Antigen expression level threshold tunes the fate of CD8 T cells during primary hepatic immune responses

CD8 T-cell responses to liver-expressed antigens range from deletional tolerance to full effector differentiation resulting in overt hepatotoxicity. The reasons for these heterogeneous outcomes are not well understood. To identify factors that govern the fate of CD8 T cells activated by hepatocyte-expressed antigen, we exploited recombinant adenoassociated viral vectors that enabled us to vary potential parameters determining these outcomes in vivo. Our findings reveal a threshold of antigen expression within the liver as the dominant factor determining T-cell fate, irrespective of T-cell receptor affinity or antigen cross-presentation. Thus, when a low percentage of hepatocytes expressed cognate antigen, high-affinity T cells developed and maintained effector function, whereas, at a high percentage, they became functionally exhausted and silenced. Exhaustion was not irreversibly determined by initial activation, but was maintained by high intrahepatic antigen load during the early phase of the response; cytolytic function was restored when T cells primed under high antigen load conditions were transferred into an environment of low-level antigen expression. Our study reveals a hierarchy of factors dictating the fate of CD8 T cells during hepatic immune responses, and provides an explanation for the different immune outcomes observed in a variety of immune-mediated liver pathologic conditions.The liver is acknowledged to possess unique tolerogenic properties, which have likely evolved to maintain immunological unresponsiveness toward food-derived and microbial antigens that enter the circulation via the gut (1, 2). This tolerogenic capability of the liver is demonstrated in animal models of liver transplantation, in which liver allografts are accepted across complete MHC mismatch barriers and are able to protect other donor tissues from rejection (reviewed in ref. 3). In humans, the tolerogenic hepatic environment is likely to contribute to impaired immune clearance of the hepatitis B virus (HBV) and hepatitis C virus (HCV), which result in persistent infection in a significant proportion of exposed individuals and are associated with major morbidity and mortality. In contrast, effective immune responses to hepatotropic pathogens leading to resolution of infection are observed in most hepatitis A and E virus infections, the majority of individuals infected with HBV during adulthood, and a minority of those infected by HCV (reviewed in refs. 4, 5). The liver is also susceptible to a variety of autoimmune-mediated conditions (6). Collectively, these observations indicate that effective immune responses can be initiated and/or sustained in the liver despite its apparent predisposition toward the generation of tolerance. Unfortunately, there is no small animal model in which to study the parameters that determine the balance between intrahepatic immunity and tolerance in viral hepatitis. Thus, the factors that shape immune outcome have not yet been identified.By studying the fate of antigen-specific CD8 T cells transferred into mice expressing antigen in the liver, it has been shown that, despite being a nonlymphoid organ, the liver is able to support primary CD8 T-cell activation (7). However, depending on the choice of antigen expressed and mode of delivery, the outcome of intrahepatic CD8 T-cell activation has been varied, ranging from deletion and/or functional silencing (8–10) to cytotoxic T lymphocyte (CTL) development (11, 12). This observed diversity of T-cell fates parallels the heterogeneous outcomes of liver-immune interactions observed during hepatotropic viral infections in humans. Thus, reconciliation of these findings holds the potential to yield critical insights into the immunopathological basis of immune-mediated liver disease as well as liver-associated tolerance.In this study, we developed an integrated system in which we manipulated parameters predicted to influence the generation of effector CD8 T cells encountering their cognate antigen on hepatocytes. By identifying three key determinants of the generation of functional effector cells in response to hepatocyte-expressed antigen, this study provides, for the first time to our knowledge, a unified model that explains and predicts the functional outcome of CD8 T-cell activation by liver-expressed antigen and reconciles findings from a number of previous studies that addressed this question.     

Epidemiology,clinical picture and long-term outcomes of FIP1L1-PDGFRA-positive myeloid neoplasm with eosinophilia: Data from 151 patients

