Real-Time Monitoring of Infectious Disease Outbreaks with a Combination of Google Trends Search Results and the Moving Epidemic Method: A Respiratory Syncytial Virus Case Study.

The COVID-19 pandemic has disrupted the seasonal patterns of several infectious diseases. Understanding when and where an outbreak may occur is vital for public health planning and response. We usually rely on well-functioning surveillance systems to monitor epidemic outbreaks. However, not all countries have a well-functioning surveillance system in place, or at least not for the pathogen in question. We utilized Google Trends search results for RSV-related keywords to identify outbreaks. We evaluated the strength of the Pearson correlation coefficient between clinical surveillance data and online search data and applied the Moving Epidemic Method (MEM) to identify country-specific epidemic thresholds. Additionally, we established pseudo-RSV surveillance systems, enabling internal stakeholders to obtain insights on the speed and risk of any emerging RSV outbreaks in countries with imprecise disease surveillance systems but with Google Trends data. Strong correlations between RSV clinical surveillance data and Google Trends search results from several countries were observed. In monitoring an upcoming RSV outbreak with MEM, data collected from both systems yielded similar estimates of country-specific epidemic thresholds, starting time, and duration. We demonstrate in this study the potential of monitoring disease outbreaks in real time and complement classical disease surveillance systems by leveraging online search data.

Safety, tolerability, and immunogenicity of V114 pneumococcal vaccine compared with PCV13 in a 2+1 regimen in healthy infants: A phase III study (PNEU-PED-EU-2).

BACKGROUND: This phase III study evaluated safety, tolerability, and immunogenicity of V114 (15-valent pneumococcal conjugate vaccine) in healthy infants. V114 contains all 13 serotypes in PCV13 and additional serotypes 22F and 33F. METHODS: Healthy infants were randomized to two primary doses and one toddler dose (2+1 regimen) of V114 or PCV13 at 3, 5, and 12 months of age; diphtheria, tetanus, pertussis (DTaP), inactivated poliovirus (IPV), Haemophilus influenzae type b (Hib), hepatitis B (HepB) vaccine was administered concomitantly. Adverse events (AEs) were collected on Days 1-14 following each vaccination. Serotype-specific anti-pneumococcal immunoglobulin G (IgG) was measured 30 days post-primary series, immediately prior to toddler dose, and 30 days post-toddler dose. Primary objectives included non-inferiority of V114 to PCV13 for 13 shared serotypes and superiority of V114 to PCV13 for serotypes 22F and 33F. RESULTS: 1191 healthy infants were randomized to V114 (n = 595) or PCV13 (n = 596). Proportions of participants with solicited AEs and serious AEs were comparable between groups. V114 met non-inferiority criteria for 13 shared serotypes, based on difference in proportions with serotype-specific IgG ≥0.35 µg/mL (lower bound of two-sided 95% confidence interval [CI] >-10.0) and IgG geometric mean concentration (GMC) ratios (lower bound of two-sided 95% CI >0.5) at 30 days post-toddler dose. V114 met superiority criteria for serotypes 22F and 33F, based on response rates (lower bound of two-sided 95% CI >10.0) and IgG GMC ratios (lower bound of two-sided 95% CI >2.0) at 30 days post-toddler dose. Antibody responses to DTaP-IPV-Hib-HepB met non-inferiority criteria, based on antigen-specific response rates. CONCLUSION: A two-dose primary series plus toddler dose of V114 was well-tolerated in healthy infants. Compared with PCV13, V114 provided non-inferior immune responses to 13 shared serotypes and superior immune responses to additional serotypes 22F and 33F.

Phase 3, open-label, Russian, multicenter, single-arm trial to evaluate the immunogenicity of varicella vaccine (VARIVAX™) in healthy infants, children, and adolescents.

