Showing papers by "Carlos A. Guzmán published in 2017"

Blockade of Neutrophil's Chemokine Receptors CXCR1/2 Abrogate Liver Damage in Acute-on-Chronic Liver Failure.

Abstract: BACKGROUND: Neutrophils serve as critical players in the pathogenesis of liver diseases. Chemokine receptors CXCR1 and CXCR2 are required for neutrophil chemotaxis to the site of inflammation/injury and are crucial in hepatic inflammatory response. However key mechanism of neutrophil mediated liver injury in acute-on-chronic liver failure (ACLF) remains highly elusive; which could be targeted for the development of new therapeutic interventions. METHODS: To demonstrate the role of CXCR1/CXCR2 expressing neutrophils in hepatic injury, we investigated CXCR1/CXCR2 receptor expression in 17 hepatitis B virus (HBV)-related ACLF patients in comparison to 42 chronic hepatitis B (CHB) and 18 healthy controls (HC). Mechanism of neutrophil mediated cell death was analyzed by in vitro co-culture assays and correlated with the patient data. In addition, to find out any etiological based variations in ACLF, 19 alcohol-related ACLF patients were also included. RESULTS: In ACLF, neutrophils have high expression of CXCR1/CXCR2 receptors which potentially participate in hepatocyte death through early apoptosis and necrosis in contact dependant and independent mechanisms. Importantly, blockade of CXCR1/CXCR2 with SCH 527123 antagonist significantly reduced cell death by targeting both the mechanisms. No etiology based differences were seen between ACLF groups. Importantly, absolute neutrophil count (ANC) was particularly higher in clinically severe ACLF patients and non-survivors (p73.5% (sensitivity:76.5% and specificity:76.5%) and CXCL8/IL-8 >27% (sensitivity:70% and specificity:73%) in prediction of mortality. CONCLUSION: Blockade of CXCR1/CXCR2 diminished the production of inflammatory mediators and reduced cell death; therefore pharmacological neutralization of CXCR1/CXCR2 could provide novel therapeutic target in the management of ACLF.

A New RNA-Based Adjuvant Enhances Virus-Specific Vaccine Responses by Locally Triggering TLR- and RLH-Dependent Effects.

Abstract: Among innovative adjuvants conferring a Th1-shift, RNAdjuvant is a promising candidate. This adjuvant consists of a 547-nt uncapped noncoding ssRNA containing polyU repeats that is stabilized by a cationic carrier peptide. Whereas vaccination of mice with an influenza subunit vaccine induced moderate virus-specific IgG1, vaccination together with RNAdjuvant significantly enhanced this IgG1 and additionally promoted the formation of IgG2b/c, which is indicative of Th1 responses. Furthermore, such sera neutralized influenza virus, whereas this effect was not detected upon vaccination with the subunit vaccine alone. Similarly, upon vaccination with virus-like particles displaying vesicular stomatitis virus G protein, RNAdjuvant promoted the formation of virus-specific IgG2b/c and enhanced neutralizing IgG responses to an extent that mice were protected against lethal virus infection. RNAdjuvant induced dendritic cells to upregulate activation markers and produce IFN-I. Although these effects were strictly TLR7 dependent, RNAdjuvant-mediated augmentation of vaccine responses needed concurrent TLR and RIG-I-like helicase signaling. This was indicated by the absence of the adjuvant effect in vaccinated MyD88-/-Cardif-/- mice, which are devoid of TLR (with the exception of TLR3) and RIG-I-like helicase signaling, whereas in vaccinated MyD88-/- mice the adjuvant effect was reduced. Notably, i.m. RNAdjuvant injection induced local IFN-I responses and did not induce systemic effects, implying good tolerability and a favorable safety profile for RNAdjuvant.

