Akkermansia muciniphila Is Beneficial to a Mouse Model of Parkinson's Disease, via Alleviated Neuroinflammation and Promoted Neurogenesis, with Involvement of SCFAs.

Increasing evidence suggests that the gut microbiota may represent potential strategies for Parkinson's disease (PD) treatment. Our previous research revealed a decreased abundance of Akkermansia muciniphila (Akk) in PD mice; however, whether Akk is beneficial to PD is unknown. To answer this question, the mice received MPTP intraperitoneally to construct a subacute model of PD and were then supplemented with Akk orally for 21 consecutive days. Motor function, dopaminergic neurons, neuroinflammation, and neurogenesis were examined. In addition, intestinal inflammation, and serum and fecal short-chain fatty acids (SCFAs) analyses, were assessed. We found that Akk treatment effectively inhibited the reduction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and partially improved the motor function in PD mice. Additionally, Akk markedly alleviated neuroinflammation in the striatum and hippocampus and promoted hippocampal neurogenesis. It also decreased the level of colon inflammation. Furthermore, these aforementioned changes are mainly accompanied by alterations in serum and fecal isovaleric acid levels, and lower intestinal permeability. Our research strongly suggests that Akk is a potential neuroprotective agent for PD therapy.

Fecal Microbiota Transplantation from Aged Mice Render Recipient Mice Resistant to MPTP-Induced Nigrostriatal Degeneration Via a Neurogenesis-Dependent but Inflammation-Independent Manner.

Accumulating data support a crucial role of gut microbiota in Parkinson's disease (PD). However, gut microbiota vary with age and, thus, will affect PD in an age-dependent, but unknown manner. We examined the effects of fecal microbiota transplantation (FMT) pretreatment, using fecal microbiota from young (7 weeks) or aged mice (23 months), on MPTP-induced PD model. Motor function, pathological changes, striatal neurotransmitters, neuroinflammation, gut inflammation and gut permeability were examined. Gut microbiota composition and metabolites, namely short-chain fatty acids (SCFAs), were analyzed. Neurogenesis was also evaluated by measuring the number of doublecortin-positive (DCX+) neurons and Ki67-positive (Ki67+) cells in the hippocampus. Expression of Cd133 mRNA, a cellular stemness marker, in the hippocampus was also examined. Mice who received FMT from young mice showed MPTP-induced motor dysfunction, and reduction of striatal dopamine (DA), dopaminergic neurons and striatal tyrosine hydroxylase (TH) levels. Interestingly and unexpectedly, mice that received FMT from aged mice showed recovery of motor function and rescue of dopaminergic neurons and striatal 5-hydroxytryptamine (5-HT), as well as decreased DA metabolism after MPTP challenge. Further, they showed improved metabolic profiling and a decreased amount of fecal SCFAs. High-throughput sequencing revealed that FMT remarkably reshaped the gut microbiota of recipient mice. For instance, levels of genus Akkermansia and Candidatus Saccharimonas were elevated in fecal samples of recipient mice receiving aged microbiota (AM + MPTP mice) than YM + MPTP mice. Intriguingly, both young microbiota and aged microbiota had no effect on neuroinflammation, gut inflammation or gut permeability. Notably, AM + MPTP mice showed a marked increase in DCX+ neurons, as well as Ki67+ cells and Cd133 expression in the hippocampal dentate gyrus (DG) compared to YM + MPTP mice. These results suggest that FMT from aged mice augments neurogenesis, improves motor function and restores dopaminergic neurons and neurotransmitters in PD model mice, possibly through increasing neurogenesis.

Orally Induced High Serum Level of Trimethylamine N-oxide Worsened Glial Reaction and Neuroinflammation on MPTP-Induced Acute Parkinson's Disease Model Mice.

