ERG regulates lymphatic vessel specification genes and its deficiency impairs wound healing-associated lymphangiogenesis.

OBJECTIVE: Rarefaction of blood and lymphatic vessels in the skin has been reported in SSc (systemic sclerosis, scleroderma). ERG and FLI1 are important regulators of angiogenesis, but their role in lymphatic vasculature is less known. The goal of this study was to determine the role of ERG and FLI1 in postnatal lymphangiogenesis and SSc lymphatic system defects. METHODS: Immunofluorescence was used to detect ERG and FLI1 in SSc and healthy control (HC) skin biopsies. Transcriptional analysis of ERG or FLI1 silenced human dermal lymphatic endothelial cells (LECs) was performed using microarrays. Effects of ERG/FLI1 deficiency on in vitro tubulogenesis in human dermal LECs was examined using a Matrigel assay. Erg and Fli1 endothelial specific knockouts and Erg lymphatic specific knockouts were generated to examine vessel regeneration in mice. RESULTS: ERG and FLI1 protein levels were reduced in the blood and lymphatic vasculature in SSc skin biopsies. ERG was shown to regulate genes involved in lymphatic vessel specification, including VEGFR3/FLT4, LYVE-1, SOX18, and PROX1, while FLI1 enhanced the function of ERG. ERG/FLT4 pathway regulated in vitro tubulogenesis in human LECs. Deficiency of Erg or Fli1 similarly impaired the function of blood vessels in mice. However, only Erg deficiency affected the regeneration of lymphatic vessels during wound healing. CONCLUSION: ERG and FLI1 are essential regulators of blood and lymphatic vessel regeneration. Deficiency of ERG and FLI1 in SSc endothelial cells, may contribute to impairment of blood and lymphatic vasculature in SSc patients.

SPRED2 loss-of-function causes a recessive Noonan syndrome-like phenotype.

Upregulated signal flow through RAS and the mitogen-associated protein kinase (MAPK) cascade is the unifying mechanistic theme of the RASopathies, a family of disorders affecting development and growth. Pathogenic variants in more than 20 genes have been causally linked to RASopathies, the majority having a dominant role in promoting enhanced signaling. Here, we report that SPRED2 loss of function is causally linked to a recessive phenotype evocative of Noonan syndrome. Homozygosity for three different variants-c.187C>T (p.Arg63∗), c.299T>C (p.Leu100Pro), and c.1142_1143delTT (p.Leu381Hisfs∗95)-were identified in four subjects from three families. All variants severely affected protein stability, causing accelerated degradation, and variably perturbed SPRED2 functional behavior. When overexpressed in cells, all variants were unable to negatively modulate EGF-promoted RAF1, MEK, and ERK phosphorylation, and time-course experiments in primary fibroblasts (p.Leu100Pro and p.Leu381Hisfs∗95) documented an increased and prolonged activation of the MAPK cascade in response to EGF stimulation. Morpholino-mediated knockdown of spred2a and spred2b in zebrafish induced defects in convergence and extension cell movements indicating upregulated RAS-MAPK signaling, which were rescued by expressing wild-type SPRED2 but not the SPRED2Leu381Hisfs∗95 protein. The clinical phenotype of the four affected individuals included developmental delay, intellectual disability, cardiac defects, short stature, skeletal anomalies, and a typical facial gestalt as major features, without the occurrence of the distinctive skin signs characterizing Legius syndrome. These features, in part, characterize the phenotype of Spred2-/- mice. Our findings identify the second recessive form of Noonan syndrome and document pleiotropic consequences of SPRED2 loss of function in development.

Telogen hair loss and androgenetic-like alopecia in GAPO syndrome.

Growth retardation, Alopecia, Pseudoanodontia and Optic atrophy (GAPO) syndrome is a rare autosomal recessive condition whose cardinal features include a recognizable craniofacial dysmorphosis, growth retardation, alopecia, pseudoanodontia, and premature aging. We report on a 2-year-old Pakistani man affected with GAPO syndrome who additionally shows an androgenetic-like alopecia with normal testosterone levels and telogen hair loss. These are novel findings in GAPO syndrome.

Mycobacterium tuberculosis Virulent Factor ESAT-6 Drives Macrophage Differentiation Toward the Pro-inflammatory M1 Phenotype and Subsequently Switches It to the Anti-inflammatory M2 Phenotype.

