Characterisation of the protein composition of peripheral blood mononuclear cell microsomes by SDS-PAGE and mass spectrometry

Immune modulation of goat monocytes by Fasciola gigantica Legumain-1 protein (Fg-LGMN-1)

Legumains belonging to C_13 peptidase family of proteins, and are ubiquitously disseminated among all vertebrate and invertebrate organisms, and have been implicated in innumerable biological and cellular functionality. Herein, we characterized and evaluated immunoregulatory characteristics of Legumain-1 from Fasciola gigantica (Fg-LGMN-1) during its interaction with host immune cells. The isopropyl-ß-d-thiogalactopyranoside (IPTG) stimulated RFg-LGMN-1 protein was positively detected by rat serum containing anti-RFg-LGMN-1 polyclonal antibodies. Furthermore, the uptake of RFg-LGMN-1 by goat monocytes was successfully confirmed using Immunofluorescence Assay (IFA). The immunohistochemical analysis revealed the native localization of LGMN-1 protein on the periphery and internal structures such as suckers, pharynx, and genital pore of the adult parasite, thereby validating its presence in excretory-secretory (ES) products of F. gigantica. The RFg-LGMN-1 co-incubated with concanavalin-A (Con-A) stimulated the increase of interleukin 2 (IL-2), IL-10, and IL-17 in monocytes derived from peripheral blood mononuclear cells (PBMCs) in the concentration-dependent manner. However, the IL-4 cytokine in response to the RFg-LGMN-1 protein declined. These results illuminated the role of LGMN-1 during the parasite-host interface. Our findings elaborated additional evidence that Legumain protein play a role in the manipulating host immune responses during parasite infections. However, further evaluation of RFg-LGMN-1 protein in context of its immunomodulatory roles should be conducted to enhance our understandings of the mechanisms employed by F. gigantica to evade host immune responses.

Characteristics of Biotin lipoyl attachment and 2-oxoacid dehydrogenase acyltransferase of the parasitic nematode Haemonchus contortus and its modulatory functions on goat PBMCs in vitro

Biotin lipoyl attachment and 2-oxoacid dehydrogenase acyltransferase (BLAODA), as an essential excretion of Haemonchus contortus (HcESPs), was identified to have antigenic functions. T helper-9 (Th9) cells secrete interleukin (IL)-9, a signature cytokine associated with tumour immunology, allergy and autoimmunity. Nonetheless, the understanding of modulatory functions of BLAODA on Th9 and other immune cells is limited. In this study, the BLAODA gene was cloned, and the recombinant (r) protein of BLAODA (rHcBLAODA) was expressed and immunoblotting was performed. The results revealed that HcBLAODA gene was successfully cloned and rHcBLAODA protein was expressed. The localization of rHcBLAODA was confirmed on the surface of gut sections from adult H. contortus. The rHcBLAODA protein capability to react precisely with anti-H. contortus antibodies were confirmed by immunoblotting and immunofluorescence assay (IFA). Further functional analysis showed that interaction of rHcBLAODA with host cells significantly enhanced Th9 cells generation, IL-9 expression, nitric oxide production and cell apoptosis while suppressing the cells proliferation and cells migration depending on the concentration. Overall, these findings suggest that rHcBLAODA protein could modulate the host immune response by inducing Th9 cells to secrete IL-9 cytokine in vitro.

Fasciola gigantica tegumental calcium-binding EF-hand protein 4 exerts immunomodulatory effects on goat monocytes

Background

The liver fluke Fasciola gigantica secretes excretory-secretory proteins during infection to mediate its interaction with the host. In this study, we investigated the immunomodulatory effects of a recombinant tegumental calcium-binding EF-hand protein 4 of F. gigantica (rFg-CaBP4) on goat monocytes.

Methods

The rFg-CaBP4 protein was induced and purified by affinity chromatography. The immunogenic reaction of rFg-CaBP4 against specific antibodies was detected through western blot analysis. The binding of rFg-CaBP4 on surface of goat monocytes was visualized by immunofluorescence assay. The localization of CaBP4 within adult fluke structure was detected by immunohistochemical analysis. The cytokine transcription levels in response to rFg-CaBP4 were examined using ABI 7500 real-time PCR system. The expression of the major histocompatibility complex (MHC) class-II molecule (MHC-II) in response to rFg-CaBP4 protein was analyzed using Flow cytometry.

