Multiple sclerosis (MS) is a chronic autoinflammatory disease of unknown origin, involving characterized by immune cell infiltration into the target tissue, central nervous system (CNS), resulting in local and/or systemic inflammation. The symptoms vary from gait disturbance, visual impairment and learning and memory impairment and are being managed with corticosteroid and/or immunosuppressive agents. However, several patients do not respond to these treatments, which can also elevate the risk of severe infections. Therefore, there remains an ongoing need to identify new therapeutic targets. MS exhibits distinctive pathology, clinical course, and treatment responses, suggesting the importance of targeting disease site-specific immune cells to mitigate immune system-induced inflammation, rather than employing broad immunosuppression. Chemokines and chemokine receptors play a crucial role in the pathogenesis of MS by recruiting immune cells to the CNS, leading to inflammation and demyelination. Therapies targeting chemokines have shown promising results in preclinical studies and clinical trials, but more research is needed to fully understand their mechanisms and optimize their efficacy.

Leukocytes are blood-borne cells derived from the bone marrow that must migrate into tissues to mediate inflammation. Controlling this migration, therefore, represents a critical point for the development of new therapeutic strategies to attenuate inflammation. Traditional endpoint studies have not allowed us to fully dissect the migratory behavior of leukocytes in vivo. Recent advances in imaging technology, however, have provided unprecedented insights into immune cell migration in live animals, greatly enhancing our understanding of the molecular regulation of immune cell trafficking. Here, we present a detailed protocol for in vivo imaging of the joints using a murine type II collagen-induced arthritis (CIA) model. Mice are immunized with type II collagen emulsified in complete Freund's adjuvant, and arthritis progression is monitored by clinical scoring and paw thickness measurements. At the peak of arthritis, leukocytes are visualized in vivo using confocal microscopy in transgenic mice expressing fluorescent proteins or in wild-type mice after intravenous injection of fluorescently labeled antibodies and high-molecular-weight Dextran for vessel staining. Careful surgical exposure of the joint, application of agarose, and proper positioning of the leg allow stable long-term imaging, typically lasting several hours. This approach enables real-time analysis of leukocyte arrest, crawling, and transendothelial migration within inflamed joints. This protocol will be valuable for research groups investigating leukocyte trafficking in arthritis and other inflammatory diseases. It may also serve as a platform for preclinical evaluation of therapies targeting immune cell migration.

Excessive activation of immune cells by environmental factors, such as infection or individual genetic risk, causes various autoimmune diseases. Streptococcus species are gram-positive bacteria that colonize the nasopharynx, respiratory tract, gastrointestinal tract, genitourinary tract, and skin. Group A Streptococcus (GAS) species cause various symptoms, ranging from mild infections, such as tonsillitis and pharyngitis, to serious infections, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The contribution of GAS infections to several autoimmune diseases, including acute rheumatic fever, vasculitis, and neuropsychiatric disorders, has been studied. In this review, we focus on the association between streptococcal infections and autoimmune diseases, and discuss current research on the mechanisms underlying the initiation and progression of autoimmune diseases.

We report a rare case of granulomatosis with polyangiitis (GPA) who presented with relapsing erythema nodosum (EN)-like eruption as a solo vasculitis-associated cutaneous manifestation. We suggest that EN-like eruption alone can be a cutaneous symptom of GPA if subcutaneous medium-sized vessels are exclusively affected.

