Staphylococcus aureus and host interaction in the flare‐ups of hidradenitis suppurativa

Inflammatory loop involving Staphylococcus aureus, IL-36γ, and cathepsin S drives immunity disorders in familial acne inversa keratinocytes

Acne inversa (AI) is an inflammatory skin disease associated with nicastrin (NCSTN) mutations. Despite the dysregulated bacterial-host immune interactions being an essential event in AI, the interaction between bacteria and keratinocytes in AI pathophysiology remains unclear. In this study, the NCSTN gene was suppressed using short hairpin RNA in HaCaT cells. Using RNA sequencing, real-time polymerase chain reaction, and western blotting, the expression of IL-36 cytokines was analyzed. The impact of Staphylococcus aureus on AI keratinocyte inflammation and underlying regulatory molecules was investigated by exposing the HaCaT cells to S. aureus. By stimulating NCSTN knockdown HaCaT cells with IFN-γ, the expression and regulatory mechanism of Cathepsin S (Cat S), an IL-36γ cleavage and activating protease, were investigated. After NCSTN knockdown, the IL-36α expression increased, and the IL-36Ra expression was downregulated. NCSTN/MEK/ERK impairment-induced Krüppel-like factor 4 (KLF4) up-regulation in concert with S. aureus-induced nuclear factor kappa B elevation acts synergistically to promote IL-36γ production with the subsequent IL-8 activation in HaCaT cells. NCSTN/MEK/ERK impairment was also observed in familial AI lesions. IFN-γ-induced Cat S in keratinocytes was enhanced after NCSTN knockdown. The expression of IFN-II pathway molecules was significantly upregulated in both NCSTN knockdown HaCaT cells and familial AI lesions. The Cat S expression was significantly elevated in the patient's AI lesions. Our findings suggested a synergistic relationship between S. aureus and NCSTN/MAPK/KLF4 axis in IL-36γ-induced familial AI keratinocytes.

Consistency of Bacterial Triggers in the Pathogenesis of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is an inflammatory skin disease whose pathogenesis remains poorly defined. Over the past decades, the bacterial role in HS patients has been a focus of research. According to the literature, the HS skin (and probably gut) bacterial composition is different to that of healthy controls. To date, a key question is whether compositional changes in the microbial populations are responsible for the development of HS (primum movens), or only secondarily reflect the ongoing inflammatory process. The great diversity of methodologies that have been used to study microbial role in HS have led to an accumulation of conflicting results. Thus, in view of these considerations, the aim of this article is to provide the reader with an overview about different hypotheses proposed to explain the bacterial role in HS pathogenesis.

Flares as dynamic predictive factor of response to adalimumab in hidradenitis suppurativa, real-life data

BACKGROUND

Hidradenitis suppurativa (HS) is characterized by periodic worsening of both clinical manifestations and symptoms. The aim was to investigate the role of flare outbreak as a possible predictive factor of response to Adalimumab.

METHODS

115 HS patients in treatment with adalimumab, with moderate-severe HS, ≥3 abscesses and inflammatory-nodules (ANs) from 5 Italian centers were included in this retrospective analysis. The information about gender, ages at onset/baseline, therapeutic delay, family history, body mass index, smoking, comorbidities, phenotypes, body areas, severity indexes at baseline was collected. Baseline characteristics, total number and timeline of flares were analysed by regression and survival analysis with Hidradenitis Suppurativa Clinical Response (HiSCR).

RESULTS

During the observational period, 80.9% of patients developed flares, detecting 252 flares. Univariate model identified five factors associated with the absence of response: age (p-value=0.020), comorbidities (p-value=0.030), genital-perineal involvement (pvalue= 0.004), no response at week-12 (p-value=0.027), and flares outbreak (p-value=0.010). Joint analysis of recurrent and terminal events showed a positive correlation between flare recurrence and no-response (p-value<0.001). Among the identified variables associated with poor response to the therapy: occurrence of a flare before week-12 was the one with the highest risk of no response (p-value<0.001). The limitations are: study's retrospective design, limited number of patients, absence either of a consensus about flare definition, placebo control group or standard therapy of flares during adalimumab therapy.