Results

The isopropyl-ß-D-thiogalactopyranoside-induced rFg-CaBP4 protein reacted with rat sera containing anti-rFg-CaBP4 polyclonal antibodies in a western blot analysis. The adhesion of rFg-CaBP4 to monocytes was visualized by immunofluorescence and laser scanning confocal microscopy. Immunohistochemical analysis localized native CaBP4 to the oral sucker, pharynx, genital pore, acetabulum and tegument of adult F. gigantica. Co-incubation of rFg-CaBP4 with concanavalin A-stimulated monocytes increased the transcription levels of interleukin (IL)-2, IL-4, interferon gamma and transforming growth factor-β. However, a reduction in the expression of IL-10 and no change in the expression of tumor necrosis factor-α were detected. Additionally, rFg-CaBP4-treated monocytes exhibited a marked increase in the expression of the major histocompatibility complex (MHC) class-II molecule (MHC-II) and a decrease in MHC-I expression, in a dose-dependent manner.

Conclusions

These findings provide additional evidence that calcium-binding EF-hand proteins play roles in host-parasite interaction. Further characterization of the immunomodulatory role of rFg-CaBP4 should expand our understanding of the strategies used by F. gigantica to evade the host immune responses.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04784-5.

Unveiling the Immunomodulatory Characteristics of Haemonchus contortus Ephrin Domain Containing Protein in the Parasite-Host Interactions

Simple Summary

Haemonchus contortus excretory/secretory products (HcESPs) contain many proteins that can perform various functions including modulating the host immune response. Recent studies indicate that IL-9 can be secreted by a specialized population of T cells called Th9 cells, which mediate anti-parasite immunity. Furthermore, HcESPs could enhance goat peripheral blood mononuclear cells (PBMCs) derived Th9 cells production. Ephrin domain containing protein (EPH) was identified as one of the HcESPs that can be isolated from different stages of this helminth. Nonetheless, the understanding of immunomodulatory roles of EPH on Th9 and other immune cells remains limited. In this study, the correlation between recombinant H. contortus Ephrin domain containing protein(rHcEPH)and goat PBMCs significantly enhanced Th9 cells differentiation, IL-9 expression, cell apoptosis efficiency, and cell migration, whereas cell proliferation was suppressed significantly depending on the concentration. Our findings illustrated that rHcEPH protein is linked to modulate the host immune cells and could enhance protective immunity by inducing Th9 cells secreted IL-9 in vitro.

Abstract

Ephrin domain containing protein (EPH), a significant excreted and secreted product (ESPs) of Haemonchus contortus, has been identified to have antigenic functions. Over the past years, a new subset of CD4 + T named as T helper 9 cells that secrete interleukin-9 (IL-9) as a signature cytokine is associated with tumor immunity and allergy. Nonetheless, the understanding of immunomodulatory roles of EPH on goat Th9 and other immune cells remains limited. Herein, EPH from H. contortus (HcEPH) was cloned and expressed in pET-28a. Immunofluorescence assay (IFA) was carried-out to localize rHcEPH within H. contortus adult worms and to bind with goat peripheral blood mononuclear cells (PBMCs). Besides, the impact of rHcEPH on signature cytokine IL-9 expression in goat PBMCs was evaluated. Flow cytometry was employed to examine Th9 cells production and cell apoptosis. The results revealed success in the expression and localization of rHcEPH in surface of adult H. contortus gut sections. According to IFA analysis, the rHcEPH protein was capable to react precisely with anti-H. contortus antibodies. Further functional analysis showed that correlation between rHcEPH and host PBMCs significantly enhanced Th9 cell differentiation, IL-9 expression, cell apoptosis efficiency, and cell migration, whereas cell proliferation was suppressed significantly depending on the concentration. Our observations indicated that rHcEPH protein is linked to modulate the host immune cells and could enhance protective immunity by inducing Th9 responses.

