Lower numbers of natural killer T cells in HIV-1 and Mycobacterium leprae co-infected patients

Natural killer T (NKT) cells are a heterogeneous population of lymphocytes that recognize antigens presented by CD1d and have attracted attention because of their potential role linking innate and adaptive immune responses. Peripheral NKT cells display a memory-activated phenotype and can rapidly secrete large amounts of pro-inflammatory cytokines upon antigenic activation. In this study, we evaluated NKT cells in the context of patients co-infected with HIV-1 and Mycobacterium leprae. The volunteers were enrolled into four groups: 22 healthy controls, 23 HIV-1-infected patients, 20 patients with leprosy and 17 patients with leprosy and HIV-1-infection. Flow cytometry and ELISPOT assays were performed on peripheral blood mononuclear cells. We demonstrated that patients co-infected with HIV-1 and M.leprae have significantly lower NKT cell frequencies [median 0.022%, interquartile range (IQR): 0.0070.051] in the peripheral blood when compared with healthy subjects (median 0.077%, IQR: 0.0320.405, P < 0.01) or HIV-1 mono-infected patients (median 0.072%, IQR: 0.0300.160, P < 0.05). Also, more NKT cells from co-infected patients secreted interferon-? after stimulation with DimerX, when compared with leprosy mono-infected patients (P = 0.05). These results suggest that NKT cells are decreased in frequency in HIV-1 and M.leprae co-infected patients compared with HIV-1 mono-infected patients alone, but are at a more activated state. Innate immunity in human subjects is strongly influenced by their spectrum of chronic infections, and in HIV-1-infected subjects, a concurrent mycobacterial infection probably hyper-activates and lowers circulating NKT cell numbers.National Institutes of Health [R01-AI52731, AI060379]Fogarty International Center [D43 TW00003]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo [04/15856-9/Kallas, 2010/05845-0/Kallas]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Brazilian Ministry of Science and Technology [484230/2011-5]New York Community Trus

DUX4c Is Up-Regulated in FSHD. It Induces the MYF5 Protein and Human Myoblast Proliferation

Facioscapulohumeral muscular dystrophy (FSHD) is a dominant disease linked to contractions of the D4Z4 repeat array in 4q35. We have previously identified a double homeobox gene (DUX4) within each D4Z4 unit that encodes a transcription factor expressed in FSHD but not control myoblasts. DUX4 and its target genes contribute to the global dysregulation of gene expression observed in FSHD. We have now characterized the homologous DUX4c gene mapped 42 kb centromeric of the D4Z4 repeat array. It encodes a 47-kDa protein with a double homeodomain identical to DUX4 but divergent in the carboxyl-terminal region. DUX4c was detected in primary myoblast extracts by Western blot with a specific antiserum, and was induced upon differentiation. The protein was increased about 2-fold in FSHD versus control myotubes but reached 2-10-fold induction in FSHD muscle biopsies. We have shown by Western blot and by a DNA-binding assay that DUX4c over-expression induced the MYF5 myogenic regulator and its DNA-binding activity. DUX4c might stabilize the MYF5 protein as we detected their interaction by co-immunoprecipitation. In keeping with the known role of Myf5 in myoblast accumulation during mouse muscle regeneration DUX4c over-expression activated proliferation of human primary myoblasts and inhibited their differentiation. Altogether, these results suggested that DUX4c could be involved in muscle regeneration and that changes in its expression could contribute to the FSHD pathology

ccdc80-l1 Is Involved in Axon Pathfinding of Zebrafish Motoneurons

Axon pathfinding is a subfield of neural development by which neurons send out axons to reach the correct targets. In particular, motoneurons extend their axons toward skeletal muscles, leading to spontaneous motor activity. In this study, we identified the zebrafish Ccdc80 and Ccdc80-like1 (Ccdc80-l1) proteins in silico on the basis of their high aminoacidic sequence identity with the human CCDC80 (Coiled-Coil Domain Containing 80). We focused on ccdc80-l1 gene that is expressed in nervous and non-nervous tissues, in particular in territories correlated with axonal migration, such as adaxial cells and muscle pioneers. Loss of ccdc80-l1 in zebrafish embryos induced motility issues, although somitogenesis and myogenesis were not impaired. Our results strongly suggest that ccdc80-l1 is involved in axon guidance of primary and secondary motoneurons populations, but not in their proper formation. ccdc80-l1 has a differential role as regards the development of ventral and dorsal motoneurons, and this is consistent with the asymmetric distribution of the transcript. The axonal migration defects observed in ccdc80-l1 loss-of-function embryos are similar to the phenotype of several mutants with altered Hedgehog activity. Indeed, we reported that ccdc80-l1 expression is positively regulated by the Hedgehog pathway in adaxial cells and muscle pioneers. These findings strongly indicate ccdc80-l1 as a down-stream effector of the Hedgehog pathway

Thalidomide and a Thalidomide Analogue Drug Costimulate Virus-Specific CD8+ T Cells In Vitro

CD8+ T cell immunity is critical for protection from viral disease, such as that caused by the human immunodeficiency virus (HIV) or cytomegalovirus (CMV). It is therefore important to identify therapies that can boost antiviral immunity. The recent finding that thalidomide acts as a T cell costimulator suggested that this drug may boost antiviral CD8+ T cell responses. In this in vitro study, in a human autologous CD8+ T cell/dendritic cell (DC) coculture system, thalidomide and a potent thalidomide analogue were shown to enhance virus-specific CD8+ T cell cytokine production and cytotoxic activity. The drug-enhanced antiviral activity was noted in cells from both healthy donors and persons chronically coinfected with HIV and CMV. This stimulatory effect was directed at CD8+ T cells, and not DCs. These results suggest an application for thalidomide and the thalidomide analogue as a novel immune-adjuvant therapy in chronic viral infection

