Background Food allergy has been a significant public health issue with growing severity, prevalence and limited treatments. The neutrophil-activating protein A subunit (NapA) of Helicobacter pylori, a Th1-activating immune modulator, has been shown to have therapeutic potential in allergic diseases. Objective We adopted Lactococcus lactis (L. lactis) as mucosal delivery vehicles of NapA and sought to determine the regulatory effect of recombinant bacterium (L. lactis NZ3900/pNZ8149-NapA) on food allergy in mice. Methods The NapA expression efficiency of recombinant bacterium were determined. The effects of recombinant bacterium on food allergy in Balb/c mice were also investigated. Results NapA were delivered and expressed efficiently via L. lactis. The intervention of the engineered bacterium ameliorated food allergy symptoms (acute diarrhea and intestinal inflammation) and decreased serum histamine levels. In addition, the secretion of OVA-specific IgG2a, IFN-γ was promoted and the level of IL-4, OVA-specific IgE was restrained. Conclusions The recombinant strain may attenuate food allergy in mice through immune regulatory effect. Thus, L. lactis NZ3900/pNZ8149-NapA may be a promising approach for preventing or treating food allergy.

IntroductionDengue fever is a vector-borne disease with an estimate of 390 million persons getting the infection each year with a significant public health impact. It has been reported DENV patients with vitamin D deficiency led to severe form of dengue infection; while H. pylori coinfection alters vitamin D receptors leading to vitamin D deficiency. We hypothesize that DENV patient's having low vitamin D along with H. pylori coinfection could have worsen dengue severity as well as vitamin D deficiency. In this case-control study, we compared (I) the vitamin D deficiency in dengue fever cases with or without H. pylori coinfection, and (II) negative dengue fever as a control with or without H. pylori coinfection. We have also assessed the correlation between vitamin D levels and its effect on warning signs of the dengue fever. Further, we have investigated whether coinfection with H. pylori has any effect on warning signs in the dengue fever patients and the vitamin D deficiency in all serotypes of the dengue virus infected patients.MethodsIn this case control study the association of the vitamin D levels with age, gender and H. pylori coinfection in dengue fever hospitalized patients was assessed using chi-square and multivariate logistic regression analysis.ResultsFour hundred dengue fever patients with H. pylori coinfection were compared with 400 dengue negative controls with H. pylori coinfection. The mean age was 29.96 ± 10.5 and 29.88 ± 10.7 years among cases and controls, respectively. Most dengue fever patients with H. pylori coinfection were deficient in vitamin D compared with negative dengue controls with H. pylori coinfection. In multivariate logistic regression, the dengue cases with H. pylori coinfection were.056 times (95% CI: 0.024, 0.128, P = 0.000) more likely to have vitamin D “deficiency', while compared with the cases who did not have H. pylori coinfection.ConclusionThe present study proposes that vitamin D deficiency in dengue fever patients coinfected with H. pylori is much higher than the dengue fever negative controls coinfected with H. pylori. As hypothesized the DENV patient with H. pylori coinfection has vitamin D deficiency as well as increased dengue severity.