Immunomodulatory dynamics of excretory and secretory products on Th9 immune response during Haemonchus contortus infection in goat

CD4+ T cells play critical roles in mediating adaptive immunity to a variety of pathogens. Recently, new subset of CD4+T named as T helper 9 cells that express the prototypical interleukin-9 (IL-9) cytokine have been recognized in human and mice models during different parasitic infections. Haemonchus contortus is a gastrointestinal nematode of small ruminants which cause high mortality in young animals. During infection, Excretory and Secretary Products (ESPs) are released in the host body. No other study has reported yet on immunomodulatory dynamics of H. contortus ESPs on Th9 immune response in vitro or in vivo. In this study, immunomodulatory effects of ESPs (5, 10, 20, 40, 80; μg/mL) incubated with goat PBMCs on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated in vitro. Moreover, for in vivo study, goats were infected with different doses (P-800, P-2400, and P-8000) of H. contortus infective larva (L3) and immunomodulatory effects on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated at 7, 10, 14, 18, 21, 28 Days Post Infection (DPI). Flow cytometry was performed to evaluate the effects on Th9 cells and quantitative real time polymerase chain reaction was performed to evaluate the IL-9 cytokine transcription level. Additionally, fecal egg counting was also performed in parallel to confirm the infection. All goats were dewormed at 29 DPI and all experiments were also performed at 35 DPI, one week post deworming. The finding indicated that 10, 20, 40, 80 μg/mL concentration of ESPs incubated with goat PBMCs showed significant increase in the production of Th9 cells, signature cytokine IL-9 and expression of TGF-β/Smad signaling regulator as compared to control group in vitro.All infected groups showed significant increase in production of Th9 cells and IL-9 cytokine and expression of TGF-β/Smad key genes at 18, 21, and 28 DPI as compared to control group. Likewise, at 14 DPI, P-2400 and P-8000 groups showed significant increase in production of Th9 cells, IL-9 cytokine and expression of TGF-β/Smad key genes. While at 10 DPI, production of Th9 cells and IL-9 was significantly increased in P-2400 & P-8000 groups, and at 7 DPI only P-8000 showed significantly increase in IL-9 production. No immunomodulatory effects were observed at 0 and 3 DPI. Additionally, significant gradually up-regulated key genes expression of TGF-β/Smad signaling regulator in all infected groups confirmed the above results. After deworming, production of Th9 cells, associated immune response and expression of signaling regulator in each group were significantly decreased. Based on this study, it is concluded that Th9 immune response was induced during H. contortus infection in goat by up-regulation of TGF-β/Smad signaling key genes.

Haemonchus contortus is one of the most pathogenic nematodes of small ruminants in tropical and sub-tropical areas of the world. This parasite is responsible for anemia, edema, and death in young animal which can lead to billions of economic losses globally. Excretory and secretory products (ESPs) are produced by the parasite to modulate the immune response and to protect both parasite and the host. Th9 cells are a subset of CD4+ T cells producing IL-9 cytokine. Th9 cells were increasingly recognized for being important in immunity to intestinal infection with helminths. In this study, immunomodulatory effects of ESPs on PBMCs derived Th9 cells, IL-9 cytokine and TGF-β/Smad signalling were evaluated in vitro and in vivo. Furthermore, Th9 cells production was significantly enhanced on 7, 10, 14, 18, 21, and 28 Days Post Infection (DPI), while no effect was observed at 0 and 3 DPI in vivo. Moreover, the production of IL-9 and TGF-β/Smad Pathway key genes increased gradually from 7 to 28 DPI in vivo. After deworming, production of Th9 cells was gradually decreased in each group.

Identification of a novel methyltransferase-type 12 protein from Haemonchus contortus and its effects on functions of goat PBMCs

Background

Methyltransferases (MTFs) are broad range of enzymes, which are ubiquitously expressed in diverse organisms ranging from bacteria to animals. MTFs proteins have been associated with various biological/cellular processes including transcriptional regulation, subcellular protein and RNA localization, signal transduction and DNA-damage repair. However, the role of MTFs in immune mechanism during host–parasite interaction has not been addressed yet.

