Human papilloma virus-16-specific CD8+ T-cell expansions characterize different clinical forms of lichen planus and not lichen sclerosus et atrophicus.

Lichen planus (LP) is a cutaneomucosal chronic inflammatory disease characterized by a CD8+ cytotoxic T-lymphocytes (CTL) infiltrate. In erosive oral LP, we found HPV16-specific activated CTL in lesions, supporting a pathogenic contribution of HPV16. Here, we investigated whether a similar scenario occurs in other clinical forms of LP and in lichen sclerosus et atrophicus (LSA), another chronic disease also affecting the mucosa and/or the skin. Blood CTL from LP and LSA patients expressed significant higher levels of granzyme B, perforin and CD107a proteins than healthy donors. Expansions of TCRVß3+ CTL, with presence of TCR clonotypes identical to those previously detected in erosive oral LP, were found both in blood and mucosal/skin lesions of LP, and not of LSA patients. These expansions were enriched with HPV16-specific CD8+ T-cells as shown by their recognition of the E711-20 immunodominant epitope. In LSA patients, the peripheral repertoire of CTL was oligoclonal for TCRVß6+ CTL. Finally, although patients with LP and LSA have developed antibodies against HPV16 capsid L1, antibodies against HPV16 E6 were only observed in patients with LP. Overall, our data collectively suggest an involvement of HPV16-specific CTL in different clinical forms of LP, not only in erosive oral LP, while a different scenario operates in LSA.

HMGB1 Is Involved in IFN-α Production and TRAIL Expression by HIV-1-Exposed Plasmacytoid Dendritic Cells: Impact of the Crosstalk with NK Cells.

Plasmacytoid dendritic cells (pDCs) are innate sensors of viral infections and important mediators of antiviral innate immunity through their ability to produce large amounts of IFN-α. Moreover, Toll-like receptor 7 (TLR7) and 9 (TLR9) ligands, such as HIV and CpG respectively, turn pDCs into TRAIL-expressing killer pDCs able to lyse HIV-infected CD4+ T cells. NK cells can regulate antiviral immunity by modulating pDC functions, and pDC production of IFN-α as well as cell-cell contact is required to promote NK cell functions. Impaired pDC-NK cell crosstalk was reported in the setting of HIV-1 infection, but the impact of HIV-1 on TRAIL expression and innate antiviral immunity during this crosstalk is unknown. Here, we report that low concentrations of CCR5-tropic HIV-1Ba-L promote the release of pro-inflammatory cytokines such as IFN-α, TNF-α, IFN-γ and IL-12, and CCR5-interacting chemokines (MIP-1α and MIP-1ß) in NK-pDCs co-cultures. At high HIV-1BaL concentrations, the addition of NK cells did not promote the release of these mediators, suggesting that once efficiently triggered by the virus, pDCs could not integrate new activating signals delivered by NK cells. However, high HIV-1BaL concentrations were required to trigger IFN-α-mediated TRAIL expression at the surface of both pDCs and NK cells during their crosstalk. Interestingly, we identified the alarmin HMGB1, released at pDC-NK cell synapse, as an essential trigger for the secretion of IFN-α and IFN-related soluble mediators during the interplay of HIV-1 exposed pDCs with NK cells. Moreover, HMGB1 was found crucial for mTRAIL translocation to the plasma membrane of both pDCs and NK cells during their crosstalk following pDC exposure to HIV-1. Data from serum analyses of circulating HMGB1, HMGB1-specific antibodies, sTRAIL and IP-10 in a cohort of 67 HIV-1+ patients argue for the in vivo relevance of these observations. Altogether, these findings identify HMGB1 as a trigger for IFN-α-mediated TRAIL expression at the surface of pDCs and NK cells, and they suggest a novel mechanism of innate control of HIV-1 infection.

MAIT cells detect and efficiently lyse bacterially-infected epithelial cells.