The Journal of DermatologyVolume 50, Issue 1 p. 102-103 RESEARCH NOTE Nephritis-associated plasmin receptor in the cutaneous vessels in IgA vasculitis Chie Miyabe, Corresponding Author Chie Miyabe [email protected] orcid.org/0000-0003-3051-4179 Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, Japan Correspondence Chie Miyabe, Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: [email protected]Search for more papers by this authorTakashi Oda, Takashi Oda Department of Nephrology and Blood Purification, Kidney Disease Center, Tokyo Medical University Hachioji Medical Center, Tokyo, JapanSearch for more papers by this authorRyujin Miyata, Ryujin Miyata Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYoshishige Miyabe, Yoshishige Miyabe Department of Immunology and Medicine, St. Marianna University School of Medicine, Kawasaki, JapanSearch for more papers by this authorNaoko Ishiguro, Naoko Ishiguro Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this author Chie Miyabe, Corresponding Author Chie Miyabe [email protected] orcid.org/0000-0003-3051-4179 Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, Japan Correspondence Chie Miyabe, Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: [email protected]Search for more papers by this authorTakashi Oda, Takashi Oda Department of Nephrology and Blood Purification, Kidney Disease Center, Tokyo Medical University Hachioji Medical Center, Tokyo, JapanSearch for more papers by this authorRyujin Miyata, Ryujin Miyata Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYoshishige Miyabe, Yoshishige Miyabe Department of Immunology and Medicine, St. Marianna University School of Medicine, Kawasaki, JapanSearch for more papers by this authorNaoko Ishiguro, Naoko Ishiguro Division of Dermatology, Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this author First published: 24 September 2022 https://doi.org/10.1111/1346-8138.16574Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. CONFLICT OF INTEREST The authors have no conflicting financial interests. REFERENCES 1Jennette JC, Falk RJ, Bacon PA, Basu N, Cid MC, Ferrario F, et al. 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis Rheum. 2013; 65: 1– 11. 2Brogan P, Eleftheriou D. Vasculitis update: pathogenesis and biomarkers. Pediatr Nephrol. 2018; 33: 187– 98. 3Oda T, Yoshizawa N, Yamakami K, Sakurai Y, Takechi H, Yamamoto K, et al. The role of nephritis-associated plasmin receptor (NAPlr) in glomerulonephritis associated with streptococcal infection. J Biomed Biotechnol. 2012; 2012:417675. 4Masuda M, Nakanishi K, Yoshizawa N, Iijima K, Yoshikawa N. Group A streptococcal antigen in the glomeruli of children with Henoch-Schönlein nephritis. Am J Kidney Dis. 2003; 41: 366– 70. 5Inoue T, Takeuchi K, Saeki H, Oda T, Shimizu A. Nephritis-associated plasmin receptor (NAPlr) in streptococcal infection associated cutaneous IgA vasculitis. Clin Exp Nephrol. 2022. https://doi.org/10.1007/s10157-022-02251-8 6Blyth CC, Robertson PW. Anti-streptococcal antibodies in the diagnosis of acute and post-streptococcal disease: streptokinase versus streptolysin O and deoxyribonuclease B. Pathology. 2006; 38: 152– 6. 7Uchida T, Oda T. Glomerular deposition of nephritis-associated plasmin receptor (NAPlr) and related plasmin activity: key diagnostic biomarkers of bacterial infection-related glomerulonephritis. Int J Mol Sci. 2020; 21:2595. Supporting Information Filename Description jde16574-sup-0001-TableS1.docxWord 2007 document , 44.6 KB Table S1 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume50, Issue1January 2023Pages 102-103 ReferencesRelatedInformation

Vasculitis is a systemic autoimmune disease characterized by leukocyte infiltration into blood vessels. Various microorganisms have been associated with the pathogenesis of vasculitis; however, the causal microbial agents and underlying mechanisms are not fully understood, possibly because of the technical limitations of pathogen detection. In the present study, we characterized the microbiome profile of patients with cutaneous vasculitis using comprehensive metagenome shotgun sequencing. We found that the abundance of the SEN virus was increased in the affected skin and serum of patients with vasculitis compared to healthy donors. In particular, the abundance of SEN virus reads was increased in the sera of patients with cutaneous arteritis. Among the bacteria identified, Corynebacteriales was the most differentially associated with vasculitis. Linear discriminant analysis effect size also indicated differences in the microbial taxa between patients with vasculitis and healthy donors. These findings demonstrate that vasculitis is associated with considerable alteration of the microbiome in the blood and skin and suggest a role for the infectious trigger in vasculitis.

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.

International Journal of DermatologyEarly View Correspondence Lithium carbonate-induced Stevens-Johnson syndrome: the first case report Madoka Itoh MD, Madoka Itoh MD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYasuko Fukuya MD,PhD, Corresponding Author Yasuko Fukuya MD,PhD fukuya.yasuko@twmu.ac.jp orcid.org/0000-0002-5582-319X Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorChihiro Endo MD, PhD, Chihiro Endo MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorRyujin Miyata MD, Ryujin Miyata MD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe MD, PhD, Chie Miyabe MD, PhD orcid.org/0000-0003-3051-4179 Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYuichiro Tsunemi MD, PhD, Yuichiro Tsunemi MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, Japan Department of Dermatology, Saitama Medical University, Saitama, JapanSearch for more papers by this authorMiki Izumi MD, PhD, Miki Izumi MD, PhD Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan Department of Medical Education, Showa University School of Medicine, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro MD, PhD, Naoko Ishiguro MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this author Madoka Itoh MD, Madoka Itoh MD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYasuko Fukuya MD,PhD, Corresponding Author Yasuko Fukuya MD,PhD fukuya.yasuko@twmu.ac.jp orcid.org/0000-0002-5582-319X Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorChihiro Endo MD, PhD, Chihiro Endo MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorRyujin Miyata MD, Ryujin Miyata MD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe MD, PhD, Chie Miyabe MD, PhD orcid.org/0000-0003-3051-4179 Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this authorYuichiro Tsunemi MD, PhD, Yuichiro Tsunemi MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, Japan Department of Dermatology, Saitama Medical University, Saitama, JapanSearch for more papers by this authorMiki Izumi MD, PhD, Miki Izumi MD, PhD Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan Department of Medical Education, Showa University School of Medicine, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro MD, PhD, Naoko Ishiguro MD, PhD Department of Dermatology, Tokyo Women's Medical University, Tokyo, JapanSearch for more papers by this author First published: 04 August 2022 https://doi.org/10.1111/ijd.16367 Conflict of interest: None. Funding source: None. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

