Immunomodulatory Drugs in the Treatment of Hidradenitis Suppurativa-Possibilities and Limitations

The role of interleukin inhibitors in the treatment of hidradenitis suppurativa; a systematic review of clinical trials

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder that presents significant treatment challenges. Recent advancements have enhanced our understanding of its pathophysiology, leading to the development of novel therapeutic strategies. This systematic review evaluates the role of interleukin (IL) inhibitors as emerging treatment options for HS. A systematic search was conducted in PubMed/Medline, Scopus, and Web of Science databases for studies published up to September 2nd, 2024, with inclusion limited to clinical trials available in English. The National Institute of Health (NIH) Quality Assessment Tool for clinical trials and before-after studies with no control group was used to assess the methodological quality of the included studies. Out of 1289 studies, 20 met our inclusion criteria involving 3957 patients. Moreover, four ongoing trials were retrieved from ClinicalTrials.gov. Secukinumab showed sustained hidradenitis Suppurativa Clinical Response (HiSCR) improvements, particularly in biologic-naïve patients with common adverse events (AEs). Bimekizumab was effective with biweekly dosing, while the four-week regimen had inconsistent results, with rare reports of AEs. Brodalumab and bermekimab provided rapid and sustained HiSCR responses with lesion reductions, which were well tolerated. Guselkumab and ustekinumab showed promising but statistically nonsignificant improvements with mild AEs. Risankizumab did not significantly improve HiSCR rates but showed Dermatology Life Quality Index (DLQI) benefits. Anakinra offered moderate efficacy with prolonged exacerbation-free periods but led to some treatment discontinuations. Spesolimab reduced inflammatory lesions and draining tunnels while maintaining a favorable safety profile. IL inhibitors, especially IL-17 inhibitors, have demonstrated efficacy in treating moderate-to-severe HS, while IL-23 inhibitors have shown inconsistent results. Despite their generally favorable safety profiles, further research is needed to optimize treatment strategies and assess long-term outcomes.

Australasian hidradenitis suppurativa management guidelines

Hidradenitis Suppurativa is a burdensome inflammatory skin disease with significant quality of life impact. These management guidelines were developed to direct appropriate clinical management in the Australasian context. A systematic review was used for the basis of the consensus guidelines. Thirteen clinical experts were involved in a modified Delphi consensus process to develop the guidelines and treatment algorithms. Overall management strategies include appropriate severity assessment of disease and comorbidities, multimodal therapy with systemic and local treatments, and evidence-based progression along the therapeutic ladder in the event of inadequate response. Sequential monotherapy with antibiotics and/or single agent therapy is discouraged and aggressive treatment of moderate to severe disease to capture the window of opportunity is highly emphasised. Specific considerations in the setting of disease comorbidities, pregnancy and breastfeeding are also addressed. Overall, the complex nature of HS requires a complex and multimodal therapeutic response with medical, physical and surgical therapies to achieve best patient outcomes.

What Do We Know About Bacterial Infections in Hidradenitis Suppurativa?-A Narrative Review

Background/Objectives: Hidradenitis suppurativa is an inflammatory skin condition of the pilosebaceous unit of a chronic, painful, and progressive nature. It affects intertriginous parts of the body, including the axillae, groin, submammary region, and anogenital region. The risk of infection in HS patients is not well understood. Thus, presenting the most recent findings in the study of bacterial infections in relation to hidradenitis suppurativa was the objective of this review. Methods: The presented article is a narrative review. The PubMed and Scopus databases were searched for articles applicable to this review. All types of study design were included in this review. Results: Among reported infections in patients with HS, Fournier's gangrene, osteomyelitis, Clostridium difficile infection, and biofilm were significant. Attention should also be paid to post-procedural infections. Conclusions: A wide range of bacterial infections, from localized purulent infections to serious systemic consequences, can affect patients with HS. Comorbid diseases like diabetes mellitus and obesity change the cutaneous microbiota and produce a pro-inflammatory systemic milieu, which makes the disease more severe and makes HS patients more susceptible to infections. Additionally, those with untreated or unmanaged HS are more likely to experience infectious complications.