Mucosal associated invariant T cells (MAIT) are innate T lymphocytes that detect a large variety of bacteria and yeasts. This recognition depends on the detection of microbial compounds presented by the evolutionarily conserved major-histocompatibility-complex (MHC) class I molecule, MR1. Here we show that MAIT cells display cytotoxic activity towards MR1 overexpressing non-hematopoietic cells cocultured with bacteria. The NK receptor, CD161, highly expressed by MAIT cells, modulated the cytokine but not the cytotoxic response triggered by bacteria infected cells. MAIT cells are also activated by and kill epithelial cells expressing endogenous levels of MRI after infection with the invasive bacteria Shigella flexneri. In contrast, MAIT cells were not activated by epithelial cells infected by Salmonella enterica Typhimurium. Finally, MAIT cells are activated in human volunteers receiving an attenuated strain of Shigella dysenteriae-1 tested as a potential vaccine. Thus, in humans, MAIT cells are the most abundant T cell subset able to detect and kill bacteria infected cells.

Apoptosis as an HIV strategy to escape immune attack.

Viruses have evolved numerous mechanisms to evade the host immune system and one of the strategies developed by HIV is to activate apoptotic programmes that destroy immune effectors. Not only does the HIV genome encode pro-apoptotic proteins, which kill both infected and uninfected lymphocytes through either members of the tumour-necrosis factor family or the mitochondrial pathway, but it also creates a state of chronic immune activation that is responsible for the exacerbation of physiological mechanisms of clonal deletion. This review discusses the molecular mechanisms by which HIV manipulates the apoptotic machinery to its advantage, assesses the functional consequences of this process and evaluates how new therapeutics might counteract this strategy.

Highlights from the 2014 International Symposium on HIV & Emerging Infectious Diseases (ISHEID): from cART management to the end of the HIV pandemic.

The 2014 International Symposium on HIV and Emerging Infectious Diseases (ISHEID) provided a forum for investigators to hear the latest research developments in the clinical management of HIV and HCV infections as well as HIV cure research. Combined anti-retroviral therapy (c-ART) has had a profound impact on the disease prognosis and transformed this infection into a chronic disease. However, HIV is able to persist within the infected host and the pandemic is still growing. The main 2014 ISHEID theme was, hence "Together for a world without HIV and AIDS". In this report we not only give details on this main topic but also summarize what has been discussed in the areas of HCV coinfection and present a short summary on currently emerging viral diseases.

IFN-α and CD46 stimulation are associated with active lupus and skew natural T regulatory cell differentiation to type 1 regulatory T (Tr1) cells.

Immune suppressive activities exerted by regulatory T-cell subsets have several specific functions, including self-tolerance and regulation of adaptive immune reactions, and their dysfunction can lead to autoimmune diseases and contribute to AIDS and cancer. Two functionally distinct regulatory T-cell subsets are currently identified in peripheral tissues: thymus-developed natural T regulatory cells (nTregs) controlling self-tolerance and antiinflammatory IL-10-secreting type 1 regulatory T cells (Tr1) derived from Ag-stimulated T cells, which regulate inflammation-dependent adaptive immunity and minimize immunopathology. We establish herein that cell contact-mediated nTreg regulatory function is inhibited by inflammation, especially in the presence of the complement C3b receptor (CD46). Instead, as with other T-cell subsets, the latter inflammatory conditions of stimulation skew nTreg differentiation to Tr1 cells secreting IL-10, an effect potentiated by IFN-α. The clinical relevance of these findings was verified in a study of 152 lupus patients, in which we showed that lupus nTreg dysfunction is not due to intrinsic defects but is rather induced by C3b stimulation of CD46 and IFN-α and that these immune components of inflammation are directly associated with active lupus. These results provide a rationale for using anti-IFN-α Ab immunotherapy in lupus patients.

IFN-α and TRAIL: a double edge sword in HIV-1 disease?

