[The Place of Groin, Colson and McGregor Flaps in the Acute Care of Deep Burns to the Hand Dorsum : A Series of 6 Cases In Lille's Burn Centre]

The acute management of deep burns to the dorsum of the hand and fingers represents a challenge for the reconstructive surgeon. The exposure of osteo-tendinous structures often requires flap coverage, in a context where loco-regional or free flaps are not always feasible. The aims of reconstruction are to preserve a maximum of digital length, provide supple tissue, obtain protective sensitivity, and achieve a functional hand at 1 year. We report here on a series of 8 deep burns to the dorsum of the hand. Six hands were covered by Colson abdominal flap-graft and two by pedicled inguinal flap. Four out of 6 patients were reviewed in consultation, 1 patient was lost to follow-up, and 1 patient died. Clinical evaluation was performed by a surgeon other than the operator. Functional results are highly variable. Coverage time varies according to lesion depth and patient severity. Flap weaning took place at an average of 30 days. DASH scores ranged from 17.5 to 93/100, with average to poor total active motion (TAM) scores. The aesthetic result was satisfactory, with a Vancouver score of 4.5/13 on average, and an overall patient opinion of 3.75/10 on the POSAS scale. For deep burns to the dorsum of the hand and fingers, local flaps are rarely possible, and loco-regional flaps are not feasible in cases of associated upper limb damage. For medium to large surface areas, pedicled inguinal flaps and pocketing are two reliable techniques. Nevertheless, they require relative immobilization of the upper limb, which leads to stiffness. The question of digital pinning in the intrinsic or straight position remains unresolved, and does not appear to prevent secondary deformities. There is also a learning curve for these two flaps, even though they are reputed to be easy to lift. McGregor's flap or pocketing can be weighed against free flaps. However, the operating time is long, the surgical technique is complex, and vascular damage is common in the burn patient population. Although there have been enormous technical advances since their descriptions, the pedicled inguinal flap and pocketing remain alternatives to be considered in the acute management of deep burns to the dorsum of the hand. In this presentation, we propose a surgical management algorithm to situate these two techniques in the plastic surgeon's therapeutic armament.

Integration of human stem cell-derived in vitro systems and mouse preclinical models identifies complex pathophysiologic mechanisms in retinal dystrophy

Rare DRAM2 coding variants cause retinal dystrophy with early macular involvement via unknown mechanisms. We found that DRAM2 is ubiquitously expressed in the human eye and expression changes were observed in eyes with more common maculopathy such as Age-related Macular Degeneration (AMD). To gain insights into pathogenicity of DRAM2-related retinopathy, we used a combination of in vitro and in vivo models. We found that DRAM2 loss in human pluripotent stem cell (hPSC)-derived retinal organoids caused the presence of additional mesenchymal cells. Interestingly, Dram2 loss in mice also caused increased proliferation of cells from the choroid in vitro and exacerbated choroidal neovascular lesions in vivo. Furthermore, we observed that DRAM2 loss in human retinal pigment epithelial (RPE) cells resulted in increased susceptibility to stress-induced cell death in vitro and that Dram2 loss in mice caused age-related photoreceptor degeneration. This highlights the complexity of DRAM2 function, as its loss in choroidal cells provided a proliferative advantage, whereas its loss in post-mitotic cells, such as photoreceptor and RPE cells, increased degeneration susceptibility. Different models such as human pluripotent stem cell-derived systems and mice can be leveraged to study and model human retinal dystrophies; however, cell type and species-specific expression must be taken into account when selecting relevant systems.

Rare CIDEC coding variants enriched in age-related macular degeneration patients with small low-luminance deficit cause lipid droplet and fat storage defects

BACKGROUND

The basis of Age-related macular degeneration (AMD) genetic risk has been well documented; however, few studies have looked at genetic biomarkers of disease progression or treatment response within advanced AMD patients. Here we report the first genome-wide analysis of genetic determinants of low-luminance vision deficit (LLD), which is seen as predictive of visual acuity loss and anti-VEGF treatment response in neovascular AMD patients.

