripheral blood mediated by CD4 + and CD45RA + cells indicates their importance in the onset of this disease (3). Oral lichen planus can be associated with AIDs and disorders with CD4 + and CD45RA + cell reduction (3). The association of chronic liver disease with the onset of OLP has also been noted, especially autoimmune liver diseases such as primary biliary cirrhosis (PBC) and chronic active hepatitis (9, 10). Diabetes mellitus (DM) is often described as an important etiologic factor in OLP formation (11). A possible etiological background of ulcerative colitis in the onset of OLP has also been described (12, 13). Among other intestinal diseases, celiac disease (14) and Chron's disease (15) are associated with OLP. A more common occurrence of OLP has also been reported in patients with some skin diseases such as psoriasis or lichen sclerosus (3).
Previous studies have shown significant increase in inflammatory markers levels in OLP patients (16). Moreover, it is concluded that plasma CRP level could be a potential marker of increased risk of cancer (17).
The main objectives of this study were: 1) to investigate differences in the values of the inflammatory markers (sedimentation (SE), C-reactive protein (CRP), leukocytes (L)) between subjects with OLP and subjects without pathological changes in the oral mucosa; 2) examine differences in the incidence of the disease from other autoimmune diseases between subjects with OLP and healthy subjects of the control group.
Materials and methods
Respondents and Procedures
The study was initiated with the approval of the Ethics Committee of the University of Split, School of Medicine. It was implemented according to the principles of the Declaration of Helsinki in the period from September 2011 to July 2017. Respondents were included in the survey after signing inform consent. A total of 126 subjects participated in the study. The study group consisted of 63 subjects who were diagnosed with OLP by clinical oral examination and histopathological findings. The control group consisted of 63 randomly selected subjects with no pathological changes in the oral mucosa.
From all subjects a detailed medical history was taken during the first examination at the Department of the Oral Medicine of the Dental Polyclinic Split - Teaching Database Study of Dental Medicine, School of Medicine, University of Split. Based on the medical history, data were obtained on age, sex, cigarette smoking habits (yes / no) and daily consumption of alcoholic beverages (yes / no), and the presence of other autoimmune diseases. The medical history of the presence of another autoimmune disease is supported by detailed medical records. Pathohistological diagnosis (PHD) confirmed the clinically diagnosed OLP. A biopsy specimen for PHD was taken from the edge of a pathologically altered oral mucosa after application of a local anesthetic (0.7 ml). The histopathological criteria of OLP included the following: hyperkeratosis and various stages of orthokeratosis or parakeratosis, vacuolation of the basal layer with apoptotic keratinocytes, dense lymphocytic inflammatory cell infiltrate at the epithelial-connective border, presence of eosinophilic colloidal body bodies in the area of basal lamina (Civatte bodies) and epithelial lengthening (appearance of saw teeth). The erosive forms of OLP histopathologically have included the presence of erosion, neutrophils and fibrin deposits in the epithelium. All subjects in the test group were in the acute phase of the disease at the time of taking part in the study and their blood was taken for analysis before treatment was initiated.
The exclusion criterion for the test group was an acute febrile condition, and the subjects were asked about it before engaging in blood research and sampling.
All serological examinations were performed in the same laboratory of the Institute for Medical-Biochemical Diagnostics of the Clinical Hospital Center Split. A sample of venous blood was taken from each patient to determine SE rate and L number using standard laboratory procedures. CRP concentration was determined after blood sampling in a Vacutainer tube without anticoagulants (Becton Dickinson, Plymouth, UK). Multigent CRP Vario reagent was used for the determination of CRP on an ARCHITECT ci8200 (Abbot, Wiesbaden, Germany) following the manufacturer's instructions. The serological findings of SE, CRP and L are expressed metrically, in defined units and with defined reference values: SE (5-28 mm / h), CRP (<5.0 mg / L) and L (3,4-9, 7 x 109 / L). The values of SE, CRP, and L are also presented qualitatively; as values within the reference interval (negative) or values greater than the upper limit of the reference interval (elevated).
The collected data were entered into spreadsheets and an analysis was performed using the statistical package Statistica 12. In the statistical processing of the results, the methods of descriptive statistics, χ2-test, Fisher's exact test, and the Student's t-test were used. The values of the continuous variables are presented by the mean and the median, and the categorical variables are presented as an integer and a percentage. A χ2 test was used to compare the categorical variables between the test and control groups. Due to the limitations of the χ2 test when applied in situations where the presence of the feature modality is low, Fisher's exact test was used. T-test tested the difference in numerical values among the observed groups. The results were interpreted at a significance level of P <0.05.
A total of 126 subjects participated in the study, 23 men and 103 women. The test group consisted of 54 women (85.71%) and 9 men (14.29%), while in the control group there were 49 women (77.78%) and 14 men (22.22%). There was no statistically significant difference among the study groups with respect to the gender of the subjects (P = 0.248).
Table 1 shows the mean, median and minimum and maximum age of the test and control subjects.
OLP- oral lichen planus, N – number of participants, X – mean value, M – median.
There was no statistically significant difference between the study groups with respect to the age of the subjects (P = 0.819).
The average value of SE in subjects with OLP was 12.17 mm / h, whereas in the control group it was 12.36 mm / h. No statistically significant difference in mean SE was found between the study groups (P = 0.902). The average CRP value in subjects with OLP was 3.56 mg / L and in the control group was 2.45 mg / L (P = 0.270). The average value of L was 5.84 x 109 / L in the test group and 6.01 x 109 / L in the control group (P = 0.575).
