Autoimmunity against laminins

Autoantibodies against laminin-521 are pathogenic in anti-glomerular basement membrane disease

Anti-glomerular basement membrane (anti-GBM) disease is an organ-specific autoimmune disorder characterized by autoantibodies against GBM components. Evidence from human inherited kidney diseases and animal models suggests that the α, β, and γ chains of laminin-521 are all essential for maintaining the glomerular filtration barrier. We previously demonstrated that laminin-521 is a novel autoantigen within the GBM and that autoantibodies to laminin-521 are present in about one-third of patients. In the present study, we investigated the pathogenicity of autoantibodies against laminin-521 with clinical and animal studies. Herein, a rare case of anti-GBM disease was reported with circulating autoantibodies binding to laminin-521 but not to the NC1 domains of α1-α5(IV) collagen. Immunoblot identified circulating IgG from this patient bound laminin α5 and γ1 chains. A decrease in antibody levels was associated with improved clinical presentation after plasmapheresis and immunosuppressive treatments. Furthermore, immunization with laminin-521 in female Wistar-Kyoto rats induced crescentic glomerulonephritis with linear IgG deposits along the GBM, complement activation along with infiltration of T cells and macrophages. Lung hemorrhage occurred in 75.0% of the rats and was identified by the presence of erythrocyte infiltrates and hemosiderin-laden macrophages in the lung tissue. Sera and kidney-eluted antibodies from rats immunized with laminin-521 demonstrated specific IgG binding to laminin-521 but not to human α3(IV)NC1, while the opposite was observed in human α3(IV)NC1-immunized rats. Thus, our patient data and animal studies imply a possible independent pathogenic role of autoantibodies against laminin-521 in the development of anti-GBM disease.

Paraneoplastic autoimmune Laminin-332 syndrome (PALS): Anti-Laminin-332 mucous membrane pemphigoid as a prototype

IMPORTANCE

Laminin-332 is an important component of the basement membrane. Recently, autoantibodies to Laminin-332 have been described in several autoimmune diseases. Many of these autoimmune diseases have a high incidence of malignancy. The importance of Laminin-332 autoantibodies and its relationship to malignancy is highlighted by using Laminin-332 Pemphigoid (LM-332Pg) as a prototype.

OBJECTIVE

To identify several autoimmune diseases that have autoantibodies to Laminin-332 present, and to determine the prevalence of malignancy in them. Using Laminin-332 Pemphigoid (LM-332Pg) as a prototype, to compare clinical profiles of LM-332Pg patients with and without cancer. By identifying the temporal detection of cancer, can the influence of autoantibodies to Laminin-332 on prognosis be determined.

EVIDENCE REVIEW

A literature search was conducted to identify autoimmune and inflammatory diseases in which autoantibodies to Laminin-332 were present. Subsequently, the rate of malignancy in these autoimmune diseases was determined. A search for publications on LM-332Pg patients to determine cancer rates and clinical outcomes to examine if a relationship can be proposed, was performed.

FINDINGS

Autoantibodies to Laminin-332 were detected in recent studies of systemic lupus erythematosus (SLE), psoriasis, bronchiolitis obliterans (BO), graft-vs-host disease (GVH), bullous pemphigoid (BP), lichen planus (LP), epidermolysis bullosa acquisita (EBA), and membranous glomerulonephropathy (MGN). A high incidence of cancer rate was reported in these autoimmune diseases including primary Sjögren's syndrome (pSS), systemic sclerosis (SS), dermatomyositis (DM), multiple sclerosis (MS), immune thrombocytopenia purpura (ITP), and rheumatoid arthritis (RA). Data analysis demonstrated that LM-332Pg patients had a higher risk of developing ovarian, uterine, lung, gastric cancers and leukemia. The incidence for breast cancer was lower, when compared with global cancer rates. Patients diagnosed with cancer after the presence of LM-332Pg had higher rates of mortality and lower rates of remission, compared to those diagnosed with cancer prior to the discovery/diagnosis of LM-332Pg. When studied, levels of Laminin-332 autoantibodies correlated with the presence or absence of malignancy.

