A nano particle vector comprised of poly lactic-co-glycolic acid and monophosphoryl lipid A and recombinant Mycobacterium avium subsp paratuberculosis peptides stimulate a pro-immune profile in bovine macrophages

Polyanhydride nanoparticles encapsulating innate sensor agonists activate epithelial and airway cells and reduce Respiratory Syncytial Virus infection in mice

Acute respiratory tract infections (ARTI) are a leading cause of morbidity and mortality in infants worldwide. Considering the emergence of antimicrobial resistance as a global threat, there is increasing interest in immunomodulatory strategies to prevent respiratory infections. Since ARTIs are caused by several pathogens, immunomodulatory strategies aiming to engage innate responses represent a promising strategy to prevent ARTIs. Here, innate-stimulating nanoparticles (NPs) synthesized from combinations of polyanhydride copolymers and pattern recognition receptor (PRR) agonists were developed to increase disease resistance by activating innate mechanisms at the mucosal level. In vitro analysis on human and bovine respiratory epithelial cells showed that innate-sensor agonist-loaded NPs triggered transcription of inflammatory, antiviral, and antimicrobial mediators. Moreover, pre-treatment with NPs reduced human and bovine orthopneumovirus (RSV) infectious titers in vitro. Intranasal administration of PRR-containing polyanhydride NPs to mice led to transient production of cytokines and chemokines in lungs, suggesting immune activation. The immunogenicity and antiviral properties of NPs were dependent on both polyanhydride copolymer chemistry and the innate agonist encapsulated within the NPs. Prophylactic administration of NPs containing either TLR2/1, TLR4, or TLR2/7 agonists resulted in reduced RSV morbidity and viral lung loads. Selected NPs also showed protective effects when administered 14 days before infection. These results indicate that NPs efficiently prime human and bovine respiratory tract epithelial cells and trigger antiviral defenses in vitro and reduce RSV disease in mice. STATEMENT OF SIGNIFICANCE: Our research focuses on the use of polyanhydride nanoparticles (NPs) encapsulating innate sensor agonists to activate epithelial and airway cells. This innovative approach leverages the unique properties of nanotechnology to harness the innate immune system's potential, providing broad resistance against multiple pathogens. We designed a panel of PRR agonist-loaded polyanhydride NPs with varying chemistries and investigated their effectiveness as innate immunomodulators in the respiratory tract. We demonstrate that NPs activate protective innate immune responses in airway epithelial cells and reduce RSV infectious titers in vitro. NP-treated mice showed protection against RSV-induced morbidity and had reduced viral loads. These findings highlight the potential of polyanhydride NPs as a versatile platform for prophylactic intervention against respiratory viruses in both humans and livestock.

Vaccination of cattle with a virus vector vaccine against a major membrane protein of Mycobacterium avium subsp. paratuberculosis elicits CD8 cytotoxic T cells that kill intracellular bacteria

Analysis of the recall response ex vivo in cattle vaccinated with a Mycobacterium avium subsp. paratuberculosis (Map) rel deletion mutant revealed the immune response was directed toward a 35 kD major membrane protein (MMP) of Map. Antigen presenting cells (APC) primed with MMP elicited expansion of CD8 cytotoxic memory T cells (CTL) with ability to kill intracellular bacteria. Development of CTL was MHC-restricted. The gene MAP2121c, encoding MMP, was modified for expression of MMP (tPA-MMP-2mut) in a mammalian cell line to explore the potential of developing MMP as a vaccine. Ex vivo stimulation of PBMC, from Map free cattle, with APC primed with tPA-MMP-2mut expressed p35 elicited a primary CD8 CTL response comparable to the recall response elicited with PBMC from cattle vaccinated with either the Maprel deletion mutant or MMP. In the present study, the modified gene for MMP, now referred to as p35NN, was placed into a bovine herpes virus-4 (BoHV4) vector to determine the potential use of BoHV-4AΔTK-p35NN as a peptide-based vaccine. Subcutaneous vaccination of healthy cattle with BoHV-4AΔTK-p35NN elicited a CTL recall response, as detected ex vivo. The results show use of a virus vector is an effective way for delivery of MMP as a vaccine. The immunogenic activity of MMP was not lost when modified for expression in mammalian cells. The next step is to conduct a field trial to determine if presence of an immune response to MMP prevents Map from establishing an infection.