Neuroinflammation mediated by brain glial cells is one of the pathological drivers of Parkinson's disease (PD). Recent studies have shown that higher circulating trimethylamine N-oxide (TMAO, a gut microbiota-derived metabolite) can induce neuroinflammation and are strongly related to a variety of central nervous system diseases and adverse brain events. Herein, we explored the effect of pre-existing higher circulating TMAO on dopamine system and neuroinflammation in acute PD model mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP). TMAO pretreatment was given by adding 3% (w/v) TMAO to drinking water of mice for 21 days to induce higher circulating TMAO status, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to construct an acute PD model mice and treated with TMAO continuously until the end of the experiment. Results demonstrated that TMAO treatment significantly increased serum TMAO levels. Moreover, high serum TMAO significantly increased activation of microglia and astrocytes both in striatum and in substantia nigra. And strikingly, high serum TMAO significantly promoted the metabolism of striatal dopamine (DA) of PD model mice, although it had no significant effect on the number of dopaminergic neurons or the content of DA. Furthermore, immunofluorescence, ELISA, and RT-qPCR results of the hippocampus also showed that high serum TMAO significantly promoted the activation of microglia and astrocytes in the dentate gyrus, increased the levels of TNF-α and IL-1ß, and upregulated gene expression of M1 microglia-related markers (including CD16, CD32, and iNOS) and A2 astrocyte-related markers (including S100a10, Ptx3, and Emp1) in mRNA levels. In summary, we found that pre-existing high serum levels of TMAO worsened the PD-related brain pathology by promoting DA metabolism, aggravating neuroinflammation and regulating glial cell polarization.

RIPK1-Induced A1 Reactive Astrocytes in Brain in MPTP-Treated Murine Model of Parkinson's Disease.

Neuroinflammation is one of the hallmarks of Parkinson's disease, including the massive activation of microglia and astrocytes and the release of inflammatory factors. Receptor-interacting protein kinase 1 (RIPK1) is reported to mediate cell death and inflammatory signaling, and is markedly elevated in the brain in PD mouse models. Here, we aim to explore the role of RIPK1 in regulating the neuroinflammation of PD. C57BL/6J mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg four times/day), followed by necrostatin-1 treatment (Nec-1, RIPK1 inhibitor; 1.65 mg/kg once daily for seven days. Notably, the first Nec-1 was given 12 h before MPTP modeling). Behavioral tests indicated that inhibition of RIPK1 greatly relieved motor dysfunction and anxiety-like behaviors of PD mice. It also increased striatal TH expression, rescue the loss of dopaminergic neurons, and reduce activation of astrocytes in the striatum of PD mice. Furthermore, inhibition of RIPK1 expression reduced A1 astrocytes' relative gene expression (CFB, H2-T23) and inflammatory cytokine or chemokine production (CCL2, TNF-α, IL-1ß) in the striatum of PD mice. Collectively, inhibition of RIPK1 expression can provide neuroprotection to PD mice, probably through inhibition of the astrocyte A1 phenotype, and thus RIPK1 might be an important target in PD treatment.

Trimethylamine N-Oxide Exacerbates Neuroinflammation and Motor Dysfunction in an Acute MPTP Mice Model of Parkinson's Disease.

Observational studies have shown abnormal changes in trimethylamine N-oxide (TMAO) levels in the peripheral circulatory system of Parkinson's disease (PD) patients. TMAO is a gut microbiota metabolite that can cross the blood-brain barrier and is strongly related to neuroinflammation. Neuroinflammation is one of the pathological drivers of PD. Herein, we investigated the effect of TMAO on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. TMAO pretreatment was given by adding 1.5% (w/v) TMAO to the drinking water of the mice for 21 days; then, the mice were administered MPTP (20 mg/kg, i.p.) four times a day to construct an acute PD model. Their serum TMAO concentrations, motor function, dopaminergic network integrity, and neuroinflammation were then assayed. The results showed that TMAO partly aggravated the motor dysfunction of the PD mice. Although TMAO had no effect on the dopaminergic neurons, TH protein content, and striatal DA level in the PD mice, it significantly reduced the striatal 5-HT levels and aggravated the metabolism of DA and 5-HT. Meanwhile, TMAO significantly activated glial cells in the striatum and the hippocampi of the PD mice and promoted the release of inflammatory cytokines in the hippocampus. In summary, higher-circulating TMAO had adverse effects on the motor capacity, striatum neurotransmitters, and striatal and hippocampal neuroinflammation in PD mice.