Tuberculosis, a human infectious disease caused by Mycobacterium tuberculosis (M.tb), is still a major cause of morbidity and mortality worldwide. The success of M.tb as a pathogen relies mainly on its ability to divert the host innate immune responses. One way by which M.tb maintains a persistent infection in a "silent" granuloma is to inhibit inflammation and induce an immunoregulatory phenotype in host macrophages (MΦs). However, M.tb effectors governing the switch of MΦs from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype remain to be determined. The Early Secreted Antigenic Target 6 kDa or ESAT-6, has been implicated in the virulence and pathogenesis of tuberculosis. Here, we investigated roles of ESAT-6 in MΦ differentiation and polarization. We found that treatment of human monocytes with ESAT-6 did not interfere with differentiation of M1 MΦs. However, ESAT-6 promoted differentiation of M0 and M2 MΦs toward the M1 phenotype, as indicated by secretion of pro-inflammatory cytokines IL-6, IL-12, and TNF-α, and induction of a typical M1 transcriptional signature. Interestingly, we found that ESAT-6 switched terminal full activation of M1 polarized MΦs to the M2 phenotype. Indeed, in the pro-inflammatory M1 MΦs, ESAT-6 was able to inhibit IL-12 and TNF-α secretion and stimulate that of IL-10. Moreover, gene expression profiling of these cells showed that ESAT-6 induced downregulation of M1 MΦ cell surface molecules CD80 and CD86, transcription factors IRF5 and c-MAF, cytokines IL-12, IL-10, and IL-6, as well as chemokines CXCL10 and CXCL1. Overall, our findings suggest ESAT-6 as being one of the effectors used by M.tb to induce the pro-inflammatory M1 phenotype at the primo-infection; a prerequisite step to promote granuloma formation and subsequently drive the phenotype switch of MΦ polarization from M1 to M2 at a later stage of the infection. Our study improves current knowledge regarding mechanisms of virulence of M.tb and may be helpful to develop novel tools targeting ESAT-6 for a better and more efficient treatment of tuberculosis.

Prediction of T Cell Epitopes from Leishmania major Potentially Excreted/Secreted Proteins Inducing Granzyme B Production.

Leishmania-specific cytotoxic T cell response is part of the acquired immune response developed against the parasite and contributes to resistance to reinfection. Herein, we have used an immune-informatic approach for the identification, among Leishmania major potentially excreted/secreted proteins previously described, those generating peptides that could be targeted by the cytotoxic immune response. Seventy-eight nonameric peptides that are predicted to be loaded by HLA-A*0201 molecule were generated and their binding capacity to HLA-A2 was evaluated. These peptides were grouped into 20 pools and their immunogenicity was evaluated by in vitro stimulation of peripheral blood mononuclear cells from HLA-A2+-immune individuals with a history of zoonotic cutaneous leishmaniasis. Six peptides were identified according to their ability to elicit production of granzyme B. Furthermore, among these peptides 3 showed highest affinity to HLA-A*0201, one derived from an elongation factor 1-alpha and two from an unknown protein. These proteins could constitute potential vaccine candidates against leishmaniasis.

Validation of Recombinant Salivary Protein PpSP32 as a Suitable Marker of Human Exposure to Phlebotomus papatasi, the Vector of Leishmania major in Tunisia.

BACKGROUND: During a blood meal, female sand flies, vectors of Leishmania parasites, inject saliva into the host skin. Sand fly saliva is composed of a large variety of components that exert different pharmacological activities facilitating the acquisition of blood by the insect. Importantly, proteins present in saliva are able to elicit the production of specific anti-saliva antibodies, which can be used as markers for exposure to vector bites. Serological tests using total sand fly salivary gland extracts are challenging due to the difficulty of obtaining reproducible salivary gland preparations. Previously, we demonstrated that PpSP32 is the immunodominant salivary antigen in humans exposed to Phlebotomus papatasi bites and established that humans exposed to P. perniciosus bites do not recognize it. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we have validated, in a large cohort of 522 individuals, the use of the Phlebotomus papatasi recombinant salivary protein PpSP32 (rPpSP32) as an alternative method for testing exposure to the bite of this sand fly. We also demonstrated that screening for total anti-rPpSP32 IgG antibodies is sufficient, being comparable in efficacy to the screening for IgG2, IgG4 and IgE antibodies against rPpSP32. Additionally, sera obtained from dogs immunized with saliva of P. perniciosus, a sympatric and widely distributed sand fly in Tunisia, did not recognize rPpSP32 demonstrating its suitability as a marker of exposure to P. papatasi saliva. CONCLUSIONS/SIGNIFICANCE: Our data indicate that rPpSP32 constitutes a useful epidemiological tool to monitor the spatial distribution of P. papatasi in a particular region, to direct control measures against zoonotic cutaneous leishmaniasis, to assess the efficiency of vector control interventions and perhaps to assess the risk of contracting the disease.

