Marie-Charlotte Brüggen

Diverse T-cell responses characterize the different manifestations of cutaneous graft-versus-host disease.

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HCT) and can present in an acute (aGVHD), a chronic lichenoid (clGVHD), and a chronic sclerotic form (csGVHD). It is unclear whether similar or different pathomechanisms lead to these distinct clinical presentations. To address this issue, we collected lesional skin biopsies from aGVHD (n = 25), clGVHD (n = 17), and csGVHD (n = 7) patients as well as serial nonlesional biopsies from HCT recipients (prior to or post-HCT) (n = 14) and subjected them to phenotypic and functional analyses. Our results revealed striking differences between aGVHD and clGVHD. In aGVHD, we found a clear predominance of T helper (Th)2 cytokines/chemokines and, surprisingly, of interleukin (IL)-22 messenger RNA as well as an increase of IL-22-producing CD4(+) T cells. Thymic stromal lymphopoietin, a cytokine skewing the immune response toward a Th2 direction, was elevated at day 20 to 30 post-HCT in the skin of patients who later developed aGVHD. In sharp contrast to aGVHD, the immune response occurring in clGVHD showed a mixed Th1/Th17 signature with upregulated Th1/Th17 cytokine/chemokine transcripts and elevated numbers of interferon-γ- and IL-17-producing CD8(+) T cells. Our findings shed new light on the T-cell responses involved in the different manifestations of cutaneous GVHD and identify molecular signatures indicating the development of the disease.

Host Defense Mechanisms in Secondary Syphilitic Lesions: A Role for IFN-γ-/IL-17-Producing CD8+ T Cells?

Cell-mediated immunity is thought to be of critical importance in antisyphilitic host defense, but the exact mechanisms are still unknown. This fact is particularly true for HIV-infected persons with a deficit in CD4+ T-cell number. We therefore obtained lesional skin samples from HIV+ and HIV- patients with secondary syphilis at different time points of lesional age to search both for causative microorganisms and to characterize the inflammatory infiltrate. By doing so, we detected Treponema pallidum spirochetes with a much greater abundance in late lesions of HIV+ individuals compared with the HIV- cohort. The dominating inflammatory cells were T cells, macrophages, and neutrophils at all stages and plasma cells in older lesions. In HIV- persons, T cells consisted of equal numbers of CD4+ and CD8+ T-cells, whereas in HIV+ patients, the majority of T cells belonged to the CD8 lineage and produced both IFN-γ and IL-17. Regulatory T cells and Langerhans cells were reduced in these patients compared with their HIV- counterparts. Because of our observations, we propose that T cells of both the CD4 and CD8 lineage are needed for an at least partial protective antisyphilitic immunity. Compensation mechanisms in HIV+ individuals, such as an increase of Tc1/17 cells as well as a reduction in immunoregulatory Langerhans cells and T cells, apparently do not overcome the deficiencies in these patients to eliminate the spirochete.

Antagonistic effect of the inflammasome on thymic stromal lymphopoietin expression in the skin

BACKGROUND Innate immune sensors control key cytokines that regulate T-cell priming and T-cell fate. This is particularly evident in allergic reactions, which represent ideal systems to study the interplay of innate and adaptive immunity. In patients with contact dermatitis, inflammasome-mediated IL-1 activation is responsible for a TH1 immune response. Surprisingly, the IL-1 signaling pathway was also proposed to control the activation of thymic stromal lymphopoietin (TSLP), a cytokine implicated in development of the T(H)2 response in patients with atopic dermatitis (AD) and asthma. OBJECTIVES We sought to assess the effect of the inflammasome on TSLP expression levels and the development of AD. METHODS We studied the effect of the inflammasome activator 2,4-dinitrofluorobenzene, and IL-1β on TSLP mRNA expression levels in mouse and human cell lines (in vitro assays), as well as in live mice and on human skin transplants. We also assessed the effect of 2,4-dinitrofluorobenzene on TSLP and the TH2 response in mice in which the inflammasome and IL-1 signaling pathways were blocked, either genetically or pharmacologically, in 2 models of AD. RESULTS We provide in vitro and in vivo evidence that inflammasome activation has an inhibitory role on TSLP mRNA expression and T(H)2 cell fate in the skin. We also show that solvents influence the activation of TSLP and IL-1β and direct the T-cell fate to a given hapten. CONCLUSION Our observations strongly suggest that the TH1 versus TH2 cell fate decision is regulated at multiple levels and starts with innate immune events occurring within peripheral epithelial tissues.

