Immunopathological Mechanisms of Acantholysis in Pemphigus Vulgaris: An Explanation by Ultrastructural Observations

Do serum prolactin levels correlate with antibodies against desmoglein in pemphigus vulgaris?

Background:

Pemphigus vulgaris is a chronic inflammatory disease of skin, the etiology of which is not completely known. Despite the latter, anti-desmoglein antibodies play a proven role in the pathogenesis. Recent studies showed an etiologic effect for prolactin in the pemphigus vulgaris. This study aimed to quantify the correlation between serum prolactin levels and anti-desmoglein antibodies in patients with pemphigus vulgaris.

Materials and Methods:

Prolactin and antibodies against desmoglein 1 and 3 measured with ELISA in 14 new subjects of pemphigus vulgaris.

Results:

There was no statistically significant relation between both serum prolactin and anti-desmoglein1 levels (r = 0.02, P = 0.47) and serum prolactin and anti-desmoglein 3 levels (r= -0.09, P = 0.38).

Conclusion:

This study indicates that no correlation was found between serum prolactin levels and anti-desmoglein 1 levels and serum prolactin and anti-desmoglein 3 levels. However, other studies should be initiated regarding exact molecular and cellular effects of prolactin in the pathogenesis of pemphigus vulgaris.

Vitamin D inhibits captopril-induced cell detachment and apoptosis in keratinocytes

BACKGROUND

Captopril, an angiotensin I-converting enzyme inhibitor, is a commonly prescribed antihypertensive drug. Its cutaneous side-effects include pemphigus vulgaris acantholysis and bullous pemphigoid-like cell-matrix detachment. This medication also triggers apoptosis in human keratinocytes. Calcitriol, the hormonally active vitamin D metabolite, protects keratinocytes from programmed cell death induced by various noxious stimuli.

OBJECTIVES

To examine if calcitriol protects proliferating keratinocytes from the damage inflicted by captopril.

METHODS

Autonomously proliferating HaCaT keratinocytes, used as a model for basal layer keratinocytes, were exposed to captopril. Cell detachment was examined visually by light microscopy. Cytotoxicity was assessed by Hoechst 33342 staining and lactate dehydrogenase release. Apoptotic death was assessed by monitoring caspase 3-like activity.

RESULTS

Cells exposed to captopril detached and became round. This process was accompanied by programmed cell death. From time-dependent monitoring of cell detachment and apoptosis, and examination of pan-caspase inhibitor effects on cell detachment we concluded that cell death is the consequence of cell detachment from the culture plate and not vice versa. Pretreatment with calcitriol significantly attenuated these events. The effects of calcitriol were already evident at 1 nmol L(-1) concentration of the hormone.

CONCLUSIONS

The results of this study show that calcitriol protects keratinocytes from captopril-induced cell detachment and apoptosis.

Mechanisms of blister induction by autoantibodies

Autoimmune diseases are characterized by defined self-antigens, organ specificity, autoreactive T cells and/or autoantibodies that can transfer disease. Autoimmune blistering diseases are organ-specific autoimmune diseases associated with an immune response directed to structural proteins mediating cell-cell and cell-matrix adhesion in the skin. While both autoreactive T and B cells have been detected and characterized in patients with autoimmune blistering diseases, current evidence generally supports a pathogenic role of autoantibodies for blister formation. The immunopathology associated with blisters induced by autoantibodies relies on several mechanisms of action. Autoantibodies from patients with pemphigus diseases can exert a direct effect just by binding to their target mediated by steric hindrance and/or by triggering the transduction of a signal to the cell. In most subepidermal autoimmune blistering conditions, in addition to the binding to their target antigen, autoantibodies need to interact with factors of the innate immune system, including the complement system and inflammatory cells, in order to induce blisters. Generally, decisive progress has been made in the characterization of the mechanisms of blister formation in autoimmune skin diseases. However, various aspects, including the exact contribution of steric hindrance and signal transduction for pemphigus IgG-induced acantholysis or the fine tuning of the inflammatory cascade triggered by autoantibodies in some subepidermal blistering diseases, still need to be addressed. Understanding the mechanisms by which autoantibodies induce blisters should facilitate the development of more specific therapeutic strategies of autoimmune blistering diseases.