Bioinformatic analysis of PD 1 checkpoint blockade responsive immune microenvironment in severe influenza infection

Background: The programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) signaling pathway is significantly upregulated in severe influenza virus infection, which impairs the immune system and causes increased tissue inflammation and damage. Blocking this signaling pathway will reduce the damage, lower the virus titer in lung tissue, and alleviate the symptoms of infection to promote recovery. The aim of this study was to identify the key factors and regulatory mechanisms in the PD-1 checkpoint blockade–responsive immune microenvironment in severe influenza infection. Methods: A BALB/c mouse model of severe influenza A/H1N1 infection was constructed, and whole-transcriptome sequencing of mice treated with PD-1 checkpoint blockade before severe A/PR8(H1N1) influenza infection and IgG2a isotype control before infection were performed. Subsequently, the differential expression of nucleic acids between these two groups was analyzed, followed by functional interaction prediction analysis to investigate gene-regulatory circuits. Results: In total, 84 differentially expressed (dif) mRNAs, 36 dif-microRNAs (miRNAs), 90 dif‑lncRNAs (long noncoding RNAs), and 22 dif-circRNAs (circular RNAs) were found in PD-1 antagonist treated A/PR8(H1N1) influenza infection lung compared with the controls (IgG2a isotype control treated before infection). In spleens between the above two groups, 45 dif-mRNAs, 36 dif-miRNAs, 57 dif-lncRNAs, and 24 dif-circRNAs were identified. Direct function enrichment analysis of dif-mRNAs and dif-miRNAs showed that these genes were mainly involved in myocardial damage related to viral infection, mitogen activated protein kinase (MAPK) signaling pathways, RAP1 (Ras-related protein 1) signaling pathway, and Axon guidance. Finally, 595 interaction pairs were obtained for the lungs and 462 interaction pairs for the spleen were obtained in the competing endogenous RNA (ceRNA) complex network, in which the downregulated mmu‑miR-7043-3p and Vps39-204 were enriched significantly. Conclusions: The present study provided a basis for the identification of potential pathways and hub genes that might be involved in the PD-1 checkpoint blockade–responsive immune microenvironment in severe influenza infection.

Differential Immune Response against RecombinantLeishmania donovaniPeroxidoxin 1 and Peroxidoxin 2 Proteins in BALB/c Mice

We assessed the immune response against recombinant proteins of two related, albeit functionally different, peroxidoxins fromLeishmania donovani: peroxidoxin 1 (LdPxn1) and peroxidoxin 2 (LdPxn2) in BALB/c mice. We also evaluated the effect of coadministration of TLR agonists (CpG ODN and GLA-SE) on the antigen-specific immune response. Immunization with recombinant LdPxn1 alone induced a predominantly Th2 type immune response that is associated with the production of high level of IgG1 and no IgG2a isotype while rLdPxn2 resulted in a mixed Th1/Th2 response characterized by the production of antigen-specific IgG2a in addition to IgG1 isotype. Antigen-stimulated spleen cells from mice that were immunized with rLdPxn1 produced low level of IL-10 and IL-4 and no IFN-γ, whereas cells from mice immunized with rLdPxn2 secreted high level of IFN-γ, low IL-4, and no IL-10. Coadministration of CpG ODN or GLA-SE with rLdPxn1 skewed the immune response towards a Th 1 type as indicated by robust production of IgG2a isotype. Furthermore, the presence of TLR agonists together with rLdPxn1 antigen enhanced the production of IFN-γand to a lesser extent of IL-10. TLR agonists also enhanced a more polarized Th 1 type immune response against rLdPxn2.

Pathogenic characterization in mice of Neospora caninum isolates obtained from asymptomatic calves

SUMMARYIn this study, we characterized 8 new isolates obtained from healthy but congenitally infected calves using a BALB/c mouse model. Neospora caninum-infected mice survived without exhibiting any clinical signs of disease. Nevertheless, differences among isolates in parasite organ distribution, parasite burden and the severity of histopathological lesions were determined. Mice infected with the Nc-Spain 5H, Nc-Spain 7 and Nc-Spain 9 isolates showed higher parasite burdens and more severe brain lesions during the late phase of infection compared to mice infected with the Nc-Spain 2H, Nc-Spain 3H or Nc-Spain 6 isolates. Furthermore, differences in the immunoglobulin IgG1 and IgG2a isotype kinetics induced by these isolates were observed, with a more rapid IgG2a response seen in mice infected with the Nc-Spain 2H and Nc-Spain 3H isolates. These results confirm the intra-species variability of N. caninum pathogenicity.