Maizels RM et al. (1993) Experimental Parasitology "Forms and functions of nematode surfaces."

Blaxter ML, Maizels RM, Selkirk ME

[Experimental Parasitology, 1993]

Nematodes possess biologically unusual surfaces. The dominant feature is the cuticle, a collagen-rich extracellular matrix which acts as the exoskeleton and is synthesized in the outermost tissue layer of the organism, the epidermis or hypodermis. The cuticle, which may be 1 um or more in depth, has on its external face a lipid-rich epicuticle which in some species resembles a unit membrane. There may be an additional envelope, loosely attached and distal to the epicuticle, in the form of a surface coat or glycocalyx, or as a thin sheath retained by some larval nematodes from previous developmental stages. The organisation of these components is depicted in Fig. 1. Detailed studies of these structures are now becoming available in both parasitic and free-living nematodes such as Caenorhabditis elegans...

Maizels RM et al. (2001) Int J Parasitol "Immune evasion genes from filarial nematodes."

Maizels RM, Gomez-Escobar N, Murray J, Zang X, Gregory WF

[Int J Parasitol, 2001]

Helminth parasites have large genomes (approximately 10(8) bp) which are likely to encode a spectrum of products able to block or divert the host immune response. We have employed three parallel approaches to identify the first generation of 'immune evasion genes' from parasites such as the filarial nematode Brugia malayi. The first strategy is a conventional route to characterise prominent surface or secreted antigens. In this way we have identified a 15-kDa protein, which is located on the surface of both L3 and adult B. malayi, and secreted by these parasites in vitro, as a member of the cystatin (cysteine protease inhibitor) family. This product, Bm-CPI-2, blocks conventional cysteine proteases such as papain, but also the aspariginyl endopeptidase involved in the Class II antigen processing pathway in human B cells. In parallel, we identified the major T cell-stimulating antigen from the microfilarial stage as a serpin (serine protease inhibitor), Bm-SPN-2. Microfilariae secrete this product which blocks two key proteases of the neutrophil, a key mediator of inflammation and innate immunity. The second route involves a priori hypotheses that helminth parasites encode homologues of mammalian cytokines such as TGF-beta which are members of broad, ancient metazoan gene families. We have identified two TGF-beta homologues in B. malayi, and shown that one form (Bm-TGH-2) is both secreted by adult parasites in vitro and able to bind to host TGF-beta receptors. Likewise, B. malayi expresses homologues of mammalian MIF, which are remarkably similar in both structure and function to the host protein, even though amino acid identity is only 28%. Finally, we deployed a third method of selecting critical genes, using an expression-based criterion to select abundant mRNAs taken from key points in parasite life histories. By this means, we have shown that the major transcript present in mosquito-borne infective larvae, Bm-ALT, is a credible vaccine candidate for use against lymphatic filariasis, while a second abundantly-expressed gene, Bm-VAL-1, is similar to a likely vaccine antigen being developed against hookworm parasites.

Maizels RM et al. (2001) Parasite Immunol "Immunological genomics of Brugia malayi: filarial genes implicated in immune evasion and protective immunity."

Maizels RM, Blaxter ML, Scott AL

[Parasite Immunol, 2001]

Filarial nematodes are metazoan parasites with genome sizes of> 100 million base pairs, probably encoding 15 000-20 000 genes. Within this considerable gene complement, it seems likely that filariae have evolved a spectrum of immune evasion products which underpin their ability to live for many years within the human host. Moreover, no suitable vaccine currently exists for human filarial diseases, and few markers have yet been established for diagnostic use. In this review, we bring together biochemical and immunological data on prominent filarial proteins with the exciting new information provided by the Filarial Genome Project's expressed sequence tag (EST) database. In this discussion, we focus on those genes with the highest immunological profile, such as inhibitors of host enzymes, cytokine homologues and stage-specific surface proteins, as well as products associated with the mosquito-borne infective larva which offer the best opportunity for an anti-filarial vaccine. These gene products provide a fascinating glimpse of the molecular repertoire which helminth parasites have evolved to manipulate and evade the mammalian immune response.

Maizels RM et al. (1987) Parasite Immunol "Phosphorylcholine-bearing antigens in filarial nematode parasites: analysis of somatic extracts, in-vitro secretions and infection sera from Brugia malayi and B. pahangi."