METHODS

AMD patients were separated into small- and large-LLD groups for comparison and whole genome sequencing was performed. Genetic determinants of LLD were assessed by common and rare variant genetic analysis. Follow-up functional analysis of rare coding variants identified by the burden test was then performed in vitro.

RESULTS

We identified four coding variants in the CIDEC gene. These rare variants were only present in patients with a small LLD, which has been previously shown to indicate better prognosis and better anti-VEGF treatment response. Our in vitro functional characterization of these CIDEC alleles revealed that all decrease the binding affinity between CIDEC and the lipid droplet fusion effectors PLIN1, RAB8A and AS160. The rare CIDEC alleles all cause a hypomorphic defect in lipid droplet fusion and enlargement, resulting in a decreased fat storage capability in adipocytes.

CONCLUSIONS

As we did not detect CIDEC expression in the ocular tissue affected by AMD, our results suggest that the CIDEC variants do not play a direct role in the eye and influence low-luminance vision deficit via an indirect and systemic effect related to fat storage capacity.

"Extensive necrosis following extravasation of alkali in the crease of the elbow after voluntary intravenous injection: A case report"

Chemical burns are often deep with difficult initial clinical evaluation, especially those due to alkalic agents, which have a strong penetrating power. They therefore require specialized care in a Burn Unit. Self-inflicted burns are infrequent but their management represents a real challenge. We report the case of a 47-year-old referred to our Burn Center for the evaluation of a self-inflicted corrosion with an alkalic agent (soda), injected at the crease of the left elbow. The patient, right handed, was a nurse and had notably a psychiatric history of depressive syndrome. We observed a deep, well-defined necrosis area, associated with intense peri-lesional inflammation and extensive cellulitis. Faced with this unusual clinical appearance for a chemical burn, the patient's questioning was repeated and the patient finally admitted to having injected himself with a basic caustic product intravenously. Surgical treatment was carried out in two stages: debridement with exposure of vascular and neural structures then coverage with a free anterolateral thigh flap. The postoperative consequences were uneventful with a satisfactory functional result. Factitious disorders are underestimated and often misleading. Among factitious disorders, self-inflicted wounds remain a real challenge requiring multidisciplinary management. Many etiologies exist, among which injection of drugs or substances, in any anatomical localization, leading to variable loss of substance. The use of a free flap for acute extravasation is rare but sometimes essential. The anterolateral thigh flap allows good resurfacing on areas with important functional requirements.

Engelures Liées À L’Usage Festif De Protoxyde D’Azote. Cas Clinique Et Revue De La Littérature

The recreational consumption of nitrous oxide has steadily increased in recent years. Before being inhaled, the nitrous oxide is contained in a gas cylinder held firmly between the thighs and then the gas is transferred to a rubber balloon. During the deconditioning steps, the cylinder cools down and causes frostbite. We report the case of six third-degree burns on the inner side of the thighs. At first superficial, this burn will deepen and require surgical management.

Identification of fibronectin 1 as a candidate genetic modifier in a Col4a1 mutant mouse model of Gould syndrome

