Escheriosome entrapped soluble blood stage antigens impart protective immunity against a multi-drug resistant isolate of Plasmodium yoelii nigeriensis in BALB/c mice

Mast cells-derived exosomes worsen the development of experimental cerebral malaria

Cerebral malaria (CM) is the most severe neurological complication caused by Plasmodium falciparum infection. The accumulating evidence demonstrated that mast cells (MCs) and its mediators played a critical role in mediating malaria severity. Earlier studies identified that exosomes were emerging as key mediators of intercellular communication and can be released from several kinds of MCs. However, the potential functions and pathological mechanisms of MCs-derived exosomes (MCs-Exo) impacting on CM pathogenesis remain largely unknown. Herein, we utilized an experimental CM (ECM) model (C57BL/6 mice infected with P. berghei ANKA strain), and then intravenously (i.v.) injected MCs-Exo into P. berghei ANKA-infected mice to unfold this mechanism and investigate the effect of MCs-Exo on ECM pathogenies. We also used an in vitro model by investigating the pathogenesis development of brain microvascular endothelial cells line (bEnd.3 cells) co-cultured with P. berghei ANKA blood-stage soluble antigen (PbAg) after MCs-Exo treatment. The higher numbers of MCs and levels of MCs degranulation were observed in skin, cervical lymph node, and brain of ECM mice than those of the uninfected mice. Exosomes were successfully isolated from culture supernatants of mouse MCs line (P815 cells) and characterized by spherical vesicles with the diameter of 30-150 nm, and expression of typical exosomal markers (e.g., CD9, CD63, and CD81). The i.v. injection of MCs-Exo dramatically elevated incidence of ECM in the P. berghei ANKA-infected mice, exacerbated liver and brain histopathological damage, promoted Th1 cytokine response, aggravated brain vascular endothelial activation and blood brain barrier breakdown in ECM mice. In addition, the treatment of MCs-Exo led to the decrease of cells viability and mRNA levels of Ang-1, ZO-1, and Claudin-5, but increase of mRNA levels of Ang-2, CCL2, CXCL1, and CXCL9 in bEnd.3 cells co-cultured with PbAg in vitro. Taken together, our data indicated that MCs-Exo could worsen pathogenesis of ECM in mice.

Hypothesis: Designation of Liposomal Scavenger System for Fighting against 2019-nCoV

2019 novel coronavirus (2019-nCoV), also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 virus, is a member of the family Coronaviridae, which is responsible for the current pandemic of disease COVID-19. It is the seventh member of the family Coronaviridae, which infects humans, after 229E, OC43, NL63, HKU1, SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV). Fever, dry cough and severe pneumonia are seen as common symptoms at the early stages of COVID-19. Some cases progress to acute respiratory stress syndrome, septic shock, organ failure, and death. The development of an effective treatment or vaccination for treating or preventing this lethal condition is an urgent need in order to fight this crisis. Up to now, some effective vaccines with different efficacy profiles have been introduced. Herein, we have theoretically designed a scavenger system for gathering 2019-nCoVs, breaking them, and re-introducing them to the immune system.

The Use of Synthetic Carriers in Malaria Vaccine Design

Malaria vaccine research has been ongoing since the 1980s with limited success. However, recent improvements in our understanding of the immune responses required to combat each stage of infection will allow for intelligent design of both antigens and their associated delivery vaccine vehicles/vectors. Synthetic carriers (also known as vectors) are usually particulate and have multiple properties, which can be varied to control how an associated vaccine interacts with the host, and consequently how the immune response develops. This review comprehensively analyzes both historical and recent studies in which synthetic carriers are used to deliver malaria vaccines. Furthermore, the requirements for a synthetic carrier, such as size, charge, and surface chemistry are reviewed in order to understand the design of effective particle-based vaccines against malaria, as well as providing general insights. Synthetic carriers have the ability to alter and direct the immune response, and a better control of particle properties will facilitate improved vaccine design in the near future.