Maizels RM, Denham DA, Burke J

[Parasite Immunol, 1987]

A set of cross-reactive antigens is described which are present in somatic extracts and in-vitro secretions of the filarial nematodes Brugia pahangi and B. malayi. A monoclonal antibody reactive with a repeating epitope on these molecules readily detects circulating antigen in the serum of animals infected with lymphatic filariae, using either an immunoradiometric assay or enzyme-linked immunosorbent assay (ELISA). This epitope has the immunological reactivity and chemical characteristics of the phosphorylcholine (PC) hapten. The anti-PC monoclonal has been used to define the antigens bearing this epitope, and in chromatographic studies on material from extracts of Brugia adult worms, a heterogeneous profile of PC-positive molecules are found. In sera from Brugia-infected jirds, an antigen with a native molecular weight of approximately 500,000 is observed, which displays limited sensitivity to protease degradation. However, denatured samples on Western blots show a major parasite circulating antigen of Mr 90,000. The detection of this antigen in the presence of excess host antibody is also demonstrated, taking advantage of the stability of the target epitope to a range of treatments designed to dissociate and eliminate immune complexes.

Ma C et al. (2015) Molecules "Potent Activities of Roemerine against Candida albicans and the Underlying Mechanisms."

Yan L, Xu G, Wang C, He G, Du F, Jiang Y, Ma C, Rao G, He J

[Molecules, 2015]

Roemerine (RM) is an aporphine alkaloid isolated from the fresh rattan stem of Fibraurea recisa, and it has been demonstrated to have certain antifungal activity. This study aimed to investigate the antifungal activity of RM and the underlying mechanisms in Candida albicans (C. albicans). The in vitro antifungal activity of RM was evaluated by a series of experiments, including the XTT reduction assay, confocal laser scanning microscopy assay, scanning electron microscope assay. Results showed that 1 g/mL RM inhibited biofilm formation significantly (p < 0.01) both in Spider medium and Lee's medium. In addition, RM could inhibit yeast-to-hyphae transition of C. albicans in a dose-dependent manner. The biofilm-specific and hypha-specific genes such as YWP1, SAP5, SAP6, HWP1, ECE1 were up-regulated and EFG1 was down-regulated after 8 g/mL RM treatment. Furthermore, the toxicity of RM was investigated using C. elegans worms, three cancer cells and one normal cell. The date showed that RM had no significant toxicity. In conclusion, RM could inhibited the formation of C. albicans biofilm in vitro, but it had no fungicidal effect on planktonic C. albicans cells, and the anti-biofilm mechanism may be related to the cAMP pathway.

Gems DH et al. (1993) International C. elegans Meeting "Molecular anatomy of the surface coat of the infective L2 of the parasitic nematode Toxocara canis."

Gems DH, Maizels RM

[International C. elegans Meeting, 1993]

Gems DH et al. (1996) Proc Natl Acad Sci U S A "An abundantly expressed mucin-like protein from Toxocara canis infective larvae: the precursor of the larval surface coat glycoproteins."

Gems DH, Maizels RM

[Proc Natl Acad Sci U S A, 1996]

Evasion of host immunity by Toxocara canis infective larvae is mediated by the nematode surface coat, which is shed in response to binding by host antibody molecules or effector cells. The major constituent of the coat is the TES-120 glycoprotein series. We have isolated a 730-bp cDNA from the gene encoding the apoprotein precursor of TES-120. The mRNA is absent from T. canis adults but hyperabundant in larvae, making up approximately 10% of total mRNA, and is trans-spliced with the nematode 5' leader sequence SL1. It encodes a 15.8-kDa protein (after signal peptide removal) containing a typical mucin domain: 86 amino acid residues, 72.1% of which are Ser or Thr, organized into an array of heptameric repeats, interspersed with proline residues. At the C-terminal end of the putative protein are two 36-amino acid repeats containing six Cys residues, in a motif that can also be identified in several genes in Caenorhabditis elegans. Although TES-120 displays size and charge heterogeneity, there is a single c opy gene and a homogeneous size of mRNA. The association of overexpression of some membrane-associated mucins with immunosuppression and tumor metastasis suggests a possible model for the role of the surface coat in immune evasion by parasitic nematodes.

Gregory WF et al. (2008) Int J Biochem Cell Biol "Cystatins from filarial parasites: evolution, adaptation and function in the host-parasite relationship."

