Single-Cell RNA Sequencing Reveals Cellular and Transcriptional Changes Associated With M1 Macrophage Polarization in Hidradenitis Suppurativa.

Melodi Javid Whitley, MD, PhD
Assistant Professor of Dermatology
Assistant Program Director for Trainee Research
Director of Transplant Dermatology

I am a physician scientist focused on the dermatologic care of solid organ transplant recipients.  Clinically, I manage the the complex dermatologic side effects of immunosuppression with a focus on high-risk skin cancer.  My research focuses on understanding the drivers of cutaneous malignancy in this population using translational approaches.

David A. Brown, M.D., Ph.D. is Associate Professor of Surgery and Vice Chief of Research in the Division of Plastic, Maxillofacial, and Oral Surgery at Duke University. Dr. Brown is originally from Colorado and studied engineering at the University of Colorado followed by a Ph.D. in biomedical engineering at UCLA. He subsequently attended medical school at UC Irvine and went on to complete general surgery residency at University of Washington Medical Center followed by plastic surgery residency at Duke University Medical Center. Dr. Brown practices general reconstructive surgery, including the surgical treatment of skin defects resulting from cancer, infection, and trauma. His clinical interests include targeted muscle reinnervation and soft tissue reconstruction of the back. He is an NIH-funded researcher exploring mechanisms of limb and digit regeneration in mammals with the hope of one day applying regeneration-based therapies to human diseases. He is the medical director of the Duke Wound Healing Clinic and co-director of the Duke Regeneration Center. Dr. Brown is a Fellow of the American College of Surgeons and is board-certified by the American Board of Surgery, the American Board of Plastic Surgery, and the American Board of Wound Management.

Dr. Gregory is the Margaret Harris and David Silverman Distinguished Professor and Director of the Brain Tumor Omics Program in the Duke Department of Neurosurgery, the Vice Chair of Research in the Department of Neurology, and Director of the Molecular Genomics Core at the Duke Molecular Physiology Institute. 

As a neurogenomicist, Dr. Gregory applies the experience gained from leading the sequencing of chromosome 1 for the Human Genome Project to elucidating the mechanisms underlying multi-factorial diseases using genetic, genomic, and epigenetic approaches. Dr. Gregory’s primary areas of research involve understanding the molecular processes associated with disease development and progression in brain tumors and Alzheimer’s disease, drug induced white matter injury repair in multiple sclerosis, and the characterization of lesion microenvironmental changes in MS.

He is broadly regarded across Duke as a leader in the development of novel single cell and spatial molecular technologies towards understanding the pathogenic mechanisms of disease development. Dr. Gregory is also the Section Chair of Genomics and Epigenetics at the DMPI and Director of the Duke Center of Autoimmunity and MS in the Department of Neurology.

Epidermis of the skin constitutes the largest organ and the outer most barrier of the body. It is one of the few organs that undergo lifelong self-renewal through a tight balance of cell growth, differentiation, and programmed cell death. Deregulation of this balance is manifested in many diseases, including various immune diseases and cancer. 

Our lab is focused on 3 interrelated topics:

1. Gene regulation of epithelial cell proliferation and differentiation

Using regenerated human skin tissues and murine genetic models, we have demonstrated important functions NF-kB and AP-1 gene regulators in epidermal cell growth and differentiation. Currently, our efforts are focused on understating how loss-of-function of CYLD, a deubiquitinase and tumor suppressor, leads to the development of hair follicle defects, skin inflammation, and cancer. Specifically, we want to determine how CYLD integrates NF-kB, AP1, Myc, and other transcription factors to control epidermal cell growth and lineage differentiation.

De novo skin regeneration is life-saving procedure for severely burned patients and lethal genetic skin diseases such as epidermal bullosa. An additional aspect of our study is to improve new skin regeneration techniques and to create experimental skin disease models with gene transduced keratinocytes, as illustrated below.

2. Keratinocytes as instigators of inflammatory responses

Keratinocytes are constantly challenged by external insults, as well as immune cells. Disarray of the crosstalk between keratinocytes and immune cells underlies various immune diseases, including dermatitis, psoriasis, and cutaneous graft-versus-host disease (GVHD). GVHD is a common complication and the leading cause of non-relapse mortality among patients after receiving allogenic hematopoietic stem cell transplantation.  The skin is the most commonly affected organ in both the acute and chronic forms of this disease.  Treatment options for GVHD are limited and the current standard therapy is high dose systemic corticosteroid which is itself associated with significant morbidity. Our goal is to understand how keratinocytes contribute to the progression of GVHD, and may therefore be targeted to mitigate the disease.

3. Ubiquitination enzymes in melanoma

Melanoma most lethal and difficult to treat skin cancer. In the recent years, BRAF/MEK-targeted therapies have produced exciting results, but they suffer from short duration. Our goal is to uncover novel mechanisms crucial for melanoma malignancy. Specifically, we want to understand how ubiquitination enzymes contribute to melanoma growth. Previously, we have demonstrated that CYLD inhibits melanoma growth through suppression of JNK/AP1 and b1-integrin signaling pathways. In contrast, UBE2N, a K63-Ubiquitin conjusage, promotes melanoma growth in part through activation of the MEK/FRA/SOX10 signaling cascade. Currently, our efforts are focused on understanding how UBE2N and other ubiquitin enzymes regulate the MAPK signaling pathway and whether they can be targeted for melanoma therapy.

