Hso-Chi Chaung

Phenotypic and functional modulation of bone marrow-derived dendritic cells by porcine reproductive and respiratory syndrome virus

It is well documented that there is a delay in the development of effective immunity to porcine reproductive and respiratory syndrome virus (PRRSV) in infected and vaccinated pigs. This suggests that PRRSV might possess some inherent properties to evade host defense mechanisms during the early stage of infection. Dendritic cells (DCs) play a crucial role in the activation and control of T-cells in response to viral antigens. In this study, we investigated the phenotypic and functional property changes of bone marrow-derived immature DCs (BM-imDCs) that take place after infection by PRRSV. Results showed that BM-imDCs were permissive to PRRSV infection, as productive replication took place in these cells. A down-regulated expression of MHC I molecules along with an up-regulated expression of CD80/86 is observed at 48 h following infection. Also at 48h following PRRSV infection, a significant increase of IL-10 secretion by BM-imDCs was noticed. Results suggest that the inhibited expression of MHC I and the enhanced secretion of IL-10 by BM-imDCs after PRRSV infection might be among the strategies used by the virus to evade the host immune defenses.

Docosahexaenoic acid and phosphatidylserine supplementations improve antioxidant activities and cognitive functions of the developing brain on pentylenetetrazol-induced seizure model

Epilepsy provoked by pentylenetetrazol (PTZ) is caused by an abnormal excitatory postsynaptic potential, which results in increased production of reactive oxygen species, and finally reducing cognitive functions. The objective of this study was to investigate the effects of dietary supplementation with DHA and PS, administered either alone or in combination, on oxidative stress and behavioral and cognitive spatial memory in neonatal rats with PTZ-induced epileptic seizure. In this study, rat pups received repetitive doses of PTZ for induction of epileptic seizure and docosahexaenoic acid (DHA, C22:6, n-3) and phosphatidylserine (PS) were orally administrated alone or together to the PTZ-induced epileptic animals daily for 36 d. The spatial memory, nitric mono-oxide (NO) production, and enzymatic activities of superoxide dismutase (SOD) and catalase in brain and liver tissues were determined. PTZ administration significantly reduced the cell numbers in the hippocampus, shortened the escape latency in the safe target region, decreased activities of SOD and catalase, but increased NO content in both brain and liver tissues, while DHA and PS significantly extended the escape latency, reversed the oxidative parameters observed in the brain, and enhanced SOD activity in the liver. Dietary supplementation with DHA and PS may protect brain tissue from the oxidative stress caused by epileptic seizures and could serve to improve learning and memory ability in vivo.

Expression of Toll-like receptor mRNA and cytokines in pigs infected with porcine reproductive and respiratory syndrome virus

Field observations have suggested that porcine reproductive and respiratory syndrome virus (PRRSV) predispose pigs to secondary infections. The interaction between PRRSV and the secondary invaders has not yet been well elucidated. In this study, we investigated the mRNA expression of Toll-like receptors (TLR) in lymphoid organs and cells, and cytokine secretions by alveolar macrophages (AMs) and peripheral blood mononuclear cells (PBMCs) in response to pathogen-associated molecular patterns (PAMPs) in PRRSV-challenged pigs. TLR mRNA expressions were measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and cytokine concentrations were determined using commercially available ELISA kits. PRRSV infection led to significantly increased secretions of IL-1beta and IL-6 by AMs of PRRSV-infected pigs. Infection of pigs with PRRSV also resulted in an increased secretion of IL-1beta by AMs in response to lipoteichoic acid (LTA) stimulation, and IL-6 by PBMCs in response to lipopolysaccharide (LPS) and LTA stimulation. Infection of pigs with PRRSV tended to up-regulate the mRNA expression of TLR2, 3, 4, 7 and 8 in at least one of the lymphoid tissues and cells. Further research is required to demonstrate the association between the enhanced expressions of the specific TLRs and the increased susceptibility to secondary agents with more severe clinical outcomes in PRRSV-infected pigs.