Engineered trivalent immunogen adjuvanted with a STING agonist confers protection against Trypanosoma cruzi infection

Abstract: The parasite Trypanosoma cruzi is the causative agent of Chagas disease, a potentially life-threatening infection that represents a major health problem in Latin America. Several characteristics of this protozoan contribute to the lack of an effective vaccine, among them: its silent invasion mechanism, T. cruzi antigen redundancy and immunodominance without protection. Taking into account these issues, we engineered Traspain, a chimeric antigen tailored to present a multivalent display of domains from key parasitic molecules, combined with stimulation of the STING pathway by c-di-AMP as a novel prophylactic strategy. This formulation proved to be effective for the priming of functional humoral responses and pathogen-specific CD8+ and CD4+ T cells, compatible with a Th1/Th17 bias. Interestingly, vaccine effectiveness assessed across the course of infection, showed a reduction in parasite load and chronic inflammation in different proof of concept assays. In conclusion, this approach represents a promising tool against parasitic chronic infections.

Immunization with Tc52 or its amino terminal domain adjuvanted with c-di-AMP induces Th17+Th1 specific immune responses and confers protection against Trypanosoma cruzi.

Abstract: The development of new adjuvants enables fine modulation of the elicited immune responses. Ideally, the use of one or more adjuvants should result in the induction of a protective immune response against the specific pathogen. We have evaluated the immune response and protection against Trypanosoma cruzi infection in mice vaccinated with recombinant Tc52 or its N- and C-terminal domains (NTc52 and CTc52) adjuvanted either with the STING (Stimulator of Interferon Genes) agonist cyclic di-AMP (c-di-AMP), a pegylated derivative of α-galactosylceramide (αGC-PEG), or oligodeoxynucleotides containing unmethylated CpG motifs (ODN-CpG). All groups immunized with the recombinant proteins plus adjuvant: Tc52+c-di-AMP, NTc52+c-di-AMP, CTc52+c-di-AMP, NTc52+c-di-AMP+αGC-PEG, NTc52+CpG, developed significantly higher anti-Tc52 IgG titers than controls. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 showed the highest Tc52-specific IgA titers in nasal lavages. All groups immunized with the recombinant proteins plus adjuvant developed a strong specific cellular immune response in splenocytes and lymph node cells with significant differences for groups immunized with c-di-AMP and Tc52, NTc52 or CTc52. These groups also showed high levels of Tc52-specific IL-17 and IFN-γ producing cells, while NTc52+CpG group only showed significant difference with control in IFN-γ producing cells. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 developed predominantly a Th17 and Th1immune response, whereas for NTc52+CpG it was a dominant Th1 response. It was previously described that αGC-PEG inhibits Th17 differentiation by activating NKT cells. Thus, in this work we have also included a group immunized with both adjuvants (NTc52+c-di-AMP+αGC-PEG) with the aim to modulate the Th17 response induced by c-di-AMP. This group showed a significant reduction in the number of Tc52-specific IL-17 producing splenocytes, as compared to the group NTc52+c-di-AMP, which has in turn correlated with a reduction in protection against infection. These results suggest that the Th17 immune response developed after immunizing with NTc52+c-di-AMP could have a protective role against T. cruzi infection. Groups NTc52+c-di-AMP, Tc52+c-di-AMP and NTc52PB, were the ones that showed better protection against infection with lower parasitemia and weight loss, and higher survival.

Anti-nuclear autoantibodies in the general German population: prevalence and lack of association with selected cardiovascular and metabolic disorders-findings of a multicenter population-based study.

