To characterise the phenotypes associated with the p.A16V mutation of PRSS1.
Clinical and epidemiological data were collected for any family in which a p.A16V mutation was identified, either referred ...directly to the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer or via a collaborator. DNA samples were tested for mutations in PRSS1, SPINK1, CFTR and CTRC.
Participants were recruited on the basis of either family history of pancreatitis (acute or chronic) or the results of genetic testing. Families were categorised as having hereditary pancreatitis (HP), idiopathic disease or pancreatitis in a single generation. HP was defined as >or=2 cases in >or=2 generations. Main outcome measures Onset of painful episodes of pancreatitis, death from pancreatic cancer, diagnosis of diabetes mellitus and exocrine pancreatic failure.
Ten families with p.A16V mutations were identified (22 affected individuals): six HP families, three with idiopathic disease and one with only a single generation affected. The median age of onset, ignoring non-penetrants, was 10 years (95% CI 5 to 25). There were eight confirmed cases of exocrine failure, four of whom also had diabetes mellitus. There were three pancreatic cancer cases. Two of these were confirmed as p.A16V carriers, only one of whom was affected by pancreatitis. Those with p.A16V pancreatitis were compared to affected individuals with p.R122H, p.N29I and no PRSS1 mutation. No significant differences were proven using logrank or Mann-Whitney U tests.
Penetrance of p.A16V is highly variable and family dependent, suggesting it contributes to multigenic inheritance of a predisposition to pancreatitis.
Recent studies have demonstrated that many parasites release extracellular vesicles (EVs), yet little is known about the specific interactions of EVs with immune cells or their functions during ...infection. We show that EVs secreted by the gastrointestinal nematode Heligmosomoides polygyrus are internalized by macrophages and modulate their activation. EV internalization causes downregulation of type 1 and type 2 immune-response-associated molecules (IL-6 and TNF, and Ym1 and RELMα) and inhibits expression of the IL-33 receptor subunit ST2. Co-incubation with EV antibodies abrogated suppression of alternative activation and was associated with increased co-localization of the EVs with lysosomes. Furthermore, mice vaccinated with EV-alum generated protective immunity against larval challenge, highlighting an important role in vivo. In contrast, ST2-deficient mice are highly susceptible to infection, and they are unable to clear parasites following EV vaccination. Hence, macrophage activation and the IL-33 pathway are targeted by H. polygyrus EVs, while neutralization of EV function facilitates parasite expulsion.
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•EVs from a nematode parasite suppress type 1 and type 2 activation of macrophages•Antibodies block EV function and increase their co-localization with the lysosome in macrophages•EV vaccination generates strong antibody responses and protective immunity against infection•EVs target both the IL-33 pathway and macrophage activation to counter parasite expulsion
Coakley et al. find that extracellular vesicles (EVs) from a nematode parasite can suppress host macrophage activation and the alarmin receptor ST2 and that this can be blocked by antibodies. Vaccination with EVs drives strong antibody responses, conferring protection against infection. The authors thus highlight a role for EVs in parasite-host crosstalk.
Helminth infection is frequently associated with the expansion of regulatory T cells (Tregs) and suppression of immune responses to bystander antigens. We show that infection of mice with the chronic ...gastrointestinal helminth Heligmosomoides polygyrus drives rapid polyclonal expansion of Foxp3(+)Helios(+)CD4(+) thymic (t)Tregs in the lamina propria and mesenteric lymph nodes while Foxp3(+)Helios(-)CD4(+) peripheral (p)Treg expand more slowly. Notably, in partially resistant BALB/c mice parasite survival positively correlates with Foxp3(+)Helios(+)CD4(+) tTreg numbers. Boosting of Foxp3(+)Helios(+)CD4(+) tTreg populations by administration of recombinant interleukin-2 (rIL-2):anti-IL-2 (IL-2C) complex increased worm persistence by diminishing type-2 responsiveness in vivo, including suppression of alternatively activated macrophage and granulomatous responses at the sites of infection. IL-2C also increased innate lymphoid cell (ILC) numbers, indicating that Treg functions dominate over ILC effects in this setting. Surprisingly, complete removal of Tregs in transgenic Foxp3-DTR mice also resulted in increased worm burdens, with "immunological chaos" evident in high levels of the pro-inflammatory cytokines IL-6 and interferon-γ. In contrast, worm clearance could be induced by anti-CD25 antibody-mediated partial depletion of early Treg, alongside increased T helper type 2 responses and without incurring pathology. These findings highlight the overarching importance of the early Treg response to infection and the non-linear association between inflammation and the prevailing Treg frequency.
