The immunohistochemical investigation of TNF-α expressions in macrorhabdus ornithogaster infection in birds

Macrorhabdosis, a significant and contagious disease in birds, causes pathological lesions in the stomach and intestines. Treatment is extremely challenging and often unsuccessful. It leads to substantial losses, especially in psittacine and passerine birds. For this reason, various methods are being explored for its treatment. TNF-α is a cytokine whose expression increases in many diseases, and its inhibition is known to be utilized in the treatment of several conditions. This study aimed to evaluate TNF-α expression immunohistochemically in sections obtained from archived blocks of birds diagnosed with macrorhabdosis and assess whether TNF-α inhibition could be used as a treatment strategy for this disease. For this purpose, paraffin blocks containing gastrointestinal tissues from 25 budgerigars previously diagnosed with macrorhabdosis were used. Four sections were prepared from each block for histopathological examination using hematoxylin-eosin staining, detection of pathogens with Periodic Acid-Schiff (PAS) and Gomori Methanamine Silver staining, and evaluation of TNF-α expression via immunohistochemistry.Histopathological examination revealed erosive and ulcerative lesions, particularly pronounced in the proventriculus region, along with a high density of pathogens. Pathogens were more clearly identified with PAS and Gomori Methanamine Silver staining. Immunohistochemically, TNF-α expression was significantly increased in the lesion areas, notably in epithelial cells and other cell types.The results of this study demonstrated the critical role of TNF-α in the pathogenesis of this disease, which causes significant losses in budgerigars. These findings suggest that TNF-α antagonists or inhibitors could be considered as a potential treatment option for macrorhabdosis. Further comprehensive studies are needed on this topic.