Varicella (chickenpox) is a common, highly contagious disease caused by primary infection with varicella zoster virus (VZV), which can result in bacterial superinfection, central nervous system complications, and hospitalization. Stage 2 of this Phase 3 open-label study (ClinicalTrials.gov identifier: NCT03843632) enrolled 100 healthy infants, children, and adolescents (12 months-6 years, n = 37; 7-12 years, n = 33; 13-17 years, n = 30) without a clinical history of varicella. Participants aged 12 months-12 years were administered 1 dose of VARIVAX™ 0.5 mL (Varicella Virus Vaccine Live [Oka/Merck]) and adolescents aged 13-17 years were administered 2 doses 6 weeks apart. For participants seronegative at baseline (VZV antibody titer <1.25 glycoprotein enzyme-linked immunosorbent assay [gpELISA] units/mL), immunogenicity was assessed by seroconversion (VZV antibody titer ≥5 gpELISA units/mL) and VZV antibody geometric mean titers 6 weeks after the final dose. For participants who were VZV seropositive at baseline (VZV antibody titer ≥1.25 gpELISA units/mL), immunogenicity was assessed by antibody titer geometric mean fold rise and percentage of participants with ≥4-fold rise in antibody titer 6 weeks after the final dose. A Vaccine Report Card was used to report solicited and unsolicited adverse events through 42 days post-vaccination. After series completion among seronegative participants across age groups (n = 74), 98.6% demonstrated seroconversion 6 weeks post-vaccination; among seropositive participants (n = 26), 65.4% had ≥4-fold rise in antibody titer 6 weeks post-vaccination. No new safety signals were observed. Administering VARIVAX to infants, children, and adolescents resulted in an acceptable immune response with a safety profile consistent with the licensed product.

Immunogenicity and safety of a nine-valent human papillomavirus vaccine in women 27-45 years of age compared to women 16-26 years of age: An open-label phase 3 study.

BACKGROUND: Efficacy of the nine-valent human papillomavirus (9vHPV; HPV types 6/11/16/18/31/33/45/52/58) vaccine was demonstrated in a phase 3 study in women 16-26 years of age. We present a phase 3 immunogenicity and safety study of the 9vHPV vaccine in women 27-45 versus 16-26 years of age. METHODS: This international, open-label study (NCT03158220) was conducted in women 16-45 years of age. Participants (16-26 years, n = 570 and 27-45 years, n = 642) received a three-dose 9vHPV vaccination regimen (day 1, month 2, month 6). Month 7 geometric mean titers (GMTs) and seroconversion percentages to anti-HPV 6/11/16/18/31/33/45/52/58 were assessed. Participants were followed for safety throughout the study. RESULTS: At month 7, anti-HPV 6/11/16/18/31/33/45/52/58 GMTs in women 27-45 years were compared to those in women 16-26 years of age. The primary hypothesis of non-inferiority of anti-HPV 16/18/31/33/45/52/58 GMTs in older versus younger women was met. The lower bound of the GMT ratio 95% confidence interval (27-45 years to 16-26 years) was 0.60-0.67 depending on HPV type, exceeding the non-inferiority margin of 0.5 for all HPV types. Month 7 seroconversion percentages in women 27-45 years of age were >99% for all HPV types. Injection-site and vaccine-related systemic adverse events (AEs) were observed in 87.5% and 25.1% of women 16-26 years, and 85.2% and 24.1% of women 27-45 years of age, respectively; no vaccine-related serious AEs were reported and no deaths occurred during the study. CONCLUSIONS: The 9vHPV vaccine elicited non-inferior anti-HPV GMTs in women 27-45 years compared with women 16-26 years of age for HPV 16/18/31/33/45/52/58. The vaccine was generally well tolerated with a similar AE profile across the age groups. These data support bridging 9vHPV vaccine efficacy findings in women 16-26 years to women 27-45 years of age. Clinical trial registration NCT03158220.

Afabicin, a First-in-Class Antistaphylococcal Antibiotic, in the Treatment of Acute Bacterial Skin and Skin Structure Infections: Clinical Noninferiority to Vancomycin/Linezolid.

