Heat Shock Proteins 90 kDa: Immunomodulators and Adjuvants in Vaccine Design Against Infectious Diseases

A study of antigen selection by extracellular vesicles as vaccine candidates against Mycobacterium tuberculosis infection

Introduction. Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis (M. tb), remains a significant global public health concern. It is crucial to develop more effective vaccines for TB in order to achieve global control of the disease. Extracellular vesicles (EVs) are spherical membrane-bound structures released by pathogens and host cells. During the course of an infection, both pathogen- and host-derived EVs are produced and play important roles in determining the course of the infection. EVs offer intriguing tools as potential vaccines due to their ability to deliver multiple pathogen or host antigens.Hypothesis /Gap Statement. We hypothesized that EVs derived from M. tb and EVs from M. tb-infected macrophages may serve as potential vaccine candidates against M. tb infection.Aim. This study aims to compare the immunogenicity and immune protection between M. tb EVs and M. tb-infected macrophage-derived EVs.Methodology. In this study, EVs were extracted from culture supernatants of M. tb and M. tb-infected macrophages, respectively. Mass spectrometry was employed to explore the antigen composition of H37Rv-Mφ-EVs and H37Rv-EVs. Cytokine profiling and antibody response assays were used to analyse the immunogenicity offered by EVs. Additionally, we used histological examination to evaluate and protective efficacy of the EVs.Results. Our results demonstrated that mice immunized by EVs released from M. tb-infected macrophages induced stronger inflammatory cytokine response than M. tb. Moreover, EVs from M. tb-infected macrophages reinforced T-cell activation and antibody response compared to M. tb EVs. Proteomic analysis revealed that EVs from M. tb-infected macrophages containing immunodominant cargos have stronger binding ability with major histocompatibility complex molecules, which may contribute to the protection from M. tb infection. Indeed, immunization of EVs released from M. tb-infected macrophages significantly reduced the bacterial load and better protection against M. tb infection than EVs from M. tb. Importantly, the selected antigens (Ag85B, ESAT-6 and the Rv0580c) from EVs of M. tb-infected macrophages exhibited effective immunogenicity.Conclusion. Our results suggested that EVs derived from M. tb-infected macrophages might serve as a proper antigenic library for vaccine candidates against M. tb challenge.

Safe plant Hsp90 adjuvants elicit an effective immune response against SARS-CoV2-derived RBD antigen

To better understand the role of pHsp90 adjuvant in immune response modulation, we proposed the use of the Receptor Binding Domain (RBD) of the Spike protein of SARS-CoV2, the principal candidate in the design of subunit vaccines. We evaluated the humoral and cellular immune responses against RBD through the strategy "protein mixture" (Adjuvant + Antigen). The rRBD adjuvanted with rAtHsp81.2 group showed a higher increase of the anti-rRBD IgG1, while the rRBD adjuvanted with rNbHsp90.3 group showed a significant increase in anti-rRBD IgG2b/2a. These results were consistent with the cellular immune response analysis. Spleen cell cultures from rRBD + rNbHsp90.3-immunized mice showed significantly increased IFN-γ production. In contrast, spleen cell cultures from rRBD + rAtHsp81.2-immunized mice showed significantly increased IL-4 levels. Finally, vaccines adjuvanted with rNbHsp90.3 induced higher neutralizing antibody responses compared to those adjuvanted with rAtHsp81.2. To know whether both chaperones must form complexes to generate an effective immune response, we performed co-immunoprecipitation (co-IP) assays. The results indicated that the greater neutralizing capacity observed in the rRBD adjuvanted with rNbHsp90.3 group would be given by the rRBD-rNbHsp90.3 interaction rather than by the quality of the immune response triggered by the adjuvants. These results, together with our previous results, provide a comparative benchmark of these two novel and safe vaccine adjuvants for their capacity to stimulate immunity to a subunit vaccine, demonstrating the capacity of adjuvanted SARS-CoV2 subunit vaccines. Furthermore, these results revealed differences in the ability to modulate the immune response between these two pHsp90s, highlighting the importance of adjuvant selection for future rational vaccine and adjuvant design.