The role of piperacillin/tazobactam in the treatment of Hidradenitis suppurativa

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease. Most patients with moderate-to-severe disease require long-term antibiotic treatment, or biologic treatments to control their disease. Despite these interventions, relapses are common. This study evaluated the effectiveness of piperacillin/tazobactam treatment in patients with Hurley stage II and III HS who experienced disease flares and did not respond to conventional antibiotic and biologic treatment. Methods: Patients with HS hospitalized at the Department of Dermatology, Sheba Medical Center between August 2021 and January 2023 were retrospectively analyzed. Results: A cohort of ten such patients were treated with piperacillin/tazobactam for 6-21 days. Eight (80%) and two (20%) patients respectively demonstrated 2- and 1-grade improvements, from their baseline HS-Physician Global Assessment score. During the follow-up period, nine patients were monitored. HS Clinical Response (HiSCR) was achieved in six (66.7%) and five (55.6%) patients at the 3- and 6-month follow-up visits, respectively. Conclusions: In conclusion, Piperacillin/tazobactam emerges as a promising therapeutic option for disease flare-up in patients with Hurley stage II and III HS who do not respond to conventional treatment. Thus, piperacillin/tazobactam should be considered as crisis therapy for this patient subset.

Assessment of therapeutic response to photodynamic therapy with the Zn-Phthalocyanine RLP068/Cl versus topical Clindamycin in patients affected by Hidradenitis Suppurativa: a comparative clinical pilot study

Hidradenitis suppurativa is a chronic skin disorder characterized by painful inflammatory nodules and abscesses, significantly impacting patients' quality of life. Current treatment strategies, including topical antibiotics, often yield limited efficacy and pose risks of antibiotic resistance. Photodynamic therapy has emerged as a potential option, with RLP068/Cl (ELKOFAST®, non-sterile formulation) showing promising efficacy due to its broad-spectrum bactericidal activity. We conducted a pilot study assessing the therapeutic response to photodynamic therapy with RLP068/Cl versus topical clindamycin gel in patients affected by hidradenitis suppurativa of Hurley score I, II, and III. Results revealed higher efficacy of photodynamic therapy in combination with RLP068/Cl, particularly in mild cases. Its efficacy remains reliable even in more severe cases when combined with adalimumab. The observed faster lesion improvement and pain relief were ascribed to the bactericidal effects of RLP068/Cl against Gram+ and Gram- bacteria. Furthermore, photoactivated RLP068/Cl was well tolerated with no adverse events reported. Therefore, photodynamic therapy following RLP068/Cl application represents a novel therapeutic option for hidradenitis suppurativa with potential implications for antibiotic stewardship in dermatology.

Activated and Naïve Allogenic Human Placental Mesenchymal Stromal Cells Exert an Immunomodulatory Effect on Hidradenitis Suppurativa Patient Peripheral Blood Mononuclear Cells

This pilot study aimed to evaluate the immunomodulatory effect of placental mesenchymal stem/stromal cells (MSCs) on peripheral blood mononuclear cells (PBMCs) from patients with hidradenitis suppurativa (HS). Blood samples were collected from 3 healthy and 3 patients with HS. Isolated PBMCs were stained with carboxyfluorescein succinimidyl ester (CFSE) and stimulated with phorbol 12-myristate 13-acetate (PMA)/Ionomycin solution. The PBMCs of patients with HS were co-cultured with naïve MSCs (n-MSCs), activated with tumor necrosis factor (TNF)-α (10 ng/mL) and interferon (IFN)-γ (10 ng/mL) MSCs (a-MSCs), or adalimumab (30 μg/mL). The division index (proliferation inhibition) of PBMCs was analyzed by flow cytometry using the Proliferation Modeling tool after 5 days of coculture. The relative inflammatory gene expression dynamics and cytokine secretion were quantified in triplicate using real-time polymerase chain reaction (PCR) and Luminex assays. PBMCs from the HS control group showed statistically significant increases in interleukin (IL)-6 and IFN-γ cytokine concentrations and IL-17A gene expression when compared with healthy subjects. Statistically significant reduction of the division index was found in the a-MSCs group (P = 0.04). Also, the Luminex assay revealed significantly reduced proinflammatory cytokine concentrations of IL-9 (P = 0.022) and IL-17A (P = 0.022) in the a-MSCs group with the same trend of numerical lowering in n-MSCs group when compared to HS control. The results of real-time PCR revealed a numerical increase in the expression of the IL-1β, IL-36α, and TNF-α genes in both the a-MSCs and n-MSCs groups compared with the HS control. In conclusion, our findings suggest that MSCs can effectively curb PBMCs proliferation and suppress the production of inflammatory cytokines. Moreover, the preactivation of MSCs with IFN-γ and TNF-α before use can enhance their therapeutic effectiveness. Nevertheless, a larger sample size is imperative to validate these results.