CONCLUSIONS AND RELEVANCE

Preliminary analysis suggests that autoantibodies to Laminin-332 are present in multiple autoimmune diseases, which also have a high incidence of malignancy. Detailed analysis of available data highlights that patients who developed LM-332Pg after cancer was diagnosed, had a more favorable prognosis, compared to patients who developed cancer when LM-332Pg was previously present. Preliminary data would suggest that autoantibodies to Laminin-332 could serve as an important biomarker in certain patients, for correlation with possible incidence of malignancy.

Subunit-Specific Reactivity of Autoantibodies Against Laminin-332 Reveals Direct Inflammatory Mechanisms on Keratinocytes

Laminin-332 pemphigoid is a rare and severe autoimmune blistering disease, caused by IgG autoantibodies targeting laminin-332 in the dermal-epidermal basement zone. Laminin-332 pemphigoid is characterized by variable inflammatory infiltrate and the predominance of non-complement-fixing antibodies. Given these findings, we hypothesized that IgG autoantibodies to laminin-332 directly resulted in keratinocyte expression of inflammatory factors. We performed RNA-seq on primary human keratinocytes treated with IgG from patients with laminin-332 pemphigoid. Genes for numerous cytokines and chemokines were upregulated, including CSF2, CSF3, CXCL1, CXCL5, CXCL3, CXCL8, CXCL10, CXCL1, IL6, IL7, IL15, IL23, IL32, IL37, TGFB2 as well as metalloproteases. Considering the pro-inflammatory and proteolytic effect of autoantibodies from patients with laminin-332 pemphigoid identified in our initial experiment, we next questioned whether the reactivity against specific laminin subunits dictates the inflammatory and proteolytic keratinocyte response. Then, we treated keratinocytes with IgG from a separate cohort of patients with reactivity against individual subunits of laminin-332. We identified upregulation of IL-1α, IL-6, IL-8, CXCL1, MMP9, TSLP, and GM-CSF at the protein level, most notably in keratinocytes treated with IgG from laminin β3-reactive patients. We for the first time demonstrated a pro-inflammatory response, similar to that described in keratinocytes treated with IgG autoantibodies from patients with bullous pemphigoid, providing novel insight into the pathogenesis of laminin-332 pemphigoid and laminin-332 biology.

Laminin-521 is a Novel Target of Autoantibodies Associated with Lung Hemorrhage in Anti-GBM Disease

BACKGROUND

Antiglomerular basement membrane (anti-GBM) disease is characterized by GN and often pulmonary hemorrhage, mediated by autoantibodies that typically recognize cryptic epitopes within α345(IV) collagen-a major component of the glomerular and alveolar basement membranes. Laminin-521 is another major GBM component and a proven target of pathogenic antibodies mediating GN in animal models. Whether laminin-521 is a target of autoimmunity in human anti-GBM disease is not yet known.

METHODS

A retrospective study of circulating autoantibodies from 101 patients with anti-GBM/Goodpasture's disease and 85 controls used a solid-phase immunoassay to measure IgG binding to human recombinant laminin-521 with native-like structure and activity.

RESULTS

Circulating IgG autoantibodies binding to laminin-521 were found in about one third of patients with anti-GBM antibody GN, but were not detected in healthy controls or in patients with other glomerular diseases. Autoreactivity toward laminin-521 was significantly more common in patients with anti-GBM GN and lung hemorrhage, compared with those with kidney-limited disease (51.5% versus 23.5%, P=0.005). Antilaminin-521 autoantibodies were predominantly of IgG1 and IgG4 subclasses and significantly associated with lung hemorrhage (P=0.005), hemoptysis (P=0.008), and smoking (P=0.01), although not with proteinuria or serum creatinine at diagnosis.

CONCLUSIONS

Besides α345(IV) collagen, laminin-521 is another major autoantigen targeted in anti-GBM disease. Autoantibodies to laminin-521 may have the potential to promote lung injury in anti-GBM disease by increasing the total amount of IgG bound to the alveolar basement membranes.

