scholarly journals Protection against malaria in mice is induced by blood stage–arresting histamine-releasing factor (HRF)–deficient parasites

2016 ◽  
Vol 213 (8) ◽  
pp. 1419-1428 ◽  
Author(s):  
Claudia Demarta-Gatsi ◽  
Leanna Smith ◽  
Sabine Thiberge ◽  
Roger Peronet ◽  
Pierre-Henri Commere ◽  
...  
Keyword(s):  
Immune Responses ◽  
Plasmodium Berghei ◽  
Blood Cells ◽  
Housekeeping Genes ◽  
Blood Stage ◽  
Parasite Development ◽  
Rodent Models ◽  
Cell Responses ◽  
Blood Stage Malaria

Although most vaccines against blood stage malaria in development today use subunit preparations, live attenuated parasites confer significantly broader and more lasting protection. In recent years, Plasmodium genetically attenuated parasites (GAPs) have been generated in rodent models that cause self-resolving blood stage infections and induce strong protection. All such GAPs generated so far bear mutations in housekeeping genes important for parasite development in red blood cells. In this study, using a Plasmodium berghei model compatible with tracking anti–blood stage immune responses over time, we report a novel blood stage GAP that lacks a secreted factor related to histamine-releasing factor (HRF). Lack of HRF causes an IL-6 increase, which boosts T and B cell responses to resolve infection and leave a cross-stage, cross-species, and lasting immunity. Mutant-induced protection involves a combination of antiparasite IgG2c antibodies and FcγR+ CD11b+ cell phagocytes, especially neutrophils, which are sufficient to confer protection. This immune-boosting GAP highlights an important role of opsonized parasite-mediated phagocytosis, which may be central to protection induced by all self-resolving blood stage GAP infections.

scholarly journals Role of CD28 in Polyclonal and Specific T and B Cell Responses Required for Protection against Blood Stage Malaria

2005 ◽  
Vol 174 (2) ◽  
pp. 790-799 ◽  
Author(s):  
Rosa M. Elias ◽  
Luiz R. Sardinha ◽  
Karina R. B. Bastos ◽  
Cláudia A. Zago ◽  
Ana Paula Freitas da Silva ◽  
...  
Keyword(s):  
B Cell ◽  
Blood Stage ◽  
Cell Responses ◽  
B Cell Responses ◽  
Blood Stage Malaria

scholarly journals The role of B7 family molecules in hematologic malignancy

Blood ◽  
2013 ◽  
Vol 121 (5) ◽  
pp. 734-744 ◽  
Author(s):  
Paul Greaves ◽  
John G. Gribben
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Immune Responses ◽  
Hematologic Malignancy ◽  
Surface Proteins ◽  
Cell Responses ◽  
Inducible Costimulator ◽  
Programmed Cell Death 1 ◽  
B7 Family

AbstractThe B7 family consists of structurally related, cell-surface proteins that regulate immune responses by delivering costimulatory or coinhibitory signals through their ligands. Eight family members have been identified to date including CD80 (B7-1), CD86 (B7-2), CD274 (programmed cell death-1 ligand [PD-L1]), CD273 (programmed cell death-2 ligand [PD-L2]), CD275 (inducible costimulator ligand [ICOS-L]), CD276 (B7-H3), B7-H4, and B7-H6. B7 ligands are expressed on both lymphoid and nonlymphoid tissues. The importance of the B7 family in regulating immune responses is clear from their demonstrated role in the development of immunodeficiency and autoimmune diseases. Manipulation of the signals delivered by B7 ligands shows great potential in the treatment of cancers including leukemias and lymphomas and in regulating allogeneic T-cell responses after stem cell transplantation.

scholarly journals IgM in human immunity to Plasmodium falciparum malaria

2019 ◽  
Vol 5 (9) ◽  
pp. eaax4489 ◽  
Author(s):  
M. J. Boyle ◽  
J. A. Chan ◽  
I. Handayuni ◽  
L. Reiling ◽  
G. Feng ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Blood Cells ◽  
Plasmodium Falciparum Malaria ◽  
Clinical Malaria ◽  
Blood Stage ◽  
Dependent Manner ◽  
Human Immunity ◽  
Lifetime Exposure ◽  
Blood Stage Malaria ◽  
Reduced Risk

Most studies on human immunity to malaria have focused on the roles of immunoglobulin G (IgG), whereas the roles of IgM remain undefined. Analyzing multiple human cohorts to assess the dynamics of malaria-specific IgM during experimentally induced and naturally acquired malaria, we identified IgM activity against blood-stage parasites. We found that merozoite-specific IgM appears rapidly in Plasmodium falciparum infection and is prominent during malaria in children and adults with lifetime exposure, together with IgG. Unexpectedly, IgM persisted for extended periods of time; we found no difference in decay of merozoite-specific IgM over time compared to that of IgG. IgM blocked merozoite invasion of red blood cells in a complement-dependent manner. IgM was also associated with significantly reduced risk of clinical malaria in a longitudinal cohort of children. These findings suggest that merozoite-specific IgM is an important functional and long-lived antibody response targeting blood-stage malaria parasites that contributes to malaria immunity.