Collagen type IV alpha 1 and alpha 2 (COL4A1 and COL4A2) are major components of almost all basement membranes. COL4A1 and COL4A2 mutations cause a multisystem disorder that can affect any organ but typically involves the cerebral vasculature, eyes, kidneys and skeletal muscles. In recent years, patient advocacy and family support groups have united under the name of Gould syndrome. The manifestations of Gould syndrome are highly variable, and animal studies suggest that allelic heterogeneity and genetic context contribute to the clinical variability. We previously characterized a mouse model of Gould syndrome caused by a Col4a1 mutation in which the severities of ocular anterior segment dysgenesis (ASD), myopathy and intracerebral hemorrhage (ICH) were dependent on genetic background. Here, we performed a genetic modifier screen to provide insight into the mechanisms contributing to Gould syndrome pathogenesis and identified a single locus [modifier of Gould syndrome 1 (MoGS1)] on Chromosome 1 that suppressed ASD. A separate screen showed that the same locus ameliorated myopathy. Interestingly, MoGS1 had no effect on ICH, suggesting that this phenotype could be mechanistically distinct. We refined the MoGS1 locus to a 4.3 Mb interval containing 18 protein-coding genes, including Fn1, which encodes the extracellular matrix component fibronectin 1. Molecular analysis showed that the MoGS1 locus increased Fn1 expression, raising the possibility that suppression is achieved through a compensatory extracellular mechanism. Furthermore, we found evidence of increased integrin-linked kinase levels and focal adhesion kinase phosphorylation in Col4a1 mutant mice that is partially restored by the MoGS1 locus, implicating the involvement of integrin signaling. Taken together, our results suggest that tissue-specific mechanistic heterogeneity contributes to the variable expressivity of Gould syndrome and that perturbations in integrin signaling may play a role in ocular and muscular manifestations.

Traces pilot pharmacokinetic study dataset

The dataset displays the pharmacokinetics data obtained from the TRACES pilot study. The nine patients included were undergoing haemorrhagic caesarean section (blood loss > 800 mL) and receiving a single i.v dose of tranexamic acid (0.5, 1 or 2 g over 1 min).

The dataset gathers the tranexamic acid blood and urinary concentrations. With these first elements, a pharmacokinetic compartment model was built as described in Gilliot et al. and the individual pharmacokinetic parameters were estimated. In parallel, the patients anthropometric, biological, and clinical characteristics were collected. The correlation between the patient data and the estimated individual pharmacokinetic parameters were tested.

The correlation tests revealed that the dose, the height, the body weight, and the ideal bodyweight had and impact on the volume of distribution of tranexamic acid. According to these results, these latter covariates were explored using a multi-regression analysis in Gilliot et al.

Integration of eQTL and a Single-Cell Atlas in the Human Eye Identifies Causal Genes for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of vision loss. To better understand disease pathogenesis and identify causal genes in GWAS loci for AMD risk, we present a comprehensive database of human retina and retinal pigment epithelium (RPE). Our database comprises macular and non-macular RNA sequencing (RNA-seq) profiles from 129 donors, a genome-wide expression quantitative trait loci (eQTL) dataset that includes macula-specific retina and RPE/choroid, and single-nucleus RNA-seq (NucSeq) from human retina and RPE with subtype resolution from more than 100,000 cells. Using NucSeq, we find enriched expression of AMD candidate genes in RPE cells. We identify 15 putative causal genes for AMD on the basis of co-localization of genetic association signals for AMD risk and eye eQTL, including the genes TSPAN10 and TRPM1. These results demonstrate the value of our human eye database for elucidating genetic pathways and potential therapeutic targets for ocular diseases.

Comparison of multiple cardiac signal acquisition technologies for heart rate variability analysis

Heart rate variability analysis is a recognized non-invasive tool that is used to assess autonomic nervous system regulation in various clinical settings and medical conditions. A wide variety of HRV analysis methods have been proposed, but they all require a certain number of cardiac beats intervals. There are many ways to record cardiac activity: electrocardiography, phonocardiography, plethysmocardiography, seismocardiography. However, the feasibility of performing HRV analysis with these technologies and particularly their ability to detect autonomic nervous system changes still has to be studied. In this study, we developed a technology allowing the simultaneous monitoring of electrocardiography, phonocardiography, seismocardiography, photoplethysmocardiography and piezoplethysmocardiography and investigated whether these sensors could be used for HRV analysis. We therefore tested the evolution of several HRV parameters computed from several sensors before, during and after a postural change. The main findings of our study is that even if most sensors were suitable for mean HR computation, some of them demonstrated limited agreement for several HRV analyses methods. We also demonstrated that piezoplethysmocardiography showed better agreement with ECG than other sensors for most HRV indexes.

