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1.
BMC Genomics ; 25(1): 663, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38961347

ABSTRACT

BACKGROUND: The Atlantic cod is a prolific species in the Atlantic, despite its inconsistent specific antibody response. It presents a peculiar case within vertebrate immunology due to its distinct immune system, characterized by the absence of MHCII antigen presentation pathway, required for T cell-dependent antibody responses. Thorough characterisation of immunoglobulin loci and analysis of the antibody repertoire is necessary to further our understanding of the Atlantic cod's immune response on a molecular level. RESULTS: A comprehensive search of the cod genome (gadmor3.0) identified the complete set of IgH genes organized into three sequential translocons on chromosome 2, while IgL genes were located on chromosomes 2 and 5. The Atlantic cod displayed a moderate germline V gene diversity, comprising four V gene families for both IgH and IgL, each with distinct chromosomal locations and organizational structures. 5'RACE sequencing revealed a diverse range of heavy chain CDR3 sequences and relatively limited CDR3 diversity in light chains. The analysis highlighted a differential impact of V-gene germline CDR3 length on receptor CDR3 length between heavy and light chains, underlining different recombination processes. CONCLUSIONS: This study reveals that the Atlantic cod, despite its inconsistent antibody response, maintains a level of immunoglobulin diversity comparable to other fish species. The findings suggest that the extensive recent duplications of kappa light chain genes do not result in increased repertoire diversity. This research provides a comprehensive view of the Atlantic cod's immunoglobulin gene organization and repertoire, necessary for future studies of antibody responses at the molecular level.


Subject(s)
Gadus morhua , High-Throughput Nucleotide Sequencing , Animals , Gadus morhua/genetics , Immunoglobulin Heavy Chains/genetics , Immunoglobulins/genetics , Genetic Loci , Genes, Immunoglobulin , Immunoglobulin Variable Region/genetics
2.
Sci Adv ; 9(44): eadj0101, 2023 11 03.
Article in English | MEDLINE | ID: mdl-37910624

ABSTRACT

The constant exposure of the fish branchial cavity to aquatic pathogens causes local mucosal immune responses to be extremely important for their survival. Here, we used a marker for T lymphocytes/natural killer (NK) cells (ZAP70) and advanced imaging techniques to investigate the lymphoid architecture of the zebrafish branchial cavity. We identified a sub-pharyngeal lymphoid organ, which we tentatively named "Nemausean lymphoid organ" (NELO). NELO is enriched in T/NK cells, plasma/B cells, and antigen-presenting cells embedded in a network of reticulated epithelial cells. The presence of activated T cells and lymphocyte proliferation, but not V(D)J recombination or hematopoiesis, suggests that NELO is a secondary lymphoid organ. In response to infection, NELO displays structural changes including the formation of T/NK cell clusters. NELO and gill lymphoid tissues form a cohesive unit within a large mucosal lymphoid network. Collectively, we reveal an unreported mucosal lymphoid organ reminiscent of mammalian tonsils that evolved in multiple teleost fish families.


Subject(s)
Palatine Tonsil , Zebrafish , Humans , Animals , Lymphoid Tissue , Pharynx , T-Lymphocytes , Mammals
3.
Commun Biol ; 5(1): 689, 2022 07 11.
Article in English | MEDLINE | ID: mdl-35821077

ABSTRACT

Atlantic Cod (Gadus morhua) has lost the major histocompatibility complex class II presentation pathway. We recently identified CD8-positive T cells, B cells, and plasma cells in cod, but further characterisation of lymphocyte subsets is needed to elucidate immune adaptations triggered by the absence of CD4-positive T lymphocytes. Here, we use single-cell RNA sequencing to examine the lymphocyte heterogeneity in Atlantic cod spleen. We describe five T cell subsets and eight B cell subsets and propose a B cell trajectory of differentiation. Notably, we identify a subpopulation of T cells that are CD8-negative. Most of the CD8-negative T lymphocytes highly express the homologue of monocyte chemotactic protein 1b, and another subset of CD8-negative T lymphocytes express the homologue of the scavenger receptor m130. Uncovering the multiple lymphocyte cell sub-clusters reveals the different immune states present within the B and T cell populations, building a foundation for further work.