FIP1L1-PDGFRA-positive myeloid neoplasm with eosinophilia (F/P+ MN-eo) is a rare disease: robust epidemiological data are lacking and reported issues are scarce, of low sample-size and limited follow-up. Imatinib mesylate (IM) is highly efficient but no predictive factor of relapse after discontinuation has yet been identified. One hundred and fifty-one patients with F/P+ MN-eo (143 males; mean age at diagnosis 49 years; mean annual incidence: 0.18 case per million population) were included in this retrospective nationwide study involving all French laboratories who perform the search of F/P fusion gene (study period: 2003-2019). The main organs involved included the spleen (44%), skin (32%), lungs (30%), heart (19%) and central nervous system (9%). Serum vitamin B12 and tryptase levels were elevated in 74/79 (94%) and 45/57 (79%) patients, respectively, and none of the 31 patients initially treated with corticosteroids achieved complete hematologic remission. All 148 (98%) IM-treated patients achieved complete hematologic and molecular (when tested, n = 84) responses. Forty-six patients eventually discontinued IM, among whom 20 (57%) relapsed. In multivariate analysis, time to IM initiation (continuous HR: 1,01 [0.99-1,03]; P = .05) and duration of IM treatment (continuous HR: 0,97 [0,95-0,99]; P = .004) were independent factors of relapse after discontinuation of IM. After a mean follow-up of 80 (56) months, the 1, 5- and 10-year overall survival rates in IM-treated patients were 99%, 95% and 84% respectively. In F/P+ MN-eo, prompt initiation of IM and longer treatment durations may prevent relapses after discontinuation of IM.     

Skeletal phenotype/genotype in progressive pseudorheumatoid chondrodysplasia

Clinical Rheumatology - Axial and extra-axial deceleration in function and progressive joint pain with subsequent development of antalgic gait associated with swellings, and stiffness of the joints...     

Perforated diverticulitis of the sigmoid colon causing a subcutaneous emphysema

INTRODUCTION

Although diverticular disease of the colon is frequent, perforated diverticulitis causing subcutaneous emphysema is a uncommon entity. We wish to present this extremely rare case of perforated colonic diverticulum in the subcutaneous tissue, which is the first one that we have encountered in our practice, along with the accompanying diagnostic and therapeutic issues and a review of the literature.

PRESENTATION OF CASE

We report the case of an 83-year-old man who admitted to the emergency room due to an abdominal subcutaneous emphysema. Physical examination revealed a severe subcutaneous emphysema especially in the left iliac fossa and abdominal pain. An urgent contrast enhanced abdominal CT scan showed multiple diverticula in the sigmoid colon and multiple air bubbles in the subcutaneous tissue. The exploratory laparotomy identified a perforation of diverticular in subcutaneous tissue. Forty centimeters of colon were resected. The subcutaneous emphysema resolved without specific treatment. The postoperative period was uncomplicated.

DISCUSSION

Subcutaneous emphysema of anterior abdomen wall is an obvious physical sign but its etiology is complex to determine and may be potentially lethal. The pathophysiological mechanism involved is the emergence of a pressure gradient between the peritoneum and surrounding structures, causing rupture of the anterior abdominal wall, allowing gas from a perforation to diffuse along tissue planes.

CONCLUSION

This physical sign may be of especial value in elderly patient groups amongst whom perforation may be less clinically obvious. General surgeons should bear in mind this rare complication of colonic diverticulosis.     

Development of a whole cell pneumococcal vaccine: BPL inactivation,cGMP production,and stability

Pneumococcal infections impose a large burden of disease on the human population, mainly in developing countries, and the current pneumococcal vaccines offer serotype-specific protection, but do not cover all pathogenic strains, leaving populations vulnerable to disease caused by non-vaccine serotypes. The pneumococcal whole cell vaccine is a low-cost strategy based on non-capsular antigens common to all strains, inducing serotype-independent immunity. Therefore, we developed the process for the cGMP production of this cellular vaccine. Initially, three engineering runs and two cGMP runs were performed in 60-L bioreactors, demonstrating the consistency of the production process, as evaluated by the growth curves, glucose consumption and metabolite formation (lactate and acetate). Cell recovery by tangential filtration was 92 ± 13%. We optimized the conditions for beta-propiolactone (BPL) inactivation of the bacterial suspensions, establishing a maximum cell density of OD₆₀₀ between 27 and 30, with a BPL concentration of 1:4000 (v/v) at 150 rpm and 4 °C for 30 h. BPL was hydrolyzed by heating for 2 h at 37 °C. The criteria and methods for quality control were defined using the engineering runs and the cGMP Lots passed all specifications. cGMP vaccine Lots displayed high potency, inducing between 80 and 90% survival in immunized mice when challenged with virulent pneumococci. Sera from mice immunized with the cGMP Lots recognized several pneumococcal proteins in the extract of encapsulated strains by Western blot. The cGMP whole cell antigen bulk and whole cell vaccine product lots were shown to be stable for up to 12 and 18 months, respectively, based upon survival assays following i.p. challenge. Our results show the consistency and stability of the cGMP whole cell pneumococcal vaccine lots and demonstrate the feasibility of production in a developing country setting.     