Phylogenetic and Structural Analysis of Porcine Circovirus Type 2 from 2016 to 2021 in Jilin Province, China.

Porcine circovirus disease (PCVD) caused by porcine circovirus type 2 (PCV2) is widely distributed in pig farms. Up until now, nine genotypes of PCV2, PCV2a to 2i, have been identified in diseased pigs worldwide. This study analyzed 302 samples collected in the Jilin Province of China from 2016 to 2021, followed by genetic analysis of the PCV2 isolates. Meanwhile, the antigen epitopes, amino acid mutations, 3D structure of the PCV2 isolates and commercially available vaccine strains were evaluated and compared. The results showed that the predominant genotypes of PCV2 were PCV2b, followed by PCV2e and PCV2d in Jilin Province during 2016-2021. Although mutations were detected in the isolates, no recombination occurred in the PCV2 isolates, indicating a stable genotype of PCV2 in Jilin Province during these years. Moreover, the B cell epitopes in the Cap and Rep proteins of eighteen PCV2 isolates and T cell epitopes in the Cap of the isolates were changed compared to three currently used vaccine strains. The mutations in the Cap and Rep proteins did not affect their spatial conformation. Therefore, bivalent or multivalent vaccines with different genotypes of PCV2 might improve the protective effect of vaccines.

DSS-induced acute colitis causes dysregulated tryptophan metabolism in brain: an involvement of gut microbiota.

Inflammatory bowel disease can cause pathological changes of certain organs, including the gut and brain. As the major degradation route of tryptophan (Trp), Kynurenine (Kyn) pathway are involved in multiple pathologies of brain. This study sought to explore the effects of Dextran sulphate sodium (DSS)-induced colitis on serum and brain Trp metabolism (especially the Kyn pathway) and its mechanisms. We induced acute colitis and sub-chronic colitis with 3% DSS and 1% DSS respectively and found more severe intestinal symptoms in acute colitis than sub-chronic colitis. Both of the colitis groups altered Trp-Kyn-Kynurenic acid (Kyna) pathway in serum by regulating the expression of rate-limiting enzyme (IDO-1, KAT2). Interestingly, only 3% DSS group activated Trp-Kyn pathway under the action of metabolic enzymes (IDO-1, TDO-2 and KAT2) in brain. Furthermore, intestinal flora 16S rRNA sequencing showed significantly changes in both DSS-induced colitis groups, including microbial diversity, indicator species, and the abundance of intestinal microflora related to Trp metabolism. The functional pathways of microbiomes involved in inflammation and Trp biosynthesis were elevated after DSS treatment. Moreover, correlation analysis showed a significant association between intestinal flora and Trp metabolism (both in serum and brain). In conclusion, our study suggests that DSS-induced acute colitis causes dysregulation of Trp-Kyn-Kyna pathways of Trp metabolism in serum and brain by affecting rate-limiting enzymes and intestinal flora.

Vancomycin Pretreatment on MPTP-Induced Parkinson's Disease Mice Exerts Neuroprotection by Suppressing Inflammation Both in Brain and Gut.