Targeting Plasmodium Life Cycle with Novel Parasite Ligands as Vaccine Antigens

The WHO reported an estimated 249 million malaria cases and 608,000 malaria deaths in 85 countries in 2022. A total of 94% of malaria deaths occurred in Africa, 80% of which were children under 5. In other words, one child dies every minute from malaria. The RTS,S/AS01 malaria vaccine, which uses the Plasmodium falciparum circumsporozoite protein (CSP) to target sporozoite infection of the liver, achieved modest efficacy. The Malaria Vaccine Implementation Program (MVIP), coordinated by the WHO and completed at the end of 2023, found that immunization reduced mortality by only 13%. To further reduce malaria death, the development of a more effective malaria vaccine is a high priority. Three malaria vaccine targets being considered are the sporozoite liver infection (pre-erythrocytic stage), the merozoite red blood cell infection (asexual erythrocytic stage), and the gamete/zygote mosquito infection (sexual/transmission stage). These targets involve specific ligand-receptor interactions. However, most current malaria vaccine candidates that target two major parasite population bottlenecks, liver infection, and mosquito midgut infection, do not focus on such parasite ligands. Here, we evaluate the potential of newly identified parasite ligands with a phage peptide-display technique as novel malaria vaccine antigens.

Immunostimulatory effects of Hsp70 fragments and Hsp27 in design of novel HIV-1 vaccine formulations

BACKGROUND

Heat shock proteins (HSPs) as an adjuvant induce antigen-specific immunity through facilitating antigen presentation and stimulating T cells. In this study, the immunostimulatory properties of two major fragments of Hsp70 (N-Hsp70(aa 1-387) with ATPase property and C-Hsp70 (aa 508-641) with peptide-binding capacity) and the full length of Hsp27 as vaccine adjuvants were evaluated to boost HIV-1 Nef antigen-specific immunity in both in vitro and in vivo experiments.

METHODS

At first, the nanoparticles harbouring DNA fusion constructs (i.e. N-Hsp70-Nef, C-Hsp70-Nef and Hsp27-Nef) complexed with HIV Rev (34-50) cell-penetrating peptide were generated to deliver DNA into the cells. Then, the recombinant Nef, Hsp27-Nef, N-Hsp70-Nef and C-Hsp70-Nef proteins were generated in E.coli expression system. Next, the immunostimulatory properties of these fusion constructs were evaluated in both in vitro and in vivo studies. Finally, the secretion of main cytokines from single-cycle replicable (SCR) HIV-1 virion-exposed splenocytes was investigated.

RESULTS

Our data showed that the stable and non-toxic DNA/Rev nanoparticles could successfully deliver the genes of interest into the cells. Moreover, higher secretion of antibodies and cytokines was detected in mice receiving the Hsp-Nef constructs than in mice receiving Nef antigen. The C-Hsp70 was also superior for inducing Nef-specific Th1 and CTL immunity compared with N-Hsp70 and Hsp27. The T-cell activity was maintained in the SCR-exposed splenocytes, especially the splenocytes of mice receiving the C-Hsp70-Nef regimen.

CONCLUSION

Altogether, these findings demonstrate the significance of Hsps as enhancers of antigen-specific immunity. Notably, the C-Hsp70 region showed better adjuvant properties for inducing cellular immunity in the improvement of HIV-1 therapeutic vaccines.

Association of single nucleotide polymorphisms in heat stress protein 70 (HSP70) and 90 (HSP90) with the susceptibility of Pakistani sheep breeds to hemoparasitic infections

The present study was designed to report the genotypic and allelic frequency of single nucleotide polymorphism (SNP) at 222 G > A in HSP70 and at ex6-7390T22G in the HSP90 gene of 204 sheep (Baluchi = 11, Kajli = 29, Latti = 06 and Mundri = 158) enrolled from District Rajanpur in Punjab and to report the susceptibility of these sheep to the blood-borne parasitic infection. The tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) approach revealed a significant variation (p < 0.001) in the genotype frequency of four enrolled sheep breeds at SNP 222 G > A in the HSP70 gene while the allelic frequency remained unaffected (p = 0.08). In all sheep breeds, GG (wild) genotype was most common. T-ARMS-PCR analysis revealed a similar trend for ex6-7390T22G in the HSP90 gene and it was observed that sheep had significantly higher wild-type (GG) (p < 0.05) at the studied SNPs. Studied epidemiological factors (sex and sampling sites) were not found associated with both SNPs. Chi-square test revealed that no specific genotype and allelic frequency at 222 G > A in HSP70 and at ex6-7390T22G in the HSP90 gene of the enrolled sheep breed was associated with the susceptibility to blood-borne parasitic infection (p > 0.05). In conclusion, we are reporting that Pakistan is blessed to have majority of sheep, from all breeds, having wild genotype at analyzed SNPs in heat stress genes. We highly recommend the genotypic screening of sheep before their selection as breeders to reduce the possibility of having sheep with polymorphic genotypes at 222 G > A in HSP70 and at 7390T22G in HSP90 genes that will improve the profitability and sustainability of animal production systems in Pakistan.

