Evaluation of acute-phase proteins and inflammatory mediators changes in native chickens experimentally infected with Salmonella typhimurium

Harnessing probiotics capability to combat Salmonella Heidelberg and improve intestinal health in broilers

The poultry industry faces significant challenges in controlling Salmonella contamination while reducing antibiotic use, particularly with the emergence of Salmonella Heidelberg (SH) strains posing risks to food safety and public health. Probiotics, notably lactic acid bacteria (LAB) and Saccharomyces boulardii (SB) offer promising alternatives for mitigating Salmonella colonization in broilers. Understanding the efficacy of probiotics in combating SH and their impact on gut health and metabolism is crucial for improving poultry production practices and ensuring food safety standards. This study aimed to assess the inhibitory effects of LAB and SB against SH both in vitro and in vivo broilers, while also investigating their impact on fecal metabolites and caecal microbiome composition. In vitro analysis demonstrated strong inhibition of SH by certain probiotic strains, such as Lactiplantibacillus plantarum (LP) and Lacticaseibacillus acidophilus (LA), while others like SB and Lactobacillus delbrueckii (LD) did not exhibit significant inhibition. In vivo testing revealed that broilers receiving probiotics had significantly lower SH concentrations in cecal content compared to the positive control (PC) at all ages, indicating a protective effect of probiotics against SH colonization. Metagenomic analysis of cecal-content microbiota identified predominant bacterial families and genera, highlighting changes in microbiota composition with age and probiotic supplementation. Additionally, fecal metabolomics profiling showed alterations in metabolite concentrations, suggesting reduced oxidative stress, intestinal inflammation, and improved gut health in probiotic-supplemented birds. These findings underscore the potential of probiotics to mitigate SH colonization and improve broiler health while reducing reliance on antibiotics.

Intestinal Colonization of Campylobacter jejuni and Its Hepatic Dissemination Are Associated with Local and Systemic Immune Responses in Broiler Chickens

Campylobacter jejuni is an important foodborne pathogen. Despite the lack of clinical signs associated with its colonization in poultry, it has been reported to interact with the intestinal immune system. However, little is known about the interaction between C. jejuni and the chicken immune system, especially in the context of hepatic dissemination. Therefore, to follow up on our previous study showing intestinal colonization and hepatic spread of C. jejuni, cecal tonsils and liver samples were collected from these birds to determine the mRNA levels of chemokines and cytokines. Serum samples were also collected to determine serum amyloid A (SAA) concentrations and specific IgY titers. Lack of Th17 induction was observed in the cecal tonsils of only the liver-contaminated groups. This hepatic dissemination was accompanied by innate, Th1 and Th2 immune responses in livers, as well as an increase in SAA concentrations and specific IgY levels in sera. Campylobacter appears to be able to restrain the induction of the chicken gut immunity in particular conditions, possibly enhancing its hepatic dissemination and thus eliciting systemic immune responses. Although Campylobacter is often recognized as a commensal-like bacterium in chickens, it seems to modulate the gut immune system and induce systemic immunity.

Comparative Effects of Dexamethasone and Meloxicam on Magnitude of the Acute Inflammatory Response Induced by Escherichia coli Lipopolysaccharide in Broiler Chickens

Purpose

Dexamethasone has been widely used to treat acute inflammatory diseases and endotoxic shocks in animal models. Meloxicam is one of the most commonly used anti-inflammatory agents in avian species. However, little is known about the effects of dexamethasone and meloxicam on lipopolysaccharide (LPS)-induced acute inflammatory response in birds. In the present study, LPS-challenged broiler chickens were used to investigate the comparative protective effects of meloxicam and dexamethasone on LPS-induced acute inflammatory responses.

Methods

Lipopolysaccharide (LPS)-induced acute lung injury (ALI) histopathological scores, selected serum acute phase reactants, inflammatory mediators, and gangliosides were evaluated in broiler chickens inoculated with E. coli LPS and simultaneously treated with two doses of meloxicam (0.5 and 2 mg/kg BW) and dexamethasone (2 and 4 mg/kg BW).

Results

LPS-induced ALI scores were not significantly different between the meloxicam-treated, dexamethasone-treated, and untreated positive control groups at 4 hours after LPS inoculation. Interleukin-6 concentrations were also statistically the same among the positive control, dexamethasone-treated, and meloxicam-treated groups at 3 and 12 hours after LPS inoculation. However, these anti-inflammatory drugs reduced adenosine deaminase, ceruloplasmin, lipid-bound sialic acid, protein-bound sialic acid, and total sialic acid in LPS-inoculated broiler chickens at 12, 24, and 48 hours after LPS inoculation in a drug- and dose-dependent manner. Ovotransferrin concentrations were not significantly different between positive control and treatment groups at 12 hours after LPS inoculation. However, twenty-four hours after LPS inoculation, all the treated groups, except the one treated with 0.5 mg/kg meloxicam, showed significantly lower concentrations of ovotransferrin as compared with the positive control group.

Conclusion

Our results showed that dexamethasone was more effective than meloxicam in inhibiting the LPS-induced response in broiler chickens by diminishing the serum levels of adenosine deaminase, ceruloplasmin, and gangliosides.

Serum amyloid A (SAA) mRNA expression in chicken and quails in response to bacterial stress

Monitoring of acute phase proteins such as serum amyloid A at gene expression level may provide quick information about immune status of the host and its susceptibility towards common infections. Present study was carried out to evaluate and compare the mRNA expression of SAA gene in Rhode Island Red chicken (RIR) and Japanese quails using real time PCR analysis in response to inactivated Salmonella gallinarum culture. The results showed that expression of SAA gene was approximately 17-33 folds higher in case of birds administered with bacterial culture when compared to un-inoculated controls and expression was higher and quicker in case of quails than RIR chicken. The SAA genes from chicken and quail were cloned and upon sequence analysis it was observed that deduced amino acid sequence of SAA from chicken and quails were having approximately seven percent variation which might have significance in function of this protein in these species.