Deposition of membrane attack complex in cutaneous lesions of lupus erythematosus

Neutrophil extracellular traps drive lupus flares with acute skin and kidney inflammation triggered by ultraviolet irradiation

Sunlight triggers lupus flares causing both local skin and systemic inflammation, including lupus nephritis, through poorly understood mechanisms. To address this knowledge gap, we found that UVB irradiation of asymptomatic, young female lupus-prone mice induced skin and kidney inflammation with proteinuria, accompanied by neutrophil infiltration and neutrophil extracellular trap (NET) formation. Furthermore, UVB irradiation induced co-expression of CXCR4 and cytokines/C3 by neutrophils in vitro and in vivo, in the skin and kidneys of lupus-prone mice, indicating their transmigratory and pro-inflammatory potentials. A causality study demonstrated that inhibiting CXCR4 attenuated renal neutrophil infiltration, accumulation of NETs, NET-associated cytokines/C3, and proteinuria in UVB-irradiated lupus-prone mice. Remarkably, inhibiting NETosis through a novel strategy targeting nuclear envelope integrity reduced deposition of NET-associated cytokines/C3 in skin and kidneys, attenuating proteinuria in UVB-irradiated MRL/lpr·lmnB1 Tg mice. Our investigation unveils a new mechanism by which neutrophil NETs drive the early onset of lupus flares triggered by UVB-irradiation. Targeting neutrophil transmigration and NETosis could be promising therapeutic strategies.

Vacuolar Interface Dermatitis as a Histologic Reaction Pattern of Sjögren's Syndrome: A Case Report

Sjögren's syndrome (SS) has been widely known for its dry mouth and dry eyes presentation. Extraglandular disease manifestations may be protean and pose a challenge for clinicians, especially when the typical known manifestations are absent. Skin involvement of SS is variable, and cutaneous signs and symptoms may be the initial presentation of this syndrome. Vacuolar interface dermatitis has been linked to dermatomyositis and systemic lupus erythematosus, but rarely to SS. Herein, we present the case of an 87-year-old man who presented for widespread itchy erythematous scaly plaques that were refractory to topical corticosteroids as well as discontinuation of possible offending medications. A biopsy demonstrated vacuolar interface dermatitis in the setting of strongly positive anti-SSA. Hydroxychloroquine treatment was effective in resolving the plaques.

Inhibition of terminal complement: a novel therapeutic approach for the treatment of systemic lupus erythematosus

The importance of the complement system in the pathophysiology of systemic lupus erythematosus (SLE) is clear although individual complement components play very different roles in the disease process. Early complement proteins are critical in the clearance of immune complexes and apoptotic bodies, and their absencepredisposesindividualsto SLE. Conversely, activationof terminalcomplement is associated with exacerbations of disease and damage to tissues and organs, particularly in lupus nephritis. Monoclonal antibodies that specifically inhibit terminal complement activation while preserving the critical functions of the early complement cascade have now been developed. These antibodies target the C5 complement protein, blocking its cleavage and the subsequent generation of potent proinflammatory molecules. Anti-C5 therapeutics have recently been investigated in an animal model of SLE and in a Phase I single dose study in humans. The results of these studiesand the multiple roles of complement in SLE are discussed.

Correlation of cutaneous immunoreactants in lesional skin with the serological disorders and disease activity of systemic lupus erythematosus

Detection of immunoreactants including IgG, IgM, IgA, and C3 by direct immunofluorescence (DIF) from skin is useful for distinguishing lupus lesions from other skin disorders. Despite their diagnostic value, the type and number of cutaneous immunoreactants as they relate to serological disorders and disease severity has been poorly studied. We examined 36 patients with systemic lupus erythematosis (SLE) with positive DIF (DIF+) and 28 patients with negative DIF (DIF-) tests performed on lesional skin. Among DIF+ patients, the most frequent patterns of immunoreactants were IgM alone (36%) and the coexistence of IgM with C3 (28%). IgM was the highest detected individual immunoreactant (86%). As classified by number, 17 of 36 DIF+ patients had one immunoreactant (= 1), while the remaining patients had two to four immunoreactants (>1). Compared with DIF- patients, DIF+ patients were more likely to have severe disease as indicated by lower serum C3 levels and a higher SLE disease activity index (SLEDAI). The coexistence of IgM with any other immunoreactants indicated a more severe disease than that present in the DIF- group, whereas the IgM-alone group was comparable with the DIF- group in both serum C3 levels and SLEDAI. These findings were also applicable in the comparison of patients with more than one (>1) immunoreactant and patients with no (DIF-) and one ( = 1) immunoreactant. Collectively, the presence of multiple immunoreactants in lesional skin implies a more severe disease activity of SLE, while a single immunoreactant may be equal to the absence of immunoreactants (DIF-) in terms of predicting disease activity.

