Cutting Edge: PD-1 Regulates Imiquimod-Induced Psoriasiform Dermatitis through Inhibition of IL-17A Expression by Innate γδ-Low T Cells.

Programmed cell death 1 (PD-1) is a key regulatory molecule that has been targeted in human cancers, including melanoma. In clinical testing, Abs against PD-1 have resulted in psoriasiform dermatitis (PsD). To determine whether PD-1 regulates PsD, we compared skin responses of PD-1-deficient (PD-1KO) mice and wild-type (WT) controls in an imiquimod (IMQ)-induced murine model of psoriasis. PD-1KO mice showed severe epidermal hyperplasia, greater neutrophilic infiltration, and higher expression of Th17 cytokines (versus WT mice). IMQ exposure increased PD-1 expression by skin γδ-low (GDL) T cells and enhanced expression of PD-L1 by keratinocytes. Three-fold increases in the percentage of IL-17A(+) GDL T cells were observed in skin cell suspensions derived from IMQ-treated PD-1KO mice (versus WT controls), suggesting that the lack of PD-1 has a functional effect not only on αß T cells, but also on GDL T cells, and that PD-1 may play a regulatory role in PsD.

[Congenital self-healing Langerhans cell histiocytosis]. / Kongenitale selbst heilende Langerhans-Zell-Histiozytose.

A male infant, born at term after an uncomplicated pregnancy, presented with multiple red-brown papules and nodules spread over his body. The infant's general condition was not affected and there was no systemic involvement. After only 6 weeks the lesions had healed completely without recurrence. Based on histological and immunohistochemical findings, the clinical appearance and the self-healing course, the diagnosis of congenital self-healing Langerhans cell histiocytosis was established.

[Renal involvement in autoimmune enteropathies]. / Atteinte rénale des entéropathies auto-immunes.

The authors report on a infant who presented with an auto-immune enteropathy characterized by the association of a protracted diarrhea, a neonatal insulin-dependent diabetes, and a dermatitis and who developed a nephrotic syndrome at 4 months of age. A renal biopsy showed a membranous glomerulonephritis (MGN) with IgG linear deposits along the tubular basement membranes (TMB). By indirect immunofluorescence anti-enterocyte antibodies together with anti-TMB antibodies and anti-renal brush border (BB) antibodies were found in the serum of the patient. The patient received various immunosuppressive drugs that failed to improve the disease. In the course of the disease the anti-TBM antibodies disappeared progressively but the BB antibodies persisted. A review of the literature indicates that renal involvement is not uncommon in auto-immune enteropathy and in 5 cases it has been reported as being characterized by a nephrotic syndrome related to the presence of a MGN. In 4 of these cases MGN was associated with the presence of anti-TBM antibodies and in the remaining one with anti-BB antibodies. This case report shows that in human pathology, auto-antibodies to BB proteins may, as well as in experimental models, be responsible for the development of a MGN. It suggests a close relationship (probably a common epitope) between the renal BB proteins and the proteins of the gut epithelium.

Lyme disease during pregnancy.

Lyme disease is an increasingly recognized tick-borne illness caused by a spirochete, Borrelia burgdorferi. Because the etiologic agent of Lyme disease is a spirochete, there has been concern about the effect of maternal Lyme disease on pregnancy outcome. We reviewed cases of Lyme disease in pregnant women who were identified before knowledge of the pregnancy outcomes. Nineteen cases were identified with onset between 1976 and 1984. Eight of the women were affected during the first trimester, seven during the second trimester, and two during the third trimester; in two, the trimester of onset was unknown. Thirteen received appropriate antibiotic therapy for Lyme disease. Of the 19 pregnancies, five had adverse outcomes, including syndactyly, cortical blindness, intrauterine fetal death, prematurity, and rash in the newborn. Adverse outcomes occurred in cases with infection during each of the trimesters. Although B burgdorferi could not be implicated directly in any of the adverse outcomes, the frequency of such outcomes warrants further surveillance and studies of pregnant women with Lyme disease.