Subject(s)
Gadus morhua , Animals , Gadus morhua/genetics , Lymphocyte Subsets , Spleen
6.
J Allergy Clin Immunol ; 134(3): 613-621.e7, 2014 Sep.
Article in English | MEDLINE | ID: mdl-24958565

ABSTRACT

BACKGROUND: Thymic stromal lymphopoietin (TSLP) controls allergic TH2 inflammatory responses through induction of distinct activation programs in dendritic cells (DCs). However, knowledge about TSLP receptor expression and functional consequences of receptor activation by DCs residing in the human respiratory tract is limited. OBJECTIVE: We wanted to identify TSLP-responding DC populations in the human upper airway mucosa and assess the TSLP-mediated effects on such DCs in allergic airway responses. RESULTS: We found that the TSLP receptor was constitutively and preferentially expressed by myeloid CD1c(+) DCs in the human airway mucosa and that the density of this DC subset in nasal mucosa increased significantly after in vivo allergen challenge of patients with allergic rhinitis. In vitro, TSLP strongly enhanced the capacity of CD1c(+) DCs to activate allergen-specific memory CD4(+) T cells. Moreover, TSLP rapidly induced CCR7 expression on CD1c(+) DCs. However, TH2 cytokines attenuated TSLP-mediated CCR7 induction, thus inhibiting the TSLP-induced DC migration potential to the draining lymph nodes. CONCLUSION: Our results suggest that TSLP-mediated activation of human nasal mucosal CD1c(+) DCs triggers CCR7-dependent migration to the draining lymph nodes and enhances their capacity to initiate TH2 responses. However, the observation that TH2 cytokines abrogate the induction of CCR7 implies that during a TH2-mediated inflammatory reaction, TLSP-activated CD1c(+) DCs are retained in the inflamed tissue to further exacerbate local inflammation by activating local antigen-specific memory TH2 cells.


Subject(s)
Cytokines/immunology , Dendritic Cells/immunology , Myeloid Cells/immunology , Respiratory Mucosa/immunology , Rhinitis, Allergic/immunology , Th2 Cells/immunology , Adolescent , Adult , Aged , Allergens/immunology , Antigens, CD1/metabolism , Cell Differentiation/immunology , Cell Movement , Cells, Cultured , Cytokines/metabolism , Female , Glycoproteins/metabolism , Humans , Immunologic Memory , Lymphocyte Activation , Male , Middle Aged , Receptors, CCR7/genetics , Receptors, CCR7/metabolism , Receptors, Cytokine/metabolism , Up-Regulation , Young Adult , Thymic Stromal Lymphopoietin
7.
Am J Gastroenterol ; 108(5): 842-50, 2013 May.
Article in English | MEDLINE | ID: mdl-23588237

ABSTRACT

OBJECTIVES: In celiac disease (CD), gluten induces both adaptive and innate immune responses. Non-celiac gluten sensitivity (NCGS) is another form of gluten intolerance where the immune response is less characterized. The aim of our study was to explore and compare the early mucosal immunological events in CD and NCGS. METHODS: We challenged 30 HLA-DQ2(+) NCGS and 15 CD patients, all on a gluten-free diet, with four slices of gluten-containing bread daily for 3 days. Duodenal biopsy specimens were collected before and after challenge. The specimens were examined for cytokine mRNA by quantitative reverse transcriptase-PCR and for MxA-expression and CD3(+) intraepithelial lymphocytes (IELs) by immunohistochemistry and compared with specimens from untreated CD patients and disease controls. RESULTS: In CD patients, tumor necrosis factor alpha (P=0.02) and interleukin 8 (P=0.002) mRNA increased after in vivo gluten challenge. The interferon gamma (IFN-γ) level of treated CD patients was high both before and after challenge and did not increase significantly (P=0.06). Four IFN-γ-related genes increased significantly. Treated and untreated CD patients had comparable levels of IFN-γ. Increased expression of MxA in treated CD patients after challenge suggested that IFN-α was activated on gluten challenge. In NCGS patients only IFN-γ increased significantly (P=0.03). mRNA for heat shock protein (Hsp) 27 or Hsp70 did not change in any of the groups. Importantly, we found that the density of IELs was higher in NCGS patients compared with disease controls, independent of challenge, although lower than the level for treated CD patients. CONCLUSIONS: CD patients mounted a concomitant innate and adaptive immune response to gluten challenge. NCGS patients had increased density of intraepithelial CD3(+) T cells before challenge compared with disease controls and increased IFN-γ mRNA after challenge. Our results warrant further search for the pathogenic mechanisms for NCGS.


