Suppressor of cytokine signaling 3 plays an important role in porcine circovirus type 2 subclinical infection by downregulating proinflammatory responses

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.

Blocking tumor necrosis factor-α delays progression of chronic obstructive pulmonary disease in rats through inhibiting MAPK signaling pathway and activating SOCS3/TRAF1

The present study was conducted in order to study the detailed molecular mechanism of tumor necrosis factor (TNF)-α in chronic obstructive pulmonary disease (COPD). The rats were treated with cigarette smoke (CS) and lipopolysaccharide (LPS) to establish the COPD model. Next, the changes in lung injury in COPD rats with TNF-α knockdown was tested. Meanwhile, the regulation of TNF-α on MAPK pathway and its downstream molecules (SOCS3/TRAF1) was determined by western blotting. On this basis, the activation of MAPK and inhibition of SOCS3/TRAF1 was also examined. Subsequently, the lung function was tested with the plethysmograph, the cells of bronchoalveolar lavage fluid was counted and classified. Furthermore, lung tissue sections were stained with hematoxylin and eosin to verify whether the treatment of MAPK pathway and downstream molecules affected the effect of TNF-α knockdown on COPD. The present study showed that TNF-α knockdown could alleviate the decrease in the function and inflammatory injury of the lungs of rats with COPD. Western blot analysis verified that TNF-α knockdown could inhibit the activation of MAPK pathway and increase the expression of SOCS3/TRAF1. The following experimental results showed that the relief of lung injury caused by TNF-α knockdown could be deteriorated by activating MAPK pathway. It was also found that the symptom of COPD was decreased following transfection with sh-TNF-α but worsened by SOCS3/TRAF1 knockdown. Overall, TNF-α knockdown inhibited the activation of MAPK pathway and increased the expression of SOCS3/TRAF1, thus delaying the process of COPD.

The cytokine storms of COVID-19, H1N1 influenza, CRS and MAS compared. Can one sized treatment fit all?

An analysis of published data appertaining to the cytokine storms of COVID-19, H1N1 influenza, cytokine release syndrome (CRS), and macrophage activation syndrome (MAS) reveals many common immunological and biochemical abnormalities. These include evidence of a hyperactive coagulation system with elevated D-dimer and ferritin levels, disseminated intravascular coagulopathy (DIC) and microthrombi coupled with an activated and highly permeable vascular endothelium. Common immune abnormalities include progressive hypercytokinemia with elevated levels of TNF-α, interleukin (IL)-6, and IL-1β, proinflammatory chemokines, activated macrophages and increased levels of nuclear factor kappa beta (NFκB). Inflammasome activation and release of damage associated molecular patterns (DAMPs) is common to COVID-19, H1N1, and MAS but does not appear to be a feature of CRS. Elevated levels of IL-18 are detected in patients with COVID-19 and MAS but have not been reported in patients with H1N1 influenza and CRS. Elevated interferon-γ is common to H1N1, MAS, and CRS but levels of this molecule appear to be depressed in patients with COVID-19. CD4+ T, CD8+ and NK lymphocytes are involved in the pathophysiology of CRS, MAS, and possibly H1N1 but are reduced in number and dysfunctional in COVID-19. Additional elements underpinning the pathophysiology of cytokine storms include Inflammasome activity and DAMPs. Treatment with anakinra may theoretically offer an avenue to positively manipulate the range of biochemical and immune abnormalities reported in COVID-19 and thought to underpin the pathophysiology of cytokine storms beyond those manipulated via the use of, canakinumab, Jak inhibitors or tocilizumab. Thus, despite the relative success of tocilizumab in reducing mortality in COVID-19 patients already on dexamethasone and promising results with Baricitinib, the combination of anakinra in combination with dexamethasone offers the theoretical prospect of further improvements in patient survival. However, there is currently an absence of trial of evidence in favour or contravening this proposition. Accordingly, a large well powered blinded prospective randomised controlled trial (RCT) to test this hypothesis is recommended.

Combined Effect of Deoxynivalenol (DON) and Porcine Circovirus Type 2 (Pcv2) on Inflammatory Cytokine mRNA Expression

A host’s immune system can be invaded by mycotoxin deoxynivalenol (DON) poisoning and porcine circovirus type 2 (PCV2) infections, which affect the host’s natural immune function. Pro-inflammatory cytokines, IL-1β and IL-6, are important regulators in the process of natural immune response, which participate in inflammatory response and enhance immune-mediated tissue damage. Preliminary studies have shown that DON promotes PCV2 infection by activating the MAPK signaling pathway. Here, we explored whether the mRNA expression of IL-1β and IL-6, induced by the combination of DON and PCV2, would depend on the MAPK signaling pathway. Specific pharmacological antagonists U0126, SP600125 and SB203580, were used to inhibit the activities of ERK, JNK and p38 in the MAPK signaling pathway, respectively. Then, the mRNA expression of IL-1β and IL-6 in PK-15 cells was detected to explore the effect of the MAPK signaling pathway on IL-1β and IL-6 mRNA induced by DON and PCV2. The results showed that PK-15 cells treated with DON or PCV2 induced the mRNA expression of IL-1β and IL-6 in a time- and dose-dependent manner. The combination of DON and PCV2 has an additive effect on inducing the mRNA expression of IL-1β and IL-6. Additionally, both DON and PCV2 could induce the mRNA expression of IL-1β and IL-6 via the ERK and the p38 MAPK signal pathways, while PCV2 could induce it via the JNK signal pathway. Taken together, our results suggest that MAPKs play a contributory role in IL-1β and IL-6 mRNA expression when induced by both DON and PCV2.

