Increased CD69+ Tissue-resident Memory T (TRM) Cells andSTAT3 Expression in Cutaneous Lupus Erythematosus Patients Recalcitrant to Antimalarials

Summary: Background/Purpose: Cutaneous lupus erythematosus (CLE) is an autoimmune disease withvarious subsets and clinical manifestations. T lymphocytes are the predominant cell type found inlesional skin, but plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs) also playan important role in the pathogenesis. Oral antimalarials, including hydroxychloroquine (HCQ)and quinacrine (QC) are first-line systemic therapy for all CLE sub-types. Although HCQ is effectivein approximately 50% of patients, some patients still do not respond to antimalarials. Some ofthese patients benefit from additional QC, but there is a subset of patients who remain refractoryto both antimalarials. Refractoriness poses a huge challenge as patients continue to have activedisease despite antimalarial therapy. To better understand reasons for refractoriness in CLE, weinvestigated the immunologic characteristics of patients who responded to antimalarials versusthose who did not. Methods: One hundred fifteen patients with a diagnosis of CLE were recruited from theAutoimmune Skin Disease Center at the Hospital of the University of Pennsylvania. Sixty-five werewell-characterized in terms of response to treatment as (i) HCQ-responders (n=22), (ii) HCQ+QC-responders (n=24), or (iii) HCQ+QC-nonresponders (n=19). Lesional skin was biopsied beforestarting treatment with antimalarials. We defined treatment failure to HCQ as continued skinactivity requiring a second intervention after at least 2 months of HCQ therapy.Immunohistochemistry was used to characterize the inflammatory cells and cytokine expressionin lesional skin biopsies from patients. Total RNA was extracted from these biopsies to analyze specific gene signatures. The patient’s CLASI score – a measure of disease activity – at the time ofthe biopsy was also determined. Results: Immunohistochemistry showed that CD69+ tissue-resident memory T (T) cells weresignificantly higher in HCQ+QC-nonresponders compared to HCQ- and HCQ+QC-responders.mDCs were significantly higher in HCQ+QC-responders compared to HCQ- and HCQ+QC-nonresponders. There were significantly higher pDCs in the HCQ-responders compared to thenonresponders. There was no significant difference in the number of autoreactive T cells,macrophages, and neutrophils among the three groups (Figure 1). The HCQ+QC-nonrespondergroup was distinct from the other groups in that their CLASI scores correlated positively with thenumber of Tcells (r=0.6254, p=0.017) and macrophages (r=0.5726, p=0.041) (Figure 2). mRNAexpression demonstrated high STAT3 expression in HCQ+QC-nonresponders (Figure 3). There wasa significantly higher percentage of area stained for IL-17 in the HCQ+QC-responders compared toHCQ-responders and HCQ+QC-nonresponders while IL-22 expression was not significantlydifferent between groups. Conclusion: An increased number of CD69+ T cells and correlation between CD69+T cellsand macrophages with CLASI scores in the HCQ+QC-nonresponders, a finding not seen in eitherHCQ or HCQ+QC-responders, may indicate that CD69+ T cells and macrophages are involved inantimalarial-refractory skin disease.