Afabicin (formerly Debio 1450, AFN-1720) is a prodrug of afabicin desphosphono, an enoyl-acyl carrier protein reductase (FabI) inhibitor, and is a first-in-class antibiotic with a novel mode of action to specifically target fatty acid synthesis in Staphylococcus spp. The efficacy, safety, and tolerability of afabicin were compared with those of vancomycin/linezolid in the treatment of acute bacterial skin and skin structure infections (ABSSSI) due to staphylococci in this multicenter, parallel-group, double-blind, and double-dummy phase 2 study. Randomized patients (1:1:1) received either low-dose (LD) afabicin (intravenous [i.v.] 80 mg, followed by oral 120 mg, twice a day [BID]), high-dose (HD) afabicin (i.v. 160 mg, followed by oral 240 mg, BID), or vancomycin/linezolid (i.v. vancomycin 1 g or 15 mg/kg, followed by oral linezolid 600 mg, BID). The most frequent baseline pathogen was Staphylococcus aureus (97.5% of microbiological intent-to-treat [mITT] population), and 50.4% of patients had methicillin-resistant S. aureus Clinical response rates at 48 to 72 h postrandomization in the mITT population were comparable among treatment groups (94.6%, 90.1%, and 91.1%, respectively). Both LD and HD afabicin were noninferior to vancomycin/linezolid (differences, -3.5% [95% confidence interval {CI}, -10.8%, 3.9%] and 1.0% [95% CI, -7.3%, 9.2%], respectively). Most common treatment-emergent adverse events were mild and were headache (9.1% and 16.8%) and nausea (6.4% and 8.4%) with LD and HD afabicin, respectively. Afabicin was efficacious and well tolerated in the treatment of ABSSSI due to staphylococci, and these data support further development of afabicin for the treatment of ABSSSI and potentially other types of staphylococcal infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02426918.).

Bone and Joint Tissue Penetration of the Staphylococcus-Selective Antibiotic Afabicin in Patients Undergoing Elective Hip Replacement Surgery.

Afabicin (formerly Debio 1450, AFN-1720) is a prodrug of afabicin desphosphono (Debio 1452, AFN-1252), a novel antibiotic in development which targets the staphylococcal enoyl-acyl carrier protein reductase (FabI) and exhibits selective potent antibacterial activity against staphylococcal species, including methicillin-resistant Staphylococcus aureus As part of clinical development in bone and joint infections, a distribution study in bone was performed in 17 patients who underwent elective hip replacement surgery. Patients received 3 doses of 240 mg afabicin orally (every 12 h) at various time points before surgery. Afabicin desphosphono concentrations were measured by liquid chromatography-tandem mass spectrometry in plasma, cortical bone, cancellous bone, bone marrow, soft tissue, and synovial fluid collected during surgery at 2, 4, 6, or 12 h after the third afabicin dose. The study showed good penetration of afabicin desphosphono into bone tissues, with mean area under the curve ratios for cortical bone-, cancellous bone-, bone marrow-, soft tissue-, and synovial fluid-to-total plasma concentrations of 0.21, 0.40, 0.32, 0.35, and 0.61, respectively. When accounting for the free fraction in plasma (2%) and synovial fluid (9.4%), the mean ratio was 2.88, which is indicative of excellent penetration and which showed that the afabicin desphosphono concentration was beyond the MIC90 of S. aureus over the complete dosing interval. These findings, along with preclinical efficacy data, clinical efficacy data for skin and soft tissue staphylococcal infection, the availability of both intravenous and oral formulations, and potential advantages over broad-spectrum antibiotics for the treatment of staphylococcal bone or joint infections, support the clinical development of afabicin for bone and joint infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02726438.).

Functional activity of maternal and cord antibodies elicited by an investigational group B Streptococcus trivalent glycoconjugate vaccine in pregnant women.

OBJECTIVES: The main aim of this exploratory study was to evaluate functional activity of antibodies elicited by a maternal Group B Streptococcus (GBS) investigational vaccine composed of capsular polysaccharides Ia, Ib, and III conjugated to genetically detoxified Diphtheria toxin CRM197. The second objective was to investigate the relationship between serotype-specific IgG concentrations and functional activity in maternal and cord sera. METHODS: Maternal and cord sera collected at baseline and at delivery from vaccine and placebo recipients during a double-blind placebo-controlled Phase II study (www.clinicaltrials.gov, NCT01446289) were tested in an opsono-phagocytic bacterial killing assay. Cord sera from vaccine recipients were also passively transferred to newborn mice to investigate conferred protection against bacterial challenge. RESULTS: Antibody-mediated GBS phagocytic killing was significantly increased in maternal serum at delivery and in cord sera from the investigational vaccine group as compared to the placebo group. Anti-capsular IgG concentrations above 1 µg/mL mediated in vitro killing against GBS strains belonging to all three serotypes and IgG levels correlated with functional titers. Passively administered cord sera elicited a dose-dependent protective response against all GBS serotypes in the in vivo model. CONCLUSIONS: The maternal vaccine elicited functional antibodies that were placentally transferred. Anti-capsular IgG concentrations in maternal and cord sera were predictive of functional activity and in vivo protection in the mouse model.