Therapeutic peptides for the treatment of systemic lupus erythematosus: a place in therapy

INTRODUCTION

Studies in vitro and in vivo have identified several peptides that are potentially useful in treating systemic lupus erythematosus (SLE). The rationale for their use lies in the cost-effective production, high potency, target selectivity, low toxicity, and a peculiar mechanism of action that is mainly based on the induction of immune tolerance. Three therapeutic peptides have entered clinical development, but they have yielded disappointing results. However, some subsets of patients, such as those with the positivity of anti-dsDNA antibodies, appear more likely to respond to these medications.

AREAS COVERED

This review evaluates the potential use of therapeutic peptides for SLE and gives an opinion on how they may offer advantages for SLE treatment.

EXPERT OPINION

Given their acceptable safety profile, therapeutic peptides could be added to agents traditionally used to treat SLE and this may offer a synergistic and drug-sparing effect, especially in selected patient populations. Moreover, they could temporarily be utilized to manage SLE flares, or be administered as a vaccine in subjects at risk. Efforts to ameliorate bioavailability, increase the half-life and prevent immunogenicity are ongoing. The formulation of hybrid compounds, like peptibodies or peptidomimetic small molecules, is expected to yield renewed treatments with a better pharmacologic profile and increased efficacy.

Aberrant interactions between amyloid-beta and alpha5 laminins as possible driver of neuronal disfunction in Alzheimer's disease

It has been widely accepted that laminins are involved in pathogenesis of Alzheimer's disease (AD). Amyloid plaques in AD patients are associated with immunostaining using antibodies raised against laminin-111, and laminin-111 has been shown to prevent aggregation of amyloid peptides. Although numerous articles describe small peptides from laminin-111 that are capable to disaggregate amyloid buildups and reduce neurotoxicity in in vitro and in vivo models, there is no approved laminin-111-based therapeutic approaches for treatment of AD. Also, it has been shown that immunoreactivity to laminin-111 appears late in development of cerebral amyloidosis. Based on the published data, we hypothesize that aberrant interaction between amyloid-beta and α5-laminins such as laminin-511 prevents the necessary laminin signaling into neurons leading to neurodegeneration and contributing to the early development of AD. Laminin-511 is the key extracellular protein that protects neurons from anoikis, inhibits excitoxicity and provides signaling that stabilizes dendritic spines and synapses in the developed brain. Absence of the signaling from laminin-511 leads to behavioral defects in mice. Laminin-511 and hippocampal neurons are in direct contact and accumulation of amyloid-beta that has been shown to avidly bind laminin-511 may physically decouple the interaction between α5-laminins and the neuronal membrane receptors inhibiting the signaling. Under this hypothesis, protein domains and peptides from laminin α5 chain may have a therapeutic potential in treatment of AD and the appearance of laminin-111 in the amyloid plaques is simply a consequence of the disease.

From bench to bedside: evolving therapeutic targets in autoimmune blistering disease

Autoimmune blistering diseases comprise a group of heterogenous conditions characterized by the loss of tolerance and subsequent development of autoantibodies targeting epidermal and subepidermal adhesion proteins. Blisters and erosions form on the skin and mucous membranes leading to significant morbidity and mortality. Traditional therapies rely on systemic immunosuppression. Advancements in our understanding of the pathophysiology of pemphigus and pemphigoid have led to the development of molecules which target specific pathways involved in induction and perpetuation of disease. In this review, we outline the novel therapeutic strategies including B-cell depletion, T-regulatory cell repletion, cell signalling inhibitors and small molecular inhibitors, inhibitory monoclonal antibodies, as well as complement inhibition. We additionally review their current level of clinical evidence. We lastly review therapeutics targets gleaned from the experimental epidermolysis bullosa acquisita mouse model. These emerging treatments offer an exciting progression from basic science discoveries that have the potential to transform the treatment paradigm in autoimmune blistering diseases.