Parasite killing in murine malaria does not require nitric oxide production

Parasitology ◽  
1999 ◽  
Vol 118 (2) ◽  
pp. 139-143 ◽  
Author(s):  
N. FAVRE ◽  
B. RYFFEL ◽  
W. RUDIN
Keyword(s):  
Nitric Oxide ◽  
Blood Stage ◽  
No Production ◽  
Nos Inhibitor ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Stage Parasite ◽  
Blood Stage Malaria ◽  
Inducible Nitric Oxide

Nitric oxide (NO) production has been suggested to play a role as effector molecule in the control of the malarial infections. However, the roles of this molecule are debated. To assess whether blood-stage parasite killing is NO dependent, we investigated the course of blood-stage Plasmodium chabaudi chabaudi (Pcc) infections in inducible nitric oxide synthase (iNOS)-deficient mice. Parasitaemia, haematological alterations, and survival were not affected by the lack of iNOS. To exclude a role of NO produced by other NOS, controls included NO suppression by oral administration of aminoguanidine (AG), a NOS inhibitor. As in iNOS-deficient mice, no difference in the parasitaemia course, survival and haematological values was observed after AG treatment. Our results indicate that NO production is not required for protection against malaria in our murine experimental model. However, C57BL/6 mice treated with AG lost their resistance to Pcc infections, suggesting that the requirement for NO production for parasite killing in murine blood-stage malaria might be strain dependent.

scholarly journals Malaria Blood Stage Suppression of Liver Stage Immunity by Dendritic Cells

2003 ◽  
Vol 197 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Carlos Ocaña-Morgner ◽  
Maria M. Mota ◽  
Ana Rodriguez
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Blood Stage ◽  
Liver Stage ◽  
Cell Responses ◽  
Blood Stage Infection ◽  
Stage Infection

Malaria starts with Plasmodium sporozoites infection of the host's liver, where development into blood stage parasites occurs. It is not clear why natural infections do not induce protection against the initial liver stage and generate low CD8+ T cell responses. Using a rodent malaria model, we show that Plasmodium blood stage infection suppresses CD8+ T cell immune responses that were induced against the initial liver stage. Blood stage Plasmodium affects dendritic cell (DC) functions, inhibiting maturation and the capacity to initiate immune responses and inverting the interleukin (IL)-12/IL-10 secretion pattern. The interaction of blood stage parasites with DCs induces the secretion of soluble factors that inhibit the activation of CD8+ T cells in vitro and the suppression of protective CD8+ T cell responses against the liver stage in vivo. We propose that blood stage infection induces DCs to suppress CD8+ T cell responses in natural malaria infections. This evasion mechanism leaves the host unprotected against reinfection by inhibiting the immune response against the initial liver stage of the disease.

scholarly journals An essential amino acid synchronises malaria parasite development with daily host rhythms

2020 ◽  
Author(s):  
Kimberley F. Prior ◽  
Benita Middleton ◽  
Alíz T.Y. Owolabi ◽  
Mary L. Westwood ◽  
Jacob Holland ◽  
...  
Keyword(s):  
Amino Acid ◽  
Large Scale ◽  
Blood Stage ◽  
Parasite Development ◽  
Host Feeding ◽  
Malaria Parasites ◽  
Disease Symptoms ◽  
Development Cycle ◽  
Feeding Rhythms ◽  
Blood Stage Malaria

SummaryThe replication of blood-stage malaria parasites is synchronised to the host’s daily feeding rhythm. We demonstrate that a metabolite provided to the parasite from the host’s food can set the schedule for Plasmodium chabaudi’s intraerythrocytic development cycle (IDC). First, a large-scale screen reveals multiple rhythmic metabolites in the blood that match the timing of the IDC, but only one - the amino acid isoleucine - that malaria parasites must scavenge from host food. Second, perturbing the timing of isoleucine provision and withdrawal demonstrate that parasites use isoleucine to schedule and synchronise their replication. Thus, periodicity in the concentration of isoleucine in the blood, driven by host-feeding rhythms, explains why timing is beneficial to the parasite and how it coordinates with host rhythms. Blood-stage replication of malaria parasites is responsible for the severity of disease symptoms and fuels transmission; disrupting metabolite-sensing by parasites offers a novel intervention to reduce parasite fitness.

scholarly journals Immune Responses Following Locoregional Treatment for Hepatocellular Carcinoma: Possible Roles of Adjuvant Immunotherapy

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1387
Author(s):  
Ji-Won Han ◽  
Seung-Kew Yoon
Keyword(s):  
Hepatocellular Carcinoma ◽  
Immune Responses ◽  
Immunomodulatory Effects ◽  
Long Term Outcomes ◽  
Locoregional Treatment ◽  
Adjuvant Immunotherapy ◽  
Common Cause ◽  
Cell Responses