Results

An open reading frame (764 bp) of methyltransferase-type 12 gene of H. contortus denoted as HcMTF-12, was successfully cloned using reverse transcriptase-polymerase chain reaction (RT-PCR) followed by prokaryotic expression in Escherichia coli BL21 (DE3 strain). The recombinant HcMTF-12 protein (rHcMTF-12) was about 47 kDa along with a fusion vector protein of 18 kDa. Immunoblot results identified the native protein MTF-12 with antibodies produced in rats against rHcMT-12, whereas rHcMTF-12 protein was recognized with sera of goat experimentally infected with H. contortus. Immunohistochemical analysis revealed that the native MTF-12 protein was mainly located in the periphery (cuticle) of parasite sections as well as within the pharynx and intestinal region. An immunofluorescence assay validated that rHcMTF-12 attached to the surface of goat PBMCs. Furthermore, the cytokines transcription of IL-2, IFN-γ and IL-4 transcripts of PBMCs incubated with rHcMTF-12 were enhanced in a dose-dependent manner. The secretion of TGF-β1 and IL-10 was significantly decreased. However, IL-6 production was not significantly different as compared to the control groups. Moreover, the migration activity and nitric oxide (NO) production by PBMCs were induced considerably, whereas the proliferation of PBMCs cells was negatively affected when incubated with the rHcMTF-12 protein.

Conclusions

Our findings suggest that HcMTF-12 significantly mediated the functions of PBMCs, and it might be a potential candidate for therapeutic interventions against haemonchosis.

Tropomyosin: An Excretory/Secretory Protein from Haemonchus contortus Mediates the Immuno-Suppressive Potential of Goat Peripheral Blood Mononuclear Cells In Vitro

During host-parasite interactions, binding of excretory/secretory proteins (ESPs) on the host immune cells is considered the fundamental phase for regulation of immune responses. In this study, gene encoding Haemonchus contortus tropomyosin (Hc-TpMy), was successfully cloned and expressed, and the recombinant protein after host cell surface attachment was evaluated for immune functional analysis with goat peripheral blood mononuclear cells (PBMCs) in vitro. The isopropyl-β-D-thiogalactopyranoside (IPTG)-induced recombinant protein was successfully recognized by the sera of rat experimentally infected with rHc-TpMy. The immunofluorescence assay detected attachment of rHc-TpMy on the surface of host PBMCs. Furthermore, immunoregulatory roles of rHc-TpMy on cytokines expression, PBMC proliferation, migration, nitric oxide (NO) production, apoptosis and monocytes phagocytosis were observed. The results showed that expression of IL-4 and IFN-γ cytokines, cell proliferation, NO production and PBMC migration were significantly suppressed by goat PBMCs after co-incubation with rHc-TpMy protein. However, the productions of IL-10, IL-17 and TGF-β1 cytokines, PBMCs apoptosis and monocytes phagocytosis were elevated at dose dependent manner. Our findings indicated that rHc-TpMy is an important ES binding protein exhibit distinct immuno-suppressive roles on goat PBMCs which might be a potential molecular target to control haemonchosis in future.

Recombinant elongation factor 1 alpha of Haemonchus contortus affects the functions of goat PBMCs

Excretory/secretory proteins of Haemonchus contortus (HcESPs) intermingle comprehensively with host immune cells and modulate host immune responses. In this study, H contortus ES antigen named as elongation factor 1 alpha (HcEF‐1α) was cloned and expressed. The influences of recombinant HcEF‐1α on multiple functions of goat peripheral blood mononuclear cells (PBMCs) were observed in vitro. Immunoblot analysis revealed that rHcEF‐1α was recognized by the serum of goat infected with H contortus. Immunofluorescence analysis indicated that rHcEF‐1α was bound on surface of PBMCs. Moreover, the productions of IL‐4, TGF‐β1, IFN‐γ and IL‐17 of cells were significantly modulated by the incubation with rHcEF‐1α. The production of interleukin IL‐10 was decreased. Cell migration, cell proliferation and cell apoptosis were significantly increased; however, nitric oxide production (NO) was significantly decreased. The MHC II molecule expression of cells incubated with rHcEF‐1α was increased significantly, whereas MHC‐I was not changed as compared to the control groups (PBS control and pET32a). These findings indicated that rHcEF‐1α protein might play essential roles in functional regulations of HcESPs on goat PBMC and mediate the immune responses of the host during host‐parasite relationship.

