No abstract

Summary Lipid microencapsulation of Mycobacterium bovis bacille Calmette-Guérin (BCG) produces an oral delivery vaccine that can establish systemic cell-mediated immune reactivity and protection against aerosol mycobacterial challenge in mice. Here, we describe the lymphatic and mucosal sites of bacterial replication, and location of Mycobacterium -specific IFN-γ -secreting cell populations, following oral vaccination of BALB/c mice. Eight weeks following a single oral dose of lipid-encapsulated BCG, viable BCG organisms were recovered from the mesenteric lymph nodes (MLN) of 11/12 mice investigated (93%). Live bacteria were also occasionally recovered from the cervical lymph nodes (17%) and Peyer's patches (8%), but not from homogenates of the lungs or spleen. Strong Mycobacterium -specific IFN-γ production was recorded among isolated splenocytes, but not among populations of mononuclear cells derived from the MLN or lungs. Oral vaccination of mice with lipid-encapsulated BCG thus appears to promote a state of systemic immunological reactivity more akin to that observed following parenteral rather than conventional oral vaccination, despite the fact that replicating bacilli are restricted to lymphatic tissues of the alimentary tract. Possible patterns of lymphocyte sensitization and trafficking are discussed.

Necrotizing enterocolitis (NEC) is an important disease of low birth-weight neonates. The immaturity of the gut mucosa may result in close contact between the host epithelium and microorganisms which are normally confined to the gut lumen. Damage of the mucosa due to endotoxin, cytokine production or other factors is believed to then occur. The aim of this study was to determine whether spray-dried bovine colostrum demonstrated potential in vitro as a prophylactic for NEC. Antiadherence was measured using a tissue culture assay and antibody levels against Enterobacteriaceae were determined by ELISA. The effect of bovine colostrum on the production of cytokines implicated in NEC was determined by a multiplex bead assay. Enterobacter cloacae, Klebsiella oxytoca, Escherichia coli, Serratia marcescens and Klebsiella pneumoniae ssp. pneumoniae were common in both NEC positive and NEC negative infants and IgA and IgG1 antibodies to these species were present in the bovine colostrum. Pretreatment with bovine colostrum produced a significant decrease (P<0.001) in attachment of bacteria to HT-29 cells. Bovine colostrum significantly increased the production of IL-8 in HT-29 cells and IL-8, IL-6 and TNF-alpha in THP-1 cells (P<0.001). The potential of bovine colostrum to increase the production of inflammatory mediators could limit its usefulness.

In this paper, we report the in vitro biocompatibility and cellular interactions of a chitosan/dextran-based (CD) hydrogel and its components as determined by mutagenicity, cytotoxicity, cytokine/chemokine response, and wound healing assays. The CD hydrogel, developed for postsurgical adhesion prevention in ear, nose, and throat surgeries, was shown by previously published experiments in animal and human trials to be effective. The hydrogel was synthesized from the reaction between succinyl chitosan (SC) and oxidized dextran (DA). Cytotoxicity was assessed in an xCELLigence system and cytokine/chemokine responses were measured by ELISA in human macrophage, nasopharyngeal epithelial, and dermal fibroblast cells. A wound healing model utilized nasopharyngeal epithelial cells. CD hydrogel and DA were nonmutagenic in the Ames test. CD hydrogel showed moderate cytotoxicity for the cell lines, DA being the cytotoxic component. Some inhibition of wound healing occurred due to the cytotoxic nature of DA. Cells cultured with CD hydrogel showed no increase in TNF-α, IL-10, and IL-8 levels. It is hypothesized that the cytotoxicity of DA is moderated when reacted with SC and that CD hydrogel inhibits unwanted fibroblastic invasion preventing scarring and adhesions. Together with the previously published human and animal trial data, the results indicate CD hydrogel is biocompatible in the setting of endoscopic sinus surgery. This work represents the first study of CD hydrogel with human cell lines and provides essential information for its future application in biomedicine.

Mice that consumed a single dose of 10 7 lipid-encapsulated Mycobacterium bovis BCG bacilli showed significant pulmonary and systemic protection against aerosol challenge with M. tuberculosis H37Rv. As an extension of previous challenge studies with virulent strains of M. bovis, this report describes a reduction in M. tuberculosis infection in mice vaccinated orally with lipid-encapculated BCG comparable to that observed in mice vaccinated subcutaneously with BCG. These results are consistent with the induction of tuberculinspecific cell-mediated immune responses.