Antibody Kinetics and Response to Routine Vaccinations in Infants Born to Women Who Received an Investigational Trivalent Group B Streptococcus Polysaccharide CRM197-Conjugate Vaccine During Pregnancy.

BACKGROUND: Maternal vaccination against group B Streptococcus (GBS) might provide protection against invasive GBS disease in infants. We investigated the kinetics of transplacentally transferred GBS serotype-specific capsular antibodies in the infants and their immune response to diphtheria toxoid and pneumococcal vaccination. METHODS: This phase 1b/2, observer-blind, single-center study (NCT01193920) enrolled infants born to women previously randomized (1:1:1:1) to receive either GBS vaccine at dosages of 0.5, 2.5, or 5.0 µg of each of 3 CRM197-glycoconjugates (serotypes Ia, Ib, and III), or placebo. Infants received routine immunization: combination diphtheria vaccine (diphtheria-tetanus-acellular pertussis-inactivated poliovirus/Haemophilus influenzae type b vaccine; age 6/10/ 14 weeks) and 13-valent pneumococcal CRM197-conjugate vaccine (PCV13; age 6/14 weeks and 9 months). Antibody levels were assessed at birth, day (D) 43, and D91 for GBS serotypes; 1 month postdose 3 (D127) for diphtheria; and 1 month postprimary (D127) and postbooster (D301) doses for pneumococcal serotypes. RESULTS: Of 317 infants enrolled, 295 completed the study. In infants of GBS vaccine recipients, GBS serotype-specific antibody geometric mean concentrations were significantly higher than in the placebo group at all timepoints and predictably decreased to 41%-61% and 26%-76% of birth levels by D43 and D91, respectively. Across all groups, ≥95% of infants were seroprotected against diphtheria at D127 and ≥91% of infants had seroprotective antibody levels against each PCV13 pneumococcal serotype at D301. CONCLUSIONS: Maternal vaccination with an investigational CRM197-glycoconjugate GBS vaccine elicited higher GBS serotype-specific antibody levels in infants until 90 days of age, compared with a placebo group, and did not affect infant immune responses to diphtheria toxoid and pneumococcal vaccination. CLINICAL TRIALS REGISTRATION: NCT01193920.

A pilot study of peripheral blood BDCA-1 (CD1c) positive dendritic cells pulsed with NY-ESO-1 ISCOMATRIX™ adjuvant.

AIM: Pilot clinical trial of NY-ESO-1 (ESO) protein in ISCOMATRIX™ adjuvant pulsed onto peripheral blood dendritic cells (PBDC), to ascertain feasibility, evaluate toxicity and assess induction of ESO-specific immune responses. PATIENTS & METHODS: Eligible participants had resected cancers expressing ESO or LAGE-1 and were at high risk of relapse. PBDC were produced using CliniMACS®plus, with initial depletion of CD1c+ B cells followed by positive selection of CD1c+ PBDC. Patients received three intradermal vaccinations of ESO/IMX-pulsed PBDC at 4-week intervals. RESULTS: The process was feasible and safe. No vaccine-induced immune responses were detected. Assays of immunomodulatory cells did not correlate with outcomes. One patient had a long lasting complete remission. CONCLUSION: This method was feasible and safe but was minimally immunogenic.

Preterm birth: Case definition & guidelines for data collection, analysis, and presentation of immunisation safety data.

Preterm birth is commonly defined as any birth before 37 weeks completed weeks of gestation. An estimated 15 million infants are born preterm globally, disproportionately affecting low and middle income countries (LMIC). It contributes directly to estimated one million neonatal deaths annually and is a significant contributor to childhood morbidity. However, in many clinical settings, the information available to calculate completed weeks of gestation varies widely. Accurate dating of the last menstrual period (LMP), as well as access to clinical and ultrasonographic evaluation are important components of gestational age assessment antenatally. This case definition assign levels of confidence to categorisation of births as preterm, utilising assessment modalities which may be available across different settings. These are designed to enable systematic safety evaluation of vaccine clinical trials and post-implementation programmes of immunisations in pregnancy.

