Irma van Die

Infection with parasitic helminths affects humanity and animal welfare. Parasitic helminths have the capacity to modulate host immune responses to promote their survival in infected hosts, often for a long time leading to chronic infections. In contrast to many infectious microbes, however, the helminths are able to induce immune responses that show positive bystander effects such as the protection to several immune disorders, including multiple sclerosis, inflammatory bowel disease, and allergies. They generally promote the generation of a tolerogenic immune microenvironment including the induction of type 2 (Th2) responses and a sub-population of alternatively activated macrophages. It is proposed that this anti-inflammatory response enables helminths to survive in their hosts and protects the host from excessive pathology arising from infection with these large pathogens. In any case, there is an urgent need to enhance understanding of how helminths beneficially modulate inflammatory reactions, to identify the molecules involved and to promote approaches to exploit this knowledge for future therapeutic interventions. Evidence is increasing that C-type lectins play an important role in driving helminth-mediated immune responses. C-type lectins belong to a large family of calcium-dependent receptors with broad glycan specificity. They are abundantly present on immune cells, such as dendritic cells and macrophages, which are essential in shaping host immune responses. Here, we will focus on the role of the C-type lectin macrophage mannose receptor (MR) in helminth–host interactions, which is a critically understudied area in the field of helminth immunobiology. We give an overview of the structural aspects of the MR including its glycan specificity, and the functional implications of the MR in helminth–host interactions focusing on a few selected helminth species.

Diabetes mellitus (DM) is one of the serious non communicable diseases worldwide. Presence of DM patient in a family may be considered as risk factor for other family members to acquire the disease, due to DM inheritance nature and/or similar life style pattern among family members. This paper assessed awareness of DM patients’ family members (DMPFMs) about DM occurrence and prevention. A cross sectional study was conducted in 2014 in two suburban cities of Ethiopia, namely Kemisse, and Kombolcha using an interviewer administered questionnaire among primary or secondary degree DMPFMs and controls. Based on eligibility criteria study participants were selected by health extension workers on house to house visit. Data were analyzed using SPSS version 20, and P value less than 0.05 considered as statistically significant. Of the total 347 study participants, 45.5% (n = 158) had DMPFMs. Majority, 60.8% of DMPFMs and 73.0% of controls were males. Mean age of DMPFMs (30.06 years) was less than that of the controls (37.38 years). On living style, 51.9% DMPFMs, and 42.8% of controls were single. In both study groups, the majority of study participants attended grade 7–12. The likelihood of having good level of knowledge among DMPFMs were 2.94 times (AOR = 2.94 95% CI 1.87–4.86) higher compared to those who did not. Those attaining higher educational levels were 3.41 times (AOR = 3.41, 95% CI 1.31–8.91) more likely to have good level of knowledge, as compared to those who were unable to read and write. The likelihood of having good level of positive practice among DMPFMs were 3.38 times (AOR = 3.38% CI 2.05–5.58) higher as compared to controls. Participants who were living in Kombolcha were 2.33 times (AOR = 2.33 95% CI 1.31–4.12) more likely to have good level of practice, as compared to individuals from Kemisse. Diabetes mellitus family members in the Ethiopian suburban cities Kemisse, and Kombolcha had better knowledge and practice about DM compared to controls. But, the overall awareness about DM occurrence and prevention was relatively low. Thus, DM awareness campaigns should be strongly pursued regardless of family history and educational background to prevent further increase of DM in Ethiopia.

Clinical trials have shown that administration of the nematode Trichuris suis can be beneficial in treating various immune disorders. To provide insight into the mechanisms by which this worm suppresses inflammatory responses, an active component was purified from T. suis soluble products (TsSPs) that suppress TNF and IL‐12 secretion from LPS‐activated human dendritic cells (DCs). Analysis by liquid chromatography tandem mass spectrometry identified this compound as prostaglandin (PG)E2. The purified compound showed similar properties compared with TsSPs and commercial PGE2 in modulating LPS‐induced expression of many cytokines and chemokines and in modulating Rab7B and P2RX7 expression in human DCs. Furthermore, the TsSP‐induced reduction of TNF secretion from DCs is reversed by receptor antagonists for EP2 and EP4, indicating PGE2 action. T. suis secretes extremely high amounts of PGE2 (45–90 ng/mg protein) within their excretory/secretory products but few related lipid mediators as established by metabololipidomic analysis. Culture of T. suis with several cyclooxygenase (COX) inhibitors that inhibit mammalian prostaglandin synthesis affected the worm's motility but did not inhibit PGE2 secretion, suggesting that the worms can synthesize PGE2 via a COX‐independent pathway. We conclude that T. suis secretes PGE2 to suppress proinflammatory responses in human DCs, thereby modulating the host's immune response.—Laan, L. C., Williams, A. R., Stavenhagen, K., Giera, M., Kooij, G., Vlasakov, I., Kalay, H., Kringel, H., Nejsum, P., Thamsborg, S. M., Wuhrer, M., Dijkstra, C. D., Cummings, R. D., van Die, I. The whipworm (Trichuris suis) secretes prostaglandin E2 to suppress proinflammatory properties in human dendritic cells. FASEB J. 31, 719–731 (2017). http://www.fasebj.org