Fortuitous description of haemoglobin A2' [δ16 (A13) Gly→Arg (GGC→CGC)] in a Tunisian family: study of the molecular defect and its origin.

The most common inherited haemoglobin disorders encountered in Tunisia are ß-thalassemia and sickle cell disease, which result from mutations in the ß-globin gene. Few studies focused on δ-globin gene variations responsible for δ-thalassemia or HbA2 variants. HbA2' [δ16 (A13) Gly→Arg (GGC→CGC)] is a δ-chain variant that has been identified in several populations of African origin. We report herein for the first time the description of HbA2' in the Tunisian population. Identification of HbA2' in the studied family was carried out by high-performance liquid chromatography and confirmed by sequencing analyses of the whole δ-globin gene. Haplotypes of the ß-globin gene cluster were constructed by mapping the restriction sites using polymerase chain reaction followed by enzymatic digestion. Compound heterozygosity of HbA2' with HbO-Arab was identified in the proband. The mother and two other siblings showed heterozygous HbA2' whereas the father showed heterozygous HbO-Arab. The sum of HbA2 and HbA2' in all cases was less than 4%, thus excluding ß-thalassemia. ß-cluster haplotype analysis revealed that this mutation was associated with the F haplotype (-+--+++). The unique origin of this mutation in Africa is likely since the linked ß-cluster haplotype is one of the major haplotypes found in African populations.

Involvement of different CD4(+) T cell subsets producing granzyme B in the immune response to Leishmania major antigens.

The nature of effector cells and the potential immunogenicity of Leishmania major excreted/secreted proteins (LmES) were evaluated using peripheral blood mononuclear cells (PBMCs) from healed zoonotic cutaneous leishmaniasis individuals (HZCL) and healthy controls (HC). First, we found that PBMCs from HZCL individuals proliferate and produce high levels of IFN-γ and granzyme B (GrB), used as a marker of activated cytotoxic T cells, in response to the parasite antigens. IFN-γ is produced by CD4(+) T cells, but unexpectedly GrB is also produced by CD4(+) T cells in response to stimulation with LmES, which were found to be as effective as soluble Leishmania antigens to induce proliferation and cytokine production by PBMCs from immune individuals. To address the question of regulatory T cell (Tregs) involvement, the frequency of circulating Tregs was assessed and found to be higher in HZCL individuals compared to that of HC. Furthermore, both CD4(+)CD25(+) and CD4(+)CD25(-) T cells, purified from HZCL individuals, produced IFN-γ and GrB when stimulated with LmES. Additional experiments showed that CD4(+)CD25(+)CD127(dim/-) Tregs were involved in GrB production. Collectively, our data indicate that LmES are immunogenic in humans and emphasize the involvement of CD4(+) T cells including activated and regulatory T cells in the immune response against parasite antigens.

Over-expression of EGFR is closely correlated to poor prognosis in Tunisian patients with non-small cell lung adenocarcinoma.

We studied epidermal growth factor receptor (EGFR) expression profile with the aim of an individualized therapy for patients with non-small cell lung cancer (NSCLC) from whom tumor materials are not sufficient for molecular investigations. Using immunohistochemistry, we found a markedly increased EGFR expression with significant difference in term of intensity and distribution from normal mucosa to primary tumors (p < 0.05). Furthermore, patients with EGFR positive tumors had significantly shorter survival than those with EGFR negative tumors (p = 0.0001). Thus, EGFR over-expression is a valuable prognostic marker to predict poor outcome in Tunisian patients with NSCLC.

Association of the long QT syndrome With goiter and deafness.

We report on the long QT syndrome occurring in conjunction with nontoxic multinodular goiter and sensorineural deafness in several siblings of a large family. Autosomal and X-linked recessive and dominant modes of inheritance are possible for the different phenotypes. The affected family members had various phenotype combinations, suggesting variable expressivity and incomplete penetrance.

[Dubin-Johnson syndrome: molecular basis and pathogenesis]. / Le syndrome de Dubin-Johnson: bases moleculaires et pathogenie.

The Dubin-Johnson syndrome (DJS) is an autosomal recessive liver disorder characterized by a chronic conjugated hyperbilirubinemia a dark greenish appearance of liver tissue, a double peaked sulfobromophthalein clearance curve, and a characteristic lysosomal accumulation of black pigment "melanine-like" in the hepatocytes. Laboratory datas indicated an increased urinary excretion of coproporphrin isomer I and leukotriene metabolites. In an effort to understand the morphological pattern and the pathogenesis of this disease we reviewed four cases of DJS.