Antigen crosspresentation by human plasmacytoid dendritic cells

Crosspresentation is a specialized function of myeloid dendritic cells (mDCs), allowing them to induce CD8+ T cell responses against exogenous antigens that are not directly produced in their cytotosol. Human plasmacytoid DCs (pDCs) are not considered so far as able to perform crosspresentation. We showed here that purified human pDCs crosspresented vaccinal lipopeptides and HIV-1 antigens from apoptotic cells to specific CD8+ T lymphocytes. Apoptotic debris were internalized by phagocytosis and the lipopeptide LPPol reached nonacidic endosomes. This crosspresentation was amplified upon influenza virus infection. Importantly, the efficiency of crosspresentation by pDCs was comparable to that of mDCs. This property of human pDCs needs to be taken into account to understand the pathogenesis of infectious, allergic, or autimmune diseases and to help achieve desired responses during vaccination by targeting specifically either type of DCs.     

Marijuana use is associated with inattention in men and sleep quality in women with Attention-Deficit/Hyperactivity Disorder: A preliminary study

The study examined the association between marijuana use, Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms, and sleep quality in 56 men and 20 women with ADHD. Participants, ages 18–45, were assessed with the Assessment of Hyperactivity and Attention, drug use survey, and Pittsburgh Sleep Quality Index. Moderate to strong correlations were found between marijuana use and inattentive symptoms in men, and marijuana use and decreased sleep quality in women. Men and women with ADHD may use marijuana for different reasons.     

A prospective study of the efficacy and tolerance of a chimeric antibody to tumor necrosis factors (remicade) in severe pediatric crohn disease

OBJECTIVES: To evaluate the efficacy and toxicity of infliximab in children with severe Crohn disease (CD), the authors prospectively monitored 21 children aged 15 +/- 2 years with severe CD who they treated with infliximab (5 mg/kg) on days 0, 15, and 45. One patient received only one injection. Eighteen patients were corticosteroid dependent, and 6 were receiving parenteral nutrition. Three patients were corticoid resistant (1 mg/kg/d >15 days). Sixteen had perianal disease. RESULTS: The Harvey-Bradshaw index (HB) decreased from 8 +/- 3 on day 0 to 1 +/- 2 on day 45 (P = 0.001). The inflammation factors decreased (P = 0.001), and albumin increased (P = 0.002). Nineteen children were in complete remission (HB < 4) on day 45, and 2 had improved (HB = -6 points). Tumor necrosis factor-alpha (TNFalpha) in the stools (n = 16) decreased (P = 0.04). All perianal fistulas (n = 12) were closed by day 90. Fourteen of 21 patients had stopped taking steroids at 3 months, and all had stopped parenteral nutrition. Growth velocity was significantly greater after infliximab administration (Z score, +0.5) than before (-0.45; P = 0.004). Nineteen of 21 patients had relapsed (90%) at 1 year despite continued immunosuppressors. Seven had surgery because of an uncontrolled relapse ( 5), stenosis ( 1), or fistula ( 1). Six patients developed antinuclear antibodies (1/40-1/640e), and two had anti-DNA antibodies. Epstein-Barr virus (EBV) polymerase chain reaction (PCR) values increased (>100-fold) in eight patients. One child developed an anaphylactic reaction to the medication, and one had a catheter-related sepsis. CONCLUSION: Infliximab produces spectacular results for children with severe CD and is well tolerated. However, its effect is transitory for many (90%), with frequent relapses despite continued immunosuppressors. Long-term management with infliximab should be tested despite its worrying side effects.     

Anginal threshold between stress tests: exercise versus dobutamine stress echocardiography

PURPOSE: Dobutamine echocardiography (DOB) can be substituted to exercise testing when necessary for clinical reasons. Current literature suggests DOB is maximal when 85% of maximal predicted heart rate (%PHR) is achieved (similar to EX), but there is little evidence to determine whether this target has the same clinical significance as during EX. We therefore performed this study to compare the ischemic threshold between EX and DOB. METHODS: Twenty men with stable angina underwent in a random order DOB and EX echocardiograms after being weaned off their cardiac medications. Electrocardiography, heart rate (HR), and systolic blood pressure were recorded every minute. Ischemic threshold was defined as the precise time at which clinical angina occurred. RESULTS: Anginal threshold appeared consistently at a higher level for DOB than EX as evidenced by the higher rate-pressure product (RPP) values (22,492 +/- 4,300 vs 20,371 +/- 5,367 bpm x mm Hg, DOB vs EX, respectively, P = 0.02), HR (126 +/- 23 vs 119 +/- 15 bpm, P = 0.01), and %PHR (79 +/- 15% vs 74 +/- 10%, P < 0.01). Thirty-two percent of the subjects presented an ischemic HR above 85% of PHR and 60% had a higher ischemic HR during DOB versus EX. CONCLUSIONS: This study shows that estimation of anginal threshold during DOB is feasible and is slightly higher (approximately 10%) than during EX. Extrapolation of a cut off target heart rate from an exercise modality to a pharmaceutical one may not be valid.     