Galactofuranose (Galf)-containing glycoconjugates are present in numerous microbes, including filamentous fungi where they are important for morphology, virulence and maintaining cell wall integrity. The incorporation of Galf-residues into galactomannan, galactomannoproteins and glycolipids is carried out by Golgi-localized Galf transferases. The nucleotide sugar donor used by these transferases (UDP-Galf) is produced in the cytoplasm and has to be transported to the lumen of the Golgi by a dedicated nucleotide sugar transporter. Based on homology with recently identified UDP-Galf-transporters in A. fumigatus and A. nidulans, two putative UDP-Galf-transporters in A. niger were found. Their function and localization was determined by gene deletions and GFP-tagging studies, respectively. The two putative UDP-Galf-transporters in A. niger are homologous to each other and are predicted to contain eleven transmembrane domains (UgtA) or ten transmembrane domains (UgtB) due to a reduced length of the C-terminal part of the UgtB protein. The presence of two putative UDP-Galf-transporters in the genome was not unique for A. niger. From the twenty Aspergillus species analysed, nine species contained two additional putative UDP-Galf-transporters. Three of the nine species were outside the Aspergillus section nigri, indication an early duplication of UDP-Galf-transporters and subsequent loss of the UgtB copy in several aspergilli. Deletion analysis of the single and double mutants in A. niger indicated that the two putative UDP-Galf-transporters (named UgtA and UgtB) have a redundant function in UDP-Galf-transport as only the double mutant displayed a Galf-negative phenotype. The Galf-negative phenotype of the double mutant could be complemented by expressing either CFP-UgtA or CFP-UgtB fusion proteins from their endogenous promoters, indicating that both CFP-tagged proteins are functional. Both Ugt proteins co-localize with each other as well as with the GDP-mannose nucleotide transporter, as was demonstrated by fluorescence microscopy, thereby confirming their predicted localization in the Golgi. A. niger contains two genes encoding UDP-Galf-transporters. Deletion and localization studies indicate that UgtA and UgtB have redundant functions in the biosynthesis of Galf-containing glycoconjugates.

Inflammatory immune disorders such as inflammatory bowel disease and multiple sclerosis are major health problems. Currently, the intestinal whipworm Trichuris suis is being explored in clinical trials to reduce inflammation in these diseases; however, the mechanisms by which the parasite affects the host immune system are not known. Here we determined the effects of T. suis soluble products (SPs) on Toll-like receptor-4 (TLR4)-stimulated human dendritic cells (DCs) using Illumina bead chip gene arrays. Pathway analysis of lipopolysaccharide-stimulated DCs with or without T. suis treatment showed that co-stimulation with T. suis SPs resulted in a downregulation of both the myeloid differentiation primary response gene 88-dependent and the TIR-domain-containing adaptor-inducing interferon-β-dependent signalling pathways triggered by TLR4. These data were verified using quantitative real-time PCR of several key genes within these pathways and/or defining their protein levels. In addition, T. suis SPs induce Rab7b, a negative regulator of TLR4 signalling that interferes with its trafficking, which coincided with a reduced surface expression of TLR4. These data indicate that the mechanism by which T. suis SPs reduce inflammatory responses is through suppression of both TLR4 signalling and surface expression on DCs.

The α1,2‐fucosyltransferase activity in pancreatic tumors is much lower compared to normal pancreatic tissue. Here we show that hypoxia inducible factor (HIF) 1α is constitutively expressed in the pancreatic cancer cell lines Pa‐Tu‐8988S and Pa‐Tu‐8988T and suppresses the expression of the α1,2‐fucosyltransferase genes FUT1 and FUT2. Down regulation of HIF‐1α expression resulted in elevated FUT1 and FUT2 transcript levels and an increased expression of α1,2‐fucosylated glycan structures on the surface of these cells. In conclusion, our data are the first to identify HIF‐1α as a suppressor of FUT1/2 expression, thereby regulating α1,2‐fucosylation of cell‐surface glycans.