Subject(s)
CD3 Complex , Celiac Disease/immunology , Duodenum/immunology , Food Hypersensitivity/immunology , Glutens/immunology , Interferon-gamma/metabolism , Intestinal Mucosa/immunology , Lymphocytes , T-Lymphocytes , ATP Binding Cassette Transporter, Subfamily B, Member 2 , ATP-Binding Cassette Transporters/metabolism , Adult , Aged , Biopsy , CD3 Complex/immunology , Caspase 1/metabolism , Diet, Gluten-Free , Female , Fluorescent Antibody Technique , Humans , Immunohistochemistry , Interferon-gamma/genetics , Interleukin-8/metabolism , Lymphocyte Count , Male , Middle Aged , Oxidoreductases Acting on Sulfur Group Donors/metabolism , Proteasome Endopeptidase Complex/metabolism , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , STAT1 Transcription Factor/metabolism , T-Lymphocytes/immunology , Tumor Necrosis Factor-alpha/metabolism , Up-Regulation
8.
Eur J Immunol ; 42(11): 2959-70, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22865203

ABSTRACT

Innate and adaptive mucosal defense mechanisms ensure a homeostatic relationship with the large and complex mutualistic gut microbiota. Dimeric IgA and pentameric IgM are transported across the intestinal epithelium via the epithelial polymeric Ig receptor (pIgR) and provide a significant portion of the first line of natural or adaptive antibody-mediated immune defense of the intestinal mucosa. We found that colonic epithelial cells from pIgR KO mice differentially expressed (more than twofold change) more than 200 genes compared with cells from WT mice, and upregulated the expression of antimicrobial peptides in a commensal-dependent manner. Detailed profiling of microbial communities based on 16S rRNA genes revealed differences in the commensal microbiota between pIgR KO and WT mice. Furthermore, we found that pIgR KO mice showed increased susceptibility to dextran sulfate sodium-induced colitis, and that this was driven by their conventional intestinal microbiota. Thus, in the absence of pIgR, the stability of the commensal microbiota is disturbed, gut homeostasis is compromised, and the outcome of colitis is significantly worsened.


Subject(s)
Adaptive Immunity/immunology , Intestinal Mucosa/immunology , Intestinal Mucosa/microbiology , Metagenome/immunology , Receptors, Polymeric Immunoglobulin/deficiency , Receptors, Polymeric Immunoglobulin/immunology , Animals , Antimicrobial Cationic Peptides/genetics , Antimicrobial Cationic Peptides/immunology , Colitis/immunology , Colitis/microbiology , Epithelial Cells/immunology , Epithelial Cells/microbiology , Female , Gene Expression Profiling/methods , Gene Expression Regulation , Intestinal Mucosa/cytology , Male , Mice , Mice, Inbred BALB C , Mice, Knockout , Oligonucleotide Array Sequence Analysis , RNA/chemistry , RNA/genetics , Random Allocation , Receptors, Polymeric Immunoglobulin/genetics , Reverse Transcriptase Polymerase Chain Reaction , Specific Pathogen-Free Organisms
9.
J Am Acad Dermatol ; 66(4): 606-16, 2012 Apr.
Article in English | MEDLINE | ID: mdl-21856041