A growing body of evidence implies that gut microbiota was involved in pathogenesis of Parkinson's disease (PD), but the mechanism is still unclear. The aim of this study is to investigate the effects of antibiotics pretreatment on the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mice. In this study, vancomycin pretreatment was given by gavage once daily with either vancomycin or distilled water for 14 days to mice, then mice were administered with MPTP (20 mg/kg, i.p) for four times in one day to establish an acute PD model. Results show that vancomycin pretreatment significantly improved motor dysfunction of mice in pole and traction tests. Although vancomycin pretreatment had no effect on dopamine (DA) or the process of DA synthesis, it inhibited the metabolism of DA by suppressing the expression of striatal monoamine oxidase B (MAO-B). Furthermore, vancomycin pretreatment reduced the number of astrocytes and microglial cells in the substantia nigra pars compacta (SNpc) to alleviate neuroinflammation, decreased the expression of TLR4/MyD88/NF-κB/TNF-α signaling pathway in both brain and gut. Meanwhile, vancomycin pretreatment changed gut microbiome composition and the levels of fecal short chain fatty acids (SCFAs). The abundance of Akkermansia and Blautia increased significantly after vancomycin pretreatment, which might be related to inflammation and inhibition of TLR4 signaling pathway. In summary, these results demonstrate that the variation of gut microbiota and its metabolites induced by vancomycin pretreatment might decrease dopamine metabolic rate and relieve inflammation in both gut and brain via the microbiota-gut-brain axis in MPTP-induced PD mice. The neuroprotection of vancomycin pretreatment on MPTP-induced Parkinson's disease mice The alterations of gut microbiota and SCFAs induced by vancomycin pretreatment might not only improve motor dysfunction, but also decrease dopamine metabolism and relieve inflammation in both brain and gut via TLR4/MyD88/NF-κB/TNF-α pathway in MPTP-induced PD mice.

Mutation and Interaction Analysis of the Glycoprotein D and L and Thymidine Kinase of Pseudorabies Virus.

Pseudorabies (also called Aujeszky's disease) is a highly infectious viral disease caused by the pseudorabies virus (PRV, or Suid herpesvirus 1). Although the disease has been controlled by immunization with the PRV-attenuated vaccine, the emerging PRV variants can escape the immune surveillance in the vaccinated pig, resulting in recent outbreaks. Furthermore, the virus has been detected in other animals and humans, indicating cross-transmission of PRV. However, the mechanism of PRV cross-species transmission needs further study. In this study, we compared the amino acid sequences of glycoproteins (gD), gL, and thymidine kinase (TK) of PRV strains, human PRV hSD-1 2019 strain, and the attenuated strain Bartha-K61, followed by predication of their spatial conformation. In addition, the interactions between the viral gD protein and host nectin-1, nectin-2, and HS were also evaluated via molecular docking. The results showed that the amino acid sequence homology of the gD, gL, and TK proteins of hSD-1 2019 and JL-CC was 97.5%, 94.4%, and 99.1%, respectively. Moreover, there were mutations in the amino acid sequences of gD, gL, and TK proteins of hSD-1 2019 and JL-CC compared with the corresponding reference sequences of the Bartha strain. The mutations of gD, gL, and TK might not affect the spatial conformation of the protein domain but may affect the recognition of antibodies and antigen epitopes. Moreover, the gD protein of JL-CC, isolated previously, can bind to human nectin-1, nectin-2, and HS, suggesting the virus may be highly infectious and pathogenic to human beings.

Expression and immunogenicity analysis of the capsid proteins of porcine circovirus types 2 to 4.

Porcine circovirus (PCV) comprises four types, PCV1, PCV2, PCV3, and PCV4, which belong to the Circovirus genus of the family Circoviridae. PCV1 is nonpathogenic, whereas PCV2, PCV3, and PCV4 can infect pigs and cause disease. However, due to a lack of experimental evidence, whether vaccines based on PCV capsid (Cap) can induce cross-reactivity against PCVs remains controversial. In this study, recombinant truncated capsids (rCaps) of PCV2, PCV3, and PCV4 were highly and efficiently expressed and purified, followed by the development and evaluation of antibodies against PCVs. The results showed that monovalent and trivalent antigens based on the recombinant Caps had adequate immunogenicity to stimulate specific antibodies against the corresponding protein and virus. Furthermore, antisera prepared from the recombinant Caps also cross-reacted with different PCVs. Therefore, recombinant proteins can be used as candidate antigens to develop vaccines and ELISA diagnostic kits. In addition, the antibodies prepared in this study are promising candidates for the simultaneous prevention and treatment of PCVs in the clinic.

Advances in Crosstalk between Porcine Circoviruses and Host.

