Whole-cell vaccine coated with recombinant calreticulin enhances activation of dendritic cells and induces tumour-specific immune responses

Computational exploration and design of a multi-epitopes vaccine construct against Chlamydia psittaci

Chlamydia psittaci is an intracellular pathogen and causes variety of deadly infections in humans. Antibiotics are effective against C. psittaci however high percentage of resistant strains have been reported in recent times. As there is no licensed vaccine, we used in-silico techniques to design a multi-epitopes vaccine against C. psittaci. Following a step-wise protocol, the proteome of available 26 strains was retrieved and filtered for subcellular localized proteins. Five proteins were selected (2 extracellular and 3 outer membrane) and were further analyzed for B-cell and T-cell epitopes prediction. Epitopes were further checked for antigenicity, solubility, stability, toxigenicity, allergenicity, and adhesive properties. Filtered epitopes were linked via linkers and the 3D structure of the designed vaccine construct was predicted. Binding of the designed vaccine with immune receptors: MHC-I, MHC-II, and TLR-4 was analyzed, which resulted in docking energy scores of -4.37 kcal/mol, -0.20 kcal/mol and -22.38 kcal/mol, respectively. Further, the docked complexes showed stable dynamics with a maximum value of vaccine-MHC-I complex (7.8 Å), vaccine-MHC-II complex (6.2 Å) and vaccine-TLR4 complex (5.2 Å). As per the results, the designed vaccine construct reported robust immune responses to protect the host against C. psittaci infections. In the study, the C. psittaci proteomes were considered in pan-genome analysis to extract core proteins. The pan-genome analysis was conducted using bacterial pan-genome analysis (BPGA) software. The core proteins were checked further for non-redundant proteins using a CD-Hit server. Surface localized proteins were investigated using PSORTb v 3.0. The surface proteins were BLASTp against Virulence Factor Data Base (VFDB) to predict virulent factors. Antigenicity prediction of the shortlisted proteins was further done using VAXIGEN v 2.0. The epitope mapping was done using the immune epitope database (IEDB). A multi-epitopes vaccine was built and a 3D structure was generated using 3Dprot online server. The docking analysis of the designed vaccine with immune receptors was carried out using PATCHDOCK. Molecular dynamics and post-simulation analyses were carried out using AMBER v20 to decipher the dynamics stability and intermolecular binding energies of the docked complexes.Communicated by Ramaswamy H. Sarma.

Non-thermal plasma modulates cellular markers associated with immunogenicity in a model of latent HIV-1 infection

Effective control of infection by human immunodeficiency virus type 1 (HIV-1), the causative agent of the acquired immunodeficiency syndrome (AIDS), requires continuous and life-long use of anti-retroviral therapy (ART) by people living with HIV-1 (PLWH). In the absence of ART, HIV-1 reemergence from latently infected cells is ineffectively suppressed due to suboptimal innate and cytotoxic T lymphocyte responses. However, ART-free control of HIV-1 infection may be possible if the inherent immunological deficiencies can be reversed or restored. Herein we present a novel approach for modulating the immune response to HIV-1 that involves the use of non-thermal plasma (NTP), which is an ionized gas containing various reactive oxygen and nitrogen species (RONS). J-Lat cells were used as a model of latent HIV-1 infection to assess the effects of NTP application on viral latency and the expression of pro-phagocytic and pro-chemotactic damage-associated molecular patterns (DAMPs). Exposure of J-Lat cells to NTP resulted in stimulation of HIV-1 gene expression, indicating a role in latency reversal, a necessary first step in inducing adaptive immune responses to viral antigens. This was accompanied by the release of pro-inflammatory cytokines and chemokines including interleukin-1β (IL-1β) and interferon-γ (IFN-γ); the display of pro-phagocytic markers calreticulin (CRT), heat shock proteins (HSP) 70 and 90; and a correlated increase in macrophage phagocytosis of NTP-exposed J-Lat cells. In addition, modulation of surface molecules that promote or inhibit antigen presentation was also observed, along with an altered array of displayed peptides on MHC I, further suggesting methods by which NTP may modify recognition and targeting of cells in latent HIV-1 infection. These studies represent early progress toward an effective NTP-based ex vivo immunotherapy to resolve the dysfunctions of the immune system that enable HIV-1 persistence in PLWH.