Eosinophilic granulomatosis with polyangiitis (EGPA) belongs to the family of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis syndromes. Although increasing evidence indicates the correlation of clinical and histological features with the presence or absence of ANCAs in EGPA, the variations in cutaneous features according to their ANCA status have not been fully described. Here, we retrospectively reviewed the clinical and histological findings of 9 cases of EGPA, who presented with cutaneous lesions. Our data indicate that ANCA-positive patients often present with blisters, systemic inflammatory symptoms, and are prone to receive a higher dose of oral prednisolone and additional immunosuppressive therapies.

The Journal of DermatologyVolume 48, Issue 11 p. e556-e557 LETTER TO THE EDITOR Hypergammaglobulinemic purpura: Does hypergammaglobulinemia cause purpura? Keiko Kimura, Keiko Kimura Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe, Corresponding Author Chie Miyabe cmderma.ak@twmu.ac.jp orcid.org/0000-0003-3051-4179 Department of Dermatology, Tokyo Women’s Medical University, Tokyo, Japan Correspondence Chie Miyabe, Department of Dermatology, Tokyo Women’s Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: cmderma.ak@twmu.ac.jpSearch for more papers by this authorRyujin Miyata, Ryujin Miyata Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorYasuko Fukuya, Yasuko Fukuya orcid.org/0000-0002-5582-319X Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro, Naoko Ishiguro Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this author Keiko Kimura, Keiko Kimura Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe, Corresponding Author Chie Miyabe cmderma.ak@twmu.ac.jp orcid.org/0000-0003-3051-4179 Department of Dermatology, Tokyo Women’s Medical University, Tokyo, Japan Correspondence Chie Miyabe, Department of Dermatology, Tokyo Women’s Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: cmderma.ak@twmu.ac.jpSearch for more papers by this authorRyujin Miyata, Ryujin Miyata Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorYasuko Fukuya, Yasuko Fukuya orcid.org/0000-0002-5582-319X Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro, Naoko Ishiguro Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this author First published: 24 August 2021 https://doi.org/10.1111/1346-8138.16122Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume48, Issue11November 2021Pages e556-e557 RelatedInformation

Dysfunction of immunoinhibitory signals and persistent T cell activation reportedly play important roles in the development of vasculitis. The skin is one of the most accessible organs, and it is suitable for the characterization of immune cell signatures. However, the inhibitory checkpoint molecules in the skin and their relevance to vasculitis have not been studied. Here, we investigated the profile of immune checkpoint molecules in the skin and peripheral blood of patients with vasculitis and healthy donors. We found that some of the inhibitory checkpoint molecules, including programmed cell death 1 receptor (PD-1), were elevated in T-cells in the blood of patients with systemic and cutaneous vasculitis. In addition, programmed death-ligand 1 (PD-L1) expression was elevated in the skin of patients with cutaneous vasculitis. Histologically, PD-L1 was highly expressed in the vessels in the skin along with CD4+ and CD8+ T-cell infiltration in patients with cutaneous vasculitis. Notably, plasma soluble PD-L1 levels were increased, and these correlated with C-reactive protein in patients with systemic vasculitis. Our findings suggest that inhibitory checkpoint molecules might be differentially modulated in the skin and peripheral blood of patients with vasculitis, and that the alteration of the PD-L1/PD-1 axis may be associated with the regulation of T-cell activation in vasculitis.