Porcine circoviruses (PCVs), including PCV1 to PCV4, are non-enveloped DNA viruses with a diameter of about 20 nm, belonging to the genus Circovirus in the family Circoviridae. PCV2 is an important causative agent of porcine circovirus disease or porcine circovirus-associated disease (PCVD/PCVAD), which is highly prevalent in pigs and seriously affects the swine industry globally. Furthermore, PCV2 mainly causes subclinical symptoms and immunosuppression, and PCV3 and PCV4 were detected in healthy pigs, sick pigs, and other animals. Although the pathogenicity of PCV3 and PCV4 in the field is still controversial, the infection rates of PCV3 and PCV4 in pigs are increasing. Moreover, PCV3 and PCV4 rescued from infected clones were pathogenic in vivo. It is worth noting that the interaction between virus and host is crucial to the infection and pathogenicity of the virus. This review discusses the latest research progress on the molecular mechanism of PCVs-host interaction, which may provide a scientific basis for disease prevention and control.

PCV2 and PRV Coinfection Induces Endoplasmic Reticulum Stress via PERK-eIF2α-ATF4-CHOP and IRE1-XBP1-EDEM Pathways.

Porcine circovirus 2 (PCV2) and pseudorabies virus (PRV) are two important pathogens in the pig industry. PCV2 or PRV infection can induce endoplasmic reticulum stress (ERS) and unfolded protein response (UPR). However, the effect of PCV2 and PRV coinfection on the ERS and UPR pathways remains unclear. In this study, we found that PRV inhibited the proliferation of PCV2 mainly at 36 to 72 hpi, while PCV2 enhanced the proliferation of PRV in the middle stage of the infection. Notably, PRV is the main factor during coinfection. The results of the transcriptomic analysis showed that coinfection with PCV2 and PRV activated cellular ERS, and upregulated expressions of the ERS pathway-related proteins, including GRP78, eIF2α, and ATF4. Further research indicated that PRV played a dominant role in the sequential infection and coinfection of PCV2 and PRV. PCV2 and PRV coinfection induced the ERS activation via the PERK-eIF2α-ATF4-CHOP axis and IRE1-XBP1-EDEM pathway, and thus may enhance cell apoptosis and exacerbate the diseases.

Coinfection of Porcine Circovirus 2 and Pseudorabies Virus Enhances Immunosuppression and Inflammation through NF-κB, JAK/STAT, MAPK, and NLRP3 Pathways.

Porcine circovirus 2 (PCV2) and pseudorabies virus (PRV) are economically important pathogens in swine. PCV2 and PRV coinfection can cause more severe neurological and respiratory symptoms and higher mortality of piglets. However, the exact mechanism involved in the coinfection of PRV and PCV2 and its pathogenesis remain unknown. Here, porcine kidney cells (PK-15) were infected with PCV2 and/or PRV, and then the activation of immune and inflammatory pathways was evaluated to clarify the influence of the coinfection on immune and inflammatory responses. We found that the coinfection of PCV2 and PRV can promote the activation of nuclear factor-κB (NF-κB), c-Jun N-terminal protein kinases (JNK), p38, and nod-like receptor protein 3 (NLRP3) pathways, thus enhancing the expression of interferon-γ (IFN-γ), interferon-λ1 (IFN-λ1), interferon-stimulated gene (ISG15), interleukin 6 (IL6), and interleukin 1ß (IL1ß). Meanwhile, PCV2 and PRV also inhibit the expression and signal transduction of IFN-ß, tumor necrosis factor α (TNFα), and the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway. In addition, PCV2 and PRV infection can also weaken extracellular-signal-regulated kinase (ERK) activity. These results indicate that the regulations of cellular antiviral immune responses and inflammatory responses mediated by NF-κB, JAK/STAT, mitogen-activated protein kinase (MAPK), and NLRP3 pathways, contribute to immune escape of PCV2 and PRV and host antiviral responses.

Porcine circovirus 4 rescued from an infectious clone is replicable and pathogenic in vivo.