Biological Assessment of Zn-Based Absorbable Metals for Ureteral Stent Applications

The use of ureteral stents to relieve urinary tract obstruction is still challenged by the problems of infection, encrustation, and compression, leading to the need for early removal procedures. Biodegradable ureteral stents, commonly made of polymers, have been proposed to overcome these problems. Recently, absorbable metals have been considered as potential materials offering both biodegradation and strength. This work proposed zinc-based absorbable metals by firstly evaluating their cytocompatibility toward normal primary human urothelial cells using 2D and 3D assays. In the 2D assay, the cells were exposed to different concentrations of metal extracts (i.e., 10 mg/mL of Zn-1Mg and 8.75 mg/mL of Zn-0.5Al) for up to 3 days and found that their cytoskeletal networks were affected but were recovered at day 3, as observed by immunofluorescence. In the 3D ureteral wall tissue construct, the cells formed a multilayered urothelium, as found in native tissue, with the presence of tight junctions at the superficial layer and laminin at the basal layer, indicating a healthy tissue condition even with the presence of the metal samples for up to 7 days of exposure. The basal cells attached to the metal surface as seen in a natural spreading state with pseudopodia and fusiform morphologies, indicating that the metals were non-toxic.

Complement-Activating Capacity of Autoantibodies Correlates With Disease Activity in Bullous Pemphigoid Patients

Background: Bullous pemphigoid is a subepidermal blistering skin disease, associated with autoantibodies to hemidesmosomal proteins, complement activation at the dermal-epidermal junction, and dermal granulocyte infiltration. Clinical and experimental laboratory findings support conflicting hypotheses regarding the role of complement activation for the skin blistering induced by pemphigoid autoantibodies. In-depth studies on the pathogenic relevance of autoimmune complement activation in patients are largely lacking. Therefore, the aim of this study was to investigate the pathogenic relevance of complement activation in patients with bullous pemphigoid. Complement activation by autoantibodies in vivo as measured by the intensity of complement C3 deposits in the patients' skin and ex vivo by the complement-fixation assay in serum was correlated with the clinical disease activity, evaluated by Autoimmune Bullous Skin Disorder Intensity Score (ABSIS) and Bullous Pemphigoid Disease Area Index (BPDAI), as well as, with further immunopathological findings in patients with bullous pemphigoid. Results: Complement-activation capacity of autoantibodies ex vivo, but not deposition of complement in the perilesional skin of patients, correlates with the extent of skin disease (measured by ABSIS and BPDAI) and with levels of autoantibodies. Conclusions: Our study provides for the first time evidence in patients for a pathogenic role of complement activation in bullous pemphigoid and should greatly facilitate the development of novel diagnostic tools and of more specific therapies for complement-dependent autoimmune injury.

Diagnosis of anti-laminin γ-1 pemphigoid by immunoblot analysis

BACKGROUND

Anti-laminin-γ1 (lam-γ1) pemphigoid, a recently described immunobullous disorder sharing immune serological features of bullous pemphigoid and epidermolysis bullosa acquisita (EBA), is characterized by the detection of serum IgG autoantibodies against the lam-γ1 chain, a 200 kDa heterotrimeric component of the dermal-epidermal junction (DEJ).

OBJECTIVE

The aim of the study was to develop an easy-to-perform and reliable assay for the serological detection of anti-lam-γ1 IgG autoantibodies. The clinical appearance alone is not sufficient to establish diagnosis of anti-lam-γ1 pemphigoid and rather requires immune serological evidence of (i) IgG reactivity against the dermal portion of salt-split human skin; (ii) exclusion of IgG against other components of the DEJ; and (iii) IgG reactivity with a 200 kDa protein of dermal extracts by immunoblot analysis (IB).

METHODS

The sera of 55 patients with anti-lam-γ1 pemphigoid were tested by IB with two recombinant heterotrimers, laminin 111 (lam-111) and laminin 421 (lam-421), as well as with a recombinant lam-γ1 chain monomer. Additionally, a total of 41 control sera from patients with EBA (n = 15), psoriasis vulgaris (PV; n = 14), and healthy controls (HC; n = 12) were tested.

RESULTS

Immunoblot analysis revealed a positive reactivity with lam-111 and/or lam-421 in 46/55 (84%) of anti-lam-γ1 pemphigoid sera. Moreover, 8/9 of the initially non-reactive sera were positive with the lam-γ1 monomer, leading to an overall sensitivity of 98.2%. Analyses of 41 control sera with the three lam-γ1 recombinants led to a specificity of 88%. Specifically, 3/15 EBA sera, 1/14 PV serum and 1/12 HC serum reacted with the lam-γ1 monomer while only the 3 EBA sera reacted with lam-421.