Closed-loop administration of analgesic drugs based on heart rate variability analysis

General anesthesia is based on the use of hypnotic, muscle relaxant and analgesic drugs in order to render the patient unresponsive to the surgical procedure. The difficulty for anesthesiologists is then to determinate the minimum efficient dose to avoid any risk of under or over dosing. For several years, monitoring systems were developed in order to measure depth of hypnosis, myorelaxation and analgesia. As soon as all these monitoring systems became available, several teams worked on the closed-loop administration of anesthetic agents. We have developed a closed-loop system allowing the automatic administration of analgesic drugs. This system is based on the analysis of a heart rate variability based index: the ANI (Analgesia Nociception Index). In this paper, we describe this device and demonstrate its efficiency, repeatability and safety in a simulation environment.

Whole genome sequencing identifies a de novo 2.1 Mb balanced paracentric inversion disrupting FOXP1 and leading to severe intellectual disability

The FOXP1 gene, located on chromosome 3p13, encodes the Forkhead-box protein P1, one of the four forkhead transcription factors which repress transcription by forming active homo- and heterodimers and regulate distinct patterns of gene expression crucial for embryogenesis and normal development. FOXP1 mutations, mostly truncating, have been described in patients with mild to moderate intellectual disability (ID), autism spectrum disorder (ASD), and speech and language impairment (MIM #613670). Here, we report a small de novo heterozygous balanced inversion of 2.1 Mb located at 3p14.1p13 identified by Whole Genomic Sequencing (WGS) and disrupting the genes FAM19A4 and FOXP1. This inversion was found in a patient with severe ID, ASD, seizures and very unusual vascular anomalies which were never described in the clinical spectrum of FOXP1 mutations. We show that the neurodevelopmental phenotype observed in the patient most likely results from FOXP1 haploinsufficiency as this heterozygous inversion leads to a 60 to 85% decrease of FOXP1 mRNA levels and to the complete absence of FOXP1 full-length protein. These findings, in addition to expanding the molecular spectrum of FOXP1 mutations, emphasize the emerging role of WGS in identifying small balanced chromosomal rearrangements responsible for neurodevelopmental disorders and not detected by conventional cytogenetics.

[Deep alkali burns: Evaluation of a two-step surgical strategy]

INTRODUCTION

Chemical burns are rare but often lead to deep cutaneous lesions. Alkali agents have a deep and long lasting penetrating power, causing burns that evolve over several days. The local treatment for these patients is excision of the wound and split thickness skin graft. Early excision and immediate skin grafting of alkali burns are more likely to be complicated by graft failure and delayed wound healing. We propose a two-step method that delays skin grafting until two-three days after burn wound excision.

RESULTS

Our population included 25 controls and 16 cases. Men were predominant with a mean age of 41.9 years. In 78% of cases, burns were located on the lower limbs. The mean delay between the burn and excision was 16.5 days. In cases, the skin graft was performed at a mean of 11.3 days after the initial excision. We did not unveil any significant difference between both groups for the total skin surface affected, topography of the burns and the causal agent. Wound healing was significantly shorter in cases vs controls (37.5 days vs 50.3 days; P<0.025). Furthermore, we observed a decreased number of graft failures in cases vs controls (13.3% vs 46.7%; P=0.059).

CONCLUSION

Our study shows the relevance of a two-step surgical strategy in patients with alkali chemical burns. Early excision followed by interval skin grafting is associated with quicker wound healing and decreased rate of graft failure.

Real-time polymerase chain reaction detection of Lichtheimia species in bandages associated with cutaneous mucormycosis in burn patients

BACKGROUND

Cutaneous mucormycoses, mainly due to Lichtheimia (Absidia), have occurred on several occasions in the Burn Unit of the University Hospital of Lille, France.