IFN-α is rapidly upregulated in response to viral infections and it is an essential player in innate immunity against viruses. pDCs are the most potent IFN-α-producing cells and serve as an essential link between innate and adaptive immunity. The fate of pDCs in the course of HIV-1 infection is still a matter of debate, and the question of the detrimental role of chronic production of IFN-α remains open. In particular, IFN-α has been shown to induce the expression of the death ligand TRAIL on pDCs, transforming them into killer pDCs that may contribute to the destruction of CD4(+) T cells, the hallmark of HIV-1-induced disease. In this review, we discuss our current understanding of the protective and pathogenic roles of both IFN-α and TRAIL in HIV-1 disease.

Escape of HIV-1-infected dendritic cells from TRAIL-mediated NK cell cytotoxicity during NK-DC cross-talk--a pivotal role of HMGB1.

Early stages of Human Immunodeficiency Virus-1 (HIV-1) infection are associated with local recruitment and activation of important effectors of innate immunity, i.e. natural killer (NK) cells and dendritic cells (DCs). Immature DCs (iDCs) capture HIV-1 through specific receptors and can disseminate the infection to lymphoid tissues following their migration, which is associated to a maturation process. This process is dependent on NK cells, whose role is to keep in check the quality and the quantity of DCs undergoing maturation. If DC maturation is inappropriate, NK cells will kill them ("editing process") at sites of tissue inflammation, thus optimizing the adaptive immunity. In the context of a viral infection, NK-dependent killing of infected-DCs is a crucial event required for early elimination of infected target cells. Here, we report that NK-mediated editing of iDCs is impaired if DCs are infected with HIV-1. We first addressed the question of the mechanisms involved in iDC editing, and we show that cognate NK-iDC interaction triggers apoptosis via the TNF-related apoptosis-inducing ligand (TRAIL)-Death Receptor 4 (DR4) pathway and not via the perforin pathway. Nevertheless, once infected with HIV-1, DC(HIV) become resistant to NK-induced TRAIL-mediated apoptosis. This resistance occurs despite normal amounts of TRAIL released by NK cells and comparable DR4 expression on DC(HIV). The escape of DC(HIV) from NK killing is due to the upregulation of two anti-apoptotic molecules, the cellular-Flice like inhibitory protein (c-FLIP) and the cellular inhibitor of apoptosis 2 (c-IAP2), induced by NK-DC(HIV) cognate interaction. High-mobility group box 1 (HMGB1), an alarmin and a key mediator of NK-DC cross-talk, was found to play a pivotal role in NK-dependent upregulation of c-FLIP and c-IAP2 in DC(HIV). Finally, we demonstrate that restoration of DC(HIV) susceptibility to NK-induced TRAIL killing can be obtained either by silencing c-FLIP and c-IAP2 by specific siRNA, or by inhibiting HMGB1 with blocking antibodies or glycyrrhizin, arguing for a key role of HMGB1 in TRAIL resistance and DC(HIV) survival. These findings provide evidence for a new strategy developed by HIV to escape immune attack, they challenge the question of the involvement of HMGB1 in the establishment of viral reservoirs in DCs, and they identify potential therapeutic targets to eliminate infected DCs.

Integrative study of pandemic A/H1N1 influenza infections: design and methods of the CoPanFlu-France cohort.

BACKGROUND: The risk of influenza infection depends on biological characteristics, individual or collective behaviors and the environmental context. The Cohorts for Pandemic Influenza (CoPanFlu) France study was set up in 2009 after the identification of the novel swine-origin A/H1N1 pandemic influenza virus. This cohort of 601 households (1450 subjects) representative for the general population aims at using an integrative approach to study the risk and characteristics of influenza infection as a complex combination of data collected from questionnaires regarding sociodemographic, medical, behavioral characteristics of subjects and indoor environment, using biological samples or environmental databases. METHODS/DESIGN: Households were included between December 2009 and July 2010. The design of this study relies on systematic follow-up visits between influenza seasons and additional visits during influenza seasons, when an influenza-like illness is detected in a household via an active surveillance system. During systematic visits, a nurse collects individual and environmental data on questionnaires and obtains blood samples from all members of the household. When an influenza-like-illness is detected, a nurse visits the household three times during the 12 following days, and collects data on questionnaires regarding exposure and symptoms, and biological samples (including nasal swabs) from all subjects in the household. The end of the follow-up period is expected in fall 2012. DISCUSSION: The large amount of data collected throughout the follow-up will permit a multidisciplinary study of influenza infections. Additional data is being collected and analyzed in this ongoing cohort. The longitudinal analysis of these households will permit integrative analyses of complex phenomena such as individual, collective and environmental risk factors of infection, routes of transmission, or determinants of the immune response to infection or vaccination.

