Toxoplasma gondii (T. gondii) is an apicomplexan parasite that can cause eye disease, brain disease, and death, especially in congenitally infected and immune-compromised people. Novel medicines ...effective against both active and latent forms of the parasite are greatly needed. The current study focused on the discovery of such medicines by exploring a family of potential inhibitors whose antiapicomplexan activity has not been previously reported. Initial screening efforts revealed that niclosamide, a drug approved for anthelmintic use, possessed promising activity in vitro against T. gondii. This observation inspired the evaluation of the activity of a series of salicylanilides and derivatives. Several inhibitors with activities in the nanomolar range with no appreciable in vitro toxicity to human cells were identified. An initial structure–activity relationship was explored. Four compounds were selected for evaluation in an in vivo model of infection, and two derivatives with potentially enhanced pharmacological parameters demonstrated the best activity profiles.
Background. Family clusters and epidemics of toxoplasmosis in North, Central, and South America led us to determine whether fathers of congenitally infected infants in the National Collaborative ...Chicago-Based Congenital Toxoplasmosis Study (NCCCTS) have a high incidence of Toxoplasma gondii infection. Methods. We analyzed serum samples collected from NCCCTS families between 1981 and 2013. Paternal serum samples were tested for T. gondii antibodies with immunoglobulin (Ig) G dye test and IgM enzyme-linked immunosorbent assay. Additional testing of paternal serum samples was performed with differential-agglutination and IgG avidity tests when T. gondii IgG and IgM results were positive and serum samples were collected by the 1-year visit of the congenitally infected child. Prevalence of paternal seropositivity and incidence of recent infection were calculated. We analyzed whether certain demographics, maternal parasite serotype, risk factors, or maternal/infant clinical manifestations were associated with paternal T. gondii infection status. Results. Serologic testing revealed a high prevalence (29 of 81; 36%) of T. gondii infection in fathers, relative to the average seropositivity rate of 9.8% for boys and men aged 12–49 years in the United States between 1994 and 2004 (P < .001). Moreover, there was a higher-than-expected incidence of recent infectins among fathers with serum samples collected by the 1-year visit of their child (6 of 45; 13%; P < .001). No demographic patterns or clinical manifestations in mothers or infants were associated with paternal infections, except for sandbox exposure. Conclusions. The high prevalence of chronic and incidence of recent T. gondii infections in fathers of congenitally infected children indicates that T. gondii infections cluster within families in North America. When a recently infected person is identified, family clustering and community risk factors should be investigated for appropriate clinical management.
ALOX12 in human toxoplasmosis Witola, William H; Liu, Susan Ruosu; Montpetit, Alexandre ...
Infection and immunity,
07/2014, Letnik:
82, Številka:
7
Journal Article
Recenzirano
Odprti dostop
ALOX12 is a gene encoding arachidonate 12-lipoxygenase (12-LOX), a member of a nonheme lipoxygenase family of dioxygenases. ALOX12 catalyzes the addition of oxygen to arachidonic acid, producing ...12-hydroperoxyeicosatetraenoic acid (12-HPETE), which can be reduced to the eicosanoid 12-HETE (12-hydroxyeicosatetraenoic acid). 12-HETE acts in diverse cellular processes, including catecholamine synthesis, vasoconstriction, neuronal function, and inflammation. Consistent with effects on these fundamental mechanisms, allelic variants of ALOX12 are associated with diseases including schizophrenia, atherosclerosis, and cancers, but the mechanisms have not been defined. Toxoplasma gondii is an apicomplexan parasite that causes morbidity and mortality and stimulates an innate and adaptive immune inflammatory reaction. Recently, it has been shown that a gene region known as Toxo1 is critical for susceptibility or resistance to T. gondii infection in rats. An orthologous gene region with ALOX12 centromeric is also present in humans. Here we report that the human ALOX12 gene has susceptibility alleles for human congenital toxoplasmosis (rs6502997 P, <0.000309, rs312462 P, <0.028499, rs6502998 P, <0.029794, and rs434473 P, <0.038516). A human monocytic cell line was genetically engineered using lentivirus RNA interference to knock down ALOX12. In ALOX12 knockdown cells, ALOX12 RNA expression decreased and levels of the ALOX12 substrate, arachidonic acid, increased. ALOX12 knockdown attenuated the progression of T. gondii infection and resulted in greater parasite burdens but decreased consequent late cell death of the human monocytic cell line. These findings suggest that ALOX12 influences host responses to T. gondii infection in human cells. ALOX12 has been shown in other studies to be important in numerous diseases. Here we demonstrate the critical role ALOX12 plays in T. gondii infection in humans.
