Efficacy of laser hair removal in hidradenitis suppurativa: A systematic review and meta-analysis

OBJECTIVES

Hidradenitis suppurativa (HS) is a chronic inflammatory condition characterized by painful nodules, draining tunnels, and fibrotic scarring in intertriginous, hair-bearing areas. The pathogenesis involves follicular occlusion and subsequent rupture, leading to uncontrolled inflammation. Treatment options for HS are limited and lack universal effectiveness. Laser hair removal (LHR) has been explored as a potential treatment; however, the efficacy and appropriate laser modalities remain unclear. This systematic review examined the efficacy and adverse effects of LHR in HS.

METHODS

A comprehensive literature search was conducted from inception to September 2023 in Ovid MEDLINE, Ovid Embase, and The Cochrane Library (Wiley) with predefined inclusion and exclusion criteria, and a meta-analysis was conducted.

RESULTS

Ten studies were selected (n = 227 total patients) and included six randomized controlled trials, two nonrandomized experimental studies, and two case series. Various laser modalities, including long-pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) (n = 115), intense pulsed light (n = 18), Alexandrite (n = 54), intralesional 1064 nm diode (n = 20), and combined fractional CO2 and long-pulsed Nd:YAG laser (n = 20), consistently demonstrated significant improvement in HS disease severity, irrespective of the disease scoring method used. Minimal adverse effects (primarily mild pain and erythema) were reported. A meta-analysis of three studies utilizing long-pulsed Nd:YAG laser demonstrated a standardized mean difference in disease severity of -1.68 (95% confidence interval: -2.99; -0.37), favoring treatment with LHR for HS.

CONCLUSIONS

Hair follicles are key in HS pathogenesis and all included studies showed a significant improvement in HS disease severity after LHR regardless of the laser device used, likely related to hair follicle unit destruction. HS is a complex and heterogenous condition, and multiple disease scoring methods complicate outcome comparisons across studies. However, LHR, utilizing various techniques, is an effective treatment option for HS with minimal adverse effects.

Immune checkpoint inhibitor-induced bullous pemphigoid is characterized by interleukin (IL)-4 and IL-13 expression and responds to dupilumab treatment

Immune checkpoint inhibitor-induced bullous pemphigoid (ICI-BP) is a clinically debilitating immune-related adverse event in need of novel therapeutic approaches, as conventional treatment can counteract intended tumour immunity. Here we demonstrate that interleukin (IL)-4 and IL-13 expression is elevated in ICI-BP similar to conventional autoimmune BP, and further demonstrate partial and complete disease clearance with dupilumab in four patients with ICI-BP. These data indicate that IL-4Rα inhibition may be a promising new therapy for ICI-BP.

Hidradenitis suppurativa in Black and White patients - a clinical study

OBJECTIVE

It is suggested that hidradenitis suppurativa (HS) is more prevalent and causes greater morbidity in Black patients than in White. Clinical data are however lacking.

PATIENTS AND METHODS

We therefore describe HS risk factors, disease severity and clinical phenotypes in the Blacks and Whites. Patients referred for HS between 1984 and 2019 at the Johns Hopkins Hospital were identified using the Pathology Data System (PDS). Clinical and sociodemographic characteristics were extracted and the van der Zee & Jemec HS clinical phenotypes were recovered.

RESULTS

A total of 278 patients were identified. Ethnically, 108 (38.8%) were White, and 170 (61.2%) Black. The following HS phenotypes were found: Regular (n=193, 69.4%), scarring folliculitis (n=40, 1.4%) frictional furuncle (11.2%), conglobata (n=9, 3.2%), syndromic (n=3, 1.1%) and ectopic (n=2, 0.7%). No statistically significant ethnic differences in clinical presentation were found. Blacks however had more severe diseases than Whites (p= 0.024 for trend). With multivariate logistic regression analysis, we found that male sex, disease duration, and smoking were independent predictors of regular HS phenotype. Major limitations are the limited number of cases studied and the lack of data regarding response to therapies.

CONCLUSIONS

Demographics and phenotypical presentation of HS patients do not seem to be associated with Black ethnicity. However, there is a significant trend for Blacks to present with more Hurley stage 2 and 3 disease compared to White patients. It is speculated that ethnic differences are epiphenomena to social factors, highlighting the broader importance of ethnicity.

Lymph node stromal CCL2 limits antibody responses

Nonhematopoietic stromal cells in lymph nodes such as fibroblastic reticular cells (FRCs) can support the survival of plasmablasts and plasma cells [together, antibody-forming cells (AFCs)]. However, a regulatory function for the stromal compartment in AFC accumulation has not been appreciated. Here, we show that chemokine ligand 2 (CCL2)-expressing stromal cells limit AFC survival. FRCs express high levels of CCL2 in vessel-rich areas of the T cell zone and the medulla, where AFCs are located. FRC CCL2 is up-regulated during AFC accumulation, and we use lymph node transplantation to show that CCL2 deficiency in BP3⁺ FRCs and lymphatic endothelial cells increases AFC survival without affecting B or germinal center cell numbers. Monocytes are key expressers of the CCL2 receptor CCR2, as monocyte depletion and transfer late in AFC responses increases and decreases AFC accumulation, respectively. Monocytes express reactive oxygen species (ROS) in an NADPH oxidase 2 (NOX2)-dependent manner, and NOX2-deficient monocytes fail to reduce AFC numbers. Stromal CCL2 modulates both monocyte accumulation and ROS production, and is regulated, in part, by manipulations that modulate vascular permeability. Together, our results reveal that the lymph node stromal compartment, by influencing monocyte accumulation and functional phenotype, has a regulatory role in AFC survival. Our results further suggest a role for inflammation-induced vascular activity in tuning the lymph node microenvironment. The understanding of stromal-mediated AFC regulation in vessel-rich environments could potentially be harnessed to control antibody-mediated autoimmunity.