SOCS3 ablation enhances DC-derived Th17 immune response against Candida albicans by activating IL-6/STAT3 in vitro

AIMS

Enhancing the potency of dendritic cells (DCs) by downregulating negative immunoregulatory pathways may provide immunotherapeutic possibilities against candidiasis.

MAIN METHODS

In this study, a si-RNA method is used to repress expression of the cytokine signaling-3 suppressor (SOCS3) in murine bone marrow-DCs, and then the maturation of DCs and the subsequent T-cell response after exposure to C. albicans are monitored in vitro.

KEY FINDINGS

Along with a higher expression of the DC maturation markers CD40, CD86 and MHC-II, IL-6/STAT3 is markedly upregulated in the SOCS3 siRNA-treated DCs after exposure to C. albicans as compared with control DCs. In response to DCs maturation, CD4⁺ T cells have an increased expression of Th17 cell markers -- including the retinoic acid-related orphan nuclear hormone receptors γt (RORγt), IL-17A and IL-23R -- and increased release of IL-17. We note that this enhanced Th17 cell differentiation induced by siSOCS3-treated DCs in presence of C. albicans can be partly offset when anti-IL-6 antibody is added into the co-culture.

SIGNIFICANCE

As with SOCS1 in our previous report, suppression of SOCS3 alone also has the potential to fully activate DCs maturation. However, while SOCS1 knockdown in DCs during C. albicans infection specifically augments Th1 differentiation, SOCS3 silencing particularly increases Th17 differentiation.

Co-Infection of Swine with Porcine Circovirus Type 2 and Other Swine Viruses

Porcine circovirus 2 (PCV2) is the etiological agent that causes porcine circovirus diseases and porcine circovirus-associated diseases (PCVD/PCVAD), which are present in every major swine-producing country in the world. PCV2 infections may downregulate the host immune system and enhance the infection and replication of other pathogens. However, the exact mechanisms of PCVD/PCVAD are currently unknown. To date, many studies have reported that several cofactors, such as other swine viruses or bacteria, vaccination failure, and stress or crowding, in combination with PCV2, lead to PCVD/PCVAD. Among these cofactors, co-infection of PCV2 with other viruses, such as porcine reproductive and respiratory syndrome virus, porcine parvovirus, swine influenza virus and classical swine fever virus have been widely studied for decades. In this review, we focus on the current state of knowledge regarding swine co-infection with different PCV2 genotypes or strains, as well as with PCV2 and other swine viruses.

Mouse models of porcine circovirus 2 infection

PCV2 is considered the main pathogen of porcine circovirus diseases and porcine circovirus-associated diseases (PCVD/PCVAD). However, the exact mechanism underlying PCVD/PCVAD is currently unknown. Mouse models of PCV2 are valuable experimental tools that can shed light on the pathogenesis of infection and will enable the evaluation of antiviral agents and vaccine candidates. In this review, we discuss the current state of knowledge of mouse models used in PCV2 research that has been performed to date, highlighting their strengths and limitations, as well as prospects for future PCV2 studies.

Identification and characterization of microRNA in the lung tissue of pigs with different susceptibilities to PCV2 infection

Porcine circovirus type 2 (PCV2) is the primary cause of post-weaning multisystemic wasting syndrome (PMWS) and other PCV-associated diseases. According to our previous RNA-sequencing analysis, the differences in the susceptibility to PCV2 infection depended on the genetic differences between the Laiwu (LW) and Yorkshire × Landrace crossbred (YL) pigs, but the cellular microRNA (miRNA) that are differentially expressed between the LW and YL pigs before and after PCV2 infection remain to be determined. In this study, high-throughput sequencing was performed to determine the abundance and differential expression of miRNA in lung tissues from PCV2-infected and PCV2-uninfected LW and YL pigs. In total, 295 known and 95 novel miRNA were identified, and 23 known and 25 novel miRNA were significantly differentially expressed in the PCV2-infected vs. PCV2-uninfected LW pigs and/or the PCV2-infected vs. PCV2-uninfected YL pigs. The expression levels of ssc-miR-122, ssc-miR-192, ssc-miR-451, ssc-miR-486, and ssc-miR-504 were confirmed by quantitative real-time PCR (qRT-PCR). Analysis of the potential targets of the four up-regulated miRNA (i.e., ssc-miR-122, ssc-miR-192, ssc-miR-451 and ssc-miR-486) identified pathways and genes that may be important for disease resistance. Among the up-regulated miRNA, ssc-miR-122 can repress the protein expression and viral DNA replication of PCV2 and down-regulate the expression of the nuclear factor of activated T-cells 5 (NFAT5) and aminopeptidase puromycin sensitive (NPEPPS) by binding to their 3′ untranslated region (3′UTR) in PK15 cells. Therefore, ssc-miR-122 may indirectly suppress PCV2 infection by targeting genes related to the host immune system, such as NFAT5 and NPEPPS.