CONCLUSIONS

The analysis of a "dynamic" variable, as flares evaluation together with an appropriate clinical baseline assessment can be a useful approach to predict the middle-long-term response to adalimumab.

Factors related to the onset and recurrence of flares in hidradenitis suppurativa patients treated with adalimumab

BACKGROUND

Hidradenitis suppurativa (HS) is characterized by periodic worsening of symptoms. However, clinical parameters associated with flare are still to be established. The aim was too investigate factors associated with flare outbreak in HS patients in treatment with adalimumab.

METHODS

Moderate-severe HS patients were included in this retrospective analysis. In total, 115 HS patients treated with adalimumab from 5 Italian centers were reviewed. Gender, ages at onset/baseline, therapeutic delay, family history, body mass index, smoking, comorbidities, phenotypes, body areas involved, Hurley stage, International Hidradenitis Suppurativa Severity Score System (IHS4), Dermatology Life Quality Index (DLQI) and Visual Analogue Scale for pain (pain-VAS) were collected at baseline. Flares were modelled with baseline features using univariate and multivariate Coxregression. The factors significantly correlated with flares in the univariate model were analyzed using a recurrent event survival analysis (Andersen-Gill model) to assess the relation between them and flares recurrence.

RESULTS

During the observation period 80.9% of patients developed flares, detecting 252 flares, overall. A univariate model identified five risk factors associated with the outbreak of flares: age, therapeutic delay, groin involvement, Hurley III, higher IHS4, whereas, from multivariate model, only IHS4 resulted to be significantly correlated. Additionally, flares were positively associated with higher DLQI and pain-VAS. Finally, the Andersen-Gill model showed four factors correlated with flares recurrence: age, therapeutic delay, Hurley III and higher IHS4. The limitations are: study's retrospective design, absence of a consensus about flare definition.

CONCLUSIONS

An early treatment of HS may prevent both the disease progression and reduce the recurrence of flares.

Staphylococcus aureus Carriage in Hidradenitis Suppurativa: Impact on Response to Adalimumab

BACKGROUND

Several patients with hidradenitis suppurativa (HS) present flare-ups during treatment with adalimumab (ADA), the cause of which is not clear. ADA is the only FDA-approved biologic for the therapy of moderate-to-severe HS. A previous study of our group has shown that Staphylococcus aureus stimulation of whole blood affects the production of human β-defensin 2 and modulates HS severity. It is, therefore, hypothesized, that carriage of S. aureus may drive HS flare-ups.

OBJECTIVE

To explore the association between carriage of S. aureus and loss of response to ADA.

PATIENTS AND METHODS

Among patients with moderate-to-severe HS without carriage of S. aureus at start of treatment with ADA, we investigated for carriage of S. aureus from the nares when flare-ups occurred. Flare-ups were pre-defined as at least 25% increase of inflammatory lesions (sum of inflammatory nodules and abscesses) from baseline. Samplings were also done after completion of 12 weeks of ADA treatment from all patients who did not present flare-ups. Clinical response to ADA was assessed by the HS Clinical Response score (HiSCR).

RESULTS

Thirty-nine patients were studied; 24 with Hurley II stage HS and 15 with Hurley III stage HS. Twenty-nine patients achieved HiSCR after 12 weeks of treatment without any flare-ups; 10 patients had flare-ups and failed HiSCR. Three (10.3%) and 5 (50%) patients, respectively, had nasal carriage of S. aureus (odds ratio 8.67; 95% CI 1.54-48.49; p = 0.014). Among 32 patients reaching follow-up week 48, 20 patients achieved HiSCR and 12 had flare-ups leading to ADA failure; 2 (10%) and 5 (41.7%) patients, respectively, had positive culture for S. aureus (odds ratio 6.42; 95% CI 1.00-41.20; p = 0.05).

CONCLUSION

Nasal carriage of S. aureus may be associated with loss of response to ADA. Findings need confirmation in larger series of patients.