AIM

To investigate the potential vector role of non-sterile bandages used to hold in place sterile gauze used for wound dressing.

METHODS

Mycological analysis by conventional culture, Mucorales real-time polymerase chain reaction (qPCR), and Lichtheimia species-specific qPCR were performed on eight crepe and six elasticized bandages that were sampled on two independent occasions in March 2014 and July 2016. Characteristics of the seven Lichtheimia mucormycoses which occurred in burn patients between November 2013 and July 2016 were also collected to assess the epidemiological relationship between potentially contaminated bandages and clinical infections.

FINDINGS

One Lichtheimia corymbifera strain was isolated from a crepe bandage by culture, and Lichtheimia spp. qPCR was positive in six out of eight crepe and four out of six elasticized bandages. Using species-specific qPCR, Lichtheimia ramosa, Lichtheimia ornata, and L. corymbifera were identified in six out of ten, five out of ten, and four out of ten bandages, respectively. In patients with mucormycosis, L. ramosa and L. ornata were present in five and two cases, respectively.

CONCLUSION

Our data support the utility of Mucorales qPCR for epidemiological investigations, the potential role of these bandages in cutaneous mucormycoses in burn patients in our centre, and, consequently, the need for sterile bandages for the dressing of extensive wounds.

Influence of ECG sampling rate in fetal heart rate variability analysis

Fetal hypoxia results in a fetal blood acidosis (pH<;7.10). In such a situation, the fetus develops several adaptation mechanisms regulated by the autonomic nervous system. Many studies demonstrated significant changes in heart rate variability in hypoxic fetuses. So, fetal heart rate variability analysis could be of precious help for fetal hypoxia prediction. Commonly used fetal heart rate variability analysis methods have been shown to be sensitive to the ECG signal sampling rate. Indeed, a low sampling rate could induce variability in the heart beat detection which will alter the heart rate variability estimation. In this paper, we introduce an original fetal heart rate variability analysis method. We hypothesize that this method will be less sensitive to ECG sampling frequency changes than common heart rate variability analysis methods. We then compared the results of this new heart rate variability analysis method with two different sampling frequencies (250-1000 Hz).

Physiological Signal Processing for Individualized Anti-nociception Management During General Anesthesia: a Review

OBJECTIVE

The aim of this paper is to review existing technologies for the nociception / anti-nociception balance evaluation during surgery under general anesthesia.

METHODS

General anesthesia combines the use of analgesic, hypnotic and muscle-relaxant drugs in order to obtain a correct level of patient non-responsiveness during surgery. During the last decade, great efforts have been deployed in order to find adequate ways to measure how anesthetic drugs affect a patient's response to surgical nociception. Nowadays, though some monitoring devices allow obtaining information about hypnosis and muscle relaxation, no gold standard exists for the nociception / anti-nociception balance evaluation. Articles from the PubMed literature search engine were reviewed. As this paper focused on surgery under general anesthesia, articles about nociception monitoring on conscious patients, in post-anesthesia care unit or in intensive care unit were not considered.

RESULTS

In this article, we present a review of existing technologies for the nociception / anti-nociception balance evaluation, which is based in all cases on the analysis of the autonomous nervous system activity. Presented systems, based on sensors and physiological signals processing algorithms, allow studying the patients' reaction regarding anesthesia and surgery.

CONCLUSION

Some technological solutions for nociception / antinociception balance monitoring were described. Though presented devices could constitute efficient solutions for individualized anti-nociception management during general anesthesia, this review of current literature emphasizes the fact that the choice to use one or the other mainly relies on the clinical context and the general purpose of the monitoring.