Toll-like receptor expressions in porcine alveolar macrophages and dendritic cells in responding to poly IC stimulation and porcine reproductive and respiratory syndrome virus (PRRSV) infection

Antigen-presenting cells play critical roles in recognizing, presenting and processing antigens and consequently induce adequate immune response for defending infections. The immature DCs (imDCs) and mature DCs (mDCs) were obtained from in vitro differentiation of bone marrow haematopoietic cells. Results showed that poly IC stimulation down-regulated the expressions of TLR7 and TLR8 in alveolar macrophages (AMs) and imDCs. The release of IL-12 was inhibited from imDCs and mDCs in response to poly IC. Porcine reproductive and respiratory syndrome virus (PRRSV)-infection inhibited TLR3 and TLR7 expressions in AMs and imDCs at 6h post-infection (PI); both of expressions were then restored at 24h PI in both types of cells while they exhibited up-regulated IL-10 and IL-12 expression at 24h PI. Hence, the differential TLR expression patterns in porcine AMs and DCs in discrimination of the imitated viral dsRNA or PRRSV infection may determine their cytokine expressions and thus affect the resulting immune responses.

Salmonella flagellin enhances mucosal immunity of avian influenza vaccine in chickens

Flagellin, a bioactive Toll-like receptor (TLR) 5 ligand, may trigger the innate immunity that in turn is important for subsequent adaptive immune responses. In the present study, the adjuvant effects of the monomeric and polymeric forms of Salmonella flagellin (mFliC and pFliC, respectively) were examined in specific-pathogen free (SPF) chickens immunized intramuscularly (i.m.) or intranasally (i.n.) with formalin-inactivated avian influenza virus (AIV) H5N2 vaccines. Results showed that mFliC cooperating with the 64CpG adjuvant significantly induced influenza-specific antibody titers of plasma IgA in the i.m.-vaccinated animals. The nasal IgA levels in the i.n.-mFliC-coadministrated AIV vaccinated chickens were significantly elevated compared to levels observed in the control group (H5N2 vaccine alone). The pFliC cooperating with the 64CpG adjuvant significantly enhanced cell proliferation of splenocytes in the i.m.-vaccinated animals. TLR3 and TLR5 expressions were activated by flagellin stimulation in vitro and in vivo. These results suggest that flagellin can be used as an adjuvant in an AIV H5N2 vaccine, especially for mucosal immunity.

Modulations of phenotype and cytokine expression of porcine bone marrow-derived dendritic cells by porcine reproductive and respiratory syndrome virus.

Phenotypic and functional property changes of bone marrow-derived immature dendritic cells (BM-imDCs) after porcine reproductive and respiratory syndrome virus (PRRSV) infection have been detailed in a previous report. A down-regulated expression of MHC I molecules along with an up-regulated expression of CD80/86 were observed in BM-imDCs after the exposure to PRRSV. In this study, we further investigate the expression of surface phenotypes of BM-imDCs in relation to their infection status. Exposure of PRRSV to BM-imDCs resulted in a down-regulated expression of MHC I and an up-regulated expression of CD80/86 in infected cells, as demonstrated by significant alterations in both percentage of expressing cells and mean fluorescence intensity (MFI) in PRRSV-positive cells. A significant suppression in MFI of MHC I and an increase in percentage of cells expressing CD80/86 were observed in noninfected bystander cells. We also demonstrated that exposure of BM-imDCs to PRRSV resulted in a significantly increased secretion of IL-1, IL-6, IL-8, IL-10 and IFN-gamma but not IL-12 or TNF-alpha. In addition, the PRRSV infection modulates cytokine expressions of BM-imDCs through their response to microbial pathogen-associated molecular patterns. These results will prove helpful in clarification of the factors that mediate host defense against PRRSV, as well as the possible interaction mechanisms between PRRSV and other microbes in the pathogenesis of PRRSV infection in pigs.

Adjuvant effects of chicken interleukin-18 in avian Newcastle disease vaccine.

Interleukin-18 (IL-18) can induce interferon-gamma (IFN-gamma) production and promote Th1 immunity, and hence, it modulates immune functions. In the present study, the in vitro and in vivo immunomodulatory activities of full length or mature chicken IL-18 expressed in a prokaryotic expression system (pCHIL18-F and pCHIL18-M, respectively) and chicken IL-18 expressed in a eukaryotic expression system (euCHIL18) were examined. Results showed that pCHIL18-F, pCHIL18-M and euCHIL18 significantly enhanced IFN-gamma mRNA expression in chicken splenocytes, which successfully increased IFN-gamma-induced nitric oxide (NO) synthesis by macrophages. Vaccination with cell-cultured Newcastle disease vaccine (NDTC) co-administrated with pCHIL18-F, pCHIL18-M or euCHIL18 resulted in significant increments of hemagglutination inhibition (HI) titers, cell proliferation of peripheral blood mononuclear cells (PBMC), and ratios of CD8(+) to CD4(+) in chickens compared with inoculation of PBS or NDTC alone. Thus, full length and mature chicken IL-18 expressed using a prokaryotic system and using a eukaryotic system showed equivalent in vitro and in vivo biological activities, and all forms effectively enhanced cell-mediated and humoral immunity, suggesting possible future use as a potential adjuvant in chicken NDTC vaccine production.