ABSTRACT

BACKGROUND: Ichthyosis prematurity syndrome (IPS) is classified as a syndromic congenital ichthyosis based on the presence of skin changes at birth, ultrastructural abnormalities in the epidermis, and extracutaneous manifestations. Recently, mutations in the fatty acid transporter protein 4 gene have been identified in patients with IPS. OBJECTIVE: We sought to perform a detailed clinical evaluation of patients with IPS identified in Norway. METHODS: Clinical examination and follow-up of all patients (n = 23) and light and electron microscopic examination of skin biopsy specimens were performed. RESULTS: IPS was characterized prenatally by ultrasound findings of polyhydramnios, separation of membranes, echogenic amniotic fluid, and clear chorionic fluid. All patients were born prematurely with sometimes life-threatening neonatal asphyxia; this was likely caused by aspiration of corneocyte-containing amniotic fluid as postmortem examination of lung tissue in two patients revealed keratin debris filling the bronchial tree and alveoli. The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like "scale" at birth, and evolved rapidly to a mild chronic ichthyosis. Many patients subsequently had chronic, severe pruritus. Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation, and characteristic aggregates of curved lamellar structures in the upper epidermis. Peripheral blood eosinophilia was invariably present and most patients had increased serum immunoglobulin E levels. Over 70% of the patients had a history of respiratory allergy and/or food allergy. LIMITATIONS: The study included only 23 patients because of the rarity of the disease. CONCLUSION: IPS is characterized by defined genetic mutations, typical ultrastructural skin abnormalities, and distinct prenatal and postnatal clinical features.


Subject(s)
Ichthyosis/complications , Ichthyosis/diagnosis , Infant, Premature, Diseases/diagnosis , Lipid Metabolism, Inborn Errors/complications , Adolescent , Adult , Aniridia , Child , Child, Preschool , Female , Humans , Ichthyosis/genetics , Infant, Newborn , Infant, Premature, Diseases/genetics , Kidney/abnormalities , Male , Norway , Psychomotor Disorders , Young Adult
10.
PLoS One ; 6(3): e17996, 2011 Mar 21.
Article in English | MEDLINE | ID: mdl-21445311

ABSTRACT

BACKGROUND: Inappropriate cross talk between mammals and their gut microbiota may trigger intestinal inflammation and drive extra-intestinal immune-mediated diseases. Epithelial cells constitute the interface between gut microbiota and host tissue, and may regulate host responses to commensal enteric bacteria. Gnotobiotic animals represent a powerful approach to study bacterial-host interaction but are not readily accessible to the wide scientific community. We aimed at refining a protocol that in a robust manner would deplete the cultivable intestinal microbiota of conventionally raised mice and that would prove to have significant biologic validity. METHODOLOGY/PRINCIPAL FINDINGS: Previously published protocols for depleting mice of their intestinal microbiota by administering broad-spectrum antibiotics in drinking water were difficult to reproduce. We show that twice daily delivery of antibiotics by gavage depleted mice of their cultivable fecal microbiota and reduced the fecal bacterial DNA load by 400 fold while ensuring the animals' health. Mice subjected to the protocol for 17 days displayed enlarged ceca, reduced Peyer's patches and small spleens. Antibiotic treatment significantly reduced the expression of antimicrobial factors to a level similar to that of germ-free mice and altered the expression of 517 genes in total in the colonic epithelium. Genes involved in cell cycle were significantly altered concomitant with reduced epithelial proliferative activity in situ assessed by Ki-67 expression, suggesting that commensal microbiota drives cellular proliferation in colonic epithelium. CONCLUSION: We present a robust protocol for depleting conventionally raised mice of their cultivatable intestinal microbiota with antibiotics by gavage and show that the biological effect of this depletion phenocopies physiological characteristics of germ-free mice.


Subject(s)
Gene Expression Regulation , Intestines/microbiology , Animals , Epithelial Cells/metabolism , Germ-Free Life , Intestinal Mucosa/metabolism , Mice , Reverse Transcriptase Polymerase Chain Reaction
11.
J Biol Chem ; 285(2): 953-60, 2010 Jan 08.
Article in English | MEDLINE | ID: mdl-19910466

ABSTRACT

In intestinal secretions, secretory IgA (SIgA) plays an important sentinel and protective role in the recognition and clearance of enteric pathogens. In addition to serving as a first line of defense, SIgA and SIgA x antigen immune complexes are selectively transported across Peyer's patches to underlying dendritic cells in the mucosa-associated lymphoid tissue, contributing to immune surveillance and immunomodulation. To explain the unexpected transport of immune complexes in face of the large excess of free SIgA in secretions, we postulated that SIgA experiences structural modifications upon antigen binding. To address this issue, we associated specific polymeric IgA and SIgA with antigens of various sizes and complexity (protein toxin, virus, bacterium). Compared with free antibody, we found modified sensitivity of the three antigens assayed after exposure to proteases from intestinal washes. Antigen binding further impacted on the immunoreactivity toward polyclonal antisera specific for the heavy and light chains of the antibody, as a function of the antigen size. These conformational changes promoted binding of the SIgA-based immune complex compared with the free antibody to cellular receptors (Fc alphaRI and polymeric immunoglobulin receptor) expressed on the surface of premyelocytic and epithelial cell lines. These data reveal that antigen recognition by SIgA triggers structural changes that confer to the antibody enhanced receptor binding properties. This identifies immune complexes as particular structural entities integrating the presence of bound antigens and adds to the known function of immune exclusion and mucus anchoring by SIgA.