Comparison of pulse rate variability and heart rate variability for high frequency content estimation

Heart Rate Variability (HRV) analysis can be of precious help in most of clinical situations because it is able to quantify the Autonomic Nervous System (ANS) activity. The HRV high frequency (HF) content, related to the parasympathetic tone, reflects the ANS response to an external stimulus responsible of pain, stress or various emotions. We have previously developed the Analgesia Nociception Index (ANI), based on HRV high frequency content estimation, which quantifies continuously the vagal tone in order to guide analgesic drug administration during general anesthesia. This technology has been largely validated during the peri-operative period. Currently, ANI is obtained from a specific algorithm analyzing a time series representing successive heart periods measured on the electrocardiographic (ECG) signal. In the perspective of widening the application fields of this technology, in particular for homecare monitoring, it has become necessary to simplify signal acquisition by using e.g. a pulse plethysmographic (PPG) sensor. Even if Pulse Rate Variability (PRV) analysis issued from PPG sensors has been shown to be unreliable and a bad predictor of HRV analysis results, we have compared PRV and HRV both estimated by ANI as well as HF and HF/(HF+LF) spectral analysis on both signals.

Optimization of extra corporeal enteral prosthesis (ECEP) by selective aspiration of the digestive flow

Reinfusion is a medical process which collects digestive flow from a proximal stoma to a distal one, in patient who had a post-operative double enteral stoma. This process avoids the risk of under nutrition and frees the patient from a Total Parenteral Nutrition to offset the digestive loss. Most of the previous ways of reinfusion first collect the digestive flow into a bag before instillation. We developed an ambulatory reinfusion pump (ECEP) which had the advantage to collect the digestive flow directly from the proximal stoma and to pump it to the distal one. However, the main risk of such a continuous pumping process is to create mucosae lesions by direct suction. The aim of this study is to up-grade our device by introducing a selective aspiration based on the arrival of digestive flow.

Genotype-phenotype correlations in pathology caused by collagen type IV alpha 1 and 2 mutations

COL4A1 and COL4A2 are extracellular matrix proteins that form heterotrimers and are present in nearly all basement membranes in every organ. In the past decade, COL4A1 and COL4A2 mutations have been identified to cause a multi-system disorder for which penetrance and severity of constituent phenotypes can greatly vary. Here, we compare the outcomes of more than 100 mutations identified in patients and data from a murine allelic series to explore the presence of genotype-phenotype correlations - many of which are shared among other types of collagen. We find that there is a frequency bias for COL4A1 over COL4A2 mutations and that glycine (Gly) substitutions within the triple helical domain are the most common class of mutations. Glycine is most often replaced by a charged amino acid, however the position of the mutation, and not the properties of the substituting amino acid, appears to have a greater influence on disease severity. Moreover, the impact of position is not straightforward. Observations from a murine allelic series suggest that mutations in the NC1 domain may result in relatively mild phenotypes via a 'quantitative' mechanism similar to other types of collagens, however, this effect was not apparent in human reports. Importantly, other position-dependent effects had differential impacts depending on the phenotype of interest. For example, the severity of cerebrovascular disease correlated with an amino-to-carboxy severity gradient for triple-helical glycine substitutions whereas the penetrance and severity of myopathy and nephropathy appear to involve a functional sub-domain(s). Greater understanding of genotype-phenotype correlations and the interaction of consequences of different mutations will be important for patient prognosis and care and for developing mechanism-based therapeutics to treat individual components of this emerging syndrome.

LYN- and AIRE-mediated tolerance checkpoint defects synergize to trigger organ-specific autoimmunity

Studies of the genetic factors associated with human autoimmune disease suggest a multigenic origin of susceptibility; however, how these factors interact and through which tolerance pathways they operate generally remain to be defined. One key checkpoint occurs through the activity of the autoimmune regulator AIRE, which promotes central T cell tolerance. Recent reports have described a variety of dominant-negative AIRE mutations that likely contribute to human autoimmunity to a greater extent than previously thought. In families with these mutations, the penetrance of autoimmunity is incomplete, suggesting that other checkpoints play a role in preventing autoimmunity. Here, we tested whether a defect in LYN, an inhibitory protein tyrosine kinase that is implicated in systemic autoimmunity, could combine with an Aire mutation to provoke organ-specific autoimmunity. Indeed, mice with a dominant-negative allele of Aire and deficiency in LYN spontaneously developed organ-specific autoimmunity in the eye. We further determined that a small pool of retinal protein-specific T cells escaped thymic deletion as a result of the hypomorphic Aire function and that these cells also escaped peripheral tolerance in the presence of LYN-deficient dendritic cells, leading to highly destructive autoimmune attack. These findings demonstrate how 2 distinct tolerance pathways can synergize to unleash autoimmunity and have implications for the genetic susceptibility of autoimmune disease.

