Hsp90 blockade modulates bullous pemphigoid IgG-induced IL-8 production by keratinocytes

Abstract

Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering skin disease characterized by autoantibodies against the hemidesmosomal proteins BP180 and BP230. The cell stress chaperone heat shock protein 90 (Hsp90) has been implicated in inflammatory responses, and recent evidence suggests that it represents a novel treatment target in autoimmune bullous diseases. The aim of the study was to investigate the contribution of Hsp90 to the proinflammatory cytokine production in keratinocytes induced by autoantibodies to BP180 from BP patient serum. HaCaT cells were treated with purified human BP or normal IgG in the absence or presence of the Hsp90 blocker 17-DMAG and effects on viability, interleukin 6 (IL-6) and IL-8 (cytokines critical for BP pathology), NFκB (their major transcription factor), and Hsp70 (marker of effective Hsp90 inhibition and potent negative regulator of inflammatory responses) were investigated. We found that BP IgG stimulated IL-6 and IL-8 release from HaCaT cells and that non-toxic doses of 17-DMAG inhibited this IL-8, but not IL-6 secretion in a dose-and time-dependent fashion.

Immunomodulatory effects of heat shock protein 90 inhibition on humoral immune responses

“…In another study, we observed an aberrant expression of Hsp90 in skin and blood of patients with the most common subepidermal blistering autoimmune disorder, bullous pemphigoid (BP), characterized by autoantibodies to type XVII collagen (BP180), suggesting that Hsp90 may play a pathophysiological role and represent a novel potential treatment target also in this disease . In fact, further experiments of our group revealed that Hsp90 inhibition suppressed BP IgG‐induced production of IL‐8, a proinflammatory cytokine critical for BP pathology, by cultured keratinocytes .…”

Heat shock protein 90 inhibition: A potential double- or triple-edged sword in the treatment of mucous membrane pemphigoid

“…These future investigations could yield some relevant information about the role of Hsp90 in MMP and, together with already existing knowledge on the powerful anti-inflammatory and anti-scarring effects of anti-Hsp90 treatment [14][15][16][17][18][19][20][21]25,[28][29][30], possibly support the introduction of nontoxic Hsp90 inhibitors for future medical management of patients with this potentially devastating disease that may otherwise cause permanent damage when therapy is delayed or ineffective.…”

“…Based on the above, we hypothesize that pharmacological Hsp90 blockade could represent a double-edged sword in the treatment of MMP by pleiotropic targeting of the mentioned Hsp90 inhibitor-prone pathophysiological factors involved in both inflammatory subepidermal blister formation and cicatricial processes [19][20][21]25,[28][29][30]. Due to their additional anti-cancer activity, Hsp90 inhibitors could even be proclaimed as a triple-edged sword against the malignancy-associated anti-laminin 332 subtype of MMP [12].…”

“…These include that (i) Hsp90 inhibitors exhibit activity in mice with experimental epidermolysis bullosa acquisita and in a respective ex vivo human dermal-epidermal separation cryosection model by potently affecting inflammatory disease pathways (i.e., inhibition of effector T cells, B cells, and neutrophils; suppression of autoantibody, proinflammatory cytokine, and reactive oxygen species production; promotion of regulatory B cells) [19][20][21], (ii) secreted basement membrane-degrading and blister-provoking matrix metalloproteinases with partly profibrotic potential are complexed by extracellular Hsp90 in sera of patients with epidermolysis bullosa acquisita, thus representing additional treatment targets of Hsp90 antagonists [21][22][23], (iii) Hsp90 is aberrantly expressed and secreted in the skin and blood of patients with BP, and its blockade modulates anti-BP180 autoantibody-induced production of proinflammatory IL-8 by cultured keratinocytes [24,25], and (iv) circulating autoantibodies to Hsp90 are elevated and positively correlated with disease activity and serum anti-epidermal/tissue transglutaminase autoantibodies in patients with dermatitis herpetiformis [26]. With regard to MMP, it has previously been reported that, in contrast to healthy persons and those with atopic keratoconjunctivitis, Hsp90 expression is upregulated in the conjunctival stroma and vasculature of patients with ocular disease [27].…”

Epidermolysis Bullosa Acquisita: From Pathophysiology to Novel Therapeutic Options

“…A novel strategy to inhibit autoreactive T cell responses is derived from experiments using inhibitors of the cell stressinducible chaperone heat shock protein 90 (Hsp90) in experimental EBA (Kasperkiewicz et al, 2011). Currently tested in clinical trials for therapy of cancer patients due to its inhibitory effects on malignant cells (Solárová et al, 2015), anti-Hsp90 treatment is also increasingly becoming a research focus in autoimmune diseases, including blistering disorders, as it exerts potent immunomodulatory actions (Collins et al, 2013;de Zoeten et al, 2011;Kasperkiewicz et al, 2011;Tukaj et al, 2014aTukaj et al, , 2014bTukaj et al, , 2014cTukaj et al, , 2015aTukaj et al, , 2015b. Application of Hsp90 inhibitors before and after disease onset blocked EBA development and induced clinical recovery associated with suppressed autoantibody production compared with vehicletreated animals in immunization-induced EBA, respectively.…”