Abstract: We determined the prevalence of anti-nuclear autoantibodies (ANAs) in the German adult population and examined the association between ANAs and cardiovascular and metabolic disorders. We used data and blood samples from the pretest phases of the German National Cohort, obtained from six of the 18 study centers (n = 1199). All centers applied standardized instruments including face-to-face interviews, anthropometric measurements and collection of blood samples. Self-reported histories of diabetes mellitus, heart attack and elevated blood cholesterol and/or lipids were recorded. Height, weight and blood pressure were measured. ANAs were detected using a semi-automated system (AKLIDES®; Medipan GmbH, Dahlewitz, Germany). A positive ANA was defined as a titer ≥ 1:80. ANA were classified as weakly (1:80 or 1:160), moderately (1:320 or 1:640) or strongly (≥1:1280) positive. Specific autoantibodies against nuclear antigens were detected with second-step assays according to the ANA staining pattern. Associations between the assessed disorders and ANA positivity and pattern were examined using sex and age-adjusted mixed-effects logistic regression models. Thirty-three percent (95% confidence interval; 31–36%) of the 1196 participants (measurements could not be obtained from three samples) were ANA positive (titer ≥ 1:80). The proportions of weakly, moderately and strongly positive ANA were 29%, 3.3% and 1.3%, respectively. ANA positivity was more common among women than men across all titers (χ2, p = 0.03). ANA positivity, even when stratified according to height of titer or immunofluorescent pattern, was not associated with diabetes, elevated blood cholesterol and/or lipids, obesity or hypertension. Second-step autoantibody assays were positive in 41 of the 83 samples (49%) tested, with anti-DFS70 (n = 13) and anti-dsDNA (n = 7) being most frequent. These subgroups were too small to test for associations with the disorders assessed. The prevalence of ANA positivity in the German general population was similar to values reported from other countries. Contrary to other studies, there was no association with selected self-reported and objectively measured cardiovascular and metabolic variables.

Motivations for (non)participation in population-based health studies among the elderly – comparison of participants and nonparticipants of a prospective study on influenza vaccination

Abstract: Participation in epidemiological studies has strongly declined in recent years. We examined the reasons for (non)participation in population-based health studies among participants and nonparticipants of a prospective study on influenza vaccination among the elderly. Males and females between 65 and 80 years of age (N = 5582) were randomly selected from the residents’ registration office in Hannover, Germany, and were invited to participate in a study featuring vaccination with a seasonal adjuvanted influenza vaccine (Fluad™, Novartis) including five follow-up visits (day 0, 1/3, 7, 21, 70 with respect to vaccination). A 24-item nonresponder questionnaire, including 10 items on reasons for participating in a hypothetical health study, was mailed to 1500 randomly selected nonparticipants. The same 10 items were included in the end-of-study questionnaire administered to the participants in the vaccination study (n = 200). Logistic regression analysis with backward elimination was used to identify the reasons most strongly associated with nonparticipation. Five hundred thirty-one (35%) nonparticipants and 200 participants (100%) returned the respective questionnaires. Nonparticipation was associated with a lower interest in obtaining personal health information (OR = 3.32) and a preference for less invasive (OR = 3.01) and less time-demanding (OR = 2.19) studies. Responses to other items, e.g. regarding altruistic motives, monetary compensation, general interest of the study, or study approval through ethics committee and data security authority, did not differ between participants and nonparticipants. Participation rates in health studies among elderly individuals could potentially be improved by reducing interventions and time demand, for instance by implementing methods of self-sampling and remote data collection. No. 1100359 (ClinicalTrials.gov, date of registration: 09.02.2015).

Cyclic dinucleotides modulate induced type I IFN responses in innate immune cells by degradation of STING

Abstract: The cyclic dinucleotides, GMP-AMP (cGAMP) and c-di-AMP [bis-(3',5')-cyclic dimeric AMP], are potent type I IFN inducers via STING-TBK1-IRF3 cascade. They are promising adjuvants that promote antigen-specific humoral and cellular immune responses in different preclinical models; however, an optimal outcome of vaccination depends on a balanced immune activation. Here, we characterize the process of IFN-β induction by c-di-AMP and cGAMP in an in vitro model on the basis of primary mouse dendritic cells. Results obtained show decreased IFN-β production upon prolonged cell stimulation. We demonstrate that this effect depends on c-di-AMP/cGAMP-mediated down-regulation of stimulator of IFN gene (STING) protein levels. These results were confirmed by using human peripheral blood mononuclear cell-derived dendritic cells. Studies performed to explore the potential mechanism of STING modulation suggested proteolytic degradation to be a contributing factor to the observed decrease in cellular STING levels. Our work contributes to the elucidation of the molecular mode of action of vaccine constituents, which, in turn, is a prerequisite for the rational design of vaccines with predictable efficacy and safety profiles-Rueckert, C., Rand, U., Roy, U., Kasmapour, B., Strowig, T., Guzman, C. A. Cyclic dinucleotides modulate induced type I IFN responses in innate immune cells by degradation of STING.