The MacLeod Lab investigates the dynamic regulation of innate immunity, with specific focus on host-microbial interactions, antimicrobial host defense, antiviral proteins, and repair functions.

Skin is an active immune organ and comprises not only epithelial keratinocytes, but also harbors dendritic cells, macrophages, nerve cells, and other immune cells. Furthermore, the skin is inhabited by a multitude of microbes, including bacteria, viruses and fungi and even parasites. The healthy and controlled immune interactions of the skin barrier cells with microbes and environmental factors are critical to maintain homeostasis and to prevent overt immune responses resulting in disease. The dynamic regulation of innate host defense factors allows for critical protection against microbial pathogens in situations of barrier defects and injury.

We use interdisciplinary approaches, combining various disease mouse models, human skin tissues and cells, and techniques from immunology, stem cell biology, microbiology and pharmacology to ultimately reveal strategies that coordinate, regulate or co-opt innate immunity in the skin. This allows us to identify mechanisms that fundamentally control skin immunity and will help in the development of new immune-modulatory therapeutics and a better understanding of health and disease.

We study the interplay of innate  immune cells with microbial and additional environmental factors. Our interest is to decipher the mechanisms that facilitate antimicrobial immune surveillance and repair functions in the skin under homeostatic and challenged conditions.

I. Innate immune regulation and modulation during skin injury and microbial infection

Damage to the skin through physical injury and microbes initiates release of multiple pro-inflammatory cytokines and mediators including IL-27, IL-17, extracellular ATP, nucleic acids, NO, as well as antimicrobial peptides and proteins. Upon skin injury, inflammatory immune responses are aimed at clearing microbial contamination before a repair program can subsequently facilitate wound closure. However, prolonged inflammation is detrimental and mediates tissue damage and is considered a major pathogenic factor for the development of chronic non-healing wounds and may be a trigger for auto-inflammatory skin diseases such as psoriasis. The focus of our laboratory is on identifying and characterizing such key factors that regulate innate  immunity in the skin. Fine regulation of the cutaneous innate immune response is critical to maintain skin barrier function and protection upon injury and infection.  Our studies on innate antimicrobial peptides and proteins (AMPs), including antiviral proteins, have fundamentally advanced our knowledge of how the innate immune system works in the skin.  We further aim to understand the dynamic regulation of innate antimicrobial host immunity during aging and in early life, in response to diverse microbial stimuli, and in various complex dermatological diseases, including eczema, psoriasis, hidradenitis suppurativa, wounds etc. Decoding the microbial-epithelial-immune dialogue in the skin  may offer insights into novel strategies of treatment.

II. Role of IL-27 in cutaneous immunity

IL-27, a member of the IL-12 family of heterodimeric cytokines, consists of p28 and Epstein-Barr virus gene 3 (EBI3) and signals through its receptor composed of IL-27RA and gp130. Previous studies indicated that IL-27 can play pro-inflammatory and anti-inflammatory roles depending on the cell type and context. In the context of infectious inflammation, a recent study reported that IL-27 is produced by CD103+ dermal dendritic cells (DC) in the skin , whereas other studies identified that IL-27 is produced by mesenteric lymph node CD103- DC, splenic CD4+ DC and macrophages. Our work identified IL-27 production in dermal CD301b+ monocyte-derived DC following injury. Here, IL-27 promotes the wound healing response by promoting keratinocyte proliferation. Furthermore, we have identified multiple new and unprecedented roles for IL-27 in cutaneous immunity in response to contact allergens, microbes and in psoriasis. Our lab recently described and published that IL-27 signaling provides a novel path of antiviral protein activation in the skin and that IL-27 signaling is critical in activating host defenses against cutaneous Zika virus infections.

III. Antiviral Proteins

A large part of our laboratory's efforts are  focused to better understanding the constitutive and inducible antiviral proteins and their mode of regulation in the skin. Antiviral proteins comprise Oligoadenylate Synthases (OAS), Protein Kinase R (PKR), Interferon-stimulated Gene (ISG) 15 and 20, and multiple Interferon Induced proteins with Tetratricopeptide repeats (IFIT) and Interferon-induced transmembrane proteins (IFITM) and others. Antiviral proteins provide a natural defense mechanism against viruses. Their expression and regulation in the skin are still poorly understood and our lab is providing some new and exciting insights into cutaneous innate antiviral immunity and the regulation of expression of antiviral proteins.

http://www.ncbi.nlm.nih.gov/myncbi/browse/collection/47851812/?sort=date&direction=descending
Her maiden name Büchau was used prior to MacLeod.

Our lab website can be found here: https://sites.duke.edu/macleodlab/