A Generic Coordination Assembly-Enabled Nanocoating of Individual Tumor Cells for Personalized Immunotherapy

A generic and effective tumor cells encapsulation strategy enabled by metal-organic coordination is developed to prepare a vaccine for personalized immunotherapy. Specifically, an epigallocatechin-3-gallate (EGCG)-Al(III) coordination layer is in situ formed onto individual living cells in aqueous phase and the process can be completed within an hour. 98% of proteins in the cells are entrapped within the microparticles, which are endowed with high antigens loading capacity. The microparticles enhance the uptake efficiency of antigens, protect antigens from degradation in vivo, and delay the retention time of antigens in the lymph nodes. Moreover, dendritic cells (DCs) activation is triggered by the microparticles, and simultaneously, the expression of costimulation marker on DCs and the production of Th1-related cytokines are significantly upregulated. Moreover, six kinds of tumor cells are utilized and successfully coated with the EGCG/Al(III) layer, suggesting the generalization of this strategy. More importantly, the microparticles exhibit a comparative antitumor effect with polyinosinic-polycytidylic acid (PolyI:C) in B16 pulmonary metastasis model. Overall, the encapsulation strategy enabled by metal-organic coordination can be potentially useful for personalized immunotherapy customized to individual patient's tumor cells.

Coordination microparticle vaccines engineered from tumor cell templates

A microparticle vaccine was developed by encapsulating individual tumor cells with an EGCG–Al(iii) coordination layer, efficiently internalized via actin polymerization and clathrin-mediated endocytosis.

The Interplay Between Pattern Recognition Receptors and Autophagy in Inflammation

Pattern recognition receptors (PRRs) are sensors of exogenous and endogenous "danger" signals from pathogen-associated molecular patterns (PAMPs), and damage associated molecular patterns (DAMPs), while autophagy can respond to these signals to control homeostasis. Almost all PRRs can induce autophagy directly or indirectly. Toll-like receptors (TLRs), Nod-like receptors (NLRs), retinoic acid-inducible gene-I-like receptors (RLRs), and cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway can induce autophagy directly through Beclin-1 or LC3-dependent pathway, while the interactions with the receptor for advanced glycation end products (RAGE)/high mobility group box 1 (HMGB1), CD91/Calreticulin, and TLRs/HSPs are achieved by protein, Ca2⁺, and mitochondrial homeostasis. Autophagy presents antigens to PRRs and helps to clean the pathogens. In addition, the induced autophagy can form a negative feedback regulation of PRRs-mediated inflammation in cell/disease-specific manner to maintain homeostasis and prevent excessive inflammation. Understanding the interaction between PRRs and autophagy in a specific disease will promote drug development for immunotherapy. Here, we focus on the interactions between PRRs and autophagy and how they affect the inflammatory response.

Endoplasmic reticulum stress-mediated membrane expression of CRT/ERp57 induces immunogenic apoptosis in drug-resistant endometrial cancer cells

OBJECTIVE

To investigate the role of endoplasmic reticulum (ER) stress-mediated CRT/ERp57 complex expression underlying the mechanism of resistance to doxorubicin (DOX) in endometrial carcinoma (EC) in vivo and in vitro.

METHODS

The expression of CRT, ERp57, p-PERK, eIF2α, p-eIF2α in EC patients and EC cells was detected by Western blots and by immunofluorescence assay. MTT assay was used to determine the LC50 of EC cells to DOX and cell viability. Apoptosis was assayed using flow cytometer. The protein expression of PERK, cleaved-caspase-8, p-eIF2α and CHOP were detected by Western blot, and the expression of VAMP-1, SNAP23 and PERK was knockdown by siRNA and/or shRNA. The expression of CRT/ERp57 complex was detected by flow cytometry. In addition, the expression of eIF2α and p-eIF2α was detected by Western blot analysis after drug-resistant EC cells were transfected with lentivirus overexpressing CRT, treated with GADD34 inhibitor and ES stress inducer. MTT assay was used to detect the phagocytic activity of T cells induced by maturation of dendritic cells in drug-resistant EC cells.

