The clearance of apoptotic cells is an essential process for tissue homeostasis. To this end, cells undergoing apoptosis must display engulfment signals, such as ‘find-me' and ‘eat-me' signals. Engulfment signals are recognized by multiple types of phagocytic machinery in phagocytes, leading to prompt clearance of apoptotic cells. In addition, apoptotic cells and phagocytes release tolerogenic signals to reduce immune responses against apoptotic cell-derived self-antigens. Here we discuss recent advances in our knowledge of engulfment signals, the phagocytic machinery and the signal transduction pathways for apoptotic cell engulfment.
Apoptosis ; Autoantigens ; Homeostasis ; Phagocytes ; Signal Transduction

Neutrophils are the major antimicrobial cells of the innate immune system, which are recruited rapidly to the sites of infection and provide the primary defense against pathogens. Recent evidence suggests that neutrophils undergo a distinct cell death mechanism called NETosis, which not only contributes to the host defense, but also leads to severe pathological immune responses in cases of dysregulation. Here, we review the general features of NETosis as well as the generation of autoantigens and damage-associated molecular patterns by NETosis in autoimmune diseases. This review discusses the pathogenic role of NETosis in rheumatoid arthritis and systemic lupus erythematosus, where neutrophils may play a key role in the pathogenesis of these diseases, and suggest the possibility of neutrophil extracellular traps as biomarkers and therapeutic targets for the treatment of autoimmune diseases.
Arthritis, Rheumatoid ; Autoantigens ; Autoimmune Diseases* ; Biomarkers ; Cell Death ; Immune System ; Lupus Erythematosus, Systemic ; Neutrophils

Production of high affinity antibodies for antigens is a critical component for the immune system to fight off infectious pathogens. However, it could be detrimental to our body when the antigens that B cells recognize are of self-origin. Follicular helper T, or Tfh, cells are required for the generation of germinal center reactions, where high affinity antibody-producing B cells and memory B cells predominantly develop. As such, Tfh cells are considered as targets to prevent B cells from producing high affinity antibodies against self-antigens, when high affinity autoantibodies are responsible for immunopathologies in autoimmune disorders. This review article provides an overview of current understanding of Tfh cells and discusses it in the context of animal models of autoimmune diseases and allograft rejections for generation of novel therapeutic interventions.
Allografts* ; Antibodies ; Autoantibodies ; Autoantigens ; Autoimmune Diseases* ; Autoimmunity ; B-Lymphocytes ; Germinal Center ; Immune System ; Memory ; Models, Animal

OBJECTIVETo highlight current knowledge about M-type phospholipase A2 receptor (PLA2R) which is the first human autoantigen discovered in adult idiopathic membranous nephropathy.

DATA SOURCESRelevant articles published in English from 2000 to present were selected from PubMed. Searches were made using the terms "idiopathic membranous nephropathy, M-type PLA2R and podocyte."

STUDY SELECTIONArticles studying the role of M-type PLA2R in idiopathic membranous nephropathy were reviewed. Articles focusing on the discovery, detection and clinical observation of anti-PLA2R antibodies were selected.

RESULTSM-type PLA2R is a member of the mannose receptor family of proteins, locating on normal human glomeruli as a transmembrane receptor. The anti-PLA2R in serum samples from MN were primarily IgG4 subclass. Technologies applied to detect anti-PLA2R autoantibody are mainly WB, IIFT, ELISA and so on. Studies from domestic and overseas have identified a strongly relationship between circulating anti-PLA2R levels and disease activity.

CONCLUSIONRecent discoveries corresponding to PLA2R facilitate a better understanding on IMN pathogenesis and may provide a new tool to its diagnosis, differential diagnosis, risk evaluation, response monitoring and patient-specific treatment.

Animals ; Autoantigens ; metabolism ; Glomerulonephritis, Membranous ; immunology ; metabolism ; Humans ; Podocytes ; metabolism ; Receptors, Phospholipase A2 ; metabolism

OBJECTIVESTo establish a primary biliary cirrhosis (PBC) model by AMAM2 autoantigen injection into C57BL/6 mice.

