Professor and Chair

Dr. Hwang

Department of Dermatology, School of Medicine
University of California, Davis
3301 C Street Suite 1400, Sacramento CA 95816


Dr. Hwang is a board-certified dermatologist with extensive training as a physician scientist.  He has a strong interest in immunological diseases of the skin, including psoriasis, and in the biology of skin cancers, including melanoma and cutaneous T cell lymphoma.  Beginning with his fellowship experience with L-selectin in T cell homing with Steven Rosen at UCSF where he first successfully collaborated with Dr. Simon (ST Hwang et al.JEM, 1996), Dr. Hwang has had a long track record of successfully exploring mechanisms by which leukocytes traffic to lymph node and skin.   As a tenure-track and then senior scientist at NIH, Dr. Hwang has had over 20 years of experience in the field of leukocyte and cancer cell trafficking and has developed expertise in the role of chemokine receptors, including CCR6 and CXCR4 in immune cells as well as cancer cells, using microfluidic devices such flow chambers to model in vivo leukocyte-endothelial interactions. He currently has two major scientific interests: psoriasis, for which he has an NIAMS R01; cutaneous T cell lymphoma, for which he is actively engaged in developing new therapeutic approaches.  Prior to being appointed tenured Chair and Professor of Dermatology at the University of California Davis in 2016, he was Chair and Thomas Russell Professor of Dermatology at the Medical College of Wisconsin. He has published more than 70 original and review articles in the Journal of Clinical Investigation, Journal of Experimental Medicine, Cancer Research, Journal of Immunology, Journal of Investigative Dermatology, JAMA Dermatology, and PNAS

Dr. Hwang and colleagues at the Medical College of Wisconsin and NIH were among the first to conclusively demonstrate the role of CCR6 in the development of psoriasiform dermatitis (analogous to human psoriasis).  Dr. Hwang’s team has earned an international reputation in the use of murine models of psoriasis and CTCL for exploration of disease pathogenesis and treatment.  He and his lab proved that CCR6 was critical for the trafficking of epidermal gamma-delta T cells to the skin as Th17 effectors in murine models of psoriasis.  His lab has also shown that checkpoint inhibitors, specifically PD-1, regulate psoriasiform dermatitis in mice; this work was the first experimental model to replicate a now widely reported side effect of anti-PD-1 mAb treatment for cancer in humans.  For years, Hwang has worked collaboratively with Dr. Brian Volkman on the CXCR4 and CCR6 receptors (Takekoshi et al. Mol. Cancer Ther. 2012 and JID 2013, Getschman et al. PNAS 2017).  Together, they have worked to develop specific chemokine receptor antagonists, including the development of a novel CCL20 locked dimeric molecule (CCL20LD) with biased agonist properties, including the inhibition of CCR6-mediated T cell migration and prevention of IL-23 mediated skin inflammation in mice (Getschman et al. PNAS 2017). Lecturing nationally and internationally on psoriasis, Dr. Hwang is recognized for his impactful contributions to basic and translational psoriasis research.  He was fortunate to receive two Discovery and one Translational Research awards from the National Psoriasis Foundation as well as a NIAMS R01 for his work on CCR6 in psoriasis.

1. Singh, TP, Zhang, HH, Hwang, ST, Farber, JM. IL-23- and Imiquimod-Induced Models of Experimental Psoriasis in Mice. Current Protocols in Immunology, e71.

2. Wang H, Xu Z, Lee BH, Vu S, Hu L, Lee M, Bu D, Cao X, Hwang ST, Yang Y, Zheng J, Lin Z. Gain-of-function mutations in TRPM4 activation gate cause progressive symmetric erythrokeratoderma. Journal of Investigative Dermatology, 139(5): 1089-1097.

3. Anderson LS, Yu S, Rivara KR, Reynolds MS, Hernandez AA, Wu X, Uang HS, Isseroff RR, Miller LS, Hwang ST, Simon SI. CCR6+ γδ T Cells Home to Skin Wounds and Restore Normal Wound Healing in CCR6-Deficient Mice. Journal of Investigative Dermatology, March (epub).

4. T. Follansbee; Y. Zhou, X. Wu, J. Delahanty, A. Nguyen, D. Domocos, M. Iodi Carstens, Hwang ST, E. Carstens. Signs of chronic itch in the mouse imiquimod model of psoriasiform dermatitis: sex differences and roles of TRPV1 and TRPA1. Itch, 4(3).

5. Prasant Kumar Jena, Lili Sheng, Kyle Mcneil, Thinh Q. Chau, Sebastian Yu, Maija Kiuru, Maxwell A. Fung, Samuel T. Hwang, Yu-Jui Yvonne Wan. Long-term Western diet intake leads to dysregulated bile acid signaling and dermatitis with Th2 and Th17 pathway features in mice. Journal of Dermatological Sciences, 95(1): 13-20.

6. Sebastian Yu, Yanxi Li, Yan Zhou, Taylor Follansbee, Samuel T. Hwang. Immune mediators and therapies for pruritus in atopic dermatitis and psoriasis. Journal of Cutaneous Immunology and Allergy, 2(1): 4-14.

7. Jagdeo J, Nguyen JK, Ho D, Wang EB, Austin E, Mamalis A, Kaur R, Kraeva E, Schulman JM, Li CS, Hwang ST, Wun T, Maverakis E, Isseroff RR. Safety of light emitting diode-red light on human skin: Two randomized controlled trials. Journal of Biophotonics, 12(9).

8. Le ST, Merleev AA, Luxardi G, Shimoda M, Adamopoulos IE, Tsoi LC, Wang JZ, Alexanian C, Raychaudhuri SP, Hwang ST, Gudjonsson J, Marusina AI, Maverakis E. 2D Visualization of the Psoriasis Transcriptome Fails to Support the Existence of Dual-Secreting IL-17A/IL-22 Th17 T Cells. Frontiers in Immunology, 10: 589.