In vivo upregulation of innate and adaptive immune mechanisms in guinea pigs inoculated with Helicobacter pylori in response to Mycobacterium bovis BCG delivered by chitosan microparticles (dataset)

Abstract

In this study, we used the model of Cavia porcellus (guinea pig) experimentally infected with H. pylori to determine whether per os inoculation of animals with chitosan microparticles containing live M. bovis BCG, which are released in the stomach or in the intestine, or simultaneously in both localizations, can result in upregulation of innate and adaptive immune response towards H. pylori. This experimental model of H. pylori infection in guinea pigs was developed by us previously. After H. pylori inoculation, the gastric tissue of infected animals initiates an inflammatory response similar to that observed in humans infected with these bacteria. This model enabled us to investigate the effects of H. pylori-induced inflammatory and immune responses, as well as the induction of regeneration processes in gastric tissue in response to this infection. This study assessed the role of M. bovis BCG administered per os in chitosan microparticles (MPs) in guinea pigs in upregulating innate and adaptive immune mechanisms to neutralise H. pylori infection and related inflammatory responses. In this study animals were inoculated per os with H. pylori alone, chitosan microparticles (MPs) loaded with M. bovis-BCG modified with Gal-NAc (MPs CHI-GalNAc-BCG) to enhance the adhesion of MPs to gastric mucin, chitosan microparticles loaded with M. bovis-BCG modified with Pluronic F127 (MPs CHI-Plu-BCG) facilitating the release of the cargo in the gut, MPs CHI-GalNAc-BCG and MPs CHI-Plu-BCG together, or first with MPs CHI-Plu-BCG alone, or MPs CHI-GalNAc-BCG and MPs CHI-Plu-BCG together followed by inoculation with H. pylori. Concerning the low responsiveness of macrophages, which is caused by H. pylori components, and the role of M. bovis BCG in immune training of innate immune cells, we examined the macrophage infiltration in the gastric tissue of the studied animals. We assessed the phenotype of bone marrow cells based on selected surface markers of myeloid precursors (CD34/CD117/Ly6G), and the secretion of pro-inflammatory (TNF-α, IL-8) and anti-inflammatory/regulatory (IL-10) cytokines by bone marrow-derived macrophages (BMDM). Using BMDM, we assessed whether inoculating animals with different variants of MPs loaded with M. bovis BCG enhances the phagocytic capacity of BMDM and whether this is accompanied by increased expression of CD11d integrin, which drives macrophage migration and extravasation and is involved in phagocytosis. Considering the concept of immune training of macrophages driven by M. bovis BCG, histone 3 lysine 4 methylation was assessed in BMDM in the study. As innate and adaptive immune responses cooperate, we determined the production of secretory (sIgA) antibodies in the gastric tissue of studied animals and the number of lymphatic follicles with exposed germinal centers (GC) in the spleen, in association with the assessment of proliferation of spleen lymphocytes in vitro in response to H. pylori antigens or M. bovis BCG in contrast to spontaneous reaction of spleen lymphocytes.