Safety and immunogenicity of an investigational maternal trivalent group B streptococcus vaccine in healthy women and their infants: a randomised phase 1b/2 trial.

BACKGROUND: Maternal group B streptococcus (GBS) serotype-specific capsular antibody concentrations are correlated with susceptibility to neonatal GBS invasive disease. Maternal immunisation against GBS during pregnancy might protect infants across the period of susceptibility to invasive disease, but no licensed vaccine exists. This study assessed the safety and immunogenicity of a CRM197-conjugated trivalent GBS vaccine in non-pregnant and pregnant women, and antibody transfer to their infants. METHODS: We did a phase 1b/2, randomised, observer-blind single-centre study of an investigational trivalent GBS vaccine in healthy non-pregnant women (cohort 1), and a dose-ranging study in healthy pregnant women (cohort 2). The study was done at the Chris Hani Baragwanath Academic Hospital in Soweto, South Africa. Participants were healthy non-pregnant or pregnant (28-35 weeks' gestation) women aged 18-40 years. In cohort 1, non-pregnant women were randomly assigned (2:1) to receive the investigational vaccine (two injections, 1 month apart, of a 20 µg dose [of each serotype] of aluminium hydroxide-adjuvanted investigational vaccine) or placebo. In cohort 2, pregnant women were randomly assigned (1:1:1:1) to receive one injection at 28-35 weeks' gestation of 0·5 µg, 2·5 µg, or 5·0 µg of the non-adjuvanted investigational vaccine (for each serotype), or placebo. All study participants and study staff not involved with vaccine preparation were masked to the randomisation group. The vaccine contained an equal dose (0·5 µg, 2·5 µg, 5·0 µg, or 20 µg) of each of three glycoconjugates (serotypes Ia, Ib and III). Reactogenicity was monitored to day 7 and unsolicited adverse events (adverse events) and infant safety were recorded throughout the study. The primary outcomes were tolerability and GBS-specific antibody response (measured as geometric mean concentrations [GMCs] in µg/mL) following the two injections for cohort 1, and selection of one vaccine dose based on analysis of serotype-specific antibody responses at delivery (+72 h) for use in subsequent studies. These outcomes were assessed in participants or infants of participants who correctly received the study vaccine with no major protocol deviations, and provided evaluable serum samples at day 1 and the scheduled timepoints throughout the study. This study is registered with ClinicalTrials.gov, NCT01193920. FINDINGS: Between Oct 5, 2010, and Sept 21, 2011, we screened 75 non-pregnant and 417 pregnant healthy South African women. Of these, 60 non-pregnant women were enrolled in cohort 1 (40 randomly assigned to the GBS 20 µg group and 40 randomly assigned to the placebo group) and 320 pregnant women were enrolled in cohort 2 (80 in each of the four groups). Among the randomised groups of pregnant women, 33-40% experienced at least one local and 54-71% one systemic solicited adverse event, less than 4% of which were severe, and the rate did not differ by study group. Also, 2% of the pregnancies resulted in stillbirth and 3·5% of the liveborn babies died by 12 months age, none of these deaths were attributed to vaccination. There was one death in a GBS-vaccine recipient, which too was unrelated to vaccination. For cohort 1, serotype-specific antibody concentrations were significantly higher, as evident by no overlap of the 95% CIs of GMCs against all three serotypes in the vaccinated group than the placebo group. For cohort 2, pregnant women in all vaccine groups had significantly higher GMCs than did those in the placebo group at delivery (eg, GMCs against serotype Ia were 11 µg/mL [95% CI 7·0-18] for the GBS vaccine 0·5 µg group, 18 µg/mL [11-29] for the GBS vaccine 2·5 µg group, 22 µg/mL [13-35] for the GBS vaccine 5·0 µg group, and 0·64 µg/mL [0·42-0·98] for the placebo group) and at all measured timepoints. GMCs did not differ significantly between the vaccine doses at any of the measured timepoints (p>0·05). INTERPRETATION: The vaccine was well tolerated and induced capsular-specific antibody responses, in non-pregnant and pregnant women. Maternal vaccination led to higher GBS serotype-specific antibody concentrations in infants than did placebo, with both interventions resulting in similar safety profiles. FUNDING: Novartis Vaccines and Diagnostics division, now part of the GlaxoSmithKline group of companies.