CONCLUSIONS

Here we show a novel two-step IB assay using the two recombinant laminin trimers and lam-γ1 chain monomer for the detection of anti-lam-γ1 serum IgG with high sensitivity and specificity. This assay will facilitate the diagnosis and further characterization of this disease.

Molecular diagnosis of anti-laminin 332 (epiligrin) mucous membrane pemphigoid

BACKGROUND

Mucous membrane pemphigoid is a group of chronic subepithelial autoimmune blistering diseases that mainly affect mucous membranes. Laminin 332-specific autoantibodies are present in approximately 1/3 of the patients, being associated with an increased risk of malignancy. Because of the severe complications, an early recognition of the disease allowing a timely therapy is essential. The gold standard methods for detection of laminin 332-specific autoantibodies, including the immunoprecipitation and immunoblotting are non-quantitative, laborious and restricted to a few specialized laboratories worldwide. In addition, the use of radioimmunoassays, although highly sensitive and specific, are laborious, expensive and tightly regulated. Therefore, there is a stringent need for a quantitative immunoassay for the routine detection of laminin 332-specific autoantibodies more broadly available to diagnostic laboratories. The aim of this study was to compare different antigenic substrates, including native, recombinant laminin 332 and laminin 332-rich keratinocyte extracellular matrix, for development of an ELISA to detect autoantibodies in mucous membrane pemphigoid.

RESULTS

Using a relatively large number of sera from MMP patients with well-characterized autoantibody reactivity we show the suitability of ELISA systems using laminin 332 preparations as adjunct diagnostic tools in MMP. While glycosylation of laminin 332 does not appear to influence its recognition by MMP autoantibodies, ELISA systems using both purified, native and recombinant laminin 332 demonstrated a high sensitivity and good correlation with the detection of autoantibodies by immunoblotting. ELISA systems using different laminin 332 preparations represent a feasible and more accessible alternative for a broad range of laboratories.

CONCLUSIONS

Our findings qualify the use of immunoassays with the laminin 332-rich preparations as an ancillary diagnostic tool in mucous membrane pemphigoid.

Paraneoplastic Pemphigus and Autoimmune Blistering Diseases Associated with Neoplasm: Characteristics, Diagnosis, Associated Neoplasms, Proposed Pathogenesis, Treatment

Autoimmune paraneoplastic and neoplasm-associated skin syndromes are characterized by autoimmune-mediated cutaneous lesions in the presence of a neoplasm. The identification of these syndromes provides information about the underlying tumor, systemic symptoms, and debilitating complications. The recognition of these syndromes is particularly helpful in cases of skin lesions presenting as the first sign of the malignancy, and the underlying malignancy can be treated in a timely manner. Autoimmune paraneoplastic and neoplasm-associated bullous skin syndromes are characterized by blister formation due to an autoimmune response to components of the epidermis or basement membrane in the context of a neoplasm. The clinical manifestations, histopathology and immunopathology findings, target antigens, associated neoplasm, current diagnostic criteria, current understanding of pathogenesis, and treatment options for a selection of four diseases are reviewed. Paraneoplastic pemphigus manifests with clinically distinct painful mucosal erosions and polymorphic cutaneous lesions, and is often associated with lymphoproliferative neoplasm. In contrast, bullous pemphigoid associated with neoplasm presents with large tense subepidermal bullae of the skin, and mild mucosal involvement, but without unique clinical features. Mucous membrane pemphigoid associated with neoplasm is a disorder of chronic subepithelial blisters that evolve into erosions and ulcerations that heal with scarring, and involves stratified squamous mucosal surfaces. Linear IgA dermatosis associated with neoplasm is characterized by annularly grouped pruritic papules, vesicles, and bullae along the extensor surfaces of elbows, knees, and buttocks. Physicians should be aware that these autoimmune paraneoplastic and neoplasm-associated syndromes can manifest distinct or similar clinical features as compared with the non-neoplastic counterparts.