Cell-Mediated Immunity to NAGLU Transgene Following Intracerebral Gene Therapy in Children With Mucopolysaccharidosis Type IIIB Syndrome.

Mucopolysaccharidosis type IIIB syndrome (Sanfilippo disease) is a rare autosomic recessif disorder caused by mutations in the α-N-acetylglucosaminidase (NAGLU) gene coding for a lysosomal enzyme, leading to neurodegeneration and progressive deterioration of cognitive abilities in affected children. To supply the missing enzyme, several recent human gene therapy trials relied on the deposit of adeno-associated virus (AAV) vectors directly into the brain. We reported safety and efficacy of an intracerebral therapy in a phase 1/2 clinical trial (https://clinicaltrials.gov/ct2/show/NCT03300453), with a recombinant AAV serotype 2/5 (rAAV2/5) coding human NAGLU in four children with MPS IIIB syndrome receiving immunosuppression. It was reported that AAV-mediated gene therapies might elicit a strong host immune response resulting in decreased transgene expression. To address this issue, we performed a comprehensive analysis of cellular immunity and cytokine patterns generated against the therapeutic enzyme in the four treated children over 5.5 years of follow-up. We report the emergence of memory and polyfunctional CD4+ and CD8+ T lymphocytes sensitized to the transgene soon after the start of therapy, and appearing in peripheral blood in waves throughout the follow-up. However, this response had no apparent impact on CNS transgene expression, which remained stable 66 months after surgery, possibly a consequence of the long-term immunosuppressive treatment. We also report that gene therapy did not trigger neuroinflammation, evaluated through the expression of cytokines and chemokines in patients' CSF. Milder disease progression in the youngest patient was found associated with low level and less differentiated circulating NAGLU-specific T cells, together with the lack of proinflammatory cytokines in the CSF. Findings in this study support a systematic and comprehensive immunomonitoring approach for understanding the impact immune reactions might have on treatment safety and efficacy of gene therapies.

Intracerebral Gene Therapy in Four Children with Sanfilippo B Syndrome: 5.5-Year Follow-Up Results.

We report the safety (primary endpoint) and efficacy (secondary endpoint) of a novel intracerebral gene therapy at 5.5 years of follow-up in children with Sanfilippo B. An uncontrolled, phase 1/2 clinical trial was performed in four patients aged 20, 26, 30, and 53 months. Treatment consisted of 16 intracerebral and cerebellar deposits of a recombinant adeno-associated viral vector encoding human α-N-acetylglucosaminidase (rAAV2/5-hNAGLU) plus immunosuppression. An intermediate report at 30 months was previously published. Thirty treatment-emergent adverse events were reported between 30 and 66 months after surgery, including three classified as severe with no serious drug reactions. At 5.5 years, NAGLU activity was persistently detected in the lumbar cerebrospinal fluid (18% of unaffected control level). Circulating T cells reacting against NAGLU peptides were present, indicating a lack of acquired tolerance. Patients 2, 3, and 4 showed progressive brain atrophy and neurocognitive evolution that did not differ from untreated Sanfilippo A/B children. Patient 1, enrolled at 20 months of age, had a milder disease with normal brain imaging and a significantly better cognitive outcome than the three other patients and untreated patients, although not equivalent to normal children. After 5.5 years, the primary endpoint of this study was achieved with a good safety profile of the proposed treatment. We have also observed sustained enzyme production in the brain and absence of immunological tolerance. Cognitive benefit was not confirmed in the three oldest patients. Milder disease in the youngest patient supports further investigations of adeno-associated vector-mediated intracerebral gene therapy in Sanfilippo B.