MAPK phosphotase 5 deficiency contributes to protection against blood-stage Plasmodium yoelii 17XL infection in mice

Cell-mediated immunity plays a crucial role in the development of host resistance to asexual blood-stage malaria infection. However, little is known of the regulatory factors involved in this process. In this study, we investigated the impact of MAPK phosphotase 5 (MKP5) on protective immunity against a lethal Plasmodium yoelii 17XL blood-stage infection using MKP5 knockout C57BL/6 mice. Compared with wild-type control mice, MKP5 knockout mice developed significantly lower parasite burdens with prolonged survival times. We found that this phenomenon correlated with a rapid and strong IFN-γ-dependent cellular immune response during the acute phase of infection. Inactivation of IFN-γ by the administration of a neutralizing Ab significantly reduced the protective effects in MKP5 knockout mice. By analyzing IFN-γ production in innate and adaptive lymphocyte subsets, we observed that MKP5 deficiency specifically enhanced the IFN-γ response mediated by CD4+ T cells, which was attributable to the increased stimulatory capacity of splenic CD11c+ dendritic cells. Furthermore, following vaccination with whole blood-stage soluble plasmodial Ag, MKP5 knockout mice acquired strongly enhanced Ag-specific immune responses and a higher level of protection against subsequent P. yoelii 17XL challenge. Finally, we found the enhanced response mediated by MKP5 deficiency resulted in a lethal consequence in mice when infected with nonlethal P. yoelii 17XNL. Thus, our data indicate that MKP5 is a potential regulator of immune resistance against Plasmodium infection in mice, and that an understanding of the role of MKP5 in manipulating anti-malaria immunity may provide valuable information on the development of better control strategies for human malaria.

The pH-sensitive fusogenic 3-methyl-glutarylated hyperbranched poly(glycidol)-conjugated liposome induces antigen-specific cellular and humoral immunity

We examined the ability of a novel liposome, surface modified by 3-methyl-glutarylated hyperbranched poly(glycidol) (MGlu-HPG), to enhance antigen-specific immunity in vitro and in vivo and to function as a vaccine carrier. Murine bone marrow-derived dendritic cells took up ovalbumin (OVA) encapsulated in MGlu-HPG-modified liposomes more effectively than free OVA or OVA encapsulated in unmodified liposomes. Immunization of mice with OVA-containing MGlu-HPG-modified liposomes induced antigen-specific splenocyte proliferation and production of gamma interferon (IFN-γ) more strongly than did immunization with free OVA or OVA encapsulated in unmodified liposomes. The immune responses induced by OVA encapsulated in MGlu-HPG-modified liposomes were significantly suppressed by addition of anti-major histocompatibility complex (MHC) class I and class II monoclonal antibodies, indicating the involvement of antigen presentation via MHC class I and II. Furthermore, delayed-type hypersensitivity responses and OVA-specific antibodies were induced more effectively in mice immunized with OVA encapsulated by MGlu-HPG-modified liposomes than with unencapsulated OVA or OVA encapsulated in unmodified liposomes. These results suggested that MGlu-HPG-modified liposomes effectively induced both cell-mediated and humoral immune responses. Collectively, this study is the first to demonstrate the induction of both cell-mediated and humoral immune responses in vivo by MGlu-HPG-modified liposomes.

Adjuvanticity and protective immunity of Plasmodium yoelii nigeriensis blood-stage soluble antigens encapsulated in fusogenic liposome

