In vitro and in vivo effects of palm kernel cake oligosaccharides on Salmonella enterica serovar enteritidis infection
Non-digestible oligosaccharides (NDOs) have been reported to possess prebiotic and immunomodulatory properties. With the European Union (EU) wide ban on the use of antibiotic growth promoters (AGP) in the livestock industry, the search for AGP alternatives to maintain livestock productivity is...
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/98814/1/IPTSM%202021%2010%20UPMIR.pdf http://psasir.upm.edu.my/id/eprint/98814/ |
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| Summary: | Non-digestible oligosaccharides (NDOs) have been reported to possess
prebiotic and immunomodulatory properties. With the European Union (EU) wide
ban on the use of antibiotic growth promoters (AGP) in the livestock industry, the
search for AGP alternatives to maintain livestock productivity is highly sought
after. Previous studies have shown that NDOs from palm kernel cake (PKC), a
by-product of the palm oil industry were able to confer a protective effect against
Salmonella colonization in young chickens. Being young vertebrae with an
immature immune system, they would have to rely on the strength of their innate
immune responses to prevent Salmonella infection. Therefore the objective of
this study was to investigate the ability of NDOs from PKC to affect the innate
immune response in a Salmonella enterica serovar (ser.) Enteritidis (S.
Enteritidis) infection model utilizing in vitro and in vivo approaches. The in vitro
approach consisted of an anti-adherence assay using Caco-2 cells, a Salmonella
killing assay using U-937 macrophages and a lactate dehydrogenase (LDH)
assay to monitor cellular damage. The in vivo approached utilized zebrafish
larvae to observe the effects of NDOs from PKC on lipopolysaccharide (LPS)
induced nitric oxide (NO) levels, S. Enteritidis colonization patterns and its effect
on zebrafish’s gene expression. The results of the in vitro study revealed that the
NDOs fraction from PKC with a lower degree of polymerization (DP), termed
‘Small’ (DP ≤ 6), was better than the NDOs fraction from PKC with a larger DP,
termed ‘Big’ (DP > 6), at significantly (p ≤ 0.05) reducing S. Enteritidis adherence
to Caco-2 epithelial cells. Both Small and Big fractions were comparable to one
another at increasing the rate of Salmonella killing in U-937 macrophages. In
terms of reducing cellular damage, both the Small and Big were capable of
significantly reducing cellular damage in Caco-2 cells although the Small fraction
showed a stronger correlation between decreasing S. Enteritidis numbers and
cellular damage in U-937 macrophages than the Big fraction. When compared
to commercial NDOs fructooligosaccharide (FOS) and mannanoligosaccharide
(MOS), both the Small and Big fraction were found to be comparable, if not better than MOS and FOS at reducing S. Enteritidis adherence, increasing S. Enteritidis
elimination and reducing cellular damage in vitro. As the Small fraction was
better than Big, it was chosen for subsequent in vivo studies and renamed
‘OligoPKC’. The results of the in vivo study showed that OligoPKC was
comparable to the commercial NDOs at reducing LPS induced NO levels in
zebrafishes but showed a significant increase in S. Enteritidis colonization within
the gastrointestinal tract at 24 hours postinfection when compared to the infected
control. This might stem from a weaker upregulation of myeloperoxidase (MPX)
expression when compared to other infected groups. In conclusion, NDOs from
PKC were able to affect the innate immune response in a S. Enteritidis infection
model in vitro and in vivo but care should be taken when selecting the
appropriate animal infection model and interpreting its results. |
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