Subject(s)
Antigen-Antibody Complex/immunology , Antigens, CD/immunology , Immunoglobulin A/immunology , Peptide Hydrolases/immunology , Peyer's Patches/immunology , Receptors, Fc/immunology , Receptors, Polymeric Immunoglobulin/immunology , Animals , Antigen-Antibody Complex/metabolism , Antigens/immunology , Antigens/metabolism , Antigens, CD/metabolism , Biological Transport/immunology , Immunoglobulin A/metabolism , Mice , Mice, Inbred BALB C , Peptide Hydrolases/metabolism , Peyer's Patches/enzymology , Receptors, Fc/metabolism , Receptors, Polymeric Immunoglobulin/metabolism
12.
J Biol Chem ; 284(35): 23532-9, 2009 Aug 28.
Article in English | MEDLINE | ID: mdl-19578117

ABSTRACT

Sorting of proteins to Weibel-Palade bodies (WPB) of endothelial cells allows rapid regulated secretion of leukocyte-recruiting P-selectin and chemokines as well as procoagulant von Willebrand factor (VWF). Here we show by domain swap studies that the exposed aspartic acid in loop 2 (Ser(44)-Asp(45)-Gly(46)) of the CXC chemokine interleukin (IL)-8 is crucial for targeting to WPB. Loop 2 also governs sorting of chemokines to alpha-granules of platelets, but the fingerprint of the loop 2 of these chemokines differs from that of IL-8. On the other hand, loop 2 of IL-8 closely resembles a surface-exposed sequence of the VWF propeptide, the region of VWF that directs sorting of the protein to WPB. We conclude that loop 2 of IL-8 constitutes a critical signal for sorting to WPB and propose a general role for this loop in the sorting of chemokines to compartments of regulated secretion.


Subject(s)
Endothelial Cells/metabolism , Interleukin-8/chemistry , Interleukin-8/metabolism , Weibel-Palade Bodies/metabolism , Amino Acid Sequence , Cells, Cultured , Endothelial Cells/chemistry , Female , Humans , Interleukin-8/genetics , Molecular Sequence Data , Protein Structure, Tertiary , Protein Transport , Sequence Alignment , Weibel-Palade Bodies/chemistry , Weibel-Palade Bodies/genetics
13.
Eur J Immunol ; 39(4): 1147-56, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19266484

ABSTRACT

Here we unravel the structural features of human IgM and IgA that govern their interaction with the human Fcalpha/mu receptor (hFcalpha/muR). Ligand polymerization status was crucial for the interaction, because hFcalpha/muR binding did not occur with monomeric Ab of either class. hFcalpha/muR bound IgM with an affinity in the nanomolar range, whereas the affinity for dimeric IgA (dIgA) was tenfold lower. Panels of mutant IgM and dIgA were used to identify regions critical for hFcalpha/muR binding. IgM binding required contributions from both Cmu3 and Cmu4 Fc domains, whereas for dIgA, an exposed loop in the Calpha3 domain was crucial. This loop, comprising residues Pro440-Phe443, lies at the Fc domain interface and has been implicated in the binding of host receptors FcalphaRI and polymeric Ig receptor (pIgR), as well as IgA-binding proteins produced by certain pathogenic bacteria. Substitutions within the Pro440-Phe443 loop resulted in loss of hFcalpha/muR binding. Furthermore, secretory component (SC, the extracellular portion of pIgR) and bacterial IgA-binding proteins were shown to inhibit the dIgA-hFcalpha/muR interaction. Therefore, we have identified a motif in the IgA-Fc inter-domain region critical for hFcalpha/muR interaction, and highlighted the multi-functional nature of a key site for protein-protein interaction at the IgA Fc domain interface.