Golimumab and certolizumab pegol for the treatment of hidradenitis suppurativa: a literature review and future perspective

Hidradenitis suppurativa (HS) is an inflammatory skin condition with an underlying inflammatory process. Due to the limited efficacy of available treatments, HS remains a therapeutic challenge. The safety and efficacy of tumor necrosis factor-α (TNF-α) inhibitors, adalimumab, infliximab, and etanercept, are well studied in this patient population, and in some cases, HS was unresponsive to them. In recent years, evidence has been growing regarding the application of other anti-TNFs, including certolizumab pegol (CPZ) and golimumab. We sought to evaluate the overall safety and efficacy of golimumab and CPZ in the management of HS. A comprehensive search was performed on the PubMed, Scopus, Web of Science, and Ovid Embase databases, as well as the Google Scholar search engine from initiation to 31 August 2023. A total of nine and four studies used CPZ and golimumab to treat HS, respectively. Individuals with concomitant inflammatory immune-mediated diseases, pregnant females, and patients who were refractory to previous treatments achieved a Hidradenitis Suppurativa Clinical Response following CPZ administration. Also, golimumab showed promise in treating recalcitrant HS after the failure of other treatments, such as adalimumab and anti-interleukin-1. CPZ and golimumab can be efficacious treatment options for moderate-to-severe HS, especially in patients who are unresponsive to other TNF inhibitors, such as adalimumab.

Efficacy and safety of radiofrequency in the treatment of hidradenitis suppurativa; a systematic review

BACKGROUND AND AIMS

Hidradenitis suppurativa (HS) is an inflammatory skin disease affecting apocrine gland-bearing sites of the body. Radiofrequency (RF) is a minimally invasive method that acts by minimizing thermal damage to the dermis, resulting in collagen synthesis and scar improvement. We systematically reviewed the efficacy and safety of RF in treating HS.

METHODS

A systematic search was performed up to November 18th, 2023, in PubMed/Medline, Ovid Embase, and Web of Science. Clinical studies with English full texts were included. The National Institute of Health (NIH) Quality Assessment Tool for clinical trials and Methodological quality and synthesis of case series and case reports by Murad et al. were utilized for critical appraisal.

RESULTS

Out of 55 identified studies, 11 met our inclusion criteria with 167 subjects who underwent RF therapy alone or combined with an intense pulsed laser (IPL), known as LAight®. LAight® significantly improved clinical outcomes in mild-to-moderate HS patients based on the Dermatology Life Quality Index (DLQI), International Hidradenitis Suppurativa Score System (IHS4), Pain-Numerical Rating Scale (NRS), and Hidradenitis Suppurativa Clinical Response (HiSCR). Moreover, RF therapy alone significantly alleviated the clinical manifestations in patients with mild-to-moderate HS. Additionally, fractional microneedling RF significantly decreased HS-associated inflammatory markers. RF was found to be safe with limited adverse events. However, in moderate-to-severe HS, RF has failed to yield satisfactory results.

CONCLUSION

RF is a safe energy-based method with promising outcomes, especially for long-term application in mild-to-moderate HS. In moderate-to-severe cases, RF should be combined with a systemic medication for further beneficial impacts.

Hidradenitis Suppurativa: An Understanding of Genetic Factors and Treatment

Hidradenitis suppurativa (HS), recognized as a chronic and debilitating skin disease, presents significant challenges in both diagnosis and treatment. This review explores the clinical manifestations, genetic landscape, and molecular mechanisms underlying HS. The disease's association with a predisposing genetic background, obesity, smoking, and skin occlusion underscores the complexity of its etiology. Genetic heterogeneity manifests in sporadic, familial, and syndromic forms, with a focus on mutations in the γ-secretase complex genes, particularly NCSTN. The dysregulation of immune mediators, including TNF-α, IL-17, IL-1β, and IL-12/23, plays a crucial role in the chronic inflammatory nature of HS. Recent advancements in genetic research have identified potential therapeutic targets, leading to the development of anti-TNF-α, anti-IL-17, anti-IL-1α, and anti-IL-12/23 therapies and JAK inhibitors. These interventions offer promise in alleviating symptoms and improving the quality of life for HS patients.