METHODSMice of the model group were immunized intraperitonealy with 200 microl of purified recombinant AMAM2 autoantigen in complete Freund's adjuvant (CFA). Mice immunized with bovine serum albumin and CFA in the same way were used as negative controls. Sixty-six weeks later, mice were sacrificed and their sera were collected. Sera samples were assayed for AMAM2 autoantibody, alkaline phosphatase (ALP), ALT and total bilirubin (TBil). Their liver, stomach, muscle and kidney tissues were sectioned and stained using HE to observe the pathological changes.

RESULTSAntibodies to AMAM2 autoantigen were readily induced in the model group. The mice in the model group had no significant changes in the level of serum ALT and TBil but had an obvious increase of ALP (P<0.05). The stomach, muscle and kidney tissues showed no evident damage while the livers had obvious pathological changes, including bile duct degeneration or proliferation, and mononuclear cell infiltration.

CONCLUSIONThe AMAM2 autoantigen-induced PBC animal model was successfully established in C57BL/6 mice in our experiment and its characteristic biochemical and pathology are quite similar to that in the early stage of human PBC. This model may provide a useful experimental approach for further study of the pathogenesis and clinical treatment of human PBC.

Animals ; Autoantigens ; immunology ; Disease Models, Animal ; Liver Cirrhosis, Biliary ; etiology ; Mice ; Mice, Inbred C57BL ; Mitochondria ; immunology

Frontal fibrosing alopecia (FFA) is a rare subtype of cicatricial alopecia. It was first described in 1994 by Kossard as postmenopausal frontal fibrosing alopecia. Patients who suffer from FFA show typical frontal hairline recession, and most patients experience eyebrow loss. It usually affects mainly post-menopausal women but the hormonal change due to menopause is unclear. Etiology of FFA is not clear, but it is assumed that certain autoantigens in the frontal and eyebrow hair follicles play a key role in its pathogenesis. There is no optimal treatment thus far. However, recently, topical calcineurin inhibitor was shown to be effective in early stage FFA via follicular targeted T-cell inhibition. Here, we report a case of a premenopausal 50-year-old female patient suffering from FFA displaying typical clinical features and minimal fibrosis around follicles by histological examination, which were improved by treatment with short-term systemic steroid and long-term topical calcineurin inhibitor.
Alopecia ; Autoantigens ; Calcineurin ; Eyebrows ; Female ; Fibrosis ; Hair Follicle ; Humans ; Menopause ; Middle Aged ; Stress, Psychological ; T-Lymphocytes

BACKGROUND: Matrix metalloproteinases (MMPs) participate in extracellular matrix degradation and may play an important role in basal membrane damage in many dermatologic diseases. Recent studies implicated the importance of MMP-9 in the pathogenesis of bulla formation of bullous pemphigoid (BP). Various autoimmune bullous diseases are strongly associated with desmosome or hemidesmosome pathologies, and show an increased level of lesional MMP and exposed autoantigens from these structures. OBJECTIVE: This study evaluated the level of MMP-2, -3, and -9 in three types of autoimmune bullous disease [BP, pemphigus vulgaris (PV), pemphigus foliaceus (PF)] with the aim of investigating the role of MMPs in the pathogenesis of autoimmune bullous diseases. METHODS: Sample specimens were obtained from skin lesions of patients with BP (n=12), PV (n=10), and PF (n=12), and from normal controls (n=8). The immunohistochemical expression of MMP-2, -3, and -9 was analyzed and serum levels of MMP-2, -3, and -9 were measured by enzyme-linked immunosorbant assay (ELISA). The results were analyzed with reference to graded levels of clinical severity. RESULTS: Expression of dermal MMP-2, -3, and -9 were increased in BP, PV, and PF (p=0.036, 0.022, and 0.015, respectively). However, decreased expression of the three MMPs in the epidermis of skin lesions may have resulted from epidermal destruction. ELISA-determined serum levels of MMP-2, -3, and -9 increased in BP, PV and PF. Interestingly, MMP-2 was significantly increased in the sera of BP patients (p=0.015), consistent with the previous studies concerning the role of gelatinase (MMP-2 and -9) in the pathogenesis of BP. In BP patients, clinical severity was proportional to increased levels of MMP-2 in both skin lesions and and sera. CONCLUSION: The increased expression of MMP-2, -3, and -9 in skin lesions and sera may reflect the involvement of these enzymes in the mechanism of bulla formation in autoimmune bullous diseases including BP. In addition, expression of MMP and clinical severity may be closely connected.
Autoantigens ; Blister ; Desmosomes ; Epidermis ; Extracellular Matrix ; Gelatinases ; Hemidesmosomes ; Humans ; Matrix Metalloproteinases ; Membranes ; Pemphigoid, Bullous ; Pemphigus ; Skin