Type IV collagen drives alveolar epithelial-endothelial association and the morphogenetic movements of septation

BACKGROUND

Type IV collagen is the main component of the basement membrane that gives strength to the blood-gas barrier (BGB). In mammals, the formation of a mature BGB occurs primarily after birth during alveologenesis and requires the formation of septa from the walls of the saccule. In contrast, in avians, the formation of the BGB occurs rapidly and prior to hatching. Mutation in basement membrane components results in an abnormal alveolar phenotype; however, the specific role of type IV collagen in regulating alveologenesis remains unknown.

RESULTS

We have performed a microarray expression analysis in late chick lung development and found that COL4A1 and COL4A2 were among the most significantly upregulated genes during the formation of the avian BGB. Using mouse models, we discovered that mutations in murine Col4a1 and Col4a2 genes affected the balance between lung epithelial progenitors and differentiated cells. Mutations in Col4a1 derived from the vascular component were sufficient to cause defects in vascular development and the BGB. We also show that Col4a1 and Col4a2 mutants displayed disrupted myofibroblast proliferation, differentiation and migration. Lastly, we revealed that addition of type IV collagen protein induced myofibroblast proliferation and migration in monolayer culture and increased the formation of mesenchymal-epithelial septal-like structures in co-culture.

CONCLUSIONS

Our study showed that type IV collagen and, therefore the basement membrane, play fundamental roles in coordinating alveolar morphogenesis. In addition to its role in the formation of epithelium and vasculature, type IV collagen appears to be key for alveolar myofibroblast development by inducing their proliferation, differentiation and migration throughout the developing septum.

Triggering of organ-specific autoimmunity through synergy of defects in key tolerance checkpoints

Studies of genetic factors associated with human autoimmunity suggest a multigenic origin of autoimmune susceptibility. To address how defects in different immune tolerance pathways cooperate to result in disease, we investigated whether genetic alterations in two such pathways might synergize to produce autoimmunity in mice. The intracellular protein tyrosine kinase Lyn is critical for inhibitory receptor function in innate immune cells and B cells. Lyn-deficient mice develop systemic but not organ-specific autoimmunity. In contrast, Autoimmune Regulator (Aire) promotes expression of tissue-specific antigens by thymic epithelial cells and T-cell negative selection. Aire-deficient mice develop multiorgan autoimmunity, including autoimmune uveitis, due to lack of thymic expression of the retina-specific interphotoreceptor retinoid binding protein (IRBP). AireGW/+ knockin mice express a dominant negative allele of Aire, have low but detectable thymic expression of IRBP and do not develop uveitis. To determine whether lack of Lyn inhibitory pathways could cooperate with a partial defect in T cell central tolerance, we generated AireGW/+ Lyn−/− double mutants. Remarkably, over 50% of these mice developed severe uveitis that was accompanied by a rise in anti-IRBP antibodies and an expansion of IRBP-specific CD4 T cells. To determine the contribution of different Lyn-expressing cell subsets to uveitis, we crossed AireGW/+ mice to a panel of Cre lines with an inducible Lyn knockout allele. Deletion of Lyn selectively in dendritic cells (DCs) was sufficient to drive disease, suggesting that Lyn-deficient DCs may have increased ability to prime IRBP-specific T cells that have escaped negative selection in the AireGW/+ thymus.