Abstract Toxoplasma gondii is an intracellular parasite that causes severe neurologic and ocular disease in immune-compromised and congenitally infected individuals. There is no vaccine protective ...against human toxoplasmosis. Herein, immunization of Ld mice with HF10 (HPGSVNEFDF) with palmitic acid moieties or a monophosphoryl lipid A derivative elicited potent IFN-γ production from Ld -restricted CD8+ T cells in vitro and protected mice. CD8+ T cell peptide epitopes from T. gondii dense granule proteins GRA 3, 6, 7, and Sag 1, immunogenic in humans for HLA-A02+ , HLA-A03+ , and HLA-B07+ cells were identified. Since peptide repertoire presented by MHC class I molecules to CD8+ T cells is shaped by endoplasmic reticulum-associated aminopeptidase (ERAAP), polymorphisms in the human ERAAP gene ERAP1 were studied and associate with susceptibility to human congenital toxoplasmosis ( p < 0.05). These results have important implications for vaccine development.
Toxoplasma (T.
)
gondii
, the causative agent of toxoplasmosis, is a ubiquitous opportunistic pathogen that infects individuals worldwide, and is a leading cause of severe congenital neurologic and ...ocular disease in humans. No vaccine to protect humans is available, and hypersensitivity and toxicity limit the use of the few available medicines. Therefore, safer and more effective medicines to treat toxoplasmosis are urgently needed. Using the Hybrid Structure Based (HSB) method, we have previously identified small molecule inhibitors of
P. falciparum
that seem to target a novel protein–protein interaction between the Myosin tail interacting protein and myosin light chain. This pathway has been hypothesized to be involved in invasion of host erythrocytes by the parasite and is broadly conserved among the apicomplexans. Guided by similar computational drug design approaches, we investigated this series of small molecules as potential inhibitors of
T. gondii
. Compound C3-21, identified as the most active inhibitor in this series, exhibited an IC
50
value ~500 nM against
T. gondii
. Among the 16 structural analogs of C3-21 tested thus far, nine additional compounds were identified with IC
50
values <10.0 μM. In vitro assays have revealed that C3-21 markedly limits intracellular growth of
T. gondii
tachyzoites, but has no effect on host cell human foreskin fibroblasts (HFF) at concentrations more than a log greater than the concentration that inhibits the parasites.
Metastatic castration‐resistant prostate cancer (mCRPC) is a lethal form of treatment‐resistant prostate cancer and poses significant therapeutic challenges. Deregulated receptor tyrosine kinase ...(RTK) signalling mediated by loss of tumour suppressor Sprouty2 (SPRY2) is associated with treatment resistance. Using pre‐clinical human and murine mCRPC models, we show that SPRY2 deficiency leads to an androgen self‐sufficient form of CRPC. Mechanistically, HER2‐IL6 signalling axis enhances the expression of androgen biosynthetic enzyme HSD3B1 and increases SRB1‐mediated cholesterol uptake in SPRY2‐deficient tumours. Systemically, IL6 elevated the levels of circulating cholesterol by inducing host adipose lipolysis and hepatic cholesterol biosynthesis. SPRY2‐deficient CRPC is dependent on cholesterol bioavailability and SRB1‐mediated tumoral cholesterol uptake for androgen biosynthesis. Importantly, treatment with ITX5061, a clinically safe SRB1 antagonist, decreased treatment resistance. Our results indicate that cholesterol transport blockade may be effective against SPRY2‐deficient CRPC.