Schistosomiasis is a common debilitating human parasitic disease in (sub)tropical areas, however, schistosome infections can also protect against a variety of inflammatory diseases. This has raised broad interest in the mechanisms by which Schistosoma modulate the immune system into an anti-inflammatory and regulatory state. Human dendritic cells (DCs) show many phenotypic changes upon contact with Schistosoma mansoni soluble egg antigens (SEA). We here show that oxidation of SEA glycans, but not heat-denaturation, abrogates the capacity of SEA to suppress both LPS-induced cytokine secretion and DC proliferation, indicating an important role of SEA glycans in these processes. Remarkably, interaction of SEA glycans with DCs results in a strongly increased expression of Suppressor Of Cytokine Signalling1 (SOCS1) and SH2-containing protein tyrosine Phosphatase-1 (SHP1), important negative regulators of TLR4 signalling. In addition, SEA induces the secretion of transforming growth factor β (TGF-β), and the surface expression of the costimulatory molecules Programmed Death Ligand-1 (PD-L1) and OX40 ligand (OX40L), which are known phenotypic markers for the capacity of DCs to polarize naïve T cells into Th2/Treg cell subsets. Inhibition of mannose receptor (MR)-mediated internalization of SEA into DCs by blocking with allyl α-D-mannoside or anti-MR antibodies, significantly reduced SOCS1 and SHP1 expression. In conclusion, we demonstrate that SEA glycans are essential for induction of enhanced SOCS1 and SHP1 levels in DCs via the MR. Our data provide novel mechanistic evidence for the potential of S. mansoni SEA glycans to modulate human DCs, which may contribute to the capacity of SEA to down-regulate inflammatory responses.

Galactofuranose (Galf)-containing glycoconjugates are important to secure the integrity of the cell wall of filamentous fungi. Mutations that prevent the biosynthesis of Galf-containing molecules compromise cell wall integrity. In response to cell wall weakening, the cell wall integrity (CWI)-pathway is activated to reinforce the strength of the cell wall. Activation of CWI-pathway in Aspergillus niger is characterized by the specific induction of the agsA gene, which encodes a cell wall α-glucan synthase. In this study, we screened a collection of cell wall mutants with an induced expression of agsA for defects in Galf biosynthesis using a with anti-Galf antibody (L10). From this collection of mutants, we previously identified mutants in the UDP-galactopyranose mutase encoding gene (ugmA). Here, we have identified six additional UDP-galactopyranose mutase (ugmA) mutants and one mutant (named mutant #41) in an additional complementation group that displayed strongly reduced Galf-levels in the cell wall. By using a whole genome sequencing approach, 21 SNPs in coding regions were identified between mutant #41 and its parental strain which changed the amino acid sequence of the encoded proteins. One of these mutations was in gene An14g03820, which codes for a putative UDP-glucose-4-epimerase (UgeA). The A to G mutation in this gene causes an amino acid change of Asn to Asp at position 191 in the UgeA protein. Targeted deletion of ugeA resulted in an even more severe reduction of Galf in N-linked glucans, indicating that the UgeA protein in mutant #41 is partially active. The ugeA gene is also required for growth on galactose despite the presence of two UgeA homologs in the A. niger genome. By using a classical mutant screen and whole genome sequencing of a new Galf-deficient mutant, the UDP-glucose-4-epimerase gene (ugeA) has been identified. UgeA is required for the biosynthesis of Galf as well as for galactose metabolism in Aspergillus niger.

Recent clinical trials in patients with inflammatory diseases like multiple sclerosis (MS) or inflammatory bowel disease (IBD) have shown the beneficial effects of probiotic helminth administration, although the underlying mechanism of action remains largely unknown. Potential cellular targets may include innate immune cells that propagate inflammation in these diseases, like pro-inflammatory macrophages. We here investigated the effects of the helminth Trichuris suis soluble products (SPs) on the phenotype and function of human inflammatory (granulocyte-macrophage colony-stimulating factor (GM-CSF)-differentiated) macrophages. Interestingly, we here show that T. suis SPs potently skew inflammatory macrophages into a more anti-inflammatory state in a Toll-like receptor 4 (TLR4)-dependent manner, and less effects are seen when stimulating macrophages with TLR2 or -3 ligands. Gene microarray analysis of GM-CSF-differentiated macrophages further revealed that many TLR4-induced inflammatory mediators, including interleukin (IL)-12B, CCL1 and CXCL9, are downregulated by T. suis SPs. In particular, we observed a strong reduction in the expression and function of P2RX7, a purinergic receptor involved in macrophage inflammation, leading to reduced IL-1β secretion. In conclusion, we show that T. suis SPs suppress a broad range of inflammatory pathways in GM-CSF-differentiated macrophages in a TLR4-dependent manner, thereby providing enhanced mechanistic insight into the therapeutic potential of this helminth for patients with inflammatory diseases.