Characterization of Haemonchus contortus Excretory/Secretory Antigen (ES-15) and Its Modulatory Functions on Goat Immune Cells In Vitro

Small size excretory/secretory (ES) antigens of the Haemonchus contortus parasite have intense interest among researchers for understanding the molecular basis of helminths immune regulation in term of control strategies. Immunomodulatory roles of H. contortus ES-15 kDa (HcES-15) on host immune cells during host–parasite interactions are unknown. In this study, the HcES-15 gene was cloned and expression of recombinant protein (rHcES-15) was induced by isopropyl-ß-d-thiogalactopyranoside (IPTG). Binding activity of rHcES-15 to goat peripheral blood mononuclear cells (PBMCs) was confirmed by immunofluorescence assay (IFA) and immunohistochemical analysis showed that H. contortus 15 kDa protein localized in the outer and inner structure of the adult worm, clearly indicated as the parasite’s ES antigen. The immunoregulatory role on cytokines production, cell proliferation, cell migration, nitric oxide (NO) production, apoptosis, and phagocytosis were observed by co-incubation of rHcES-15 with goat PBMCs. The results showed that cytokines IL-4, IL-10, IL-17, the production of nitric oxide (NO), PBMCs apoptosis, and monocytes phagocytosis were all elevated after cells incubated with rHcES-15 at differential protein concentrations. We also found that IFN-γ, TGF-β1, cells proliferation and migration were significantly suppressed with the interaction of rHcES-15 protein. Our findings indicated that low molecular ES antigens of H. contortus possessed discrete immunoregulatory roles, which will help to understand the mechanisms involved in immune evasion by the parasite during host–parasite interactions.

Hepatocellular carcinoma-associated antigen 59 of Haemonchus contortus modulates the functions of PBMCs and the differentiation and maturation of monocyte-derived dendritic cells of goats in vitro

BACKGROUND

Hepatocellular carcinoma-associated antigen 59 (HCA59), which is one of the most important excretory/secretory products of Haemonchus contortus (HcESPs), is known to have antigenic functions. However, its immunomodulatory effects on host cells are poorly understood.

METHODS

Here, we cloned the HCA59 gene and expressed the recombinant protein of HCA59 (rHCA59). Binding activities of rHCA59 to goat peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) were checked by immunofluorescence assay (IFA) and the immunoregulatory effects of rHCA59 on cytokine secretions, cell migration, cell proliferation, nitric oxide production, and changes in expression of genes in related pathways were observed by co-incubation of rHCA59 with goat PBMCs and DCs. Monocyte phagocytosis and characterization of goat blood DC subsets were detected by flow cytometry.

RESULTS

The IFA results revealed that rHCA59 could bind to PBMCs and DCs. Treatment of PBMCs with rHCA59 significantly increased cellular proliferation and NO production in a dose-dependent manner, while cell migration was vigorously blocked. Treatment with rHCA59 significantly suppressed monocytes phagocytosis. The quantity of surface marker CD80 on DCs increased significantly after rHCA59 treatment. In addition, the expression of genes included in the WNT pathway was related to the differentiation and maturation of DCs, and the production of IL-10 and IL-17 produced by PBMCs was altered.

CONCLUSIONS

Our findings illustrated that rHCA59 could enhance host immune responses by regulating the functions of goat PBMCs and DCs, which would benefit our understanding of HCA59 from parasitic nematodes contributing to the mechanism of parasitic immune evasion.

The Serine/Threonine-Protein Phosphatase 1 From Haemonchus contortus Is Actively Involved in Suppressive Regulatory Roles on Immune Functions of Goat Peripheral Blood Mononuclear Cells

Serine/threonine-protein phosphatases (STPs), as integral constituents of parasitic excretory/secretory proteins, are assumed to be released during the host–parasite interactions. However, knowledge about these phosphatases and their immunoregulatory and immune protective efficiencies with host peripheral blood mononuclear cells (PBMCs) is scant. In this study, an open reading frame of STP from Haemonchus contortus designated as HcSTP-1 was amplified and cloned using reverse-transcription-polymerase chain reaction (RT-PCR) method. The 951-bp nucleotides sequence was encoded to a protein of 316 amino acid residues, conserved in characteristics motifs GDXHG, GDYVDRG, GNHE, HGG, RG, and H. The HcSTP-1 protein was detected at approximately 35 kDa as recombinant protein fused in an expression vector system and resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunohistochemically, HcSTP-1 was found to be localized in both male and female adult worm sections. Using immunofluorescence assay, the binding activity of rHcSTP-1 was confirmed on surface of goat PBMCs, which resulted in expression of multiple cytokines and various immunoregulatory activities in vitro. The RT-PCR results showed that mRNA level of interleukin-2, TGF-β1, IFN-γ, and IL-17 (with 10 µg/ml) was upregulated and IL-10 was decreased. However, IL-6 showed no change after PBMCs incubated with rHcSTP-1 protein. Further functional analysis showed that migratory activity of cells, intracellular nitrite production (NO), and apoptotic efficiency of PBMCs were elevated at significant level, whereas the proliferation of goat PBMCs and monocytes-associated major histocompatibility complex (MHC)-I and MHC-II expressions were decreased significantly at concentration-dependent fashion. Our results showed that the HcSTP-1 protein engaged in vital suppressive regulatory roles on host immune cells, which might represent a potential molecular target for controlling H. contortus infection in future.