The intestinal helminth parasite,
Heligmosomoides polygyrus bakeri offers a tractable experimental model for human hookworm infections such as
Ancylostoma duodenale and veterinary parasites such as
...Haemonchus contortus. Parasite excretory–secretory (ES) products represent the major focus for immunological and biochemical analyses, and contain immunomodulatory molecules responsible for nematode immune evasion. In a proteomic analysis of adult
H. polygyrus secretions (termed HES) matched to an extensive transcriptomic dataset, we identified 374 HES proteins by LC–MS/MS, which were distinct from those in somatic extract HEx, comprising 446 identified proteins, confirming selective export of ES proteins. The predominant secreted protein families were proteases (astacins and other metalloproteases, aspartic, cysteine and serine-type proteases), lysozymes, apyrases and acetylcholinesterases. The most abundant products were members of the highly divergent venom allergen-like (VAL) family, related to
Ancylostoma secreted protein (ASP); 25 homologues were identified, with VAL-1 and -2 also shown to be associated with the parasite surface. The dominance of VAL proteins is similar to profiles reported for
Ancylostoma and
Haemonchus ES products. Overall, this study shows that the secretions of
H. polygyrus closely parallel those of clinically important GI nematodes, confirming the value of this parasite as a model of helminth infection.
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► We identify 374 proteins secreted by adult worms of the model nematode parasite Heligmosomoides polygyrus. ► Multiple proteases, lysozymes, apyrases and acetylcholinesterase were identified. ► The dominant gene family in the secretome are members of the venom allergen-like (VAL) family of no known function. ► The secretion of VAL proteins and enzymes is also found in secretomes of major human and veterinary nematodes. ► Up to 90 novel gene products were found to be secreted, all bearing signal peptides, by the adult parasites.
Familial Pancreatic Cancer (FPC) is the autosomal dominant inheritance of a genetic predisposition to pancreatic ductal adenocarcinoma, penetrance is assumed to be high but not complete. It was first ...described in 1987 and since then many families have been identified, but the candidate disease gene remains elusive and the very existence of the syndrome is sometimes questioned. FPC identifies a target group for secondary screening. As well as being potentially life saving for the subjects, screening offers researchers the opportunity to elucidate the early pathogenesis of pancreatic cancer. The scientific incentive for screening should not blind us to the challenges facing clinicians in managing high risk patients. Early surgical treatment may dramatically improve the five year survival for pancreatic cancer, but this must be balanced against the risks of false positives, where healthy individuals are subjected to the mortality and morbidity of major pancreatic surgery.