A CO-mediated photothermal therapy to kill drug-resistant bacteria and minimize thermal injury for infected diabetic wound healing

With an increasing proportion of drug-resistant bacteria, photothermal therapy (PTT) is a promising alternative to antibiotic treatment for infected diabetic skin ulcers. However, the inevitable thermal damage to the tissues restricts its clinical practice. Carbon monoxide (CO), as a bioactive gas molecule, can selectively inhibit bacterial growth and promote tissue regeneration, which may be coordinated with PTT for drug-resistant bacteria killing and tissue protection. Herein, a CO-mediated PTT agent (CO@mPDA) was engineered by loading manganese carbonyl groups into mesoporous polydopamine (mPDA) nanoparticles via coordination interactions between the metal center and a catechol group. Compared to the traditional PTT, the CO-mediated PTT increases the inhibition ratio of the drug-resistant bacteria both in vitro and in diabetic wound beds by selectively inhibiting the co-chaperone of the heat shock protein 90 kDa (Hsp90), and lowers the heat resistance of the bacteria rather than the mammalian tissues. Meanwhile, the tissue-protective proteins, such as Hsp90 and vimentin (Vim), are upregulated via the WNT and PI3K-Akt pathways to reduce thermal injury, especially with a laser with a high-power density. The CO-mediated PTT unified the bacterial killing with tissue protection, which offers a promising concept to improve PTT efficiency and minimize the side-effects of PTT when treating infected skin wounds.

Unraveling the Virulence Factors and Secreted Proteins of an Environmental Isolate Enterobacter sp. S-16

Members of the Enterobacter genus include many pathogenic microbes of humans and plants, secrete proteins that contribute to the interactions of bacteria and their environment. Therefore, understanding of secreted proteins is vital to understand bacterial physiology and behavior. Here, we explored the secretome of an environmental isolate Enterobacter sp. S-16 by nanoLC-MS/MS and identified 572 proteins in the culture supernatant. Gene ontology (GO) analysis indicated that proteins were related to biological processes, molecular as well as cellular functions. The majority of the identified proteins are involved in microbial metabolism, chemotaxis & motility, flagellar hook-associated proteins, biosynthesis of antibiotics, and molecular chaperones to assist the protein folding. Bioinformatics analysis of the secretome revealed the presence of type I and type VI secretion system proteins. Presence of these diverse secretion system proteins in Enterobacter sp. S-16 are likely to be involved in the transport of various proteins including nutrient acquisition, adhesion, colonization, and homeostasis maintenance. Among the secreted bacterial proteins with industrial importance, lignocellulolytic enzymes play a major role, therefore, we analyzed our secretome results for any presence of glycoside hydrolases (GHs) and other hydrolytic enzymes (CAZymes). Overall, the secreted proteins may be considered an attractive reservoir of potential antigens for drug development, diagnostic markers, and other biomedical applications.

Organismal Roles of Hsp90

Heat shock protein 90 (Hsp90) is a highly conserved molecular chaperone that assists in the maturation of many client proteins involved in cellular signal transduction. As a regulator of cellular signaling processes, it is vital for the maintenance of cellular proteostasis and adaptation to environmental stresses. Emerging research shows that Hsp90 function in an organism goes well beyond intracellular proteostasis. In metazoans, Hsp90, as an environmentally responsive chaperone, is involved in inter-tissue stress signaling responses that coordinate and safeguard cell nonautonomous proteostasis and organismal health. In this way, Hsp90 has the capacity to influence evolution and aging, and effect behavioral responses to facilitate tissue-defense systems that ensure organismal survival. In this review, I summarize the literature on the organismal roles of Hsp90 uncovered in multicellular organisms, from plants to invertebrates and mammals.

Heat Shock Protein 90's Mechanistic Role in Contact Hypersensitivity

Despite the known dangers of contact allergens and their long-lasting use as models in immunology, their molecular mode of action largely remains unknown. In this study, we report that a contact allergen, 1-chloro-2,4-dinitrobenzene (DNCB), elicits contact hypersensitivity through binding the protein we identify. Starting from an unbiased sampling of proteomics, we found nine candidate proteins with unique DNCB-modified peptide fragments. More than half of these fragments belonged to heat shock protein 90 (HSP90), a common stress-response protein and a damage-associated molecular pattern, and showed the highest probability of incidence. Inhibition and short hairpin RNA knockdown of HSP90 in human monocyte cell line THP-1 suppressed the potency of DNCB by >80%. Next, we successfully reduced DNCB-induced contact hypersensitivity in HSP90-knockout mice, which confirmed our findings. Finally, we hypothesized that DNCB-modified HSP90 activates the immune cells through HSP90's receptor, CD91. Pretreatment of CD91 in THP-1 cell lines and BALB/c mice attenuated the potency of DNCB, consistent with the result of HSP90-knockout mice. Altogether, our data show that DNCB-HSP90 binding plays a role in mediating DNCB-induced contact hypersensitivity, and the activation of CD91 by DNCB-modified HSP90 proteins could mediate this process.