A randomized, observer-blind Phase Ib study to identify formulations and vaccine schedules of a trivalent Group B Streptococcus vaccine for use in non-pregnant and pregnant women.

BACKGROUND: Group B streptococcus (GBS) is a leading cause of sepsis and meningitis in early infancy. Substantial data demonstrate that women with higher levels of circulating antibody against the capsular polysaccharide (CPS) deliver infants at reduced risk of GBS infection, which serves as the basis for vaccine design. This study evaluates two different dosages, two injection schedules and three formulations of an investigational trivalent (serotypes Ia, Ib and III) CRM197-glycoconjugate GBS vaccine in healthy, non-pregnant women. METHODS: 678 healthy non-pregnant women received one or two injections of one of two dosages (5/5/5 µg or 20/20/20 µg) of the investigational vaccine, formulated with or without aluminum hydroxide (Enrollment Group 1), or with full or half dosages of MF59(®) (Enrollment Group 2); or a placebo (Enrollment Groups 1 and 2). Geometric mean serotype-specific antibody concentrations (GMCs) at Days 61 (Enrollment Group 1) and 361 (both Groups) were analyzed to select a formulation suitable for pregnant or non-pregnant women, respectively. Solicited adverse reactions were recorded up to Day 7 and adverse events (AEs) were recorded throughout the study. RESULTS: Rates of reported AEs were similar across all groups. Higher rates of local reactogenicity were seen in adjuvanted vaccine groups compared with non-adjuvanted vaccine (or placebo) groups. All vaccine groups elicited higher GMCs than placebo; differences between treatments were not statistically significant, indicating no additional potential benefit of higher antigen content, addition of adjuvant, or a second dose. CONCLUSIONS: All GBS vaccine formulations induced a persistent antibody response and showed similar immunogenicity profiles (NCT01150123).

Maternal Immunization With an Investigational Trivalent Group B Streptococcal Vaccine: A Randomized Controlled Trial.

OBJECTIVE: To evaluate the safety and immunogenicity of an investigational trivalent group B streptococcal vaccine in pregnant women and antibody transfer to their newborns. METHODS: The primary outcome of this observer-blind, randomized study was to estimate placental antibody transfer rates at birth. Secondary outcomes included measurement of serotype-specific antibodies at screening, 30 days postvaccination, at delivery, and 91 days postpartum, infant antibody levels at 3 months of age, the potential effect on routine infant diphtheria vaccination at 1 month after the third infant series dose, and safety in mother and infant participants through at least 5 months postpartum. Sample size was based on 60 participants in the vaccine group giving a probability of observing at least one adverse event of 90% if the actual rate of the event was 3.8%. RESULTS: From September 2011 to October 2013, 86 pregnant women were allocated in a 3:2 ratio to receive an investigational group B streptococcal vaccine containing glycoconjugates of serotypes Ia, Ib, and III or placebo. Demographics were similar across groups. Transfer ratios were 66-79% and maternal geometric mean concentrations increased 16-, 23-, and 20-fold by delivery against serotypes Ia, Ib, and III, respectively, Women with no detectable antibodies at inclusion had lower responses than those with detectable antibodies. Three months after birth, infant antibody concentrations were 22-25% of birth levels. Antidiphtheria geometric mean concentrations were similar across groups. In the vaccine and placebo groups, 32 of 51 women (63%) and 26 of 35 women (74%) reported adverse effects, respectively. CONCLUSION: The investigational vaccine was well-tolerated without safety signals in recipients and their infants or interference with routine infant diphtheria vaccination, although further studies on safety and effectiveness are needed. The investigational vaccine was immunogenic for all serotypes, particularly among women with detectable antibody levels at baseline. Antibody transfer to neonates was at similar levels to other maternally administered polysaccharide vaccines. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01446289.