Immunoadjuvant efficacy of plasmids with multiple copies of a CpG motif coadministrated with avian influenza vaccine in chickens

Unmethylated CpG motifs are capable of evoking a range of immunostimulatory effects in vertebrates and have tremendous potential to be used as therapeutic agents and adjuvants. This particular type of CpG motif has been demonstrated to be an excellent immune adjuvant mediated by Toll-like receptor 9 (TLR9) in various mammalian vaccines; however, only a few studies confirm its efficacy in avian vaccines. In the present study, immunomodulatory activities of plasmids with various copy numbers of a CpG motif were evaluated in chickens inoculated with an avian influenza vaccine. Results showed that the plasmid with 64 copies of the CpG motif (64CpG-plasmid) significantly enhanced the mRNA expressions of interferon-gamma (IFN-γ), TLR3 and TLR7 in chicken splenocytes compared to plasmids with lesser copies of the CpG motif in vitro. Chickens inoculated with the H5N2 avian influenza inactivated vaccines (V52) coadministrated with the 64CpG-plasmid (V52-64CpG) showed significant increments of hemagglutination inhibition (HI) titers, peripheral blood mononuclear cell (PBMC) proliferation, and mRNA expressions of IFN-α, IFN-γ, TLR3, TLR7 and TLR21 in splenocytes as compared to those of chickens inoculated with V52 alone, V52 adjuvanted with aluminum gel (V52-gel), or with V52-gel plus vector. Additionally, following challenge with a highly virulent H5N1 strain, a higher survival rate (100%) was observed in chickens inoculated with V52-64CpG as compared to those that received V52-gel (80%) or PBS (0%). The 64CpG-plasmid significantly enhanced chicken immunity in vitro and in vivo; thus it can be a potent adjuvant in an avian influenza vaccine for chickens.

Docosahexaenoic acid and phosphatidylserine improves the antioxidant activities in vitro and in vivo and cognitive functions of the developing brain

Fish oil during early postnatal period may modulate the impact of oxidative stress in the developing brain and thus improve memory and cognitive behaviour. This study investigated the impacts of docosahexaenoic acid (DHA, C22:6, n-3) and/or phosphatidylserine (PS) on antioxidant activities in vitro, and the beneficial effects of feeding with DHA and/or PS on antioxidant activities in brain and liver tissues and on the cognitive functions of the developing brain. Results indicated that DHA and/or PS significantly enhanced antioxidant activities and increased cell viabilities in vitro. Feeding with DHA and/or PS supplementation not only significantly improved escape latency of animals, but it also improved the oxidative parameters in the brain, enhanced glutathione peroxidase activity as well as reduced nitric mono-oxide levels in the liver. DHA and PS may serve to protect cells from oxidative stress and further improve learning and memory ability in vivo.

Anti-hypersensitive and anti-inflammatory activities of water extract of Zingiber zerumbet (L.) Smith

Abstract Crude extracts from traditional herbs have long been used in the treatment of a variety of acute and/or chronic diseases in many countries. Zingiber zerumbet Smith extract has been reported to have anti-inflammatory potential, especially in asthmatic patients. The aim of this study is to examine the capacity of water extract of Zingiber zerumbet (CC-ZWE) in protecting the lungs by inhibiting the release of inflammatory mediators during short-term treatment, and modulating cytokine gene expressions during long-term treatment. BALB/c mice were sensitised and challenged with ovalbumin to induce anaphylaxis. The anti-hypersensitive and anti-inflammatory potentials of water extract of Zingiber zerumbet Smith (ZZ-CWE) were evaluated using both in vitro and in vivo systems. ZZ-CWE decreased the release of tumour necrosis factor-alpha and interleukin-4 (IL-4) in vitro and effectively suppressed LTC4 release from lung tissue in vivo (p<0.05). Additionally, animals treated with ZZ-CWE expressed higher ratios of interferon-gamma/IL-4 mRNA in their splenocytes than that of the control group (p<0.05). Our results showed that ZZ-CWE should have beneficial effects for the treatment of asthmatic patients through its capabilities to inhibit the synthesis of LTC4 and through the immunomodulation of Th1/Th2 cytokine production.