A systematic review of Janus kinase inhibitors and spleen tyrosine kinase inhibitors for Hidradenitis suppurativa treatment

BACKGROUNDS AND AIMS

Hidradenitis suppurativa (HS) is a challenging skin disease with an underlying inflammatory process. Substantial progress has been made in our understanding of HS over the last few years, with the advancement of novel treatment approaches. The current systematic review aims to evaluate the safety and efficacy of Janus kinase (JAK) inhibitors and spleen tyrosine kinase (Syk) inhibitors in treating HS.

METHOD

A thorough systematic search was performed on PubMed/Medline, Web of Science, and Ovid Embase databases up to September 23th, 2023. Clinical studies published in English were included.

RESULTS

Our search yielded ten articles with a total of 165 patients treated with four types of JAK inhibitors (upadacitinib, povorcitinib, tofacitinib, and baricitinib) and one Syk inhibitor (fostamatinib). Upadacitinib, povorcitinib, and tofacitinib improved clinical outcomes, with a significant reduction in hidradenitis suppurativa clinical response (HiSCR) and abscess and inflammatory nodule count (AN count) during the treatment period. Also, these drugs are well tolerated in most HS patients with minimal adverse events (AEs). Moreover, baricitinib depicted an amelioration in signs and symptoms of HS in one case report. Also, fostamatinib exhibited favorable tolerability throughout a 12-week in moderate-to-severe HS patients. The remarkable clinical improvement, as assessed through HiSCR and hidradenitis suppurativa severity (IHS4), corresponded closely with serological indicators of inflammation following fostamatinib administration was achieved.

CONCLUSION

JAK and Syk inhibitors are potentially efficacious in managing moderate-to-severe HS since the proinflammatory cytokines are mediated by JAK and Syk signaling pathways. However, further research with a more rigorous examination is mandatory to evaluate such medication's long-term safety and efficacy.

The Pathogenesis and Treatment of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a multifactorial disease involving the skin and subcutaneous tissues characterized by deep-seated, painful nodules and abscesses with draining sinus tracts. It affects mostly younger individuals between the ages of 18 and 34. The discomfort and embarrassment that patients affected by HS experience negatively impact their daily lives. It is associated with decreased quality of life and high rates of comorbid depression and anxiety. The rate of depression in HS was reported to be as high as 26%. Its pathogenesis is multifactorial and as such requires a multimodal approach to treatment, which subsequently is reviewed here. Moreover, the pathogenesis of HS is complex and only partially understood. Autoinflammation is the key driver of disease development and is linked with dysregulated inflammasome activation with the subsequent production of inflammatory cytokines. Genetics and cutaneous microbiome play a role in the development of chronic inflammation and lesion formation. Risk factors such as obesity, metabolic syndrome, diabetes, and smoking also add to the systemic inflammation. Targeting these risk factors is a key aspect of the treatment of HS. Lifestyle modifications are used in conjunction with pharmacotherapy and procedures to effectively manage the disease.

Shorter time to initiation of biologic therapy in the setting of a hidradenitis suppurativa specialty clinic

Hidradenitis suppurativa (HS) is a chronic condition with a significant psychological and physical burden but a paucity of effective treatments. Early intervention with adalimumab improves disease outcomes. Two previous studies in Denmark and Northern Ireland have identified a time of 8.2 and 2.9 years, respectively, from first HS systemic/dermatology consultation to commencing a biologic. We aimed to evaluate the time from disease onset and from first specialty HS clinic review to the initiation of biologic therapy. We retrospectively reviewed 34 patients on biologic treatment for HS. The mean diagnostic delay was 12.4 years. The mean time from disease onset to biologic initiation was 14.8 years. Prior to a biologic, patients received a median of 3.3 treatments from the specialty HS clinic. The median time to biologic from first presentation at the specialty HS clinic was 1 year. This is shorter than the therapeutic delay reported in dermatology clinics in Denmark and Northern Ireland, providing evidence on the importance of specialized HS treatment. However, to make an impact with specialized HS care and earlier biologic initiation, diagnostic delay needs to be reduced.