Complement involvement in neovascular ocular diseases

Pathological neovascularization (NV) is a hallmark of late stage neovascular age-related macular degeneration (AMD), diabetic retinopathy (DR), and retinopathy of prematurity (ROP). There is accumulating evidence that alterations in inflammatory and immune system pathways that arise from genetic differences, injury, and disease can predispose individuals to retinal neovascular eye diseases. Yet the mechanism of disease progression with respect to the complement system in these maladies is not fully understood. Recent studies have implicated the complement system as an emerging player in the etiology of several retinal diseases. We will summarize herein several of the complement system pathways known to be involved in ocular neovascular pathologies. Current treatment for many neovascular eye diseases focuses on suppression of NV with laser ablation, photodynamic therapy, or anti-VEGF angiogenic inhibitors. However, these treatments do not address the underlying cause of many of these diseases. A clear understanding of the cellular and molecular mechanisms could bring a major shift in our approach to disease treatment and prevention.

Direct immunofluorescence in Behçet's disease: a controlled study with 108 cases

PURPOSE

Behçet's disease (BD) is a disease of unknown etiology, which has multisystemic involvement. This multisystemic involvement might be the clue for an autoimmune pathogenesis. In order to evaluate an autoimmune pathogenesis, we examined immunoreactans depositions in the skin of BD patients.

MATERIALS AND METHODS

The skin samples of 108 BD patients (28 perilesional skin, 44 positive pathergy test site, 22 negative pathergy test site, 14 normal skin) were examined for the depositions of immunoglobulin (Ig)M, IgG, IgA, complement 3 (C(3)), and fibrinogen (F) using direct immunofluorescence (DIF). The data were statistically compared to the DIF of 36 systemic lupus erythematosus (SLE) patients and 20 healthy controls using chi(2) Fisher exact test.

RESULTS

Highly significant immunoreactans depositions were obtained in BD (deposition rates: IgM 70.3%, IgG 0%, IgA 20.3%, C(3) 62.9%, F 83.3%). The comparison with SLE revealed no differences in IgM, IgA, and C(3). However, IgG deposition was higher in SLE while F deposition was higher in BD. In both BD and SLE, the Ig depositions were highly significant when the data were compared with the healthy controls.

CONCLUSION

The significant deposition of immunoreactans in BD, especially in the negative pathergy and the normal skin sites, were observed. This study is the first controlled study revealing positive Ig depositions in BD, and it is expected to help us to reconsider the autoimmune pathogenesis in BD.

Interface dermatitis

Interface dermatitis can be classified based upon the cell type that dominates the infiltrate (ie, neutrophilic, lymphocytic, or lymphohistiocytic) or by the intensity of the interface inflammation. Regarding lymphocytic interface dermatitis, there are 2 broad categories: cell-poor interface dermatitis, when only a sparse infiltrate of inflammatory cells is present along the dermoepidermal junction, or cell rich, which typically occurs as a heavy bandlike infiltrate that obscures the basal layers of the epidermis. In the case of lymphocytic interface dermatitis, the latter is often termed a lichenoid interface dermatitis. This review focuses upon the mononuclear cell-predominant forms of interface dermatitis.

Cutaneous vascular deposition of C5b-9 and its role as a diagnostic adjunct in the setting of diabetes mellitus and porphyria cutanea tarda

BACKGROUND

The cutaneous lesions of diabetes mellitus (DM) and porphyria cutanea tarda (PCT) exhibit distinctive microvascular changes including basement membrane zone thickening and lamellation, morphologically appearing as hyaline-like alterations of the vessel wall. Immunofluorescence demonstrates homogeneous mantles of immunoglobulin in the microvasculature. The staining intensity is variable and in some cases can closely approximate those immunofluorescent changes seen in photoaged skin.

OBJECTIVE

The purpose of this study was to establish an association between the microvascular changes seen in the skin from patients with DM and PCT and the presence of C5b-9 deposition, potentially defining the C5b-9 assay as an additional diagnostic adjunct.

METHODS

Routine light microscopy and immunofluorescence studies were conducted on skin biopsy specimens from 14 patients with cutaneous manifestations of DM and 17 patients with PCT. The immunofluorescence profile included IgG, IgM, IgA, C3, C3d, C4d, and C5b-9.

