Canine coronavirus (CCoV) is an enteric pathogen, currently included in the Alphacornavirus-1 species which causes mild to severe diarrhea in puppies, whereas infection is fatal if there is secondary infection by other pathogens. In pathogenesis, this infection will cause severe and prolonged lymphopenia due to a decrease in CD4 cells and lead to death in puppies.
Probiotics are beneficial live microorganisms that provide benefits to the body. Lactobacillus species are probiotics that have been studied, with physiological and immunological effects such as regulation of T (NK) cell activity, preventing influenza virus infection in experimental animals and increasing levels of interferon-γ (IFN-γ). L. acidophilus can upregulate anti-viral genes through the Toll-like receptor pathway, is able to resist bile acids, improve the physiological environment of the intestine and prevent obesity. Probiotics as dietary supplements containing live microbial have beneficial effects on host animals by increasing the balance of microflora in the digestive tract. The bacterial groups in question are L. acidophilus, B. bifidum, B. pseudolongum, and S. faecalis. These bacteria are lactic acid bacteria that have the ability to produce lactase to digest lactose and also stimulate proteolytic and cellulolytic enzymes so that the final result is an increase in nutrient uptake.
An experimental study shows that probiotics can be used to control microorganisms that contaminate food, selectively microorganisms in probiotics can reduce idiopathic diarrhea in turkeys, and also reduce salmonella colonies in turkeys and broilers. Lactic acid microbes are a group of bacteria that do not form spores and are gram-positive, producing lactic acid as the end product, which is generally good nonpathogenic bacteria. These lactic acid bacteria are known as Probiotics. Organisms that are classified as lactic acid bacteria are Lactobacillus, Pediococcus, Bifidobacterium, and Streptococcus. The most widely used probiotics belong to the Lactobacillus group such as L. casei, L. acidophilus, L. rhamnosus, and the Bifidobacterium group such as B. bifidum, B. longum, and B. breve. This study aimed to determine the administration of probiotics on duodenal TNF-α expression, and histological findings of the liver and lung in mice infected with CCoV.
In this study, TNF-α expression was revealed by the presence of brown on duodenal IHC stain. Streptokinase forms an antigen complex that is recognized by antibodies and then attaches to the duodenal cylindrical epithelium so that the antigen becomes an indicator of the inflammatory process. Furthermore, it is recognized by the Presenting Cell (APC) antigen in the form of macrophages so that the antigen is phagocytes into small pieces which will bind to MHC (Major Histocompatibility Complex). The antigen is carried to the surface of the cytoplasm which then binds to the duodenal cylindrical epithelial cells to produce TNF-α. The percentage above shows an increase in TNF-α expression due to the induction of streptokinase which activates macrophages to produce cytokines that stimulate inflammation in duodenal epithelial cells. Secretion of cytokines causes the aggregation and activation of neutrophils as well as the release of proteolytic enzymes in cell damage. Cytokines activate fibroblast tissue in the duodenal epithelium and increase the proliferation of the extracellular matrix.
TNF-α mediates a variety of biological responses including inflammation, infection, injury, and cell apoptosis. The effect of TNF-α is initiated by cytokine binding to the receptor, which causes activation of a major transcription factor including nuclear factor kappa B (NF -κB). Such activation then induces genes involved in the inflammatory response. In addition, TNF-α can also trigger apoptosis by binding to death receptors. TNF bonds with death receptors with apoptotic effects through caspase 8 or 10 activations.
The formation of this DISC (Death Inducing Signaling Complex) results in the activation of caspase-8 or -10, which then activates caspase-3 as the executor. Cytokine-activated cells may produce and secrete the same cytokines as paracrine signaling or enhance and stabilize signals in secreting cells via autocrine regulation. The autocrine or paracrine mechanism of TNF-α production involves several proteins, including NF-κB, IκBα, and A20 inhibitors, IKK and IKKK kinase signaling carriers, TNF-α cytokines, and TNFR1 receptors. TNF-α activates the NF-κB pathway in duodenal epithelial cells. In addition to being produced by active macrophages, TNF-α is also produced by epithelial cells during degeneration. In this case, TNF-α can also be autocrine produced by target cells. Increasing the production of TNF-α by an autocrine mechanism can exacerbate the effect of TNF-α.
The results of the liver histology findings showed that there were changes, both degeneration, and necrosis, as well as signs of toxicity or infection. There is hyperemia, and an indication of the presence of inflammatory cells in the form of leukocytosis is seen as if the mice were infected with infectious agents or induced by chemicals. This is due to the role of probiotics which do not interfere with the work of the liver so that it does not cause changes in its histological structure. Probiotics are beneficial living microorganisms that are taken orally into the animal’s body. It is hoped that living microbes can have a positive effect on health by improving the properties of natural microbes that live in the animal’s body so that it can restore the balance of the ratio between pathogenic and non-pathogenic bacteria in the digestive tract.
Author: Dr. Iwan Sahrial Hamid, drh., M.Si.
Source: Hamid, I. S., Ekowati, J., Solfaine, R., Chhetri, S., & Purnama, M. T. E. (2022). Efficacy of Probiotic on Duodenal TNF-α Expression and the Histological Findings in the Liver and Lung in Animal Model Canine Coronavirus. Pharmacognosy Journal, 14(3).