Safety and immunogenicity of a synthetic carbohydrate conjugate vaccine against Shigella flexneri 2a in healthy adult volunteers: a phase 1, dose-escalating, single-blind, randomised, placebo-controlled study.

BACKGROUND: Shigella remains in the top four pathogens responsible for moderate to severe diarrhoea in children below 5 years of age. The shigella O-specific polysaccharide (O-SP) is a promising vaccine target. We developed a conjugate vaccine prototype incorporating a unique well defined synthetic oligosaccharide hapten, chemically designed for optimal antigenic, conformational, structural, and functional mimicry of the O-SP from Shigella flexneri 2a (SF2a). We aimed to assess the safety, tolerability, and immunogenicity of this original synthetic oligosaccharide-based vaccine candidate, SF2a-TT15, conceived to drive the antibody response towards the key protective determinants of the native lipopolysaccharide antigen, in a first-in-human phase 1 study. METHODS: We did a first-in-human, dose-escalating, single-blind, observer-masked, randomised, placebo-controlled study at the Clinical Research Center of Tel Aviv Sourasky Medical Center (Israel). Participants were healthy adults aged 18-45 years with low titres of serum SF2a-specific IgG antibodies. 64 eligible participants were assigned to one of two cohorts. 32 participants in each of the two cohorts were randomly assigned via computer-generated algorithm in a stepwise manner to receive the 2 µg (cohort 1) and 10 µg oligosaccharide dose (cohort 2) of the SF2a-TT15 vaccine candidate non-adjuvanted or adjuvanted with aluminium hydroxide (alum) or matching placebos. The vaccine was administered as three single intramuscular injections into the arm, 28 days apart. The primary outcome was the incidence and severity of adverse events, which were assessed in the intention-to-treat safety population analysis including all participants who were randomly assigned and received at least one vaccine or placebo injection. The immunogenicity endpoints were secondary outcomes and were analysed in all participants who were randomly assigned, received all of the assigned injections before the time of the immunogenicity assessment, and provided blood samples for immunological follow-up (per-protocol immunogenicity analysis). The study is registered with ClinicalStudies.gov, NCT02797236 and is completed. FINDINGS: Of 203 volunteers initially screened, 64 participants were enrolled between Sept 20, 2016, and Sept 26, 2017. In each of the two cohorts, 12 participants received the adjuvanted vaccine, 12 received the non-adjuvanted vaccine and eight received the matching placebo (four each). The SF2a-TT15 glycoconjugate was well tolerated at both doses. No serious or severe adverse events occurred. Overall, seven (88%) of eight to 12 (100%) of 12 in each group of volunteers had one adverse event or more after receiving the study agents with the majority of adverse events, 300 (98%) of 307, considered mild in intensity. Of the seven adverse events defined as moderate in severity, one (nausea) was suspected to be related to the vaccine candidate. At all post-immunisation days and for both oligosaccharide doses, whether adjuvanted or not, SF2a-TT15 induced significantly higher serum IgG anti-SF2a lipopolysaccharide geometric mean titres (GMTs) as compared with baseline or with the corresponding GMTs in placebo recipients (p<0·01). After one injection, the non-adjuvanted 10 µg oligosaccharide dose induced a 27-times increase in IgG GMT (5080 vs 189) and the non-adjuvanted 2 µg oligosaccharide dose induced a five-times increase (1411 vs 283), compared with baseline. Alum enhanced the specific IgG response at 2 µg oligosaccharide dose after the third injection (GMTs 3200 vs 1176, p=0.045). INTERPRETATION: SF2a-TT15 was safe and well tolerated and induced high titres of anti-SF2a LPS IgG antibodies. These results support further evaluation of this original synthetic oligosaccharide-protein conjugate vaccine candidate for safety, immunogenicity, and protective efficacy in target populations. FUNDING: The European Union Seventh Framework Programme.