RESULTS

Fourteen of 14 DM and 17 of 17 PCT skin biopsy specimens revealed extensive granular and homogeneous vascular deposition of C5b-9; a similar pattern was observed for C3d and C4d. Control specimens from patients without DM and PCT, where C5b-9 was not an expected immunoreactant, were negative. Positive controls were cases of vasculitis, scleroderma, and dermatomyositis without DM and PCT where C5b-9 deposition was expected. C5b-9 deposition was observed and was of lesser magnitude than that encountered in patients with PCT or DM.

LIMITATIONS

We were unable to obtain detailed clinical information on some of the diabetic patients in regards to significant extracutaneous vascular complications. In addition, a correlation between hemoglobin 1 Ac levels and the extent of C5b-9 deposition could not be ascertained as the serum levels for hemoglobin 1 Ac were unknown.

CONCLUSION

Granular and homogeneous deposits of C5b-9 in vessels, along with homogeneous deposits of immunoglobulin within the blood vessels, are characteristic immunofluorescence findings in patients with DM and PCT. In regards to potential mechanisms of C5b-9 deposition, decreased metabolism of C5b-9 due to glycosylation of CD59 in the setting of DM and activation of complement by irradiated porphyrins in PCT are proposed. The extent of C5b-9 deposition suggests that this complex may play a pathogenetic role in the evolution of microvascular injury in patients with DM and PCT.

Activation/inactivation of the classical pathway of complement in non-lesional skin of patients with systemic lupus erythematosus

BACKGROUND

The link between the lupus band and pathogenesis remains controversial, because immunoglobulins and complement components, including the membrane attack complex, can be found in both lesional and non-lesional skin of patients with systemic lupus erythematosus (SLE). The expression of proteins that regulate complement has not been previously investigated in the skin of patients with SLE.

AIM

The aim of this study is to compare the expression of protectin (CD59), which demonstrates the activation of the classical pathway of complement, in non-lesional skin obtained from patients with SLE with its expression in normal skin. This may help us explain the link between the lupus band and pathogenesis of cutaneous lupus erythematosus.

METHODS

An indirect immunofluorescence technique was performed in order to provide unequivocal evidence for the activation of complement via the classical pathway and to compare the expression of CD59 in non-lesional skin from patients with SLE with normal skin samples obtained from healthy people.

RESULTS

The activation of the classical pathway of complement was demonstrated in non-lesional skin in more than 90% of SLE patients investigated in this study. Staining intensity of the complement regulatory protein CD59 was markedly increased in the majority of non-lesional skin samples obtained from patients with SLE, compared to that from normals.

CONCLUSIONS

CD59 is overexpressed in non-lesional skin in which complement activation has occurred. It seems likely that an increased and continuous CD59 expression may be important for maintaining the integrity of the skin BMZ during inflammatory responses involving complement activation in SLE skin. Alahlafi A, Wordsworth P, Wojnarowska F. Activation/inactivation of the classical pathway of complement in non-lesional skin of patients with systemic lupus erythematosus.

Uncertainties in the pathogenesis of adult dermatomyositis

PURPOSE OF REVIEW

Dermatomyositis is an inflammatory disorder of muscle affecting both children and adults. The pathogenesis of adult dermatomyositis is reviewed here, with particular attention to gaps and uncertainties in our current understanding of this disease, in order to focus attention on the outstanding research questions with regard to disease mechanisms.

RECENT FINDINGS

The conceptual model of the pathophysiology of dermatomyositis has been based on work extending back over at least 35 years, with important findings related to the deposition of membrane attack complex, the character of the inflammatory infiltrate, and the primacy of capillary abnormalities established over 10 years ago. The lack of significant additions to the understanding of this disease over the past few years suggests a state of contentment with current knowledge. Accordingly, we emphasize the uncertainties of this knowledge and the need for re-addressing some of its basic tenets.

SUMMARY

Although evidence remains strong that dermatomyositis is a disorder with an early involvement of the capillaries, the concept that it results from an antibody-mediated attack upon the endothelium is uncertain. It is not clear whether membrane attack complex is activated by antibody-dependent or independent means, whether or not intramuscular B cells are antigen specific and synthesize significant quantities of antibodies, whether the presence of tubuloreticular inclusions precedes, follows, or is independent of membrane attack complex deposition, what is the mechanism of perifascicular atrophy, and what is the relationship of dermatomyositis to systemic lupus erythematosus.

Complement membrane attack complexes in pathologic disc tissues

STUDY DESIGN

Complement membrane attack complexes were located in lumbar spine disc tissues by immunohistochemistry. Their occurrence was compared in control discs obtained from organ donors (CD), discs showing a normal macroscopic anatomy, samples of intervertebral disc herniations (DH), and intervertebral discs found to be degenerated by discography, but not herniated (DD).

