Localization of substance P with tumor necrosis factor-alpha in the immunocytes in the experimental gastritis

Background: Icreasing evidence indicates that the substance p (SP) is involved in the immune system, increasing the release of the multifunctional cytokine tumor necrosis factor alpha (TNF-α) and influencing the inflammation of the gastrointestinal tract. The aim was to investigate the immunoneural communication in experimental gastritis. Confocal laser microscope was used to help to assess the functional identity of colocalization of SP and TNF-α in the immunocytes. Methods: iodoacetamide-induced gastritis was used in the rats. Primary antibodies of SP and TNF-α were developed in rabbit. For detecting the colocalization of these antigens in the immunocytes SP labeling with secondary fluorscein (FITS) conjugated donkey anti-rabbit IgG antibody (green), followed by secondary antiserum raised in donkey (Alexa) for TNF-α (red) were used. The data were quantitatively analyzed in terms of the cell counts. Results: In the control gastric mucosa only the SP-containing fibres showed immunoreactivity and only a few immuncytes were positive for TNF-α. In gastritis the number of SP-IR fibres as well as the number of immunoreactive immuncytes (lymphocytes, plasma cells and mast cells) increased significantly (P<0.001). A large number of immuncytes (lymphocytes, mast cells, macrophages) showed immunreactivity also for SP and TNF-α. Confocal laser microscope investigations revealed that dense green reaction end products were distributed throughout the cytoplasm of some immunocytes and the red reaction was absent, where in the other immunocytes the reaction was opposite. The colocalization of SP and TNF-α was also demonstrated in some of them: 23,9%±1,30% immunocytes were immunoreactive for both SP and TNF-α. Conclusions: SP release from the immuncytes together with TNF-α can multiply the development of a gastric inflammation. The increase of TNF-α might probably further maintain the inflammatory processes. The strong inhibition of TNF-α production with SP antagonists could be important in future therapy for inflammatory diseases.