Epidermal Elafin Expression Is an Indicator of Poor Prognosis in Cutaneous Graft-versus-Host Disease

Graft-versus-host disease (GVHD) remains a common and potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. In the skin, GVHD can present in an acute (aGVHD), chronic lichenoid (clGVHD), or chronic sclerotic form (csGVHD). Measuring peripheral blood levels of the keratinocyte-derived protease inhibitor elafin has recently emerged as a promising tool for the diagnosis of cutaneous aGVHD. We evaluated whether the analysis of elafin expression in skin would allow distinguishing aGVHD from drug hypersensitivity rashes (DHR) and whether cutaneous elafin expression would correlate with disease severity or altered prognosis of aGVHD and clGVHD/csGVHD. Skin biopsies from aGVHD (n=22), clGVHD (n=15), csGVHD (n=7), and DHR (n=10) patients were collected and epidermal elafin expression and its association with diverse clinical/histological parameters were analyzed. Acute GVHD and DHR displayed varying degrees of elafin expression. No elafin was detectable in csGVHD, whereas the molecule was increased in clGVHD as compared with aGVHD. Elafin-high aGVHD/clGVHD lesions presented with epidermal thickening and were associated with poor prognosis-i.e., decreased overall survival in aGVHD and corticosteroid resistance in clGVHD. Although cutaneous elafin does not seem to discriminate aGVHD from DHR lesions, our study strongly suggests an association between cutaneous elafin expression and poor prognosis for patients with cutaneous GVHD.

Innate and Adaptive Components of the Cutaneous Immune Barrier: The Central Role of Dendritic Cells

Immune responses initiated in the skin can be extremely powerful at both a local and systemic level. One of the milestones in elucidating the mechanisms underlying this phenomenon was the discovery of the T cell response-inducing function of Langerhans cells (LC). In the meantime, we know that the family of dendritic antigen-presenting cells in the skin is much bigger and, in addition to LC, includes dermal dendritic cells (DDC), CD141 + DC, CD14 + DC, inflammatory DC and plasmacytoid DC. Depending on the cellular and molecular milieu, these cells can function as either sensitizing or tolerizing elements. Signals transmitted from (innate) receptors recognizing damage- or pathogen-associated patterns are involved in directing these different functions in DC. Toll-like pathogen recognition receptors (TLR) have been particularly well investigated in this regard. The distinct distribution of TLR on LC and other DC subsets allows the immune system to elegantly orchestrate the regulatory and pro-inflammatory functions of these cells. Intriguingly, TLR signaling in DC/LC not only allows to initiate adaptive immune responses, but also directly induces innate effector functions. This is demonstrated by our findings on the mechanisms underlying basal cell carcinoma (BCC) regression upon treatment with the pharmacological TLR7 agonist imiquimod. We observed that in imiquimod-treated BCC, plasmacytoid DC directly kill tumor cells via the apoptosis-inducing molecule TRAIL. Melanoma cells can also become TRAIL-susceptible, but the magnitude of this phenomenon varies from patient to patient. Our recent findings show that TRAIL susceptibility of melanoma cell lines can be increased upon exposure to the anti-inflammatory compound diclofenac.

Interstitial granulomatous dermatitis during talimogen laherparepvec treatment

A 31-year-old healthy man was diagnosed with a melanoma of the skin located on the thigh left in 2008. Breslow thickness was 0.8 mm; therefore, only wide excision was performed. In May 2014, the patient developed palpable lymphnode metastases in the left groin, without distant metastases, confirmed by PET-CT. He underwent complete lymphadenectomy, followed by adjuvant irradiation therapy. In December 2014, liver metastases were detected. The patient was included in the AMGEN 20110265-trial [2]. As per protocol, treatment started with TVEC only first (week − 5 and − 2), whereas Pembrolizumab was added at week 0. The patient had one injectable lesion in the left inguina, which was injected with 0.5 ml TVEC. Twelve days later, he developed fever, chills, and nausea. Isolated elevation of C-reactive protein of 186 mg/l was detected; an infectious focus was not found but suspected. Therefore, treatment with amoxicillin/clavulanic acid was initiated. The same day, unilateral reddish-bluish, slightly infiltrated lesions partly arranged in a linear pattern developed on the left lower leg (Fig. 1). The rash spread over the entire leg up to the buttocks during the next 4 days. The biopsy showed a perivascular and interstitial CD-68-positive mononuclear infiltrate with granulomatous aspects (Fig. 2) and discrete edema. Immunohistochemical stainings showed CD68-positive macrophages in the dermis, lymphocytes were mostly CD3-positive and CD4-positive, and some were found to be CD8-positive. On the basis of the clinical and histological features, IGD was diagnosed.

Aggressive Rare T-cell Lymphomas with Manifestation in the Skin: A Monocentric Cross-sectional Case Study

Rare T- or NK-cell lymphomas with cutaneous manifestation may display a highly aggressive clinical course and major diagnostic/therapeutic challenges. This report describes our experiences with different lymphomas of this rare category and the therapeutic options used. This retrospective, descriptive, monocentric, cross-sectional case study, identified 4 rare aggressive T-/NK-cell lymphomas with manifestation in the skin, which were diagnosed in a tertiary care centre over a period of 4 years. Two patients had an Epstein-Barr virus-associated extranodal NK/T-cell lymphoma and 2 patients had a primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma. Concomitant extracutaneous involvement was observed in 2 of all 4 patients. Two patients had fulminant disease progression and resistance to chemotherapy. Two patients underwent allogeneic haematopoietic stem cell transplantation, which resulted in one complete remission and one partial remission. This report emphasizes the importance of an early diagnostic work-up and a prompt aggressive therapeutic approach.