The role of C5a receptors in autoimmunity

The complement system is an essential component of the innate immune response and plays a vital role in host defense and inflammation. Dysregulation of the complement system, particularly involving the anaphylatoxin C5a and its receptors (C5aR1 and C5aR2), has been linked to several autoimmune diseases, indicating the potential for targeted therapies. C5aR1 and C5aR2 are seven-transmembrane receptors with distinct signaling mechanisms that play both partially overlapping and opposing roles in immunity. Both receptors are expressed on a broad spectrum of immune and non-immune cells and are involved in cellular functions and physiological processes during homeostasis and inflammation. Dysregulated C5a-mediated inflammation contributes to autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, epidermolysis bullosa acquisita, antiphospholipid syndrome, and others. Therefore, targeting C5a or its receptors may yield therapeutic innovations in these autoimmune diseases by reducing the recruitment and activation of immune cells that lead to tissue inflammation and injury, thereby exacerbating the autoimmune response. Clinical trials focused on the inhibition of C5 cleavage or the C5a/C5aR1-axis using small molecules or monoclonal antibodies hold promise for bringing novel treatments for autoimmune diseases into practice. However, given the heterogeneous nature of (systemic) autoimmune diseases, there are still several challenges, such as patient selection, optimal dosing, and treatment duration, that require further investigation and development to realize the full therapeutic potential of C5a receptor inhibition, ideally in the context of a personalized medicine approach. Here, we aim to provide a brief overview of the current knowledge on the function of C5a receptors, the involvement of C5a receptors in autoimmune disorders, the molecular mechanisms underlying C5a receptor-mediated autoimmunity, and the potential for targeted therapies to modulate their activity.

Hidradenitis suppurativa and psoriasis: the odd couple

Psoriasis and hidradenitis suppurativa are chronic inflammatory skin diseases that can develop together, negatively impacting on the patient's quality of life. We aimed to review the most up-to-date information regarding the epidemiology, pathogenesis, clinical presentation and possible therapeutical choices in patients with both psoriasis and hidradenitis suppurativa, thus linking these two autoimmune and autoinflammatory conditions. A narrative review of articles dating from 2017 to 2022 has been performed using the PubMed database. We analyzed the case reports and case series found in the literature regarding patients who suffered from both psoriasis and HS. Psoriasis arose before hidradenitis suppurativa in the majority of cases, while only a minority of them had hidradenitis suppurativa before psoriasis. Interestingly, some patients suffered from paradoxical hidradenitis suppurativa following biological therapy administered to treat the already present psoriasis. Lastly, new biological drugs have been marketed with great success for the outcome of psoriasis, but similar progress did not happen for hidradenitis. Novel therapeutic approaches and lines of research are needed for the treatment of these pathologies, even if concomitant, in order to improve patient's quality of life.

Blood T Helper Memory Cells: A Tool for Studying Skin Inflammation in HS?

Hidradenitis suppurativa (HS) is an inflammatory skin disease characterized by painful lesions on intertriginous body areas such as the axillary, inguinal, and perianal sites. Given the limited treatment options for HS, expanding our knowledge of its pathogenetic mechanisms is a prerequisite for novel therapeutic developments. T cells are assumed to play a crucial role in HS pathogenesis. However, it is currently unknown whether blood T cells show specific molecular alterations in HS. To address this, we studied the molecular profile of CD4⁺ memory T (Th_mem) cells purified from the blood of patients with HS and matched healthy participants. About 2.0% and 1.9% of protein-coding transcripts were found to be up- and down-regulated in blood HS Th_mem cells, respectively. These differentially expressed transcripts (DETs) are known to be involved in nucleoside triphosphate/nucleotide metabolic processes, mitochondrion organization, and oxidative phosphorylation. The detected down-regulation of transcripts involved in oxidative phosphorylation suggest a metabolic shift of HS Th_mem cells towards glycolysis. The inclusion of transcriptome data from skin from HS patients and healthy participants in the analyses revealed that in HS skin lesions, the expression pattern of transcripts identified as DETs in blood HS Th_mem cells was very similar to the expression pattern of the totality of protein-coding transcripts. Furthermore, there was no significant association between the extent of the expressional changes in the DETs of blood HS Th_mem cells and the extent of the expressional changes in these transcripts in HS skin lesions compared to healthy donor skin. Additionally, a gene ontology enrichment analysis did not demonstrate any association of the DETs of blood HS Th_mem cells with skin disorders. Instead, there were associations with different neurological diseases, non-alcoholic fatty liver disease, and thermogenesis. The levels of most DETs linked to neurological diseases showed a positive correlation to each other, suggesting common regulatory mechanisms. In summary, the transcriptomic changes in blood Th_mem cells observed in patients with manifest cutaneous HS lesions do not appear to be characteristic of the molecular changes in the skin. Instead, they could be useful for studying comorbidities and identifying corresponding blood biomarkers in these patients.