Subject(s)
Antibody Affinity , Immunoglobulin A/chemistry , Immunoglobulin M/chemistry , Receptors, Fc/immunology , Amino Acid Motifs , Amino Acid Substitution , Animals , Antibody Affinity/genetics , Antibody Affinity/immunology , COS Cells , Chlorocebus aethiops , Humans , Immunoglobulin A/genetics , Immunoglobulin A/immunology , Immunoglobulin M/genetics , Immunoglobulin M/immunology , Mutant Proteins/immunology , Mutation , Protein Interaction Domains and Motifs/immunology , Protein Multimerization , Protein Structure, Tertiary , Receptors, Fc/genetics
15.
Proc Natl Acad Sci U S A ; 105(27): 9337-42, 2008 Jul 08.
Article in English | MEDLINE | ID: mdl-18599440

ABSTRACT

The neonatal Fc receptor for IgG (FcRn) is a distant member of the MHC class I protein family. It binds IgG and albumin in a pH-dependent manner and protects these from catabolism by diverting them from a degradative fate in lysosomes. In addition, FcRn-mediated IgG transport across epithelial barriers is responsible for the transmission of IgG from mother to infant and can also enhance IgG-mediated antigen uptake across mucosal epithelia. We now show a previously undescribed role for FcRn in mediating the presentation of antigens by dendritic cells when antigens are present as a complex with antibody by uniquely directing multimeric immune complexes, but not monomeric IgG, to lysosomes.


Subject(s)
Antigen Presentation/immunology , Histocompatibility Antigens Class I/immunology , Immunoglobulin G/immunology , Receptors, Fc/immunology , Animals , Antigen-Antibody Complex/immunology , Antigen-Presenting Cells/cytology , Antigen-Presenting Cells/immunology , Cell Proliferation , Dendritic Cells/cytology , Dendritic Cells/immunology , Hematopoietic System/cytology , Hematopoietic System/immunology , Hemocyanins/immunology , Humans , Ligands , Lysosomal Membrane Proteins/immunology , Lysosomes/immunology , Mice , Monocytes/cytology , Monocytes/immunology , Mutation/genetics , Protein Binding , Protein Processing, Post-Translational , Protein Transport , T-Lymphocytes/cytology , T-Lymphocytes/immunology
16.
J Immunol ; 181(3): 1988-2000, 2008 Aug 01.
Article in English | MEDLINE | ID: mdl-18641336

ABSTRACT

The binding of nonspecific human IgM to the surface of infected erythrocytes is important in rosetting, a major virulence factor in the pathogenesis of severe malaria due to Plasmodium falciparum, and IgM binding has also been implicated in placental malaria. Herein we have identified the IgM-binding parasite ligand from a virulent P. falciparum strain as PfEMP1 (TM284var1 variant), and localized the region within this PfEMP1 variant that binds IgM (DBL4beta domain). We have used this parasite IgM-binding protein to investigate the interaction with human IgM. Interaction studies with domain-swapped Abs, IgM mutants, and anti-IgM mAbs showed that PfEMP1 binds to the Fc portion of the human IgM H chain and requires the IgM Cmu4 domain. Polymerization of IgM was shown to be crucial for the interaction because PfEMP1 binding did not occur with mutant monomeric IgM molecules. These results with PfEMP1 protein have physiological relevance because infected erythrocytes from strain TM284 and four other IgM-binding P. falciparum strains showed analogous results to those seen with the DBL4beta domain. Detailed investigation of the PfEMP1 binding site on IgM showed that some of the critical amino acids in the IgM Cmu4 domain are equivalent to those regions of IgG and IgA recognized by Fc-binding proteins from bacteria, suggesting that this region of Ig molecules may be of major functional significance in host-microbe interactions. We have therefore shown that PfEMP1 is an Fc-binding protein of malaria parasites specific for polymeric human IgM, and that it shows functional similarities with Fc-binding proteins from pathogenic bacteria.


