Immunohistochemical expression of aberrant Notch-1 signaling in vitiligo: An implication for pathogenesis

Poxviral Targeting of Interferon Regulatory Factor Activation

As viruses have a capacity to rapidly evolve and continually alter the coding of their protein repertoires, host cells have evolved pathways to sense viruses through the one invariable feature common to all these pathogens-their nucleic acids. These genomic and transcriptional pathogen-associated molecular patterns (PAMPs) trigger the activation of germline-encoded anti-viral pattern recognition receptors (PRRs) that can distinguish viral nucleic acids from host forms by their localization and subtle differences in their chemistry. A wide range of transmembrane and cytosolic PRRs continually probe the intracellular environment for these viral PAMPs, activating pathways leading to the activation of anti-viral gene expression. The activation of Nuclear Factor Kappa B (NFκB) and Interferon (IFN) Regulatory Factor (IRF) family transcription factors are of central importance in driving pro-inflammatory and type-I interferon (TI-IFN) gene expression required to effectively restrict spread and trigger adaptive responses leading to clearance. Poxviruses evolve complex arrays of inhibitors which target these pathways at a variety of levels. This review will focus on how poxviruses target and inhibit PRR pathways leading to the activation of IRF family transcription factors.

Combination of Follicular and Epidermal Cell Suspension as a Novel Surgical Approach in Difficult-to-Treat Vitiligo: A Randomized Clinical Trial

Importance

Epidermal cell suspension (ECS) and follicular cell suspension (FCS) are successful surgical modalities for the treatment of stable vitiligo. However, repigmentation in generalized and acrofacial vitiligo and over acral or bony sites (eg, elbows, knees, iliac crests, and malleoli), which are difficult to treat, is challenging.

Objective

To study the efficacy of transplanting a combination of autologous, noncultured ECS and FCS (ECS + FCS) compared with ECS alone in stable vitiligo.

Design, Setting, and Participants

A prospective, observer-blinded, active-controlled, randomized clinical trial was conducted at a tertiary care hospital, with treatment administered as an outpatient procedure. Thirty participants who had stable vitiligo with symmetrical lesions were recruited between October 18, 2013, and October 28, 2016. All of the lesions were resistant to medical modalities with minimum lesional stability of 1 year. Intent-to-treat analysis was used.

Interventions

ECS + FCS was prepared by mixing equal amounts (in cell number) of FCS with ECS. After manual dermabrasion, ECS was applied to 1 lesion and ECS + FCS was applied to the anatomically based paired lesion of the same patient. No adjuvant treatment was given.

Main Outcomes and Measures

Patients were followed up at 4, 8, and 16 weeks by a blinded observer and extent of repigmentation, color match, pattern of repigmentation, patient satisfaction and complications were noted. Both the visual and the computerized image analysis methods were used for outcome assessment. Cell suspensions were assessed post hoc for OCT4+ stem cell counts using flow cytometry; expression of stem cell factor and basic fibroblast growth factor was evaluated using quantitative relative messenger RNA expression.

Results

Of the 30 patients included in the study, 18 (60%) were women; mean (SD) age was 23.4 (6.4) years. Seventy-four percent of the lesions (62 of 84) were difficult-to-treat vitiligo. ECS + FCS showed superior repigmentation outcomes compared with ECS: extent (76% vs 57%, P < .001), rapidity (48% vs 31%, P = .001), color match (73% vs 61%, P < .001), and patient satisfaction (mean [SD] patient global assessment score, 23.30 [6.89] vs 20.81 [6.61], P = .047). Melanocyte stem cell counts (2% in ECS + FCS vs 0.5% in ECS) as well as expression of basic fibroblast growth factor (11.8-fold) and stem cell factor (6.0-fold) were higher in ECS + FCS suspension (P<.05 for both).

Conclusions and Relevance

The findings from this study establish ECS + FCS as a novel approach in vitiligo surgery for attaining good to excellent repigmentation in a short period with good color match, even in difficult-to-treat vitiligo.

Trial Registration

ctri.nic.in Identifier: CTRI/2017/05/008692.

Phototherapy: The vitiligo management pillar

Phototherapy has been the mainstay of vitiligo therapy for several decades. A variety of wavelengths and modalities are available, but narrowband ultraviolet B remains the safest and most commonly used treatment. Acting on multiple steps in vitiligo pathogenesis, narrowband ultraviolet B is one of the few therapies that can effectively induce stabilization and stimulate repigmentation. Achievement of optimal results involves using a combination of appropriate treatment protocols, careful patient selection, and patient education to set expectations. Individual patient characteristics, including disease activity, vitiligo phenotype, lesion location, and skin phototype, should all be considered, along with combination therapies.

Innate immune activation of NFκB and its antagonism by poxviruses

In recent years there has been an acceleration of discovery in the field of innate anti-viral immunity to the point that many of the key events in early virus sensing and the discrete anti-viral responses they trigger have been elucidated in detail. In particular, pattern recognition receptors (PRRs) that detect viruses at the plasma membrane, in endosomes, and within the cytosol have been characterized. Upon stimulation by viruses, most of these PRRs trigger signal transduction pathways culminating in NFκB activation. NFκB contributes both to type I interferon induction, and to production of pro-inflammatory cytokines from infected cells. Our understanding of host anti-viral innate immunity has been greatly aided by an appreciation of the ways in which poxviruses have evolved strategies to inhibit both innate sensing and effector responses. A recurring feature of poxviral immunomodulation is the apparent necessity for poxviruses to evolve multiple, non-redundant inhibitors of NFκB activation which often appear to act on the same innate signalling pathway. The reason for such apparent over-targeting of one transcription factor is not clear. Here we describe the current understanding of how host cells sense poxvirus infection to trigger signalling pathways leading to NFκB activation and pro-inflammatory cytokine induction, and the ways in which poxviruses have evolved to concisely antagonize these systems.

Immunohistochemical evaluation of vitiliginous hair follicle melanocyte reservoir: is it retained?

BACKGROUND

Vitiligo is an acquired depigmentaion of skin and hair. The presence of white hair within vitiligo lesions is considered a bad prognostic sign since these lesions are difficult to repigment. Melanocyte reservoir was not extensively studied in vitiliginous white hair.

OBJECTIVE

To evaluate pigment cell reservoir in vitiliginous black and white hair.

METHOD

Using immunohistochemical technique, skin biopsies from 30 vitiligo patients (including either black or white hair) and 10 age- and gender-matched healthy subjects were examined. Human Melanoma Black-45 (HMB-45) was used for detecting active melanocytes and Tyrosinase Related Protein 2 (TRP2) for detecting the whole melanocyte lineage including melanocyte stem cells (MelSC).

RESULTS

About 61.1% of black hair was positive for HMB-45 and 83.3% was positive for TRP2. About 25% of white hair was positive for HMB-45 and 75% retained TRP2 positivity. Follicular HMB-45 expression and TRP2 expression percentage were significantly lower in white than black hair (P = 0.05, 0.04 respectively). Epidermal HMB-45 and TRP2 expression percentages were significantly higher in lesions containing black rather than white hair (P < 0.001, P = 0.05 respectively). Black hair was significantly associated with histologically pigmented hair follicles (P = 0.049), and with residual interfollicular melanin pigment (P = 0.007).

CONCLUSION

Melanocytes, either active (melanotic) or inactive (amelanotic which may include MelSC), are not totally absent from vitiliginous white hair. However, intact melanocyte reservoir was observed more in black than white hair. This may add avenues for future research about the possibility of white vitiliginous hair to repigment.