Efficacy and Safety of Biologics and Small Molecules for Moderate-to-Severe Hidradenitis Suppurativa: A Systematic Review and Network Meta-Analysis

Background: Treatment of hidradenitis suppurativa (HS) is difficult and current guidelines are based mainly on expert opinion and non-randomized controlled trials. Recently, there have been some targeted therapies using uniform primary endpoints for outcome assessment. Objective: Recommendations can be provided on selecting biologics and targeted synthetic small molecules for refractory HS by comparing the efficacy and safety of these medications. Methods: Databases including ClinicalTrial.gov, Cochrane Library, and PubMed were searched. Randomized controlled trials (RCTs) for moderate-to-severe HS were eligible. We performed random-effect network meta-analysis and ranking probability. The primary outcome was Hidradenitis Suppurativa Clinical Response (HiSCR) at 12-16 weeks. Secondary outcome included Dermatology Life Quality Index (DLQI) 0/1, mean change of DLQI from baseline, and adverse effects. Results: A total of 12 RCTs involving 2915 patients were identified. Adalimumab, bimekizumab, secukinumab 300 mg q4w and secukinumab 300 mg q2w showed superiority to placebo in HiSCR at weeks 12 to 16. In addition, there was no significant difference between bimekizumab and adalimumab as measured by HiSCR (RR = 1.00; 95% CI: 0.66-1.52) and DLQI 0/1 (RR = 2.40, 95% CI: 0.88-6.50). In terms of ranking probability for achieving HiSCR at 12-16 weeks, adalimumab ranked first, followed by bimekizumab, secukinumab 300 mg q4w, and secukinumab 300 mg q2w. All biologics and small molecules did not differ in the development of adverse effects compared to placebo. Conclusions: Adalimumab, bimekizumab, secukinumab 300 mg q4w and secukinumab 300 mg q2w represent four regimens that produce better outcomes than placebo without increased risk of adverse events. Adalimumab and bimekizumab exhibited best HiSCR and DLQI 0/1 between weeks 12-16.

Neutrophilic granulocyte-derived B-cell activating factor supports B cells in skin lesions in hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by painful inflamed nodules, abscesses, and pus-draining tunnels appearing in axillary, inguinal, and perianal skin areas. HS lesions contain various types of immigrated immune cells.

OBJECTIVE

This study aimed to characterize mediators that support lesional B/plasma cell persistence in HS.

METHODS

Skin samples from several cohorts of HS patients and control cohorts were assessed by mRNA sequencing, quantitative PCR on reverse-transcribed RNA, flow cytometry, and immunohistofluorescence. Blood plasma and cultured skin biopsy samples, keratinocytes, dermal fibroblasts, neutrophilic granulocytes (neutrophils), monocytes, and B cells were analyzed. Complex systems biology approaches were used to evaluate bulk and single-cell RNA sequencing data.

RESULTS

Proportions of B/plasma cells, neutrophils, CD8+ T cells, and M0 and M1 macrophages were elevated in HS lesions compared to skin of healthy and perilesional intertriginous areas. There was an association between B/plasma cells, neutrophils, and B-cell activating factor (BAFF, aka TNFSF13B). BAFF was abundant in HS lesions, particularly in nodules and abscesses. Among the cell types present in HS lesions, myeloid cells were the main BAFF producers. Mechanistically, granulocyte colony-stimulating factor in the presence of bacterial products was the major stimulus for neutrophils' BAFF secretion. Lesional upregulation of BAFF receptors was attributed to B cells (TNFRSF13C/BAFFR and TNFRSF13B/TACI) and plasma cells (TNFRSF17/BCMA). Characterization of the lesional BAFF pathway revealed molecules involved in migration/adhesion (eg, CXCR4, CD37, CD53, SELL), proliferation/survival (eg, BST2), activation (eg, KLF2, PRKCB), and reactive oxygen species production (eg, NCF1, CYBC1) of B/plasma cells.

CONCLUSION

Neutrophil-derived BAFF supports B/plasma cell persistence and function in HS lesions.