Subject(s)
Immunoglobulin M/immunology , Plasmodium falciparum/immunology , Protozoan Proteins/immunology , Amino Acid Motifs , Amino Acid Sequence , Animals , Binding Sites , COS Cells , Chlorocebus aethiops , Erythrocytes/immunology , Erythrocytes/metabolism , Humans , Immunoglobulin Fc Fragments/immunology , Immunoglobulin M/chemistry , Ligands , Models, Molecular , Molecular Sequence Data , Protein Binding , Protein Structure, Quaternary , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Solubility
17.
Mol Immunol ; 45(8): 2380-90, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18160104

ABSTRACT

The T-cell specific adapter protein (TSAd) encoded by the SH2D2A gene is up-regulated in activated human CD4+ T-cells in a cAMP-dependent manner. Expression of SH2D2A is important for proper activation of T-cells. Here, we show that SH2D2A expression is regulated both at the transcriptional and translational level. cAMP signaling alone induces TSAd-mRNA expression but fails to induce increased TSAd protein levels. By contrast, TCR engagement provides signals for both TSAd transcription and translation. We further show that cAMP signaling can prime T-cells for a more prompt expression of TSAd protein upon TCR stimulation. Our study thus points to a novel mechanism for how cAMP signaling may modulate T-cell activation through transcriptional priming of resting cells.


Subject(s)
Adaptor Proteins, Signal Transducing/genetics , CD4-Positive T-Lymphocytes/metabolism , Gene Expression Regulation , Protein Biosynthesis , Transcription, Genetic , CD3 Complex/immunology , CD4-Positive T-Lymphocytes/cytology , CD4-Positive T-Lymphocytes/drug effects , Cross-Priming/drug effects , Cross-Priming/immunology , Cyclic AMP/metabolism , Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors , Cytoplasm/drug effects , Cytoplasm/metabolism , Gene Expression Regulation/drug effects , Humans , Isoquinolines/pharmacology , Models, Immunological , Protein Biosynthesis/drug effects , RNA Transport/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Antigen, T-Cell/immunology , Signal Transduction/drug effects , Sulfonamides/pharmacology , Transcription, Genetic/drug effects
18.
J Immunol ; 178(3): 1589-97, 2007 Feb 01.
Article in English | MEDLINE | ID: mdl-17237408

ABSTRACT

Abs of the secretory Ig (SIg) system reinforce numerous innate defense mechanisms to protect the mucosal surfaces against microbial penetration. SIgs are generated by a unique cooperation between two distinct cell types: plasma cells that produce polymers of IgA or IgM (collectively called pIgs) and polymeric Ig receptor (pIgR)-expressing secretory epithelial cells that mediate export of the pIgs to the lumen. Apical delivery of SIgs occurs by cleavage of the pIgR to release its extracellular part as a pIg-bound secretory component, whereas free secretory components are derived from an unoccupied receptor. The joining chain (J chain) is crucial in pIg/SIg formation because it serves to polymerize Igs and endows them with a binding site for the pIgR. In this study, we show that the J chain from divergent tetrapods including mammals, birds, and amphibians efficiently induced polymerization of human IgA, whereas the J chain from nurse shark (a lower vertebrate) did not. Correctly assembled polymers showed high affinity to human pIgR. Sequence analysis of the J chain identified two regions, conserved only in tetrapods, which by mutational analysis were found essential for pIgA-pIgR complexing. Furthermore, we isolated and characterized pIgR from the amphibian Xenopus laevis and demonstrated that its pIg binding domain showed high affinity to human pIgA. These results showed that the functional site of interaction between pIgR, J chain and Ig H chains is conserved in these species and suggests that SIgs originated in an ancestor common to tetrapods.


Subject(s)
Antibody Formation , Conserved Sequence/immunology , Immunoglobulin A, Secretory/immunology , Immunoglobulin J-Chains/metabolism , Immunoglobulin M/immunology , Receptors, Polymeric Immunoglobulin/metabolism , Amphibians , Animals , Binding Sites/immunology , Birds , Humans , Immunoglobulin A, Secretory/genetics , Immunoglobulin M/genetics , Mammals , Phylogeny , Protein Binding/genetics , Protein Binding/immunology , Receptors, Polymeric Immunoglobulin/genetics , Secretory Component
19.
J Immunol ; 177(9): 6281-90, 2006 Nov 01.
Article in English | MEDLINE | ID: mdl-17056558