RESULTS

The expression of CRT, ERp57, p-PERK and p-eIF2α was significantly decreased in the drug-resistant patients in EC patients. The IC₅₀ of the drug-resistant EC cells was 10 times higher than that of the wild type cells. In the drug-resistant EC cells the expression of CRT, ERp57, p-PERK, p-eIF2α, caspase-8 and CHOP was significantly lower than in the wild type cells. After treatment with DOX, CRT and ER stress-related proteins p-PERK, p-eIF2α, caspase-8 and apoptosis were significantly increased in wild-type EC cells, but not in drug-resistant EC cells. The increased expressions led to inhibition of cell growth and apoptosis. The knockdown of PERK gene and addition of DOX resulted in significant decrease of cleaved-caspase 8 and p-eIF2α in sensitive EC cells. The expression of CRT/ERp57 in sensitive EC cells was further significantly decreased by blocking VAMP and SNAP23. In addition, transfection with CRT overexpressing lentivirus and addition of GADD34 inhibitor and ER stress inducer in drug-resistant EC cells revealed a significant increase in the expression of CRT/ERp57 complex and p-eIF2α when DOX was added simultaneously, which promoted the maturation and chemotaxis of T lymphocytes to phagocytose drug-resistant EC cells.

CONCLUSION

DOX can induce the death of tumor cells by ER stress-mediated CRT/ERp57 expression in EC cells. Induction of ER stress in drug-resistant EC cells up-regulates the membrane expression of CRT/ERp57, enhances phagocytosis, induces immunogenic apoptosisand sensitizes the cells to DOX.

Apoptotic Melanoma B16-F1 Cells Induced by Lidamycin Could Initiate the Antitumor Immune Response in BABL/c Mice

In the process of tumor cell apoptosis induced by specific regents, calreticulin (CRT) was transferred from endoplasmic reticulum (ER) onto the cell membrane. These tumor cells, when used as the cellular vaccine to immunize experimental animals, could initiate effective antitumor immunoresponse against homologous tumor cells. This is referred to as immunogenic cell death. Lidamycin (LDM) is an enediyne antibiotic, which has extremely potent cytotoxicity to cancer cells. In this study, the mouse melanoma B16-F1 cancer cells were used to investigate the ability of LDM in promoting immunogenic cell death. Our data showed that LDM could induce apoptosis of B16-F1 cancer cells, accompanied by CRT translocation onto the cell membrane. These LDM-treated B16-F1 cells could be recognized and phagocytosed more efficiently by macrophage and dendritic cells. When the LDM-treated apoptotic B16-F1 cells were used as a whole-cell tumor vaccine to immune mice, the mice obtained resistance against rechallenged B16-F1 living cells. At the same time, the specific antitumor immune response was observed in these vaccinated mice. The splenocytes from the mice vaccinated with LDM-treated B16-F1 cells showed significantly enhanced NK lymphocyte activities and also faster growth rate and increased secretion of IFN-γ when encountering the cellular antigens from B16-F1 cells. All these results suggested that LDM could promote immunogenic cell death in B16-F1 cells, and these LDM-treated B16-F1 cells could be used as a sort of cell vaccine to initiate effective antitumor immunoresponse in mice.

Endoplasmic reticulum chaperones and oxidoreductases: critical regulators of tumor cell survival and immunorecognition

Endoplasmic reticulum (ER) chaperones and oxidoreductases are abundant enzymes that mediate the production of fully folded secretory and transmembrane proteins. Resisting the Golgi and plasma membrane-directed “bulk flow,” ER chaperones and oxidoreductases enter retrograde trafficking whenever they are pulled outside of the ER by their substrates. Solid tumors are characterized by the increased production of reactive oxygen species (ROS), combined with reduced blood flow that leads to low oxygen supply and ER stress. Under these conditions, hypoxia and the unfolded protein response upregulate their target genes. When this occurs, ER oxidoreductases and chaperones become important regulators of tumor growth. However, under these conditions, these proteins not only promote the folding of proteins, but also alter the properties of the plasma membrane and hence modulate tumor immune recognition. For instance, high levels of calreticulin serve as an “eat-me” signal on the surface of tumor cells. Conversely, both intracellular and surface BiP/GRP78 promotes tumor growth. Other ER folding assistants able to modulate the properties of tumor tissue include protein disulfide isomerase (PDI), Ero1α and GRP94. Understanding the roles and mechanisms of ER chaperones in regulating tumor cell functions and immunorecognition will lead to important insight for the development of novel cancer therapies.