الفهرس 
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Abstract
BD is a chronic, multi-systemic, recurrent condition that affects the vascular, ocular, mucocutaneous, and central nervous systems. The diagnosis of this disease depends on its clinical features which are similar to those observed in several autoimmune diseases. Recurrent mouth sores are generally necessary for a diagnosis of BD and are the ideal benchmark for clinical diagnosis. Moreover, recurring at least two of additional signs as eye inflammation, skin and genital sores confirm the diagnosis of BD. BD is classified as variable vessel vasculitis (VVV) because the vasculitis that can affect any size or type (arteries, veins, and capillaries) of the blood vessel. BD often leads to serious systemic problems, such as blindness, that our study recorded 4 male cases with blindness. Male patients are more likely to be affected at a younger age, and suffer vision loss over time. Various genetic and environmental factors are involved in the initiation and development of this disease, but the most robustly associated risk factor is the HLA-B51 allele.
Autophagy (autophagocytosis) is a natural, intracellular regulated mechanism characterized by the removal of aggregated proteins, infectious organisms, and damaged organelles via lysosomes, and hence plays a multitude of physiological and pathological functions. Autophagy dysfunction can contribute to the pathogenesis of several autoimmune diseases. Autophagy is carried out by autophagy-related
genes (ATG). Numerous genes, such as the immune-related GTPase family M protein (IRGM), ATG2A, ATG5, ATG7, ATG12, ATG16 like 1 (ATG16L1), leucine-rich repeat kinase 2), death-associated protein [18], mechanistic target of rapamycin (mTOR), regulatory associated protein of mTOR (RAPTOR), rapamycin insensitive companion of mTOR (RICTOR), and microtubule-associated protein light chain 3b (LC3b), have been examined in BD.
The present study was conducted to screen a panel of differentially expressed autophagy-related genes (ATG5, ATG7, ATG12, LC3b, mTOR) that have been postulated to play a role in the immunopathology and pathogenesis of BD. Additionally, correlations between the clinical heterogeneity and prognosis of the disease and the selected specific autophagy markers were determined. This work was conducted on a total of 101 subjects aged ((10–65) years; 71 patients and 30 control subjects.
qPCR technique was used to investigate the levels of mRNA expression of ATG5, ATG7, ATG12, LC3b and mTOR genes. Results revealed that the expression levels of ATG5 and mTOR were significantly decreased (p = 0.004 and 0.01, respectively), whereas that of LC3b was significantly upregulated (p < 0.001) in the BD patients when compared to those in the control subjects. No significant differences in the expression levels of ATG7 and ATG12 were observed between the two groups (p = 0.24 and 0.41; respectively).
The Association between the expression levels of the autophagy-related genes and the clinical parameters of patients with BD revealed that the mRNA expression level of ATG5 was significantly associated with patient age (mean = 35.3; p = 0.001) and the incidence of an oral ulcer (90.1%; p = 0.01). Likewise, the expression level of ATG7 was significantly associated with patient age (p = 0.001) and the presence of erythema nodosum (8.4%; p = 0.02) and vascular lesions (25.3%; p = 0.04). LC3b expression was significantly associated with the presence of pustules (25.4%; p = 0.03).
Furthermore, the ROC curve and cutoff values for the selected autophagy markers were calculated to identify the predictive diagnostic marker for BD. ATG5 and mTOR expression were accepted in their accuracy and having AUC of 68% (p = 0.004) and 66% (p = 0.01), respectively. In addition, the ATG5 expression cutoff point of <0.0034 showed (sensitivity 39% and specificity 90%). Moreover, the mTOR expression cutoff point of <0.0081 showed (sensitivity 54% and specificity 90%).
For LC3b expression, it showed accuracy with AUC = 88% (p < 0.001). The LC3b expression cutoff point of > 0.024 was the best threshold to diagnose BD. LC3b has sensitivity and specificity of 80%.
In conclusion, LC3b expression was strongly associated with BD. The expression of this gene was correlated with the presence of pustules; whereas low levels of ATG5 were associated with the presence of oral ulcers in patients with BD. The mRNA expression of ATG7 was significantly associated with age and the presence of erythema nodosum and vascular lesions. LC3b expression might prove as an accurate and reliable marker for diagnosis, early detection, and prevention of this pathological state and its unfavorable consequences especially the blindness. Hence, this study introduces LC3b to be added to the list of laboratory to help diagnosis of BD in addition to the clinical manifestations.
Recommendations
The quest for biomarkers in BD has been a long, daunting journey. National and international collaborative efforts are required to assemble enough powered sample sizes to conduct molecular and/or genetic studies in the search for diagnosis of BD.