Gregory WF, Maizels RM

[Int J Biochem Cell Biol, 2008]

Cystatins, together with stefins and kininogens, are members of the cystatin superfamily of cysteine protease inhibitors (CPI) present across the animal and plant kingdoms. Their role in parasitic organisms may encompass both essential developmental processes and specific interactions with the parasite''s vector and/or final host. We summarise information gathered on three cystatins from the human filarial nematode Brugia malayi (Bm-CPI-1, -2 and -3), and contrast them those expressed by other parasites and by the free-living nematode Caenorhabditis elegans. Bm-CPI-2 differs from C. elegans cystatin, having acquired the additional function of inhibiting asparaginyl endopeptidase (AEP), in a manner similar to some human cystatins. Thus, we propose that Bm-CPI-2 and orthologues from related filarial parasites represent a new subset of nematode cystatins. Bm-CPI-1 and CPI-3 share only 25% amino acid identity with Bm-CPI-2, and lack an evolutionarily conserved glycine residue in the N-terminal region. These sequences group distantly from the other nematode cystatins, and represent a second novel subset of filarial cystatin-like genes. Expression analyses also show important differences between the CPI-2 and CPI-1/-3 groups. Bm-cpi-2 is expressed at all time points of the parasite life cycle, while Bm-cpi-1 and -3 expression is confined to the late stages of development in the mosquito vector, terminating within 48h of infection of the mammalian host. Hence, we hypothesise that CPI-2 has evolved to block mammalian proteases (including the antigen-processing enzyme AEP) while CPI-1 and -3 function in the milieu of the mosquito vector necessary for transmission of the parasite.

Zang X et al. (2001) Trends Biochem Sci "Serine proteinase inhibitors from nematodes and the arms race between host and pathogen."

Maizels RM, Zang X

[Trends Biochem Sci, 2001]

Serine proteinase inhibitors are encoded by a large gene family of long evolutionary standing. Recent discoveries of parasite proteins that inhibit human serine proteinases, together with the complete genomic sequence from Caenorhabditis elegans, have provided a set of new serine proteinase inhibitors from more primitive metazoan animals such as nematodes. The structural features (e.g. reactive centre residues), gene organization (including intron arrangements) and inhibitory function and targets (e.g. inflammatory and coagulation pathway proteinase) all contribute important new insights into proteinase inhibitor evolution. Some parasite products have evolved that block enzymes in the mammalian host, but the human host responds with a significant immune response to the parasite inhibitors. Thus, infection produces a finely balanced conflict between host and pathogen at the molecular level, and this might have accelerated the evolution of these proteins in parasitic species as well as their hosts.

Gouveia GJ et al. (2021) Anal Chem "Long-Term Metabolomics Reference Material."

Andersen EC, Morse AM, Garcia BM, Edison AS, Shaver AO, Gouveia GJ, McIntyre LM

[Anal Chem, 2021]

The use of quality control samples in metabolomics ensures data quality, reproducibility, and comparability between studies, analytical platforms, and laboratories. Long-term, stable, and sustainable reference materials (RMs) are a critical component of the quality assurance/quality control (QA/QC) system; however, the limited selection of currently available matrix-matched RMs reduces their applicability for widespread use. To produce an RM in any context, for any matrix that is robust to changes over the course of time, we developed iterative batch averaging method (IBAT). To illustrate this method, we generated 11 independently grown <i>Escherichia coli</i> batches and made an RM over the course of 10 IBAT iterations. We measured the variance of these materials by nuclear magnetic resonance (NMR) and showed that IBAT produces a stable and sustainable RM over time. This <i>E. coli</i> RM was then used as a food source to produce a <i>Caenorhabditis elegans</i> RM for a metabolomics experiment. The metabolite extraction of this material, alongside 41 independently grown individual <i>C. elegans</i> samples of the same genotype, allowed us to estimate the proportion of sample variation in preanalytical steps. From the NMR data, we found that 40% of the metabolite variance is due to the metabolite extraction process and analysis and 60% is due to sample-to-sample variance. The availability of RMs in untargeted metabolomics is one of the predominant needs of the metabolomics community that reach beyond quality control practices. IBAT addresses this need by facilitating the production of biologically relevant RMs and increasing their widespread use.