Immunohistochemical Evaluation of TNF-α, IL-1, IL-12, IL-17, IL-23 Expression and Investigation of the Effect of Demodex in Patients with Discoid Lupus Erythematosus

Objective: Discoid lupus erythematosus (DLE) is a chronic inflammatory skin disease that can be triggered by several factors although its etiology is not yet known. Hypotheses have been reported that the demodex mites may be involved in the etiopathogenesis of DLE. In this study, we aimed to investigate the potential relationship between the frequency of immunohistochemical staining of tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-12, IL-17 and IL-23 cytokines obtained from cutaneous biopsy of DLE patients and disease severity.
Materials and Methods: Biopsy tissues of patients who were previously diagnosed with DLE in the dermatology outpatient clinic, which were also supported histopathologically, were re-sectioned and subjected to immunohistochemical examination for TNF-α, IL-1, IL-12, IL-17 and IL-23, and their staining scores were obtained. These immunohistochemical staining scores were compared with disease severity. The presence and density of demodex were evaluated in standard skin surface biopsy taken from the lesions at the time of diagnosis.
Results: In the comparison of immunohistochemical staining scores with DLE-skin score (DLE-SS), a statistically significant positive correlation was found between DLE-SS and TNF-α (p=0.003), DLE-SS and IL-17 (p=0.002). There was no difference between the presence or absence of demodex and DLE-SS (p=0.9). There was no correlation between demodex density and disease severity in demodex-positive cases (p=0.34).
Conclusion: In line with the data obtained from our study, TNF-α and IL-17 seem to be more associated with the disease severity in DLE. The fact that demodex positivity/negativity and demodex density are independent of disease severity supports that demodex mite is an etiopathogenetic factor rather than overlap in DLE cases. Further studies on this subject are needed.