NK cells, but not NKT cells, are involved in Pseudomonas aeruginosa exotoxin A-induced hepatotoxicity in mice.

Pseudomonas aeruginosa exotoxin A (PEA) causes T cell- and Kupffer cell (KC)-dependent liver injury in mice. TNF-alpha as well as IL-18 and perforin are important mediators of liver damage following PEA injection. In this study, we focus on the role of NK and NKT cells in PEA-induced liver toxicity. Depletion of both NK and NKT cells by injection of anti-NK1.1 Ab as well as depletion of NK cells alone by anti-asialo GM1 Ab protected mice from PEA-induced hepatotoxicity, whereas mice lacking only NKT cells were susceptible. Additionally, we observed infiltration of NK cells, T cells, and neutrophils into liver parenchyma after injection of PEA. The number of NKT cells, however, remained unchanged. The increase in intrahepatic NK cells depended on KCs and the TNF-alpha-dependent up-regulation of the adhesion molecule VCAM-1 in the liver, but not on NKT cells. PEA also augmented the cytotoxicity of hepatic NK cells against typical NK target cells (YAC-1 cells). This effect depended on KCs, but not on TNF-alpha or NKT cells. Furthermore, only weak expression of MHC class I was detected on hepatocytes, which was further down-regulated in PEA-treated mice. This could explain the susceptibility of hepatocytes to NK cell cytolytic activity in this model. Our results demonstrate that NK cells, activated and recruited independently of NKT cells, contribute to PEA-induced T cell-dependent liver injury in mice.

Diacylated sulfoglycolipids are novel mycobacterial antigens stimulating CD1-restricted T cells during infection with Mycobacterium tuberculosis.

Mycobacterial lipids comprise a heterogeneous group of molecules capable of inducing T cell responses in humans. To identify novel antigenic lipids and increase our understanding of lipid-mediated immune responses, we established a panel of T cell clones with different lipid specificities. Using this approach we characterized a novel lipid antigen belonging to the group of diacylated sulfoglycolipids purified from Mycobacterium tuberculosis. The structure of this sulfoglycolipid was identified as 2-palmitoyl or 2-stearoyl-3-hydroxyphthioceranoyl-2'-sulfate-alpha-alpha'-D-trehalose (Ac2SGL). Its immunogenicity is dependent on the presence of the sulfate group and of the two fatty acids. Ac2SGL is mainly presented by CD1b molecules after internalization in a cellular compartment with low pH. Ac2SGL-specific T cells release interferon gamma, efficiently recognize M. tuberculosis-infected cells, and kill intracellular bacteria. The presence of Ac2SGL-responsive T cells in vivo is strictly dependent on previous contact with M. tuberculosis, but independent from the development of clinically overt disease. These properties identify Ac2SGL as a promising candidate to be tested in novel vaccines against tuberculosis.

Human NKT cells express granulysin and exhibit antimycobacterial activity.

Human NKT cells are a unique subset of T cells that express an invariant V alpha 24 TCR that recognizes the nonclassical Ag-presenting molecule CD1d. Activation of NKT cells is greatly augmented by the marine sponge-derived glycolipid alpha-galactosylceramide (alpha GalCer). Because human monocyte-derived cells express CD1d and can harbor the intracellular pathogen Mycobacterium tuberculosis, we asked whether the addition of alpha GalCer could be used to induce effector functions of NKT cells against infected monocytes, macrophages, and monocyte-derived dendritic cells. NKT cells secreted IFN-gamma, proliferated, and exerted lytic activity in response to alpha GalCer-pulsed monocyte-derived cells. Importantly, alpha GalCer-activated NKT cells restricted the growth of intracellular M. tuberculosis in a CD1d-dependent manner. NKT cells that exhibited antimycobacterial activity also expressed granulysin, an antimicrobial peptide shown to mediate an antimycobacterial activity through perturbation of the mycobacterial surface. Degranulation of NKT cells resulted in depletion of granulysin and abrogation of antimycobacterial activity. The detection of CD1d in granulomas of tuberculosis patients supports the potential interaction of NKT cells with CD1d-expressing cells at the site of disease activity. These studies provide evidence that alpha Gal Cer-activated CD1d-restricted T cells can participate in human host defense against M. tuberculosis infection.