Prenatal Diagnosis of BMD in Morocco: Evolution and Limits

The muscular dystrophy is a group of inherited disorders characterized in the most of cases by progressive muscle weakness. The best known are X-linked disorder Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). BMD is a milder form of the disease with a later age of onset and a slower clinical progression. The DMD gene, located on Xp21, is the largest human gene in the human genome (2.3 Mb). DMD gene consists of 79 exons and codes for dystrophin protein. A 9-year-old boy, who experienced symptoms of the disease, was admitted to the Casablanca University Children’s Hospital. The patient, with no known family history of significant muscle disease, was first examined at 4 years of age because of walking difficulties and a limited hands force. Blood tests revealed elevated serum levels of creatine kinase (7.60 U/L). The electromyogram showed myopathic changes, consisting of polyphasic potentials, and the muscular biopsy revealed dystrophic aspect. Analysis of the dystrophin-encoding gene by PCR deletion analysis of the dystrophin gene was performed by multiplex PCR primer sets of Chamberlain and Beggs. The analysis showed a deletion of exons 45 to 49. Mother genetic testing showed the heterozygosis deletion.     

Rapid dopamine transmission within the nucleus accumbens: Dramatic difference between morphine and oxycodone delivery

While most drugs of abuse increase dopamine neurotransmission, rapid neurochemical measurements show that different drugs evoke distinct dopamine release patterns within the nucleus accumbens. Rapid changes in dopamine concentration following psychostimulant administration have been well studied; however, such changes have never been examined following opioid delivery. Here, we provide novel measures of rapid dopamine release following intravenous infusion of two opioids, morphine and oxycodone, in drug‐naïve rats using fast‐scan cyclic voltammetry and rapid (1 min) microdialysis coupled with high‐performance liquid chromatography ‐ tandem mass spectrometry (HPLC‐MS). In addition to measuring rapid dopamine transmission, microdialysis HPLC‐MS measures changes in GABA, glutamate, monoamines, monoamine metabolites and several other neurotransmitters. Although both opioids increased dopamine release in the nucleus accumbens, their patterns of drug‐evoked dopamine transmission differed dramatically. Oxycodone evoked a robust and stable increase in dopamine concentration and a robust increase in the frequency and amplitude of phasic dopamine release events. Conversely, morphine evoked a brief (~ 1 min) increase in dopamine that was coincident with a surge in GABA concentration and then both transmitters returned to baseline levels. Thus, by providing rapid measures of neurotransmission, this study reveals previously unknown differences in opioid‐induced neurotransmitter signaling. Investigating these differences may be essential for understanding how these two drugs of abuse could differentially usurp motivational circuitry and powerfully influence behavior.     

An active lifestyle is associated with better neurocognitive functioning in adults living with HIV infection

Studies of healthy adults show that engagement in physical, social, and mental activities is associated with better cognitive outcomes, suggesting that these activities may increase cognitive reserve. Given the prevalence and real-world impact of HIV-associated neurocognitive disorders (HAND), the present study examined the association between neurocognitive outcomes and self-reported proxies for physical exercise, social activity, and mental activity (employment was used as a proxy for mental activity) among 139 HIV-infected adults (M _age = 48.7; 48 % age 50+). Participants completed a neuromedical and neuropsychological battery and were classified based on the number of self-reported active lifestyle factors (ALFs; 0 to 3), including physical exercise, social activity, and current employment. The association between ALFs and both demographically adjusted average neuropsychological T-scores and HAND diagnoses was examined. Results revealed that an increased number of ALFs were associated with better global neurocognitive performance as well as a lower prevalence of HAND. These cross-sectional findings suggest that an active engagement in life may bolster neurocognitive functioning, perhaps by enhancing cognitive and/or brain reserve. However, an alternative explanation might be that persons with better neurocognitive functioning are more inclined and able to engage in these life activities. Future studies should utilize neuroimaging methodology, longitudinal data, and interventional approaches to establish cause–effect relationships and uncover the neural mechanisms whereby physical, social, and mental stimulation may protect neurocognition via cognitive reserve among those living with HIV.