BACKGROUNDPatients with systemic lupus erythematosus often have various autoantibodies. The relationship between these antibodies is still poorly understood. The aim of the present study was to observe the anti-SSB antibody and anti-dsDNA antibody production profiles following immunization with synthetic SSB peptide alone, DNA alone or co-immunization with these two antigens.

METHODSSSB 214 - 225 aa peptide was synthesized by organic chemistry solid-phase peptide synthesis. Rabbits were immunized with the following antigens: synthetic SSB peptide linked with keyhole limpet hemocyanin (KLH), DNA, SSB plus dsDNA, KLH and PBS. Antibodies were measured by ELISA. Histopathology and direct immufluorescence assays were also applied.

RESULTSAnti-SSB and anti-dsDNA antibodies were produced following immunization with SSB peptide and DNA respectively. The level of SSB antibody in the co-immunization group was higher than that of the SSB peptide immunization group. The level of anti-dsDNA antibody in the co-immunization group was, however, lower than that in the DNA immunization group. Meanwhile, the level of anti-SSB antibody was higher than that of anti-DNA antibody in the co-immunization group. No morphological or immunological abnormalities were found in the heart, liver, kidney, spleen or skin tissues.

CONCLUSIONInhibition of anti-dsDNA-antibody was induced by co-immunization with synthesized SSB peptide and DNA, which might explain, at least partly, the mild disease in some LE subsets associated with SSB antibody.

Animals ; Antibodies, Antinuclear ; biosynthesis ; Autoantigens ; immunology ; DNA ; immunology ; Fluorescent Antibody Technique, Direct ; Immunization ; Rabbits ; Ribonucleoproteins ; immunology

B cell activated co-receptor plays important roles in linkage of innate and acquired humoral immune responses. CD21 molecule in the co-receptor complex is a receptor for C3dg and CD19 molecule enhances BCR signal transduction. CD21 also expresses on the surface of follicular dendritic cells, which mediates the long-term maintenance of antigens and is indispensable for maintaining the memory of B cells. B cell activated co-receptor also has an effect on the negative selection of B cells reactive to autoantigens.
Animals ; Antigens, CD19 ; immunology ; Autoantigens ; immunology ; B-Lymphocytes ; immunology ; Humans ; Receptors, Complement 3d ; immunology ; Receptors, Immunologic

YKL-40, a secreted glycoprotein, may serve as an autoantigen, which mediates multiple inflammatory diseases and cancers. A high YKL-40 serum level is correlated with metastasis and poor survival in a variety of human cancers. However, the role of YKL-40 in dogs is still under evaluation. Herein, we examined the associations between plasma YKL-40 level and YKL-40 autoantibody (YAA) titers with malignancy and prognosis in canine cancer. Plasma levels of YKL-40 in healthy dogs (n = 20) and in dogs (n = 82) with cancer were evaluated using enzyme-linked immunosorbent assay. Our results indicated that plasma YKL-40 levels were significantly higher (p < 0.01) in dogs with cancer than in healthy dogs. A significant decrease in the YAA titers was detected in the dogs with cancer when compared with those of the healthy dogs (p < 0.05), although the change was not correlated with the YKL-40 levels. Among the dogs with cancer, plasma YKL-40 levels in the dogs that later relapsed or had metastasis were significantly higher than in the dogs with no signs of relapse (p < 0.01) or metastasis (p <0.05). The relapse and metastasis rates were significantly higher in the high YKL-40 group (> 180 pg/mL) than in the low YKL-40 group (< 180 pg/mL). The results imply that plasma YKL-40 levels might have the potential to be developed as a marker of malignancy progression and prognosis in canine cancers.
Animals ; Autoantibodies ; Autoantigens ; Dogs ; Enzyme-Linked Immunosorbent Assay ; Glycoproteins ; Humans ; Neoplasm Metastasis ; Plasma ; Prognosis ; Recurrence