Hepatocellular carcinoma (HCC) is a common cause of cancer-related deaths worldwide. Unlike other types of cancer, HCC can be treated with locoregional treatments (LRTs) such as radiofrequency ablation (RFA) or transarterial chemoembolization (TACE). However, recurrences following LRTs are common, and strategies to improve long-term outcomes need to be developed. The exhaustion of anti-tumor immunity in HCC has been well established in many reports and the immunomodulatory effects of LRTs (enhancement of tumor antigen-specific T cell responses after RFA, reduction of effector regulatory T cells after TACE) have also been reported in several previous studies. However, a comprehensive review of previous studies and the possible roles of immunotherapy following LRTs in HCC are not known. In this review, we discuss the immunological evidence of current clinical trials using LRTs and combined immunotherapies, and the possible role of this strategy.

scholarly journals Chlamydia Lipooligosaccharide Has Varied Direct and Indirect Roles in Evading both Innate and Adaptive Host Immune Responses

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Xisheng Wang ◽  
Daniel D. Rockey ◽  
Brian P. Dolan
Keyword(s):  
Immune Responses ◽  
Cytotoxic T Cell ◽  
Innate Immune Responses ◽  
Content Type ◽  
E Coli ◽  
Host Immune Responses ◽  
Cell Responses ◽  
Direct Delivery ◽  
Cytotoxic T Cell Responses

ABSTRACT Chlamydia bacteria are obligate intracellular pathogens which can cause a variety of disease in humans and other vertebrate animals. To successfully complete its life cycle, Chlamydia must evade both intracellular innate immune responses and adaptive cytotoxic T cell responses. Here, we report on the role of the chlamydial lipooligosaccharide (LOS) in evading the immune response. Chlamydia infection is known to block the induction of apoptosis. However, when LOS synthesis was inhibited during Chlamydia trachomatis infection, HeLa cells regained susceptibility to apoptosis induction following staurosporine treatment. Additionally, the delivery of purified LOS to the cytosol of cells increased the levels of the antiapoptotic protein survivin. An increase in survivin levels was also detected following C. trachomatis infection, which was reversed by blocking LOS synthesis. Interestingly, while intracellular delivery of lipopolysaccharide (LPS) derived from Escherichia coli was toxic to cells, LOS from C. trachomatis did not induce any appreciable cell death, suggesting that it does not activate pyroptosis. Chlamydial LOS was also a poor stimulator of maturation of bone marrow-derived dendritic cells compared to E. coli LPS. Previous work from our group indicated that LOS synthesis during infection was necessary to alter host cell antigen presentation. However, direct delivery of LOS to cells in the absence of infection did not alter antigenic peptide presentation. Taken together, these data suggest that chlamydial LOS, which is remarkably conserved across the genus Chlamydia, may act both directly and indirectly to allow the pathogen to evade the innate and adaptive immune responses of the host.

scholarly journals Cytoadherence of Plasmodium berghei-Infected Red Blood Cells to Murine Brain and Lung Microvascular Endothelial CellsIn Vitro

2013 ◽  
Vol 81 (11) ◽  
pp. 3984-3991 ◽  
Author(s):  
Fatima El-Assaad ◽  
Julie Wheway ◽  
Andrew John Mitchell ◽  
Jinning Lou ◽  
Nicholas Henry Hunt ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Red Blood Cells ◽  
Plasmodium Berghei ◽  
Blood Cells ◽  
Content Type ◽  
Murine Brain ◽  
Microvascular Endothelial ◽  
Mixed Stage

ABSTRACTSequestration of infected red blood cells (iRBC) within the cerebral and pulmonary microvasculature is a hallmark of human cerebral malaria (hCM). The interaction between iRBC and the endothelium in hCM has been studied extensively and is linked to the severity of malaria. Experimental CM (eCM) caused byPlasmodium bergheiANKA reproduces most features of hCM, although the sequestration of RBC infected byP. bergheiANKA (PbA-iRBC) has not been completely delineated. The role of PbA-iRBC sequestration in the severity of eCM is not well characterized. Using static and flow cytoadherence assays, we provide the first directin vitroevidence for the binding of PbA-iRBC to murine brain and lung microvascular endothelial cells (MVEC). We found that basal PbA-iRBC cytoadherence to MVECs was significantly higher than that of normal red blood cells (NRBC) and of RBC infected withP. bergheiK173 (PbK173-iRBC), a strain that causes noncerebral malaria (NCM). MVEC prestimulation with tumor necrosis factor (TNF) failed to promote any further significant increase in mixed-stage iRBC adherence. Interestingly, enrichment of the blood for mature parasites significantly increased PbA-iRBC binding to the MVECs prestimulated with TNF, while blockade of VCAM-1 reduced this adhesion. Our study provides evidence for the firm, flow-resistant binding to endothelial cells of iRBC from strain ANKA-infected mice, which develop CM, and for less binding of iRBC from strain K173-infected mice, which develop NCM. An understanding ofP. bergheicytoadherence may help elucidate the importance of sequestration in the development of CM and aid the development of antibinding therapies to help reduce the burden of this syndrome.

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