A Potential Role for Complement in Immune Evasion by Mycobacterium leprae

Lepromatous leprosy is a model of immune evasion wherein pathogen-specific IL-10-secreting T cells and concomitant failure of Th-1 immunity permit uncontrolled proliferation of the intracellular pathogen, Mycobacterium leprae (M. leprae). The mechanism of this immune escape is unknown. Here, the authors report that phenolic glycolipid-1 (PGL-1), a major and distinguishing feature of the M. leprae cell wall, is expressed in the cell membrane of M. leprae-infected human dendritic cells, where it can activate complement in human serum. The authors demonstrate that PGL-1 and the C3 component of complement colocalize in lipid rafts in the dendritic cell membrane, and enter the immune synapse upon co-culture of M. leprae-infected DCs and T cells. Hence, activated C3 is strategically located to costimulate naive T cells via the complement regulatory protein, CD46, a process known to stimulate the differentiation of IL-10-secreting regulatory T cells. These observations suggest a potential novel mechanism of immune evasion, wherein M. leprae may subvert host natural immunity to provoke an adaptive response that favors bacillary survival.Dana FoundationHeiser Program for Research in Leprosy and TuberculosisUniversity of Miami Diabetes Research InstituteJuvenile Diabetes Research FoundationSylvester Comprehensive Cancer CenterUniv Miami, Miller Sch Med, Dept Microbiol & Immunol, Miami, FL 33136 USAUniv Fed Sao Paulo, Sao Paulo, BrazilUniv Miami, Miller Sch Med, Dept Dermatol, Miami, FL 33136 USAUniv Fed Sao Paulo, Sao Paulo, BrazilWeb of Scienc

A whole blood assay to assess peripheral blood dendritic cell function in response to Toll-like receptor stimulation

We report a practical technique to assess peripheral blood dendritic cell (DC) maturation and function in whole blood (WB), which requires minimal blood volumes and minimizes ex vivo manipulations of clinical specimens. We determined optimal conditions for flow cytometric analysis of markers of DC maturation, including CCR7, CD25, CD80 and CD83, and of the intracellular cytokines, tumor necrosis factor-α (TNF-α) and interferon-α (IFN-α), in both myeloid (mDC) and plasmacytoid (pDC) lineages. We demonstrate concentration-dependent production of these cytokines by DC following short-term stimulation with ligands to Toll-like receptors (TLRs) 2/1, 3, 4, 7, 8 and 9. Kinetic studies revealed maximal TNF-α and IFN-α protein expression at 2 to 3 h after stimulation with certain TLR ligands. Finally, utilizing cells from a cohort of eight healthy donors, we compared DC responses to TLR activation in WB, freshly isolated peripheral blood mononuclear cells (PBMC) and cryopreserved PBMC. We found that TNF-α responses were essentially preserved, but IFN-α responses were profoundly diminished or entirely abrogated following cryopreservation. In conclusion, we propose that WB analysis of peripheral DC function is a rapid, reliable and simple method to evaluate TLR function in clinical specimens, which obviates artifact-prone cell purification. The major impact of cryopreservation on some DC responses further strengthens the case for a rapid method that uses fresh blood

Selective Defect in Plasmacyoid Dendritic Cell Function in a Patient with AIDS-Associated Atypical Genital Herpes Simplex Vegetans Treated with Imiquimod

We report a case of acquired immunodeficiency syndrome (AIDS)-associated, acyclovir-refractory genital herpes infection treated with topical imidazoquinoline therapy. The patient's plasmacytoid dendritic cells made a robust interferon-α response following in vitro stimulation with imidazoquinoline but not with herpes simplex virus. We hypothesize that disease resulting from defective herpes simplex virus-stimulated interferon-α may be overcome by stimulating intact alternative pathways

Prolyl hydroxylase 3 (PHD3) is essential for hypoxic regulation of neutrophilic inflammation in humans and mice

The regulation of neutrophil lifespan by induction of apoptosis is critical for maintaining an effective host response and preventing excessive inflammation. The hypoxia-inducible factor (HIF) oxygen-sensing pathway has a major effect on the susceptibility of neutrophils to apoptosis, with a marked delay in cell death observed under hypoxic conditions. HIF expression and transcriptional activity are regulated by the oxygen-sensitive prolyl hydroxylases (PHD1-3), but the role of PHDs in neutrophil survival is unclear. We examined PHD expression in human neutrophils and found that PHD3 was strongly induced in response to hypoxia and inflammatory stimuli in vitro and in vivo. Using neutrophils from mice deficient in Phd3, we demonstrated a unique role for Phd3 in prolonging neutrophil survival during hypoxia, distinct from other hypoxia-associated changes in neutrophil function and metabolic activity. Moreover, this selective defect in neutrophil survival occurred in the presence of preserved HIF transcriptional activity but was associated with upregulation of the proapoptotic mediator Siva1 and loss of its binding target Bcl-xL. In vivo, using an acute lung injury model, we observed increased levels of neutrophil apoptosis and clearance in Phd3-deficient mice compared with WT controls. We also observed reduced neutrophilic inflammation in an acute mouse model of colitis. These data support what we believe to be a novel function for PHD3 in regulating neutrophil survival in hypoxia and may enable the development of new therapeutics for inflammatory disease