In our previous studies we established fusogenic properties of lipids isolated from edible yeast Saccharomyces cerevisiae (S. cerevisiae). We demonstrated that liposomes prepared from S. cerevisiae membrane lipid (saccharosome) can deliver encapsulated antigen into cytosol of the antigen presenting cells and elicit antigen specific cell mediated as well as humoral immune responses. In this study, we evaluated immunological behavior of saccharosome encapsulated cytosolic proteins (sAg) of Plasmodium yoelii nigeriensis in BALB/c mice. Immunization with antigen (sAg) encapsulated in saccharosome resulted in enhancement of CD4+ and CD8+ T cell populations and also up-regulated the expression of CD80 and CD86 molecules on the surface of antigen presenting cells. Further, immunization with saccharosome-encapsulated sAg-induced elevated levels of both IFN-gamma and IL-4 cytokines in the immunized mice when compared to egg PC liposome encapsulated sAg or its IFA emulsified form. Saccharosome-mediated immunization resulted in induction of high level of total antibody response with preponderance of IgG2a isotype as well. The data of this study suggest that saccharosome-based vehicle can emerge as an effective vaccine in imparting protection against various intracellular pathogens including Plasmodium yoelii nigeriensis.

Immunomodulator effect of picroliv and its potential in treatment against resistant Plasmodium yoelii (MDR) infection in mice

PURPOSE

The present study was envisaged to evaluate potential of combination therapy comprising of immunomodulator picroliv and antimalarial chloroquine against drug resistant Plasmodium yoelii (P. yoelii) infection in BALB/c mice.

METHODS

The immunomodulatory potential of picroliv was established by immunizing animals with model antigen along with picroliv. Immune response was assessed using T-cell proliferation assay and also by determining the antibody isotype-profile induced in the immunized mice. In the next set of experiment, prophylactic potential of picroliv to strengthen antimalarial properties of chloroquine against P. yoelii (MDR) infection in BALB/c mice was assessed.

RESULTS

T-cell proliferation as well as antibody production study reveals that picroliv helps in evoking strong immuno-potentiating response against model antigen in the immunized mice. Co-administration of picroliv enhances efficacy of CHQ against experimental murine malaria.

CONCLUSION

The activation of host immune system can increase the efficacy of chloroquine for suppression of drug resistant malaria infection in BALB/c mice.

Functional group/guild modelling of inter-specific pathogen interactions: a potential tool for predicting the consequences of co-infection

Although co-infection is the norm in most human and animal populations, clinicians currently have no practical tool to assist them in choosing the best treatment strategy for such patients. Given the vast range of potential pathogens which may co-infect the host, obtaining such a practical tool may seem an intractable problem. In ecology the joint concepts of functional groups and guilds have been used to conceptually simplify complex ecosystems, in order to understand how their component parts interact and may be manipulated. Here we propose a mechanism by which to apply these concepts to pathogen co-infection systems. Further, we describe how these groups could be incorporated into a mathematical modelling framework which, after validation, could be used as a clinical tool to predict the outcome of any particular combination of pathogens co-infecting a host.

Prophylactic potential of liposomized integral membrane protein of Plasmodium yoelii nigeriensis against blood stage infection in BALB/c mice

Triton X-114 phase separated integral membrane proteins (IMPs) of a multidrug resistant strain of Plasmodium yoelii nigeriensis (P. yoelii) were screened for their potential to impart protection against malaria infection in BALB/c mice. As revealed by immunoblotting, antibodies present in parasite specific sera from convalescent (protected) as well as immunized (partially protected) animals recognized different membrane proteins. A thorough investigation reveals that P. yoelii specific convalescent sera recognized IMPs with molecular masses ranging from 21 to 81 kDa. Among various membrane proteins, the IMPs corresponding to 81 and 66 kDa molecular weight were highly prominent in the immunoblots probed with the sera from convalescent animals, whereas sera from immunized animals failed to produce impressive band pattern. Immunofluorescence assay revealed that the 66-kDa IMP specific antibodies reacted with fixed smears of mature schizonts and merozoites. Further immunization with 66 kDa IMP (PyIMP) purified through polyclonal IgG sepharose 4B affinity did not impart effective immune response (in its free form) and could provided partial protection only. On the other hand, animals immunized with 66 kDa PyIMP entrapped in phosphatidyl-choline/cholesterol (PC/chol) liposomes protected BALB/c mice against lethal P. yoelii challenge.