Arginine kinase from Haemonchus contortus decreased the proliferation and increased the apoptosis of goat PBMCs in vitro

BACKGROUND

Arginine kinase (AK), an important member of phosphagen kinase family has been extensively studied in various vertebrates and invertebrates. Immunologically, AKs are important constituents of different body parts, involved in various biological and cellular functions, and considered as immune-modulator and effector for pro-inflammatory cytokines. However, immunoregulatory changes of host cells triggered by AK protein of Haemonchus contortus, a parasitic nematode of ruminants, are still unknown. The current study was focused on cloning and characterisation of Hc-AK, and its regulatory effects on cytokines level, cell migration, cell proliferation, nitric oxide production and apoptosis of goat peripheral blood mononuclear cells (PBMCs) were observed.

METHODS

The full-length sequence of the Hc-AK gene was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sub-cloned into the prokaryotic expression vector pET-32a. The biochemical characteristics of recombinant protein Hc-AK, which was purified by affinity chromatography, were performed based on the enzymatic assay. Binding of rHc-AK with PBMCs was confirmed by immunofluorescence assay (IFA). Immunohistochemical analysis was used to detect localisation of Hc-AK within adult worms sections. The immunoregulatory effects of rHc-AK on cytokine secretions, cell proliferation, cell migration, nitric oxide production and apoptosis were determined by co-incubation of rHc-AK with goat PBMCs.

RESULTS

The full-length ORF (1080 bp) of the Hc-AK gene was successfully cloned, and His-tagged AK protein was expressed in the Escherichia coli strain BL21. The recombinant protein of Hc-AK (rHc-AK) was about 58.5 kDa together with the fused vector protein of 18 kDa. The biochemical assay showed that the protein encoded by the Hc-ak exhibited enzymatic activity. Western blot analysis confirmed that the rHc-AK was recognised by the sera from rat (rat-antiHc-AK). The IFA results showed that rHc-AK could bind on the surface of goat PBMCs. Immunohistochemically, Hc-AK was localised at the inner and outer membrane as well as in the gut region of adult worms. The binding of rHc-AK to host cells increased the levels of IL-4, IL-10, IL-17, IFN-γ, nitric oxide (NO) production and cell apoptosis of goat PBMCs, whereas, TGF-β1 levels, cell proliferation and PBMCs migration were significantly decreased in a dose dependent manner.

CONCLUSIONS

Our findings suggested that rHc-AK is an important excretory and secretory (ES) protein involved in host immune responses and exhibit distinct immunomodulatory properties during interaction with goat PBMCs.

Transmembrane protein 63A is a partner protein of Haemonchus contortus galectin in the regulation of goat peripheral blood mononuclear cells

Background

Hco-gal-m and -f were two isoforms of galectin cloned from male and female Haemonchus contortus, respectively, and it was demonstrated that recombinant Hco-gal-m and -f could act as immune suppressors. However, little is known about the receptors or binding partners of these galectins in the host. The research of the molecular mechanisms that govern the interactions between these galectins and host molecules will fill a gap in our understanding how parasite galectins interact with host cells.

Methods

A yeast two-hybrid system was used to identify the binding partners of Hco-gal-m and -f in this research. The interaction between rHco-gal-m and candidate binding protein was validated by co-immunoprecipitation. The localization of transmembrane protein 63A (TMEM63A) in peripheral blood mononuclear cells (PBMCs) was detected by immunofluorescence. The distribution of TMEM63A in T cells, B cells and monocytes in PBMCs was detected by flow cytometry. The immunomodulatory effects of Hco-gal-m and TMEM63A on cell proliferation, migration, apoptosis, nitric oxide production and cytokine secretion were observed by co-incubation of rHco-gal-m and TMEM63A-siRNA with goat PBMCs and monocytes.