The ability of CD8
+ T cells to act as cytolytic effectors and produce interferon-γ (IFN-γ) was demonstrated to mediate resistance to
Toxoplasma gondii in murine models because of the recognition of ...peptides restricted by murine major histocompatibility complex (MHC) class I molecules. However, no
T gondii–specific HLA-B07-restricted peptides were proven protective against
T gondii. Recently, 2
T gondii–specific HLA-B*0702-restricted T cell epitopes, GRA7
20-28 (LPQFATAAT) and GRA3
27-35 (VPFVVFLVA), displayed high-affinity binding to HLA-B*0702 and elicited IFN-γ from peripheral blood mononuclear cells of seropositive HLA-B*07 persons. Herein, these peptides were evaluated to determine whether they could elicit IFN-γ in splenocytes of HLA-B*0702 transgenic mice when administered with adjuvants and protect against subsequent challenge. Peptide-specific IFN-γ-producing T cells were identified by enzyme-linked immunosorbent spot and proliferation assays utilizing splenic T lymphocytes from human lymphocyte antigen (HLA) transgenic mice. When HLA-B*0702 mice were immunized with one of the identified epitopes, GRA7
20-28 in conjunction with a universal CD4
+ T cell epitope (PADRE) and adjuvants (CD4
+ T cell adjuvant, GLA-SE, and TLR2 stimulatory Pam
2Cys for CD8
+ T cells), this immunization induced CD8
+ T cells to produce IFN-γ and protected mice against high parasite burden when challenged with
T gondii. This work demonstrates the feasibility of bioinformatics followed by an empiric approach based on HLA binding to test this biologic activity for identifying protective HLA-B*0702-restricted
T gondii peptides and adjuvants that elicit protective immune responses in HLA-B*0702 mice.
We created and tested multi-epitope DNA or protein vaccines with TLR4 ligand emulsion adjuvant (gluco glucopyranosyl lipid adjuvant in a stable emulsion GLA-SE) for their ability to protect against
...in HLA transgenic mice. Our constructs each included 5 of our best down-selected CD8
T cell-eliciting epitopes, a universal CD4
helper T lymphocyte epitope (PADRE), and a secretory signal, all arranged for optimal MHC-I presentation. Their capacity to elicit immune and protective responses was studied using immunization of HLA-A*11:01 transgenic mice. These multi-epitope vaccines increased memory CD8
T cells that produced IFN-γ and protected mice against parasite burden when challenged with
.
. Endocytosis of emulsion-trapped protein and cross presentation of the antigens must account for the immunogenicity of our adjuvanted protein. Thus, our work creates an adjuvanted platform assembly of peptides resulting in cross presentation of CD8
T cell-eliciting epitopes in a vaccine that prevents toxoplasmosis.
Ability of CD8
+
T cells to act as cytolytic effectors and produce IFN-γ was shown to mediate resistance to
Toxoplasma gondii
in murine models due to recognition of peptides restricted by murine MHC ...Class I molecules. However, no
T. gondii
specific HLA-B07 restricted peptides were proven protective against
T gondii
. Recently, two
T gondii
-specific HLA-B*0702-restricted T cell epitopes, GRA7
20–28
(LPQFATAAT) and GRA3
27–35
(VPFVVFLVA), displayed high-affinity binding to HLA-B*0702, and elicited IFN-γ from PBMCs of seropositive HLA-B*0702 persons. Herein, these peptides were evaluated to determine whether they could elicit IFN-γ in splenocytes of HLA-B*0702 transgenic mice when administered with adjuvants and protect against subsequent challenge. Peptide-specific IFN-γ producing T cells were identified by ELISPOT and proliferation assays utilizing splenic T lymphocytes from HLA transgenic mice. When HLA-B*0702 mice were immunized with one of the epitopes identified, GRA7
20–28
in conjunction with a universal CD4
+
T cell epitope (PADRE) and adjuvants (CD4
+
T cell adjuvant, GLA-SE, and TLR2 stimulatory Pam
2
Cys for CD8
+
T cells), this immunization induced CD8
+
T cells to produce IFN-γ and protected mice against high parasite burden when challenged with
T gondii
. This work demonstrates feasibility of bioinformatics followed by an empirical approach based on HLA binding to test this biological activity for identifying protective HLA-B*0702 restricted
T gondii
peptides and adjuvants that elicit protective immune responses in HLA-B*0702 mice.
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