Porcine circovirus 4 (PCV4) is a newly identified porcine circovirus in pigs, belonging to the Circoviridae family Circovirus genus. The virus was detected in all age groups and aborted foetuses. However, the virus has not been isolated from the field samples to date. In this study, PCV4 was successfully rescued from an infectious clone. The rescued PCV4 was replicable in PK-15 cells and piglets, which can be detected in almost all the collected samples of the challenge groups. No obvious clinical symptoms were observed in both sham- and PCV4-inoculated piglets during the whole experiment. However, visible pathological changes were found in several organs of the PCV4-inoculated piglets, indicating that rescued PCV4 was pathogenic in piglets. Furthermore, the viremia, PCV4-specific antibody, and upregulated cytokines/chemokines were also detected in the PCV4-inoculated groups, suggesting effective humoral and cellular immune responses were stimulated in response to the virus challenge. The PCV4 rescued in this study may provide the basis for preventing and controlling the disease, and vaccine development.

Porcine Circovirus Type 4 Strains Circulating in China Are Relatively Stable and Have Higher Homology with Mink Circovirus than Other Porcine Circovirus Types.

Porcine circovirus type 4 (PCV4) is a newly identified porcine circovirus (PCV) belonging to the Circovirus genus Circoviridae family. Although several groups have conducted epidemiological investigations on PCV4 and found that PCV4 also exists widely in pigs, there are few reports on the origin and evolution of PCV4. In this study, the genetic relationship between PCV4, mink circovirus (MiCV), bat circovirus (BtCV), PCV1, PCV2, and PCV3 was analyzed, and the consistency of viral proteins in three-dimensional (3D) structure and epitopes was predicted. We found that the genome and protein structure of PCV4 was relatively stable among current circulating PCV4 strains. Furthermore, PCV4 was more similar to MiCV in terms of its genome, protein structure, and epitope levels than other PCVs and BtCVs, suggesting that PCV4 may be derived from MiCV or have a common origin with MiCV, or mink may be an intermediate host of PCV4, which may pose a great threat to other animals and/or even human beings. Therefore, it is necessary to continuously monitor the infection and variation of PCV4, analyze the host spectrum of PCV4, and establish the prevention and treatment methods of PCV4 infection in advance.

DSS-induced colitis activates the kynurenine pathway in serum and brain by affecting IDO-1 and gut microbiota.

Accumulative studies suggest that inflammatory bowel disease (IBD) may cause multiple central nervous system (CNS) pathologies. Studies have found that indoleamine-2,3-dioxygenase (IDO, rate-limiting enzyme of the kynurenine (Kyn) pathway) deficient mice were protected from endotoxin induced cognitive impairment, and Kyn administration induced cognitive memory deficits in both control and IDO-deficient mice. However, there is no investigation of the brain Kyn pathway in IBD, thus we investigated whether dextran sulfate sodium (DSS)-induced colitis could cause dysregulation of Kyn pathway in brain, and also in serum. C57BL/6J mice were given drinking water with 2% DSS for 10 consecutive days to induce colitis. In serum, we found significant increase in Kyn and kynurenic acid (Kyna) level, which was regulated by IDO-1 and KAT2 (rate-limiting enzymes of Trp-Kyn-Kyna pathway). Similarly, by analyzing GEO datasets, higher IDO-1 levels in peripheral blood monocytes and colon of UC patients was found. Furthermore, the Kyn pathway was significantly upregulated in the cerebral cortex under the action of IDO-1 after DSS treatment, which ultimately induced the neurotoxic phenotype of astrocytes. To investigate whether gut microbiota is involved in IBD-induced Kyn pathway dysregulation, we performed intestinal flora 16S rRNA sequencing and found that DSS-induced colitis significantly altered the composition and diversity of the gut microbiota. Metabolic function analysis also showed that Tryptophan metabolism, NOD-like receptor signaling pathway and MAPK signaling pathway were significantly up-regulated in the 2% DSS group. A significant association between intestinal flora and Trp metabolism (both in serum and brain) was found by correlation analysis. Overall, this study revealed that DSS-induced colitis causes dysregulation of the Kyn pathway in serum and brain by affecting rate-limiting enzymes and intestinal flora.

Recent Progress on Epidemiology and Pathobiology of Porcine Circovirus 3.