Fibroblast subtypes in tissues affected by autoimmunity: with lessons from lymph node fibroblasts

The recent advent of single-cell technologies has fast-tracked the discovery of multiple fibroblast subsets in tissues affected by autoimmune disease. In recent years, interest in lymph node fibroblasts that support and regulate immune cells has also grown, leading to an expanding framework of stromal cell subsets with distinct spatial, transcriptional, and functional characteristics. Inflammation can drive tissue fibroblasts to adopt a lymphoid tissue stromal cell phenotype, suggesting that fibroblasts in diseased tissues can have counterparts in lymphoid tissues. Here, we examine fibroblast subsets in tissues affected by autoimmunity in the context of knowledge gained from studies on lymph node fibroblasts, with the ultimate aim to better understand stromal cell heterogeneity in these immunologically reactive tissues.

A protective Langerhans cell-keratinocyte axis that is dysfunctional in photosensitivity

Photosensitivity, or skin sensitivity to ultraviolet radiation (UVR), is a feature of lupus erythematosus and other autoimmune and dermatologic conditions, but the mechanistic underpinnings are poorly understood. We identify a Langerhans cell (LC)-keratinocyte axis that limits UVR-induced keratinocyte apoptosis and skin injury via keratinocyte epidermal growth factor receptor (EGFR) stimulation. We show that the absence of LCs in Langerin-diphtheria toxin subunit A (DTA) mice leads to photosensitivity and that, in vitro, mouse and human LCs can directly protect keratinocytes from UVR-induced apoptosis. LCs express EGFR ligands and a disintegrin and metalloprotease 17 (ADAM17), the metalloprotease that activates EGFR ligands. Deletion of ADAM17 from LCs leads to photosensitivity, and UVR induces LC ADAM17 activation and generation of soluble active EGFR ligands, suggesting that LCs protect by providing activated EGFR ligands to keratinocytes. Photosensitive systemic lupus erythematosus (SLE) models and human SLE skin show reduced epidermal EGFR phosphorylation and LC defects, and a topical EGFR ligand reduces photosensitivity. Together, our data establish a direct tissue-protective function for LCs, reveal a mechanistic basis for photosensitivity, and suggest EGFR stimulation as a treatment for photosensitivity in lupus erythematosus and potentially other autoimmune and dermatologic conditions.

Specimen Collection for Translational Studies in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory disorder characterized by painful nodules, sinus tracts, and scars occurring predominantly in intertriginous regions. The prevalence of HS is currently 0.053-4%, with a predominance in African-American women and has been linked to low socioeconomic status. The majority of the reported literature is  retrospective, population based, epidemiologic studies. In this regard, there is a need to establish a repository of biospecimens, which represent appropriate gender and racial demographics amongst HS patients. These efforts will diminish knowledge gaps in understanding the disease pathophysiology. Hence, we sought to outline a step-by-step protocol detailing how we established our HS biobank to facilitate the formation of other HS tissue banks. Equipping researchers with carefully detailed processes for collection of HS specimens would accelerate the accumulation of well-organized human biological material. Over time, the scientific community will have access to a broad range of HS tissue biospecimens, ultimately leading to more rigorous basic and translational research. Moreover, an improved understanding of the pathophysiology is necessary for the discovery of novel therapies for this debilitating disease. We aim to provide high impact translational research methodology for cutaneous biology research and foster multidisciplinary collaboration and advancement of our understanding of cutaneous diseases.

Lessons learned from the development of a hidradenitis suppurativa xenograft mouse model

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease originating from the pilosebaceous unit, in which patients develop painful abscesses, sinus tracts, nodules and scarring, typically in intertriginous areas. Major gaps in our understanding of HS exist, and these may be partially due to the lack of an animal model for experimental studies. We developed an HS xenograft mouse model using human HS lesions grafted onto immunocompromised mice. Although the model had its limitations, several informative lessons were learned, which may contribute to future attempts at an HS animal model.

Lymphatic Function in Autoimmune Diseases

Lymphatic vessels are critical for clearing fluid and inflammatory cells from inflamed tissues and also have roles in immune tolerance. Given the functional association of the lymphatics with the immune system, lymphatic dysfunction may contribute to the pathophysiology of rheumatic autoimmune diseases. Here we review the current understanding of the role of lymphatics in the autoimmune diseases rheumatoid arthritis, scleroderma, lupus, and dermatomyositis and consider the possibility that manual therapies such as massage and acupuncture may be useful in improving lymphatic function in autoimmune diseases.

Tertiary lymphoid organs in systemic autoimmune diseases: pathogenic or protective?

Tertiary lymphoid organs are found at sites of chronic inflammation in autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. These organized accumulations of T and B cells resemble secondary lymphoid organs and generate autoreactive effector cells. However, whether they contribute to disease pathogenesis or have protective functions is unclear. Here, we discuss how tertiary lymphoid organs can generate potentially pathogenic cells but may also limit the extent of the response and damage in autoimmune disease.

Regulation of Lymph Node Vascular-Stromal Compartment by Dendritic Cells

During normal and pathologic immune responses, lymph nodes can swell considerably. The lymph node vascular-stromal compartment supports and regulates the developing immune responses and undergoes dynamic expansion and remodeling. Recent studies have shown that dendritic cells (DCs), best known for their antigen presentation roles, can directly regulate the vascular-stromal compartment, pointing to a new perspective on DCs as facilitators of lymphoid tissue function. Here, we review the phases of lymph node vascular-stromal growth and remodeling during immune responses, discuss the roles of DCs, and discuss how this understanding can potentially be used for developing novel therapeutic approaches.