Rotavirus, an important agent of gastroenteritis in children, causes diarrhea by infecting differentiated villus enterocytes in the small intestine. The aim of this study was to determine whether cytokines that can be expressed by mucosal cells have an effect on the rotavirus susceptibility of cultured human enterocytes.
Caco-2 and HT-29 cells were pretreated with various cytokines before challenge with rotavirus.
Interleukin (IL)-1, interferon (IFN)-alpha, and IFN-gamma pretreatment led to a dose-dependent resistance to rotavirus infection. Maximum effects occurred after 72 hours of pretreatment, whereas no detectable inhibition occurred with <12 hours of pretreatment. Liposomal transfection of single-shelled and double-shelled rotavirus particles bypassed the block to rotavirus replication in IFN-gamma- and IL-1-treated but not IFN-alpha-treated cells. Binding studies with purified, metabolically labeled rotavirus showed no significant difference among IFN-gamma- and IFN-alpha-treated and control Caco-2 cells. Viral entry into Caco-2 cells was significantly inhibited by IFN-gamma and IL-1 but not IFN-alpha.
IFN-alpha and IFN-gamma induce rotavirus resistance by different mechanisms, suggesting that cytokines play a role in host defense against viral agents by changing the phenotype of intestinal epithelial cells.
"Considering CD172a+CD11R1high and CD172a−CD11R1low cells as DCs , and as such with the ability to favour Th1, Th2, Th17 or Treg immune responses, the increases in both IFN-γ and IL-12 induced especially by Lr1505, may lead to a Th1 response if we extrapolate this data to an in vivo situation. Furthermore, IFN-γ and IL-1β have been shown to have a direct effect on IECs inducing an antiviral program, which inhibits rotavirus entry [41,42]. "
[Show abstract][Hide abstract] ABSTRACT: Background
Previous findings suggested that Lactobacillus rhamnosus CRL1505 is able to increase resistance of children to intestinal viral infections. However, the intestinal cells, cytokines and receptors involved in the immunoregulatory effect of this probiotic strain have not been fully characterized.
We aimed to gain insight into the mechanisms involved in the immunomodulatory effect of the CRL1505 strain and therefore evaluated in vitro the crosstalk between L. rhamnosus CRL1505, porcine intestinal epithelial cells (IECs) and antigen presenting cells (APCs) from swine Peyer’s patches in order to deepen our knowledge about the mechanisms, through which this strain may help preventing viral diarrhoea episodes. L. rhamnosus CRL1505 was able to induce IFN–α and –β in IECs and improve the production of type I IFNs in response to poly(I:C) challenge independently of Toll-like receptor (TLR)-2 or TLR9 signalling. In addition, the CRL1505 strain induced mRNA expression of IL-6 and TNF-α via TLR2 in IECs. Furthermore, the strain significantly increased surface molecules expression and cytokine production in intestinal APCs. The improved Th1 response induced by L. rhamnosus CRL1505 was triggered by TLR2 signalling and included augmented expression of MHC-II and co-stimulatory molecules and expression of IL-1β, IL-6, and IFN-γ in APCs. IL-10 was also significantly up-regulated by CRL1505 in APCs.
It was recently reviewed the emergence of TLR agonists as new ways to transform antiviral treatments by introducing panviral therapeutics with less adverse effects than IFN therapies. The use of L. rhamnosus CRL1505 as modulator of innate immunity and inductor of antiviral type I IFNs, IFN-γ, and regulatory IL-10 clearly offers the potential to overcome this challenge.
"Type I IFNs also inhibit the growth of RVs in cell culture, although RV is not as sensitive to IFN as vesicular stomatitis virus (VSV) [67,68]. The human intestinal epithelial cell lines HT29 and Caco-2 cells are resistant to RV infection when pretreated with IFN-α . HT29 cells do not express IFN-β mRNA following RV infection with the simian strain RRV, though evidence of NF-κB and NF-κB-dependent chemokine expression is apparent [70–72]. "
[Show abstract][Hide abstract] ABSTRACT: Rotavirus is a primary cause of severe dehydrating gastroenteritis in infants and young children. The virus is sensitive to the antiviral effects triggered by the interferon (IFN)-signaling pathway, an important component of the host cell innate immune response. To counteract these effects, rotavirus encodes a nonstructural protein (NSP1) that induces the degradation of proteins involved in regulating IFN expression, such as members of the IFN regulatory factor (IRF) family. In some instances, NSP1 also subverts IFN expression by causing the degradation of a component of the E3 ubiquitin ligase complex responsible for activating NF-κB. By antagonizing multiple components of the IFN-induction pathway, NSP1 aids viral spread and contributes to rotavirus pathogenesis.
[Show abstract][Hide abstract] ABSTRACT: Abstract: Rotavirus is the major cause of severe dehydrating diarrhea in children, mortality rates reach 600,000 annually and vaccination is an important preventive measure. For the first objective, gnotobiotic pigs were vaccinated priming with a peroral (PO) live attenuated human rotavirus (AttHRV) and boosting (2x) with non-replicating 2/6 virus-like particles (VLPs) intranasally (IN) using ISCOM as adjuvant. High protection rates against diarrhea and shedding (71%) were induced which coincided with higher IgA antibody titers in small intestinal contents and serum virus neutralizing (VN) antibody responses. Vaccination with 2/6VLP alone conferred no protection suggesting that neutralizing antigens, VP4 and VP7 were needed as part of a non-replicating vaccine formulation to induce protective immune responses in neonatal pigs. The second objective was to test a non-replicating vaccine that included RV neutralizing antigens. A combination of semipurified VP4 and 2/6/7VLP PO followed by VP4+2/6VLP IN using ISCOM as adjuvant was tested. A 67% protection rate against diarrhea and 33% protection rate against shedding were elicited with moderate numbers of intestinal IgA antibody secreting cells but low VN antibody titers in serum. This study confirmed that RV neutralizing antigens are needed for a non-replicating HRV vaccine formulation to induce protective immune responses in neonatal pigs. For the third objective, dendritic cells (DCs) ex-vivo and the association with clinical outcome were examined in gnotobiotic pigs after a high or low dose of HRV. We assessed intestinal and splenic cytokine producing DCs, their uptake/binding of fluorescent 2/4/6/7VLPs and membrane bound TGFbeta1-latency associated peptide (LAP) CD4+ regulatory T cells known to be induced by pDCs using flow cytometry. At post-inoculation day (PID) 2, only the high dose pigs developed diarrhea and induced significantly lower frequencies of intestinal IFNalpha+ pDCs, lower uptake/binding of 2/4/6/7VLP-GFP by intestinal and splenic pDCs and lower frequencies of regulatory T cells compared to a lower dose. Titers of infectious virus shed were similar. Cell-damage byproducts are known to inhibit pDCs. Higher early rates of diarrhea, possibly associated with enterocyte damage byproducts may decrease pDC function thereby preventing induction of regulatory T cells and facilitating adaptive immune responses to HRV. 1.97 MB Title from first page of PDF file. Thesis (Ph. D.)--Ohio State University, 2007. Includes bibliographical references (p. 326-400). Available online via OhioLINK's ETD Center System requirements: World Wide Web browser and PDF viewer.
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