Lipopeptide-based melanoma cancer vaccine induced a strong MART-27-35-cytotoxic T lymphocyte response in a preclinal study

Identification of tumor antigens and their optimal antigenic peptides raised hopes for the development of peptide-based immunotherapeutic vaccine strategies for human melanoma, however. Synthetic peptides alone are not immunogenic enough, and adequate formulation is critical for elaboration of peptide vaccines. To improve formulation, we evaluated 2 lipopeptide constructs, both including HLA-A2-restricted MART 27-35-CD8+ T lymphocyte (CTL) epitope covalently linked to universal tetanus toxoid (TT) 830-843 helper T lymphocyte (HTL) epitope, in HLA-A2 transgenic mouse models that mimic human CTL responses in vivo. These 2 constructs only differed in the formulation of their lipid tail. We showed that lipopeptide constructs were strongly recognized, in vitro, by human MART 27-35 cytotoxic T cells derived from tumor-infiltrating lymphocytes. The transgenic Mice immunized with these 2 MART lipopeptide formulations containing covalently linked HTL-CTL epitopes induced strong MART 27-35 cytotoxic T cells. This CTL induction was critically dependent on the presence of the helper T lymphocyte epitope. These results also showed that a single palmitoyl-lysine chain is enough to assure immunogenicity of a given peptide and that the presence of a lipid tail bypass the need for adjuvant. These results support the selection of MART-lipopeptide melanoma vaccine for evaluation in a clinical trial.     

T-Cell Response to Proinsulin and Insulin in Type 1 and Pretype 1 Diabetes

Insulin-dependent diabetes mellitus (IDDM) results from the selective destruction of pancreatic cells by a T cell-mediated autoimmune process. Insulin and proinsulin are the only known cell-specific autoantigens. Using short-term cultures of freshly isolated peripheral blood mononuclear cells, we evaluated T-cell responses to proinsulin and to insulin in IDDM patients and individuals at risk for IDDM. A proliferative T-cell response to proinsulin was observed in only 2 of 26 recent-onset IDDM subjects and 2 of 12 long-standing IDDM subjects and was associated with a proliferative response to insulin. In contrast, 5 of 13 islet cell autoantibody-positive first-degree relatives of IDDM patients showed a proliferative response to proinsulin alone, 3 of 13 to insulin alone, and 1 of 13 to both insulin and proinsulin. Overall, 9 of 13 ICA-positive first-degree relatives responded to either proinsulin or insulin. We observed an inverse relationship between antiinsulin antibodies and T-cell responses to insulin in ICA-positive first-degree relatives but not in long-standing IDDM patients. Our data indicate that proinsulin is a major antigen in IDDM and, further, illustrate the difference between the autoimmune response to insulin and the immune response to exogenous insulin.     

Rural environment and risk factors of amyotrophic lateral sclerosis: a case–control study

The aetiology of sporadic ALS is still unknown. Links with several environmental factors have been suggested, and some epidemiological studies have shown an increased incidence of ALS in rural populations. This study was designed to investigate risk exposures in a well-delimited rural population and to assess whether rural residency or occupations, such as farming, were associated with an increased risk of developing ALS. A prospective case–control-study of 108 sporadic ALS cases matched by age and sex to 122 controls was performed in Brittany from 2006 to 2008. A strong association was found between agricultural activity and ALS (odds ratio: 2.919; p = 0.01), while rural residence itself did not influence the risk of the disease. Bulbar forms of onset prevailed among agricultural workers as compared with other occupations (55 vs. 26%; p = 0.009). These results suggest a potential role of exposure to agricultural chemicals or contact with animals linked to agricultural work. The prevalence of bulbar forms of onset in agricultural workers has not been reported before. In addition to variable methodological approaches, differences in agricultural practices could explain the discrepancy between these findings and other studies.     

HLA-DR-restricted peptides identified in the Nef protein can induce HIV type 1-specific IL-2/IFN-gamma-secreting CD4+ and CD4+ /CD8+ T cells in humans after lipopeptide vaccination

We screened the Neflaiprotein to identify new HLA-DR-restricted epitopes, because this small protein is expressed early during infection, and specific CD4(+) T cells are critical for effective immunity in HIV-1 infection. We synthesized a set of peptides that covers the sequence of the Nef protein, and performed binding assays using 10 common HLA-DR molecules. We defined four large regions in this protein able to bind very efficiently to eight HLADR molecules. We took advantage of healthy volunteers immunized with an HIV-1 lipopeptide vaccine that contains three of the four HLA DR-restricted regions to investigate their capacities to stimulate T cells. In 11 vaccinated volunteers, typed for their class II molecules, we were able to correlate sequences of the vaccine displaying binding activities to specific HLA-DR molecules and the induction of CD4(+) T cell proliferation. To identify potential HLA-DR epitopes, we synthesized 31 15-mer peptides and showed that 26 bound to one or more HLA-DR molecules. Interestingly, 12 of the 26 15-mer peptides identified are included in the sequence of lipopeptides. We used IFN-gamma ELISPOT and flow cytometer assays to investigate the capacity of these potential CD4(+) T cell epitopes to induce specific T cell responses. We showed that seven of these peptides were able to stimulate HIV-specific T cell responses in five of six tested volunteers. These cells are Nef-specific CD4(+) and CD4(+) CD8(+) T cells secreting IL-2/INF-gamma or IL-2 alone. To conclude, these 26 Nef HLA-DR-restricted peptides could be helpful to better evaluate CD4(+) deficiencies in HIV infection and, for new vaccine designs.