A hypomorphic R229Q Rag2 mouse mutant recapitulates human Omenn syndrome.

Rag enzymes are the main players in V(D)J recombination, the process responsible for rearrangement of TCR and Ig genes. Hypomorphic Rag mutations in humans, which maintain partial V(D)J activity, cause a peculiar SCID associated with autoimmune-like manifestations, Omenn syndrome (OS). Although a deficient ability to sustain thymopoiesis and to produce a diverse T and B cell repertoire explains the increased susceptibility to severe infections, the molecular and cellular mechanisms underlying the spectrum of clinical and immunological features of OS remain poorly defined. In order to better define the molecular and cellular pathophysiology of OS, we generated a knockin murine model carrying the Rag2 R229Q mutation previously described in several patients with OS and leaky forms of SCID. These Rag2(R229Q/R229Q) mice showed oligoclonal T cells, absence of circulating B cells, and peripheral eosinophilia. In addition, activated T cells infiltrated gut and skin, causing diarrhea, alopecia, and, in some cases, severe erythrodermia. These findings were associated with reduced thymic expression of Aire and markedly reduced numbers of naturally occurring Tregs and NKT lymphocytes. In conclusion, Rag2(R229Q/R229Q) mice mimicked most symptoms of human OS; our findings support the notion that impaired immune tolerance and defective immune regulation are involved in the pathophysiology of OS.

A single cycle of rituximab for the treatment of severe pemphigus.

BACKGROUND: The combination of multiple cycles of rituximab and intravenous immune globulins has been reported to be effective in patients with severe pemphigus. The aim of this study was to assess the efficacy of a single cycle of rituximab in severe types of pemphigus. METHODS: We studied 21 patients with pemphigus whose disease had not responded to an 8-week course of 1.5 mg of prednisone per kilogram of body weight per day (corticosteroid-refractory disease), who had had at least two relapses despite doses of prednisone higher than 20 mg per day (corticosteroid-dependent disease), or who had severe contraindications to corticosteroids. The patients were treated with four weekly infusions of 375 mg of rituximab per square meter of body-surface area. The primary end point was complete remission 3 months after the end of rituximab treatment; complete remission was defined as epithelialization of all skin and mucosal lesions. RESULTS: Eighteen of 21 patients (86%; 95% confidence interval, 64 to 97%) had a complete remission at 3 months. The disease relapsed in nine patients after a mean of 18.9+/-7.9 months. After a median follow-up of 34 months, 18 patients (86%) were free of disease, including 8 who were not receiving corticosteroids; the mean prednisone dose decreased from 94.0+/-10.2 to 12.0+/-7.5 mg per day (P=0.04) in patients with corticosteroid-refractory disease and from 29.1+/-12.4 to 10.9+/-16.5 mg per day (P=0.007) in patients with corticosteroid-dependent disease. Pyelonephritis developed in one patient 12 months after rituximab treatment, and one patient died of septicemia 18 months after rituximab treatment. These patients had a profound decrease in the number of circulating B lymphocytes but normal serum levels of IgG. CONCLUSIONS: A single cycle of rituximab is an effective treatment for pemphigus. Because of its potentially severe side effects, its use should be limited to the most severe types of the disease. (ClinicalTrials.gov number, NCT00213512 [ClinicalTrials.gov].).

Zika Virus Inhibits IFN-α Response by Human Plasmacytoid Dendritic Cells and Induces NS1-Dependent Triggering of CD303 (BDCA-2) Signaling.