ABSTRACT

The polymeric Ig receptor (pIgR) is conserved in mammals and has an avian homologue, suggesting evolutionarily important functions in vertebrates. It transports multimeric IgA and IgM across polarized epithelia and is highly expressed in the intestine, yet little direct evidence exists for its importance in defense against common enteric pathogens. In this study, we demonstrate that pIgR can play a critical role in intestinal defense against the lumen-dwelling protozoan parasite Giardia, a leading cause of diarrheal disease. The receptor was essential for the eradication of Giardia when high luminal IgA levels were required. Clearance of Giardia muris, in which IgA plays a dominant role, was severely compromised in pIgR-deficient mice despite significant fecal IgA output at 10% of normal levels. In contrast, eradication of the human strain Giardia lamblia GS/M, for which adaptive immunity is less IgA dependent in mice, was unaffected by pIgR deficiency, indicating that pIgR had no physiologic role when lower luminal IgA levels were sufficient for parasite elimination. Immune IgA was greatly increased in the serum of pIgR-deficient mice, conferred passive protection against Giardia, and recognized several conserved giardial Ags, including ornithine carbamoyltransferase, arginine deiminase, alpha-enolase, and alpha- and beta-giardins, that are also detected in human giardiasis. Corroborative observations were made in mice lacking the J chain, which is required for pIgR-dependent transepithelial IgA transport. These results, together with prior data on pIgR-mediated immune neutralization of luminal cholera toxin, suggest that pIgR is essential in intestinal defense against pathogenic microbes with high-level and persistent luminal presence.


Subject(s)
Giardia , Giardiasis/immunology , Intestinal Mucosa/immunology , Intestinal Mucosa/parasitology , Receptors, Polymeric Immunoglobulin/physiology , Animals , Antigens, Protozoan/analysis , Antigens, Protozoan/immunology , Feces/chemistry , Giardiasis/genetics , Immunity/genetics , Immunoglobulin A/analysis , Immunoglobulin A/blood , Immunoglobulin A/metabolism , Intestines/immunology , Intestines/parasitology , Mice , Mice, Mutant Strains , Receptors, Polymeric Immunoglobulin/deficiency , Receptors, Polymeric Immunoglobulin/genetics
20.
J Exp Med ; 203(1): 21-6, 2006 Jan 23.
Article in English | MEDLINE | ID: mdl-16390940

ABSTRACT

The production of IgA is induced in an antigen-unspecific manner by commensal flora. These secretory antibodies (SAbs) may bind multiple antigens and are thought to eliminate commensal bacteria and self-antigens to avoid systemic recognition. In this study, we addressed the role of "innate" SAbs, i.e., those that are continuously produced in normal individuals, in protection against infection of the gastrointestinal tract. We used polymeric immunoglobulin receptor (pIgR-/-) knock-out mice, which are unable to bind and actively transport dimeric IgA and pentameric IgM to the mucosae, and examined the role of innate SAbs in protection against the invasive pathogen Salmonella typhimurium. In vitro experiments suggested that innate IgA in pIgR-/- serum bound S. typhimurium in a cross-reactive manner which inhibited epithelial cell invasion. Using a "natural" infection model, we demonstrated that pIgR-/- mice are profoundly sensitive to infection with S. typhimurium via the fecal-oral route and, moreover, shed more bacteria that readily infected other animals. These results imply an important evolutionary role for innate SAbs in protecting both the individual and the herd against infections, and suggest that the major role of SAbs may be to prevent the spread of microbial pathogens throughout the population, rather than protection of local mucosal surfaces.


Subject(s)
Antibodies, Bacterial/immunology , Receptors, Polymeric Immunoglobulin/deficiency , Salmonella Infections, Animal/immunology , Salmonella typhimurium/pathogenicity , Animals , Cell Line , Colony Count, Microbial , Dogs , Feces/microbiology , Immunity, Innate , Immunoglobulin A/blood , Intestine, Small/immunology , Intestine, Small/microbiology , Lethal Dose 50 , Mice , Mice, Inbred Strains , Mice, Knockout , Peyer's Patches/immunology , Peyer's Patches/microbiology , Receptors, Polymeric Immunoglobulin/blood , Receptors, Polymeric Immunoglobulin/genetics , Salmonella Infections, Animal/mortality , Salmonella Infections, Animal/transmission
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