The Journal of DermatologyVolume 48, Issue 10 p. E524-E525 LETTER TO THE EDITOR Case of hypergammaglobulinemic purpura successfully treated with colchicine Keiko Kimura, Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe, Corresponding Author cmderma.ak@twmu.ac.jp orcid.org/0000-0003-3051-4179 Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, Japan Correspondence Chie Miyabe, Department of Dermatology, Tokyo Women’s Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: cmderma.ak@twmu.ac.jpSearch for more papers by this authorShohei Nakamura, Division of Rheumatology, Department of Internal Medicine, Tokyo Women’s Medical University School of Medicine, Tokyo, JapanSearch for more papers by this authorMari Tochihara, Division of Rheumatology, Department of Internal Medicine, Tokyo Women’s Medical University School of Medicine, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro, Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this author Keiko Kimura, Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this authorChie Miyabe, Corresponding Author cmderma.ak@twmu.ac.jp orcid.org/0000-0003-3051-4179 Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, Japan Correspondence Chie Miyabe, Department of Dermatology, Tokyo Women’s Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan. Email: cmderma.ak@twmu.ac.jpSearch for more papers by this authorShohei Nakamura, Division of Rheumatology, Department of Internal Medicine, Tokyo Women’s Medical University School of Medicine, Tokyo, JapanSearch for more papers by this authorMari Tochihara, Division of Rheumatology, Department of Internal Medicine, Tokyo Women’s Medical University School of Medicine, Tokyo, JapanSearch for more papers by this authorNaoko Ishiguro, Division of Dermatology, Department of Dermatology, Tokyo Women’s Medical University, Tokyo, JapanSearch for more papers by this author First published: 19 July 2021 https://doi.org/10.1111/1346-8138.16078Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume48, Issue10October 2021Pages E524-E525 RelatedInformation

References 1 Porri~ no-Bustamante ML, S anchez-L opez J, Arias-Santiago S, Fern andez-Pugnaire MA. Pagetoid dyskeratosis of hands: report of two cases and the usefulness of dermoscopy. Indian J Dermatol Venereol Leprol 2020; 86: 424–427. 2 Toyonaga E, Inokuma D, Abe Y, et al. Pagetoid dyskeratosis with parallel ridge pattern under dermoscopy. JAMA Dermatol 2013; 149: 109–111. 3 Wang LC, Medenica MM, Shea CR, Busbey S. Pagetoid dyskeratosis of the hand. J Am Acad Dermatol 2004; 50: 483–484. 4 Armengot-Carb o M, Mart ınez-Lahuerta C, Pitarch G. Pagetoid dyskeratosis: bear it in mind when observing a parallel ridge pattern on the hand. J Dermatol 2019; 46: e427–e429. 5 Loidi L, Mitxelena J, C ordoba A, Yanguas I. Dermoscopic features of pagetoid disqueratosis of the palm. Actas Dermosifiliogr 2014; 105: 804–805.

Vasculitis is an autoimmune disease characterized by the infiltration of leukocytes in blood vessels. An increasing number of studies on human and animal models have implicated various microorganisms in the pathogenesis of vasculitis. Previous studies have shown the presence of infectious agents, including viruses, bacteria, and fungi, in diseased vessels. However, despite continued research, the link between infection and vasculitis is not fully understood, possibly owing to the lack of appropriate animal models that mirror human disease and the technical limitations of pathogen detection in blood vessels. Among the pathogen-induced animal models, Candida albicans water-soluble fraction (CAWS)-induced coronary arteritis is currently considered one of the representative models of Kawasaki (KD) disease. Advances in metagenomic next-generation sequencing have enabled the detection of all nucleic acids in tissue, which can help identify candidate pathogens, including previously unidentified viruses. In this review, we discuss the findings from reports on pathogen-associated vasculitis in animal models and humans, with a specific focus on the investigation of the pathogenesis of vasculitis. Further studies on animal models and microbes in diseased vessels may provide important insights into the pathogenesis of vasculitis, which is often considered an idiopathic disease.

EDITORIAL article Front. Pharmacol., 16 August 2021 | https://doi.org/10.3389/fphar.2021.744290

Arrest of circulating leukocytes and subsequent diapedesis is a fundamental component of inflammation. In general, the leukocyte migration cascade is tightly regulated by chemoattractants, such as chemokines. Chemokines, small secreted chemotactic cytokines, as well as their G-protein-coupled seven transmembrane spanning receptors, control the migratory patterns, positioning and cellular interactions of immune cells. Increased levels of chemokines and their receptors are found in the blood and within inflamed tissue in patients with rheumatoid arthritis (RA) and vasculitis. Chemokine ligand-receptor interactions regulate the recruitment of leukocytes into tissue, thus contributing in important ways to the pathogenesis of RA and vasculitis. Despite the fact that blockade of chemokines and chemokine receptors in animal models have yielded promising results, human clinical trials in RA using inhibitors of chemokines and their receptors have generally failed to show clinical benefits. However, recent early phase clinical trials suggest that strategies blocking specific chemokines may have clinical benefits in RA, demonstrating that the chemokine system remains a promising therapeutic target for rheumatic diseases, such as RA and vasuculitis and requires further study.