Targeted antigen delivery to dendritic cells elicits robust antiviral T cell-mediated immunity in the liver.

Abstract: Hepatotropic viruses such as hepatitis C virus cause life-threatening chronic liver infections in millions of people worldwide. Targeted in vivo antigen-delivery to cross-presenting dendritic cells (DCs) has proven to be extraordinarily efficient in stimulating antigen-specific T cell responses. To determine whether this approach would as well be suitable to induce local antiviral effector T cells in the liver we compared different vaccine formulations based on either the targeting of DEC-205 or TLR2/6 on cross-presenting DCs or formulations not involving in vivo DC targeting. As read-outs we used in vivo hepatotropic adenovirus challenge, histology and automated multidimensional fluorescence microscopy (MELC). We show that targeted in vivo antigen delivery to cross-presenting DCs is highly effective in inducing antiviral CTLs capable of eliminating virus-infected hepatocytes, while control vaccine formulation not involving DC targeting failed to induce immunity against hepatotropic virus. Moreover, we observed distinct patterns of CD8+ T cell interaction with virus-infected and apoptotic hepatocytes in the two DC-targeting groups suggesting that the different vaccine formulations may stimulate distinct types of effector functions. Our findings represent an important step toward the future development of vaccines against hepatotropic viruses and the treatment of patients with hepatic virus infection after liver transplantation to avoid reinfection.

Establishment of a cohort for deep phenotyping of the immune response to influenza vaccination among elderly individuals recruited from the general population.

Abstract: Elderly individuals have the highest burden of disease from influenza infection but also the lowest immune response to influenza vaccination. A better understanding of the host response to influenza vaccination in the elderly is therefore urgently needed. We conducted a biphasic prospective, population-based study from Dec. 2014 to May 2015 (pilot study) and Sept. 2015 to May 2016 (main study). Individuals 65-80 y of age were randomly selected from the residents' registration office in Hannover, Germany, for the pilot (n = 34) and main study (n = 200). The pilot study tested recruitment for study arms featuring 2, 4, or 5 visits/blood draws. The 5-visit (day 0, 1/3, 7, 21, 70 with respect to vaccination) study arm was selected for the main study. Both studies featured vaccination with Fluad™ (Novartis, Italy), a detailed medical history, a physical exam, recording of adverse events, completion of a questionnaire on common infections and an end-of-study questionnaire, and blood samples. Response rates in the pilot and main studies were 3.7% and 4.0%, respectively. Willingness to participate did not differ among the study arms (Fisher's exact test, p = 0.44). In both studies, there were no losses to follow-up. Compliance with study visits, blood sampling and completion of the questionnaires was very high (100%, >97%, 100%, respectively), as were participants' acceptance of and satisfaction with both phases of the study. The low response rates indicate the need for optimized recruitment strategies if the study population is to be representative of the general population. Nonetheless, the complex prospective study design proved to be highly feasible.

Roads to advanced vaccines: influenza case study.

Abstract: Vaccines represent a cornerstone to ensure healthy lives and promote well-being for all at all ages. However, there are many diseases for which vaccines are not available, are relatively ineffective or need to be adapted periodically. Advances in microbial biotechnology will contribute to overcoming these roadblocks by laying the groundwork for improving and creating new approaches for developing better vaccines, as illustrated here in the case of influenza.