Results

We found that TMEM63A, a functionally unknown protein, from goat PBMCs could bind to Hco-gal-m and -f. Immunofluorescence showed that TMEM63A was localized to the cell membrane. Flow cytometric analysis revealed that TMEM63A was expressed in the majority of goat PBMCs. After using RNA interference to knockdown expression of TMEM63A, the PBMC proliferation and migration were significantly increased, while the influence of rHco-gal-m on monocyte phagocytosis, PBMC nitric oxide production and migration were potently blocked. In addition, the production of IL-10, IFN-γ and TGF-β induced by rHco-gal-m were also altered.

Conclusions

Our results show that TMEM63A is a binding partner of Hco-gal-m/f, and involved in the immune responses of host PBMCs induced by Hco-gal-m for the first time.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0816-3) contains supplementary material, which is available to authorized users.

Medical applications of leukocyte surface molecules--the CD molecules

Leukocytes are the cells of the immune system and are centrally involved in defense against infection, in autoimmune disease, allergy, inflammation, and in organ graft rejection. Lymphomas and leukemias are malignancies of leukocytes, and the immune system is almost certainly involved in most other cancers. Each leukocyte expresses a selection of cell surface glycoproteins and glycolipids which mediate its interaction with antigen, with other components of the immune system, and with other tissues. It is therefore not surprising that the leukocyte surface molecules (CD molecules) have provided targets for diagnosis and therapy. Among the "celebrities" are CD20, a target for lymphoma therapeutic antibodies which earns $2 billion annually (and makes a significant difference to lymphoma patients), and CD4, the molecule used by the human immunodeficiency virus (HIV) as an entry portal into cells of the immune system. This short review provides a background to the CD molecules and antibodies against them, and summarizes research, diagnostic, and therapeutic applications of antibodies against these molecules.

Medical applications of leukocyte surface molecules--the CD molecules

Leukocytes are the cells of the immune system and are centrally involved in defense against infection, in autoimmune disease, allergy, inflammation, and in organ graft rejection. Lymphomas and leukemias are malignancies of leukocytes, and the immune system is almost certainly involved in most other cancers. Each leukocyte expresses a selection of cell surface glycoproteins and glycolipids which mediate its interaction with antigen, with other components of the immune system, and with other tissues. It is therefore not surprising that the leukocyte surface molecules (CD molecules) have provided targets for diagnosis and therapy. Among the "celebrities" are CD20, a target for lymphoma therapeutic antibodies which earns $2 billion annually (and makes a significant difference to lymphoma patients), and CD4, the molecule used by the human immunodeficiency virus (HIV) as an entry portal into cells of the immune system. This short review provides a background to the CD molecules and antibodies against them, and summarizes research, diagnostic, and therapeutic applications of antibodies against these molecules.

Conservation of leukocyte cell surface proteins: implications for the generation of monoclonal antibodies against newly identified leukocyte cell surface proteins

The availability of mouse monoclonal antibodies has been integral to the classification of human leukocyte cell surface proteins under the "Cluster of Differentiation" or "CD" nomenclature system. The sequencing of the human genome has identified many more proteins that have characteristics similar to the known leukocyte cell surface proteins, but which have not so far been identified using monoclonal antibodies. One factor that may have limited the generation of monoclonal antibodies to some of these proteins is the high level of sequence conservation between the mouse and human proteins, in particular in the extracellular regions that are recognized by most of the widely used antibodies. An alternative approach is to use a more distant species, such as chickens, for the generation of antibody reagents. Here we compare the extent of amino acid differences in the protein CD molecules expressed by human leukocytes and their mouse and chicken homologs. The analysis confirms that the human proteins are more similar to the mouse homologs than the chicken homologs. The results indicate that chicken antibodies have the potential to be used as an alternative to mouse reagents where human-mouse sequence conservation is high.

The human leucocyte differentiation antigens (HLDA) workshops: the evolving role of antibodies in research, diagnosis and therapy

The 8th International Workshop on Human Leucocyte Differentiation Antigens (chaired by Zola H and managed by Swart B) was run over a 4-year period and culminated in a conference in December 2004. Here we review the achievements of the HLDA Workshops and provide links to information on CD molecules and antibodies against them, including the 93 new CDs assigned in the 8th Workshop. We consider what remains to be achieved (including an estimate of the number of leucocyte surface molecules still to be discovered), and how the field can best move forward.