The recently discovered porcine circovirus 3 (PCV3) belongs to the Circovirus genus of the Circoviridae family together with the other three PCVs, PCV1, PCV2, and PCV4. As reported, PCV3 can infect pig, wild boar, and several other intermediate hosts, resulting in single or multiple infections in the affected animal. The PCV3 infection can lead to respiratory diseases, digestive disorders, reproductive disorders, multisystemic inflammation, and immune responses. Up to now, PCV3 infection, as well as the disease caused by PCV3, has been reported in many swine farms worldwide with high positive rates, which indicates that the virus may be another important pathogen in the swine industry. Therefore, we reviewed the current progress on epidemiology and pathobiology of PCV3, which may provide the latest knowledge of the virus and PCV3-related diseases.

Dynamic changes of activated AHR in microglia and astrocytes in the substantia nigra-striatum system in an MPTP-induced Parkinson's disease mouse model.

Aryl Hydrocarbon Receptor (AHR) is a ligand-activated transcription factor expressed in various brain regions. However, little is known about the role of AHR during neuroinflammation in the 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model. Here, mice were sacrificed at day 4, day 6 and day 8 respectively after MPTP or saline treatment. Behavioral tests, Tyrosine hydroxylase (TH) expression, glial reaction, and AHR expression and activation were then assayed. As expected, mice treated with MPTP showed apparent behavioral dysfunctions and significantly reduced TH content. Immunofluorescence (IF) labeling showed an increased trend of phosphorylated AHR activation in the Substantia Nigra pars compacta (SNpc) and striatum after MPTP treatment. Western blot analysis demonstrated that MPTP treatment induced a significantly increased level of AHR at each time point tested, with the highest level observed at day 6 in the striatum. To determine exactly the AHR activation in relation to changes of glial cell reactivity, double IF labeling was performed for either IBA1 (microglia marker) and p-AHR, or GFAP (astrocyte marker) and p-AHR. The results demonstrated that MPTP treatment not only increases the number of p-AHR-positive IBA1-expressing cells in the striatum and the SNpc, but also increases that of p-AHR-positive GFAP-expressing cells in the striatum. Intriguingly, the increase of the number of cells co-expressing both p-AHR and IBA1 was highest at day 4 in response to MPTP in the striatum and at day 8 in the SNpc. The number of cells co-expressing both p-AHR and GFAP was increased at days 4, 6 and 8 in the striatum. In conclusion, our study suggests that AHR activation may facilitate PD diagnosis and serve as a target for the treatment of PD.

Genotyping based on complete coding sequences of porcine circovirus type 3 is stable and reliable.

Porcine circovirus type 3 (PCV3) is a newly identified virus, which is associated with PDNS-like clinical signs, reproductive failure, cardiac and multiorgan inflammation. However, the genotype of PCV3 is still controversial. Here, we reconstructed the phylogenies of 194 complete coding sequences of PCV3 using five different phylogenetic methods. The results showed five trees reconstructed using different methods displayed similar phylogenies, indicating genotyping based on complete coding sequences of PCV3 is stable and accurate.

Porcine HMGCR Inhibits Porcine Circovirus Type 2 Infection by Directly Interacting with the Viral Proteins.

Porcine circovirus type 2 (PCV2) is the etiological agent of porcine circovirus diseases and porcine circovirus-associated diseases (PCVDs/PCVADs). However, the pathogenesis of PCV2 is not fully understood. We previously found that 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is negatively associated with PCV2 infection in vitro and in vivo. HMGCR inhibits the early stages of PCV2 infection, while PCV2 infection induces the phosphorylation of HMGCR to inactivate the protein. In this study, we investigated the possibility that adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), and protein phosphatase 2 (PP2A) participate in HMGCR-mediated inhibition of PCV2 infection and the interaction of porcine HMGCR with PCV2 proteins. The results showed that AMPK activity fluctuated in cells during the early stage of PCV2 infection, while PP2A had little effect on PCV2 infection and HMGCR activity. Furthermore, PCV2 infection may enhance or maintain the level of phosphorylated HMGCR by directly interacting with the protein in PK-15 cells. These findings may provide a better understanding of PCV2 pathogenesis, and HMGCR may be a novel PCV2 antiviral target.