Systemic cytokine and chemokine responses in immunized mice challenged with staphylococcal enterotoxin B

Dietary supplementation with spray-dried animal plasma improves vaccine protection in aged mice

Background

Senescence is characterized by an aggravated inflammatory state that reduces vaccine responsiveness. Dietary supplementation with spray-dried porcine plasma (SDP) exerts anti-inflammatory effects in different mucosal areas. We aimed to determine if the anti-inflammatory properties of SDP improve the efficiency of immunization in senescent animals.

Methods

Experiments were performed in 2-month-old and 6-month-old male SAMP8 mice fed control or SDP (8%) feeds for 4  months. The mice received nasal doses of 2.5  μg of Staphylococcus aureus enterotoxin B (SEB) or vehicle every 15  days (i.e., 3 times). Fifteen days after the last dose, a lethal shock was induced by intraperitoneal administration of SEB and LPS.

Results

Immunization increased anti-SEB IgA in intestinal and bronchoalveolar fluid (p < 0.05). After the lethal shock, all immunized aged mice that were supplemented with SDP survived, in contrast to only 66% of those fed the control feed (p < 0.05). Moreover, after the lethal challenge, aged mice showed higher expression levels of pro-inflammatory cytokines (Il-6, Tnf-α, Ifn-γ, and Il-1β) in jejunal and (Tnf-α, and Il-1β) in lung tissues (p < 0.05), which were reduced by SDP supplementation (p < 0.05). Furthermore, in senescent mice, SDP supplementation augmented Il-4 and Il-10 expression in both tissues (p < 0.05).

Conclusion

SDP reduces the mucosal inflammation associated with aging, improving vaccine protection in senescent mice.

Highly Ordered, Plasmonic Enhanced Inverse Opal Photonic Crystal for Ultrasensitive Detection of Staphylococcal Enterotoxin B

Although there is considerable interest in self-assembly of ordered, porous "inverse opal" structures for optical, electronic, and chemical applications, uncontrolled defect formation limits the usefulness of such materials. Herein, we develop a highly ordered and plasmonic enhanced sensing inverse opal photonic crystal (IOPC) material. The co-assembly of the colloidal template with the matrix material avoids the need for liquid penetration into the preassembled colloidal crystals and minimizes the associated rupture and inhomogeneity of the resulting IOPC. Au nanoparticles (Au NPs) not only act as a "bridge" between recognition elements (aptamers) and IOPCs, but also can amplify optical signals. Furthermore, the enhancement mechanism of Au NPs is simulated by COMSOL. During the detection process, the optical signal of the sensing Au-Apt IOPC responds to the Staphylococcal enterotoxin B with a concentration ranging from 10^-2 to 10³ pg mL^-1, and the limit of detection is 2.820 fg mL^-1. Spiked real sample detection indicates that the as-proposed method possessed good accuracy. The sensing Au-Apt IOPC provides an extensive biosensor platform to detect a variety of toxic and harmful substances through replacing the aptamer by other recognition elements, such as antibodies or receptors.

Determining the immunological characteristics of a novel human monoclonal antibody developed against staphylococcal enterotoxin B

Staphylococci are the main cause of nosocomial infections globally. The exotoxin staphylococcal enterotoxin B (SEB) produced by methicillin-resistant Staphylococcus aureus is a major cause of pathology after a staphylococcal infection. We previously isolated an anti-SEB human monoclonal antibody designated as M0313. Here we further characterize this antibody in vitro and in vivo. Immunoblotting analysis and ELISA results indicated that M0313 accurately recognized and bound to SEB. Its binding affinity to native SEB was measured at the low nM level. M0313 effectively inhibited SEB from inducing mouse splenic lymphocyte and human peripheral blood mononuclear cell proliferation and cytokine release in cell culture. M0313 also neutralized SEB toxicity in BALB/c female mice. Most importantly, M0313 promoted the survival of mice treated with SEB-expressing bacteria. In-vivo imaging revealed that M0313 treatment significantly reduced the replication of SEB-expressing bacteria in mice. The neutralization capacity of M0313 correlated with its ability to block SEB from binding to major histocompatibility complex II and T-cell receptor by binding to the SEB residues 85-102 and 90-92. Thus, the monoclonal antibody M0313 may be developed into a therapeutic agent.