OBJECTIVE

To look for a possible role of complement activation, specifically complement membrane attack complexes, an end product of the classic immune complex-mediated complement activation pathway, in disc pathophysiology.

SUMMARY OF BACKGROUND DATA

Recent immunohistochemical and biochemical studies suggest a possible role for immune complexes, as observed by immunohistochemical location and biochemical assay of immunoglobulins M and G in intervertebral disc pathophysiology. Immune complexes may trigger complement activation and ultimately cell lysis. There are, however, currently no reports on complement activation in disc tissues, although immune (antigen-antibody) complexes have been demonstrated. Such immune complexes have been reported to occur on or near to disc cells in DH tissues.

METHODS

Thin frozen sections of disc tissue from CD (n = 9 discs), DH (n = 58 discs), and DD (n = 11 discs) were cut and then immunostained with a monoclonal antibody to the complement membrane attack complex (C5b-9) using avidin-biotin complex (ABC) immunostaining. The presence or absence of complement membrane attack complex immunoreactivity was compared in the various subtypes of DH and also with preoperative duration of radicular pain.

RESULTS

Complement membrane attack complexes could be observed in none of the CDs studied. In contrast, in more than one third of both the DH (21/58, 36.2%) and the DD (4/11, 36.4%), immunoreactivity to complement membrane attack complexes could be observed in disc cells. In DD discs, immunoreactivity to complement membrane attack complexes was most often present in anulus fibrosus samples (5/13, 38.5%). With respect to subtype of DH, complement membrane attack complexes were observed in 19 of 36 sequestrated discs (52.8%), 1 of 16 extrusions (6.3%), and 1 of 6 protrusions (16.7%). Complement membrane attack complexes were more often present with shorter pain duration (P= 0.03), but showed no relation to age. Disc cells often showed a heavy staining pattern for complement membrane attack complexes, suggesting an abundance of these complexes lodged in the membrane of the cells.

CONCLUSIONS

The predominant presence of complement membrane attack complexes in sequestrated disc tissue could suggest a role in DH tissue-induced sciatica. Possibly immune (antigen-antibody) complexes, reported in previous studies, trigger the classic pathway of complement activation, with complement membrane attack complexes as the final product. Complement membrane attack complexes also appear to have some as yet undefined role in degenerated nonherniated disc tissue, with a predominant presence in the anulus fibrosus cells of such discs.

Complement and systemic lupus erythematosus

Complement is implicated in the pathogenesis of systemic lupus erythematosus (SLE) in several ways and may act as both friend and foe. Homozygous deficiency of any of the proteins of the classical pathway is causally associated with susceptibility to the development of SLE, especially deficiency of the earliest proteins of the activation pathway. However, complement is also implicated in the effector inflammatory phase of the autoimmune response that characterizes the disease. Complement proteins are deposited in inflamed tissues and, in experimental models, inhibition of C5 ameliorates disease in a murine model. As a further twist to the associations between the complement system and SLE, autoantibodies to some complement proteins, especially to C1q, develop as part of the autoantibody response. The presence of anti-C1q autoantibodies is associated with severe illness, including glomerulonephritis. In this chapter the role of the complement system in SLE is reviewed and hypotheses are advanced to explain the complex relationships between complement and lupus.

The cutaneous pathology of lupus erythematosus: a review

The presentation of lupus erythematosus (LE) ranges from a skin rash unaccompanied by extracutaneous stigmata to a rapidly progressive lethal multiorgan disease. The diagnosis and subclassification is traditionally based on the correlation of serological and clinical findings. The latter include a photoinduced skin rash, arthralgia, arthritis, fever, Raynaud's phenomenon, anemia, leukopenia, serositis, nephritis and central nervous sysdtem disease. The conventional classification scheme includes systemic, subacute cutaneous and discoid LE. Recent advances in our understanding of the cutaneous histopathology which correlates with the traditional forms of LE, along with certain novel LE subtypes, are the focus of this review. In addition to the main subtypes of LE, we will discuss associated vasculopathic lesions and the contribution of immunofluorescence microscopy to the diagnosis of LE and related connective tissue disease syndromes. Consideration will be given to unusual variants of LE such as anti-Ro/SSA-positive systemic lupus erythematosus (SLE), bullous SLE, lymphomatoid LE, lupus erythematosus profundus, drug induced LE, linear cutaneous LE, chiblains LE and parvovirus B19-associated LE.