INNATE IMMUNE INTERFERENCE ATTENUATES INFLAMMATION IN BACILLUS ENDOPHTHALMITIS

ABSTRACTPURPOSEBacillus endophthalmitis is a sight-threatening bacterial infection that sometimes requires enucleation. Inflammation in this disease is driven by activation of innate Toll-like receptor (TLR) pathways. Here, we explored the consequences of innate immune interference on intraocular inflammatory responses during Bacillus endophthalmitis.METHODSEndophthalmitis was induced in mice by injecting 100 CFU Bacillus thuringiensis in to the mid-vitreous. We interfered with activation of the TLR2 and TLR4 pathways by 1) injecting a group of mice with S layer protein-deficient (ΔslpA) B. thuringiensis or 2) injecting a group of wild type (WT)-infected mice with a TLR2/4 inhibitor, oxidized phospholipid (OxPAPC). At 10 hours postinfection, infected eyes were removed and total RNA was purified. mRNA expression was then analyzed by NanoString using a murine inflammation panel. We compared findings with expression data from eyes infected with eyes injected with WT B. thuringiensis, eyes injected with OxPAPC alone, and uninfected eyes.RESULTSInterference of TLR2 and TLR4 pathways resulted in differential expression of mouse inflammatory genes compared to expression in WT-infected eyes. In WT-infected eyes, 56% of genes were significantly upregulated compared to that of uninfected controls. However, compared to WT-infected eyes, the expression of 27% and 50% of genes were significantly reduced in WT+OxPAPC and ΔslpA-infected eyes, respectively. The expression of 61 genes which were significantly upregulated in WT-infected eyes was decreased in WT+OxPAPC or ΔslpA-infected eyes. Interference with activation of the TLR2 and TLR4 pathways resulted in blunted expression of complement factors (C3, Cfb, and C6) and several innate genes such as TLR2, TLR4, TLR6, TLR8, MyD88, Nod2, Nlrp3, NF-κB, STAT3, RelA, RelB, and Ptgs2. Interference with activation of the TLR2 and TLR4 pathways also reduced the expression of several inflammatory cytokines such as CSF3, IL-6, IL-1β, CSF2, IL-1α, TNFα, IL-23α, TGFβ1, and IL-12β and chemokines CCL2, CCl3, CXCL1, CXCL2, CXCL3, CXCL5, CXCL9, and CXCL10. All of the aforementioned genes were significantly upregulated in WT-infected eyes.CONCLUSIONSThese results suggest that interfering with the activation of innate immune pathways during Bacillus endophthalmitis significantly reduced the intraocular inflammatory response. This positive clinical outcome could be a strategy for anti-inflammatory therapy of an infection typically refractory to corticosteroid treatment.

The Use of Analgesics during Vaccination with a Live Attenuated Yersinia pestis Vaccine Alters the Resulting Immune Response in Mice

The administration of antipyretic analgesics prior to, in conjunction with, or due to sequelae associated with vaccination is a common yet somewhat controversial practice. In the context of human vaccination, it is unclear if even short-term analgesic regimens can significantly alter the resulting immune response, as literature exists to support several scenarios including substantial immune interference. In this report, we used a live attenuated Yersinia pestis vaccine to examine the impact of analgesic administration on the immune response elicited by a single dose of a live bacterial vaccine in mice. Mice were assessed by evaluating natural and provoked behavior, as well as food and water consumption. The resulting immune responses were assessed by determining antibody titers against multiple antigens and assaying cellular responses in stimulated splenocytes collected from vaccinated animals. We observed no substantial benefit to the mice associated with the analgesic administration. Splenocytes from both C57BL/6 and BALB/c vaccinated mice receiving acetaminophen have a significantly reduced interferon-gamma (IFN-γ) recall response. Additionally, there is a significantly lower immunoglobulin (Ig)G2a/IgG1 ratio in vaccinated BALB/c mice treated with either acetaminophen or meloxicam and a significantly lower IgG2c/IgG1 ratio in vaccinated C57BL/6 mice treated with acetaminophen. Taken together, our data indicate that the use of analgesics, while possibly ethically warranted, may hinder the accurate characterization and evaluation of novel vaccine strategies with little to no appreciable benefits to the vaccinated mice.

Structure of the SARS-Unique Domain C From the Bat Coronavirus HKU4

Coronaviruses (CoVs) that cause infections such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome phylogenetically originate from bat CoVs. The coronaviral nonstructural protein 3 (nsp3) has been implicated in viral replication, polyprotein cleavage, and host immune interference. We report the structure of the C domain from the SARS-Unique Domain of bat CoV HKU4. The protein has a frataxin fold, consisting of 5 antiparallel β strands packed against 2 α helices. Bioinformatics analyses and nuclear magnetic resonance experiments were conducted to investigate the function of HKU4 C. The results showed that HKU4 C engages in protein-protein interactions with the nearby M domain of nsp3. The HKU4 C residues involved in protein-protein interactions are conserved in group 2c CoVs, indicating a conserved function.