Table 2 shows the proportion of subjects whose values of test inflammatory markers (SE, CRP, L) were elevated (above the upper limit of the reference interval).
|OLP||14 (22.22%)||7 (11.11%)||8 (12.70%)|
|Control group||10 (15.87%)||7 (11.11%)||2 (3.17%)|
OLP- oral lichen planus, SE- sedimentation, CRP- C reactive protein, L- leukocytes
Values are expressed as an integer and a percentage.
For all three measured inflammatory markers, there was no statistically significant difference in the number of subjects with elevated values between the test and control groups (P = 0.364 for SE; P = 1.000 for CRP and P = 0.219 for L).
Table 3 shows the proportion of subjects diagnosed with another autoimmune disease in both study groups.
|OLP||25 (39.68%)||38 (60.32%)||<0,001|
|Control group||4 (6.35%)||59 (93.65%)|
OLP- oral lichen planus
Values are expressed as an integer and a percentage
Nine subjects (14.29%) with OLP has reported the presence of cutaneous LP, seven (11.11%) celiac disease, five (7.94%) DM, three subjects (4.76%) SS and one respondent (1.59%) indicated the existence of Hashimoto's thyroiditis, RA and vitiligo. In the control group of autoimmune diseases, SS was reported in two subjects (3.17%) and DM and Raynaud's syndrome in one subject (1.59%).
Anamnestic data on daily basis consumption of cigarettes and alcohol were taken. In the test group, seven subjects (11.11%) smoke every day while 11 (17.46%) consume alcoholic beverages every day. In the control group, 11 subjects (17.46%) have reported smoking cigarettes every day, and seven (11.11%) alcohol consumption. There was no statistically significant difference between smoking and drinking (P = 0.308) and drinking (P = 0.308) between the study groups.
Oral lichen planus is an inflammatory disease of the oral cavity mucosa (18), hence the aim of this study was to investigate whether there was a difference in the values of inflammatory markers (SE, CRP, and L) between the patients with OLP and subjects without pathological changes in the oral mucosa .
Determination of the rate of SE is a laboratory test which determines the presence of an inflammatory reaction in the body. Measurement demonstrates a change in plasma protein concentration, and changes in plasma composition will cause accelerated SE. The average value of SE in subjects with OLP was 12.17 mm / h and in the control group was 12.36 mm / h, which was not significantly different (P = 0.902). Nevertheless, a slightly larger number of OLP subjects than those in the control group (14 vs. 10) had increased sedimentation (> 28 mm / h).
Protein synthesis is accelerated in response to inflammation in liver cells the most important of which is CRP. Plasma CRP concentration correlates best with SE value (19). In their study, Shahidi et al. demonstrated a significant increase in CRP levels in subjects with dysplastic OLP lesions and oral squamous cell carcinoma (16). In this study, we did not include subjects with dysplastic OLP lesions as this was the exclusive criterion. In both study groups, 56 subjects (88.89%) had CRP values lower than 5 mg / L, respectively, i.e. within the reference interval. The average CRP value in subjects with OLP was 3.56 mg / L, while in the control group it was 2.45 mg / L which, although lower, was not statistically significant (P = 0.270).
Leukocytosis is a common reaction of the body to bacterial inflammation (17). The average L value was 5.84 x 109 / L in the test group and 6.01 x 109 / L in the control group, which also showed no statistically significant difference (P = 0.575). Five subjects (7.94%) with OLP and two subjects (3.17%) in the control group had the increased value L (> 9.7 x 109 / L). In our study, we did not prove a statistically significant difference in the values of inflammatory markers (SE, CRP, and L) in the blood between subjects with OLP and the subjects without pathological changes in the oral cavity mucosa.
The importance of the autoimmune reaction in the etiopathogenesis of OLP is based on studies in which changes in T lymphocyte populations in peripheral blood of patients have been noted (20). In this study, 25 subjects (39.68%) with OLP reported a history of another autoimmune disease, whereas in the control group, only four (6.35%) reported a history of another autoimmune disease, which is a statistically significant difference (P <0.001). A study by Cigić et al showed a higher incidence of celiac disease in patients with OLP than in people with healthy oral mucosa and among the ordinary population (21). This fact is confirmed by the results of our study because celiac disease was the second most common autoimmune disease in subjects with OLP.
Every day cigarette smoking and alcohol consumption did not show statistically significant differences between the study groups. Although these habits are not directly related to the development of OLP, changes in similar clinical and histopathological appearance can sometimes be caused by the toxic effect of alcohol and cigarettes on oral mucosa. Barbosa et al. do not link OLP with these habits in their research (20). Most OLP patients were non-smokers (97.3%) and they did not consume alcohol (20), as shown by our study.
Although no statistically significant difference in the mean values of the examined inflammatory markers in blood (SE, CRP, L) between OLP patients and control subjects was found in this study, there was a statistically significantly higher incidence of other autoimmune diseases in patients with OLP- a, the most common of which were cutaneous LP and celiac disease. The statistically significantly higher incidence of other autoimmune diseases in patients with OLP indicates the importance of exclusion of these diseases during the diagnostic process, but also a possible common etiopathogenetic mechanism that needs to be investigated and confirmed by further studies. There was no statistically significant difference between the study groups in daily consumption of cigarettes and alcoholic beverages. This shows that smoking and alcohol are not etiologic factors but factors that contribute to the deterioration of the clinical picture of OLP, therefore, smoking and alcohol consumption habits are not recommended for patients with OLP. Future OLP research should focus on the autoimmune mechanisms of this disease.