Recent sequencing and assembly of the genome for the fungal pathogen Candida albicans used simple automated procedures for the identification of putative genes. We have reviewed the entire assembly, ...both by hand and with additional bioinformatic resources, to accurately map and describe 6,354 genes and to identify 246 genes whose original database entries contained sequencing errors (or possibly mutations) that affect their reading frame. Comparison with other fungal genomes permitted the identification of numerous fungus-specific genes that might be targeted for antifungal therapy. We also observed that, compared to other fungi, the protein-coding sequences in the C. albicans genome are especially rich in short sequence repeats. Finally, our improved annotation permitted a detailed analysis of several multigene families, and comparative genomic studies showed that C. albicans has a far greater catabolic range, encoding respiratory Complex 1, several novel oxidoreductases and ketone body degrading enzymes, malonyl-CoA and enoyl-CoA carriers, several novel amino acid degrading enzymes, a variety of secreted catabolic lipases and proteases, and numerous transporters to assimilate the resulting nutrients. The results of these efforts will ensure that the Candida research community has uniform and comprehensive genomic information for medical research as well as for future diagnostic and therapeutic applications.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Infections with parasitic helminths such as Nippostronglyus brasiliensis induce dominant type 2 responses from antigen‐specific T helper cells. The potency of the Th2 bias can also drive Th2 ...responses to bystander antigens introduced at the same time as infection. We now report that the Th2‐promoting effect of infection can be reproduced with soluble N. brasiliensis excretory‐secretory proteins (NES) released by adult parasites in vitro. Immunization of BALB / c mice with NES results in the production of IL‐4 with elevated total serum IgE and specific IgG1 antibodies. NES is also able to stimulate IL‐4 and polyclonal IgE production in other mouse strains (C57BL / 6, B10.D2, CBA). These features are seen whether NES is administered without adjuvant as soluble protein in phosphate‐buffered saline or with complete Freund's adjuvant which normally favors Th1 responses. Thus, NES possesses intrinsic adjuvanticity. Moreover, co‐administration of hen egg lysozyme (HEL) with NES in the absence of other adjuvants results in generation of HEL‐specific lymphocyte proliferation, IL‐4 release and IgG1 antibody responses, documenting that NES can act as an adjuvant for third‐party antigens. Proteinase K digestion or heat treatment of NES before immunization abolished the IL‐4‐stimulating activity, indicating that the factors acting to promote Th2 induction are proteins secreted by the adult parasite.
The CST20 gene of Candida albicans was cloned by functional complementation of a deletion of the STE20 gene in Saccharomyces cerevisiae. CST20 encodes a homolog of the Ste20p/p65PAKfamily of protein ...kinases. Colonies of C. albicans cells deleted for CST20 revealed defects in the lateral formation of mycelia on synthetic solid ``Spider'' media. However, hyphal development was not impaired in some other media. A similar phenotype was caused by deletion of HST7, encoding a functional homolog of the S. cerevisiae Ste7p protein kinase. Overexpression of HST7 partially complemented the deletion of CST20. Cells deleted for CST20 were less virulent in a mouse model for systemic candidiasis. Our results suggest that more than one signaling pathway can trigger hyphal development in C. albicans, one of which has a protein kinase cascade that is analogous to the mating response pathway in S. cerevisiae and might have become adapted to the control of mycelial formation in asexual C. albicans.
Background: The pathogenic fungus Candida albicans is capable of a morphological transition from a unicellular budding yeast to a filamentous form. Extensive filamentous growth leads to the formation ...of mycelia displaying hyphae with branches and lateral buds. Hyphae have been observed to adhere to and invade host tissues more readily than the yeast form, suggesting that filamentous growth may contribute to the virulence of this major human pathogen. A molecular and genetic understanding of the potential role of morphological switching in the pathogenicity of C. albicans would be of significant benefit in view of the increasing incidence of candidiasis.
Results: The CaCLA4 gene of C. albicans was cloned by functional complementation of the growth defect of cells of the budding yeast Saccharomyces cerevisiae deleted for the STE20 gene and the CLA4 gene. CaCLA4 encodes a member of the Ste20p family of serine/threonine protein kinases and is characterized by a pleckstrin homology domain and a Cdc42p-binding domain in its amino-terminal non-catalytic region. Deletion of both alleles of CaCLA4 in C. albicans caused defects in hyphal formation in vitro, in both synthetic liquid and solid media, and in vivo in a mouse model for systemic candidiasis. The gene deletions reduced colonization of the kidneys in infected mice and suppressed C. albicans virulence in the mouse model.
Conclusions: Our results demonstrate that the function of the CaCla4p protein kinase is essential for virulence and morphological switching of C. albicans in a mouse model. Thus, hyphal formation of C. albicans mediated by CaCla4p may contribute to the pathogenicity of this dimorphic fungus, suggesting that regulators of morphological switching may be useful targets for antifungal drugs.
Leishmania donovani promastigotes are ingested by human monocytes, elicit phagocytic oxidative burst, and majority are killed by oxidative microbicidal mechanisms whereas amastigotes are ingested and ...survive to parasitize human monocytes successfully despite eliciting phagocytic oxidative burst
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