Progress towards the Elusive Mastitis Vaccines

Mastitis is a major problem in dairy farming. Vaccine prevention of mammary bacterial infections is of particular interest in helping to deal with this issue, all the more so as antibacterial drug inputs in dairy farms must be reduced. Unfortunately, the effectiveness of current vaccines is not satisfactory. In this review, we examine the possible reasons for the current shortcomings of mastitis vaccines. Some reasons stem from the peculiarities of the mammary gland immunobiology, others from the pathogens adapted to the mammary gland niche. Infection does not induce sterilizing protection, and recurrence is common. Efficacious vaccines will have to elicit immune mechanisms different from and more effective than those induced by infection. We propose focusing our research on a few points pertaining to either the current immune knowledge or vaccinology approaches to get out of the current deadlock. A possible solution is to focus on the contribution of cell-mediated immunity to udder protection based on the interactions of T cells with the mammary epithelium. On the vaccinology side, studies on the orientation of the immune response by adjuvants, the route of vaccine administration and the delivery systems are among the keys to success.

Nano drug delivery in intracellular bacterial infection treatments

The present work aimed to review the potential mechanisms used by macrophages to kill intracellular bacteria, their entrance to the cell, and mechanisms of escape of cellular immunity and applications of various nanoparticles. Since intracellular bacteria such as Mycobacterium and Brucella can survive in host cells and can resist the lethal power of macrophages, they can cause chronic disease or recur in 10-30% of cases in improved patients Nano drug-based therapeutics are promising tools for treating intracellular bacteria and preventing recurrence of the disease caused by these bacteria. In addition, among their unique features, we can mention the small size and the ability of these compounds to purposefully reach the target location.

Innate immune stimulation by monophosphoryl lipid A prevents chronic social defeat stress-induced anxiety-like behaviors in mice

Background

Innate immune pre-stimulation can prevent the development of depression-like behaviors in chronically stressed mice; however, whether the same stimulation prevents the development of anxiety-like behaviors in animals remains unclear. We addressed this issue using monophosphoryl lipid A (MPL), a derivative of lipopolysaccharide (LPS) that lacks undesirable properties of LPS but still keeps immune-enhancing activities.

Methods

The experimental mice were pre-injected intraperitoneally with MPL before stress exposure. Depression was induced through chronic social defeat stress (CSDS). Behavioral tests were conducted to identify anxiety-like behaviors. Real-time polymerase chain reaction (PCR) and biochemical assays were employed to examine the gene and protein expression levels of pro-inflammatory markers.

Results

A single MPL injection at the dose of 400 and 800 μg/kg 1 day before stress exposure prevented CSDS-induced anxiety-like behaviors, and a single MPL injection (400 μg/kg) five but not 10 days before stress exposure produced similar effect. The preventive effect of MPL on anxiety-like behaviors was also observed in CSDS mice who received a second MPL injection 10 days after the first MPL injection or a 4 × MPL injection 10 days before stress exposure. MPL pre-injection also prevented the production of pro-inflammatory cytokines in the hippocampus and medial prefrontal cortex in CSDS mice, and inhibiting the central immune response by minocycline pretreatment abrogated the preventive effect of MPL on CSDS-induced anxiety-like behaviors and pro-inflammatory cytokine productions in the brain.

Conclusions

Pre-stimulation of the innate immune system by MPL can prevent chronic stress-induced anxiety-like behaviors and neuroinflammatory responses in the brain in mice.

A peptide-based vaccine for Mycobacterium avium subspecies paratuberculosis

Recent efforts to develop a live attenuated vaccine against Mycobacterium avium subsp. paratuberculosis (Map), the causative agent of Johne's disease (JD), revealed relA is important in Map virulence. Deletion of the relA gene impairs the ability of Map to establish a persistent infection. Analysis of the basis for this observation revealed infection with a relA deletion mutant (ΔrelA) elicits development of cytotoxic CD8 T cells (CTL) with the ability to kill intracellular bacteria. Further analysis of the recall response elicited by ΔrelA vaccination showed a 35 kDa membrane peptide (MMP) is one of the targets of the immune response, suggesting it might be possible to develop a peptide-based vaccine based on MMP. To explore this possibility, ex vivo vaccination studies were conducted with MMP alone and incorporated into a nanoparticle (NP) vector comprised of poly (D, L-lactide-co-glycolide) and monophosphoryl lipid A (PLGA/MPLA). As reported, ex vivo vaccination studies showed CD8 CTL were elicited with classic and monocyte derived dendritic cells (cDC and MoDC) pulsed with MMP alone and incorporated into a PGLA/MPLA vector. Incorporation of MMP into a NP vector enhanced the ability of CD8 CTL to kill intracellular bacteria. The findings indicate incorporation of MMP into a PGLA/MPLA nanoparticle vector is one of the possible ways to develop a MMP based vaccine for Johne's disease.