Zika virus (ZIKV) dramatically emerged in French Polynesia and subsequently in the Americas where it has been associated with severe neurological complications in adults and newborns, respectively. Although plasmacytoid dendritic cells (pDCs) are a key sensor of viral infection and are critical for initiating an antiviral response, little is known about the impact of ZIKV infection on pDCs. Here, we investigated the susceptibility of human pDCs to infection with multiple strains of ZIKV and further investigated the impact of infection on pDCs functions. We observed that pDCs were refractory to cell-free ZIKV virions but were effectively infected when co-cultured with ZIKV-infected cells. However, exposure of pDCs to ZIKV-infected cells resulted in limited maturation/activation with significant down regulation of CD303 expression, a severe impairment of inflammatory cytokine production, and an inability to mount an IFN-α response. We show that ZIKV developed a strategy to inhibit the IFN-α response in primary human pDCs likely mediated through NS1-dependent CD303 signaling, thus suggesting a new mechanism of immune evasion.

SUGT1 controls susceptibility to HIV-1 infection by stabilizing microtubule plus-ends.

Understanding the viral-host cell interface during HIV-1 infection is a prerequisite for the development of innovative antiviral therapies. Here we show that the suppressor of G2 allele of skp1 (SUGT1) is a permissive factor for human immunodeficiency virus (HIV)-1 infection. Expression of SUGT1 increases in infected cells on human brain sections and in permissive host cells. We found that SUGT1 determines the permissiveness to infection of lymphocytes and macrophages by modulating the nuclear import of the viral genome. More importantly, SUGT1 stabilizes the microtubule plus-ends (+MTs) of host cells (through the modulation of microtubule acetylation and the formation of end-binding protein 1 (EB1) comets). This effect on microtubules favors HIV-1 retrograde trafficking and replication. SUGT1 depletion impairs the replication of HIV-1 patient primary isolates and mutant virus that is resistant to raltegravir antiretroviral agent. Altogether our results identify SUGT1 as a cellular factor involved in the post-entry steps of HIV-1 infection that may be targeted for new therapeutic approaches.

HIV-1 Envelope Overcomes NLRP3-Mediated Inhibition of F-Actin Polymerization for Viral Entry.

Purinergic receptors and nucleotide-binding domain leucine-rich repeat containing (NLR) proteins have been shown to control viral infection. Here, we show that the NLR family member NLRP3 and the purinergic receptor P2Y2 constitutively interact and regulate susceptibility to HIV-1 infection. We found that NLRP3 acts as an inhibitory factor of viral entry that represses F-actin remodeling. The binding of the HIV-1 envelope to its host cell receptors (CD4, CXCR4, and/or CCR5) overcomes this restriction by stimulating P2Y2. Once activated, P2Y2 enhances its interaction with NLRP3 and stimulates the recruitment of the E3 ubiquitin ligase CBL to NLRP3, ultimately leading to NLRP3 degradation. NLRP3 degradation is permissive for PYK2 phosphorylation (PYK2Y402∗) and subsequent F-actin polymerization, which is required for the entry of HIV-1 into host cells. Taken together, our results uncover a mechanism by which HIV-1 overcomes NLRP3 restriction that appears essential for the accomplishment of the early steps of HIV-1 entry.

A novel immunodeficiency associated with hypomorphic RAG1 mutations and CMV infection.

Amorphic mutations in the recombination activating genes RAG1 and RAG2 have been reported to cause T- B- SCID, whereas hypomorphic mutations led to the expansion of a few autoimmune T cell clones responsible for the Omenn syndrome phenotype. We report here a novel clinical and immunological phenotype associated with recessive RAG1 hypomorphic mutations in 4 patients from 4 different families. The immunological phenotype consists of the oligoclonal expansion of TCR gammadelta T cells combined with TCR alphabeta T cell lymphopenia. The clinical phenotype consists of severe, disseminated CMV infection and autoimmune blood cell manifestations. Repertoire studies suggest that CMV infection, in the setting of this particular T cell immunodeficiency, may have driven the TCR gammadelta T cell clonal expansion. This observation extends the range of clinical and immunological phenotypes associated with RAG mutations, emphasizing the role of the genetic background and microbial environment in determining disease phenotype.