Aurore Coulomb L’Herminé

The recent discovery that sporadic and familial primary pulmonary hypertension can be associated with germline mutations of genes encoding receptor members of the transforming growth factor-beta family has focused much attention on cytokines and growth factors in pulmonary vascular disorders. Production of several cytokines has been demonstrated in severe pulmonary arterial hypertension, emphasizing the possible influence of inflammatory mechanisms in this condition. Moreover, perivascular inflammatory cell infiltrates composed of macrophages and lymphocytes have been detected in plexiform lesions of primary pulmonary hypertension. Chemokine RANTES is an important chemoattractant for monocytes and T cells. We therefore hypothesize that chemokine RANTES promotes cell recruitment in the lungs of patients displaying severe pulmonary arterial hypertension. Reverse transcriptase polymerase chain reaction demonstrated elevated RANTES mRNA expression in 10 lung samples from patients with severe pulmonary arterial hypertension, as compared with seven control subjects. In situ hybridization and immunohistochemistry confirmed that endothelial cells were the major source of RANTES within the pulmonary artery wall of the patients. Serial sections analysis showed that RANTES expression was associated with CD45+ inflammatory cell infiltrates. These results support the concept that inflammatory mechanisms play a role in the natural history of pulmonary arterial hypertension.

On the basis of the results of previous national and international trials and studies, the Renal Tumour Study Group of the International Society of Paediatric Oncology (SIOP-RTSG) has developed a new study protocol for paediatric renal tumours: the UMBRELLA SIOP-RTSG 2016 protocol (the UMBRELLA protocol). Currently, the overall outcomes of patients with Wilms tumour are excellent, but subgroups with poor prognosis and increased relapse rates still exist. The identification of these subgroups is of utmost importance to improve treatment stratification, which might lead to reduction of the direct and late effects of chemotherapy. The UMBRELLA protocol aims to validate new prognostic factors, such as blastemal tumour volume and molecular markers, to further improve outcome. To achieve this aim, large, international, high-quality databases are needed, which dictate optimization and international harmonization of specimen handling and comprehensive sampling of biological material, refine definitions and improve logistics for expert review. To promote broad implementation of the UMBRELLA protocol, the updated SIOP-RTSG pathology and molecular biology protocol for Wilms tumours has been outlined, which is a consensus from the SIOP-RTSG pathology panel.

Heterozygous missense mutations in coatomer protein subunit α, COPA, cause a syndrome overlapping clinically with type I IFN-mediated disease due to gain-of-function in STING, a key adaptor of IFN signaling. Recently, increased levels of IFN-stimulated genes (ISGs) were described in COPA syndrome. However, the link between COPA mutations and IFN signaling is unknown. We observed elevated levels of ISGs and IFN-α in blood of symptomatic COPA patients. In vitro, both overexpression of mutant COPA and silencing of COPA induced STING-dependent IFN signaling. We detected an interaction between COPA and STING, and mutant COPA was associated with an accumulation of ER-resident STING at the Golgi. Given the known role of the coatomer protein complex I, we speculate that loss of COPA function leads to enhanced type I IFN signaling due to a failure of Golgi-to-ER STING retrieval. These data highlight the importance of the ER-Golgi axis in the control of autoinflammation and inform therapeutic strategies in COPA syndrome.

EBV-induced gene 3 (EBI3) can associate with p28 to form the heterodimeric cytokine IL-27, or with the p35 subunit of IL-12 to form the EBI3/p35 heterodimer, recently named IL-35. In mice, IL-35 has been shown to be constitutively expressed by CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg cells) and suggested to contribute to their suppressive activity. In this study, we investigated whether human Treg cells express IL-35. Double-staining analysis of human thymuses showed that neither Foxp3(+) nor CD25(+) cells coexpressed EBI3. Similarly, Foxp3(+) cells present in human lymph nodes, tonsils, spleens, and intestines did not express EBI3. Consistent with these in situ observations, Treg cells purified from blood or tonsils were negative for EBI3 by immunoblotting. Other human T cell subsets, including effector T cells, naive and memory CD4(+) T cells, CD8(+) and gammadelta T cells also did not constitutively express EBI3, which contrasts with IL-35 expression observed in murine CD8(+) and gammadelta T cells. Furthermore, although CD3/CD28 stimulation consistently induced low levels of EBI3 in various CD4(+) T cell subsets, no EBI3 could be detected in CD3/CD28-stimulated Treg cells. RT-PCR analysis showed that, whereas p35 transcripts were detected in both Teff and Treg cells, EBI3 transcripts were detected only in activated Teff cells, but not in resting or activated Treg cells. Thus, in contrast to their murine counterpart, human Treg cells do not express detectable amounts of IL-35.

The bcl-2 protein, which prolongs cell survival by blocking apoptosis, is expressed by progenitor cells in several self-renewing tissues and by tumoral cells in some extrahepatic neoplasms. Because the liver is a slow self-renewing tissue, an immunohistochemical study of the cellular distribution of the bcl-2 protein was performed in normal liver (12 cases), nontumoral hepatic lesions (33 cases), and benign or malignant liver tumors (46 cases). In normal liver, bcl-2 was expressed by bile ductules and small bile duct epithelium, but not by hepatocytes or large bile duct epithelium. In cirrhosis and focal nodular hyperplasia, epithelial cells of the ductular proliferation were bcl-2-positive. Eight of 11 cholangiocarcinomas stained positively for bcl-2, whereas all 15 hepatocellular carcinomas were bcl-2-negative. bcl-2 was also expressed in 6 of 14 metastatic adenocarcinomas. These findings suggest that the ductular cells and small bile duct epithelial cells might have a prolonged survival and might be hepatic progenitor cells. In addition, the bcl-2 protein appears to be a marker of cholangiocarcinoma but not of hepatocellular carcinoma and could help in distinguishing between these two primary liver tumors.