Oral Immunization With a Plant HSP90-SAG1 Fusion Protein Produced in Tobacco Elicits Strong Immune Responses and Reduces Cyst Number and Clinical Signs of Toxoplasmosis in Mice

Plant 90kDa heat shock protein (HSP90) is a potent adjuvant that increases both humoral and cellular immune responses to diverse proteins and peptides. In this study, we explored whether Arabidopsis thaliana HSP90 (AtHsp81.2) can improve the immune effects of a Toxoplasma gondii surface antigen 1 (SAG1). We designed two constructs containing the sequence of mature antigen (SAG1m), from aa77 to aa322, and B- and T-cell antigenic epitope-containing SAG1HC, from aa221 to aa319 fused to AtHsp81.2 sequence. When comparing the transient expression in Nicotiana tabacum X-27-8 leaves, which overexpress the suppressor helper component protease HC-Pro-tobacco etch virus (TEV), to that in N. benthamiana leaves, co-agroinfiltrated with the suppressor p19, optimal conditions included 6-week-old N. benthamiana plants, 7-day time to harvest, Agrobacterium tumefaciens cultures with an OD600nm of 0.6 for binary vectors and LED lights. While AtHsp81.2-SAG1m fusion protein was undetectable by Western blot in any of the evaluated conditions, AtHsp81.2-SAG1HC was expressed as intact fusion protein, yielding up to 90μg/g of fresh weight. Besides, the AtHsp81.2-SAG1HC mRNA was strongly expressed compared to the endogenous Nicotiana tabacum elongation factor-alpha (NtEFα) gene, whereas the AtHsp81.2-SAG1m mRNA was almost undetectable. Finally, mice were orally immunized with AtHsp81.2-SAG1HC-infiltrated fresh leaves (plAtHsp81.2-SAG1HC group), recombinant AtHsp81.2-SAG1HC purified from infiltrated leaves (rAtHsp81.2-SAG1HC group), non-infiltrated fresh leaves (control group), or phosphate-buffered saline (PBS group). Serum samples from plAtHsp81.2-SAG1HC-immunized mice had significantly higher levels of IgGt, IgG2a, and IgG2b anti-SAG1HC antibodies than serum from rAtHsp81.2-SAG1HC, control, and PBS groups. The number of cysts per brain in the plAtHsp81.2-SAG1HC-immunized mice was significantly reduced, and the parasite load in brain tissue was also lower in this group compared with the remaining groups. In an immunoblot assay, plant-expressed AtHsp81.2-SAG1HC was shown to react with antibodies present in sera from T. gondii-infected people. Therefore, the plant expression of a T. gondii antigen fused to the non-pathogenic adjuvant and carrier plant HSP90 as formulations against T. gondii can improve the vaccine efficacy, and plant extract can be directly used for vaccination without the need to purify the protein, making this platform a suitable and powerful biotechnological system for immunogenic antigen expression against toxoplasmosis.

Which one of the thermal approaches (heating DNA or cells) enhances the gene expression in mammalian cells?

OBJECTIVES

Heat treatment as a physical method could increase the cellular uptake of nucleic acids. In this study, the effects of heat shock were evaluated to enhance the transfection efficiency of three plasmid DNAs into HeLa and TC-1 cancerous, and HEK-293 T and Vero non-cancerous cell lines using lipofectamine 2000 reagent.

METHODS

Two methods of cell- and DNA-based heat treatment were used. Heating DNA solution was performed at 94 °C for 5, 10 and 15 min, and also 72 °C for 30, 60 and 120 min, individually. Moreover, heating the cells was done by incubation at 42 °C for 2 h in different times such as before, during and after DNA transfection.

RESULTS

Our data showed that the conformation of plasmid DNAs was changed at different temperatures with increasing time. The heat-treated plasmid DNAs (94 °C for 10 min or 72 °C for 30 min) indicated higher transfection efficiency than untreated plasmid DNAs (p < 0.05). Furthermore, heat treatment of cells before and during the transfection was higher than untreated cells (p < 0.01). Our results demonstrated that DNA transfection efficiency in cancerous cells was less than non-cancerous cells (p < 0.01).

CONCLUSION

Generally, these findings showed that transfection mediated by thermal stimulation could enhance gene transfection in mammalian cell lines.