Kojic acid (5-hydroxy-2-[hydroxymethyl]-y-pyrone) is a fungal metabolite that is widely used in medicinal and cosmetic formulations as a skin-lightening agent and as a food additive to prevent enzymatic browning based on its depigmenting activity. In human clinical studies, kojic acid has been shown to be effective in treating hyperpigmentation disorders such as melasma, but the reasons for its apparent lack of anti-melanogenic activity in mammalian melanocytes in culture are unclear. We established human induced pluripotent stem (iPS) cellderived melanocytes in large quantities within a short period and induced their differentiation and high melanogenic potency in serum-free culture conditions without supplementation by non-physiological agents. The iPS cells were established from T cells obtained from the blood of a healthy 40-year-old Japanese man. The human iPS cell-derived melanocytes were cultured in human iPS cell-derived melanocyte medium (iDMM) in 60-mm gelatinous dishes coated with Matrigel (BD Biosciences, Tokyo, Japan). In this study, we evaluated the in vitro effects of kojic acid on human iPS cell-derived melanocytes following treatment with kojic acid. Human iPS cell-derived melanocytes produced by our previously published protocol appeared as black dots and black areas in human iDMM in gelatinous dishes coated with Matrigel after culture for 5 weeks. Subsequently, 70 lg/mL kojic acid was directly added to iDMM. Human iPS cellderived melanocytes in untreated human iDMM reached confluence in Matrigel dishes after 3 weeks. In contrast, the addition of 70 lg/mL kojic acid did not result in any differences in black dots and black areas compared with the untreated control dishes. Microscopic analysis did not show any differences between human iPS cell-derived melanocytes after treatment with 70 lg/mL kojic acid and the untreated controls (Fig. 1a). We then investigated the effects of kojic acid on tyrosinase activity in human iPS cell-derived melanocytes using a modified spectroscopic method described in previous studies. The addition of 70 lg/mL kojic acid for 2 weeks had no effect on tyrosinase activity in these cells compared with the untreated control (Fig. 1b). Mammalian melanocytes produce two types of melanin pigment, eumelanin and pheomelanin. We analyzed the melanin composition in kojic acid treated and untreated control melanocytes using previously reported methods. The A650/A500 ratio reflects whether the sample is eumelanic or pheomelanic, with eumelanin giving an A650/A500 ratio of 0.25–0.33 and pheomelanin a ratio of 0.10–0.15. We performed the single determination in the spectrophotometric assay because the A650/A500 ratios showed a good reproducibility in the previous experiments. The A650/A500 ratio decreased following treatment with 70 lg/mL kojic acid compared with the untreated control (Fig. 1c). These findings suggest that kojic acid affects pheomelanin production in human iPS cell-derived melanocytes. Pyrrole-2,3,5-tricarboxylic acid (PTCA) is a 5,6-dihydroxyindole-2-carboxylic acid-related eumelanin marker while 4amino-3-hydroxyphenylalanine (4-AHP) and thiazole-2,4,5-tricarboxylic acid (TTCA) are markers for benzothiazine units and benzothiazole units in pheomelanin, respectively. Both the 4AHP and TTCA titers increased following treatment with 70 lg/ mL kojic acid compared with the untreated control cultures. On the other hand, the PTCA titer was not affected by the treatment with kojic acid (Fig. 1d). These findings indicated that treatment with kojic acid upregulates mainly pheomelanin production in human iPS cell-derived melanocytes. Kojic acid is known to inhibit mushroom tyrosinase and thus prevent melanin synthesis. Kojic acid has a competitive inhibitory effect on monophenolase activity and a mixed inhibitory effect on the diphenolase activity of mushroom tyrosinase. The ability of kojic acid to chelate copper at the active site of the enzyme explains the observed competitive inhibitory effect. These findings indicate that treatment with kojic acid downregulates mainly eumelanin production in melanocytes. We previously showed tyrosinase activity could affect pheomelanogenesis more profoundly compared with eumelanogenesis. In the present study, we demonstrated that kojic acid increases pheomelanin content in melanin produced by human iPS cell-derived melanocytes. Furthermore, these results suggest that human iPS cell-derived melanocytes could be used to investigate the mechanism of skinlightening agents and foods that include kojic acid.

We reported two cases of PPG in Japanese patients who underwent colectomy and colostomy for incurable inflammatory bowel disease. We suggest that surgical damage could be a trigger to induce PPG under aberrant immune conditions such as incurable inflammatory bowel disease.