Trained Immunity-Based Vaccines: A Ready-to-Act Strategy to Tackle Viral Outbreaks

Viral outbreaks have become significant threats to global human public health. New emerging viruses, pathogen mutations, and even the progressive loss of efficacy in some existing vaccines are behind this problem, which is amplified by the rapid virus spread given the ease of current mobility. Taking into account that these outbreaks arise in the absence of conventional effective vaccines, alternative approaches based on trained (innate) immunity are being considered. This immunity is dependent on a functional reprogramming of innate immune cells, leading to an enhanced nonspecific response towards different pathogens, including viruses. Trained immunity-based vaccines (TIbVs), defined as vaccine formulations containing trained immunity inducers, could be used during viral outbreaks to confer non-specific protection but also to enhance adaptive specific immune responses. In this chapter, we aim to illustrate how TIbVs could tackle the above-mentioned situations derived from viral outbreaks, reviewing the potential of available TIbVs in such urgent situations with a special mention to COVID-19

Targeting SHIP-1 in Myeloid Cells Enhances Trained Immunity and Boosts Response to Infection

beta-Glucan-induced trained immunity in myeloid cells leads to long-term protection against secondary infections. Although previous studies have characterized this phenomenon, strategies to boost trained immunity remain undefined. We found that beta-glucan-trained macrophages from mice with a myeloid-specific deletion of the phosphatase SHIP-1 (LysM Delta SHIP-1) showed enhanced proinflammatory cytokine production in response to lipopolysaccharide. Following beta-glucan training, SHIP-1-deficient macrophages exhibited increased phosphorylation of Akt and mTOR targets, correlating with augmented glycolytic metabolism. Enhanced training in the absence of SHIP-1 relied on histone methylation and acetylation. Trained LysM Delta SHIP-1 mice produced increased amounts of proinflammatory cytokines upon rechallenge in vivo and were better protected against Candida albicans infection compared with control littermates. Pharmacological inhibition of SHIP-1 enhanced trained immunity against Candida infection in mouse macrophages and human peripheral blood mononuclear cells. Our data establish proof of concept for improvement of trained immunity and a strategy to achieve it by targeting SHIP-1.We thank the members of the Immunobiology Lab for useful discussions. We thank the CNIC facilities and personnel, particularly Santiago Rodriguez and Ruben Mota, for their support. P.S.-L. is funded by grant BES-2015-072699 (´´Ayudas para Contratos Predoctorales para la Formacion de Doctores 2015´´) from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO). C.d.F. is supported by the Asociacion Espanola Contra el Cancer (AECC) Foundation as a recipient of an ``Ayuda Fundacion Cientifica AECC a Personal Investigador en Cancer´´ grant. Work in the Sancho laboratory is funded by CNIC and grant SAF2016-79040-R from MINECO, Agencia Estatal de Investigacion, and FEDER (European Fund for Regional Development); grant B2017/BMD-3733 Immunothercan-CM from Comunidad de Madrid; grant RD16/0015/0018-REEM from FIS-Instituto de Salud Carlos III, MINECO, and FEDER; Foundation Acteria; a Constantes y Vitales prize (Atresmedia); Foundation La Marato de TV3 (grant 201723); the European Commission (grant 635122-PROCROP H2020); and the European Research Council (ERC-2016-Consolidator Grant 725091). CNIC is supported by MINECO and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). W.G.K. is an Empire Scholar of the State of New York, the Murphy Family Professor of Children's Oncology Research, and is supported by funds from the Paige Arnold Butterfly Run.S

Bacterial Mucosal Immunotherapy with MV130 Prevents Recurrent Wheezing in Children: A Randomized, Double-Blind, Placebo-controlled Clinical Trial.

The authors thank the patients and their families for participating in this study. They are grateful to the members of the David Sancho laboratory, especially to Carlos del Fresno, for helpful critical discussion.Rationale: Recurrent wheezing in children represents a severe public health concern. Wheezing attacks (WA), mainly associated with viral infections, lack effective preventive therapies. Objectives: To evaluate the efficacy and safety of mucosal sublingual immunotherapy based on whole inactivated bacteria (MV130) in preventing WA in children. Methods: A Phase 3 randomized, double-blind, placebo-controlled, parallel-group trial including a cohort of 120 children <3 years old with ⩾3 WA during the previous year was conducted. Children with a positive skin test to common aeroallergens in the area where the clinical trial was performed were excluded from the trial. Subjects received MV130 or placebo daily for 6 months. The primary endpoint was the number of WA within 1 year after the first dose comparing MV130 and placebo. Measurements and Main Results: There was a significant lower number of WA in MV130 versus the placebo group, 3.0 (interquartile range [IQR], 2.0-4.0) versus 5.0 (IQR, 3.0-7.0) (P < 0.001). As secondary outcomes, a decrease in the duration of WA and a reduction in symptoms and medication scores in the MV130 versus placebo group were found. No adverse events were reported related to the active treatment. Conclusions: Mucosal bacterial immunotherapy with MV130 shows safety and clinical efficacy against recurrent WA in children.Clinical trial registered with www.clinicaltrials.gov (NCT01734811).S

Trained immunity induction by the inactivated mucosal vaccine MV130 protects against experimental viral respiratory infections.

MV130 is an inactivated polybacterial mucosal vaccine that confers protection to patients against recurrent respiratory infections, including those of viral etiology. However, its mechanism of action remains poorly understood. Here, we find that intranasal prophylaxis with MV130 modulates the lung immune landscape and provides long-term heterologous protection against viral respiratory infections in mice. Intranasal administration of MV130 provides protection against systemic candidiasis in wild-type and Rag1-deficient mice lacking functional lymphocytes, indicative of innate immune-mediated protection. Moreover, pharmacological inhibition of trained immunity with metformin abrogates the protection conferred by MV130 against influenza A virus respiratory infection. MV130 induces reprogramming of both mouse bone marrow progenitor cells and in vitro human monocytes, promoting an enhanced cytokine production that relies on a metabolic shift. Our results unveil that the mucosal administration of a fully inactivated bacterial vaccine provides protection against viral infections by a mechanism associated with the induction of trained immunity.We are grateful to members of the D.S. laboratory for discussions and critical reading of the manuscript. We thank the CNIC facilities and personnel for assistance. P.B. is funded by grant BES-2014-069933 (‘‘Ayudas para Contratos Predoctorales para la Formacio´ n de Doctores 2014’’) from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO). L.C. was a recipient of a European Respiratory Society Fellowship (RESPIRE2-2013- 3708). G.D. is supported by a European Molecular Biology Organization Long-term Fellowship (ALTF 379-2019). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sk1odowska-Curie grant agreement No. 892965. Work in the D.S. laboratory is funded by the CNIC; by the European Research Council (ERC-2016-consolidator grant 725091); by the European Commission (635122-PROCROP H2020); by Ministerio de Ciencia e Innovacio´ n (MICINN), Agencia Estatal de Investigacio´ n (AEI), and Fondo Europeo de Desarrollo Regional (FEDER) (SAF2016-79040-R); by AEI (PID2019-108157RB); by Comunidad de Madrid (B2017/BMD-3733 Immunothercan-CM); by FIS-Instituto de Salud Carlos III, MICINN and FEDER (RD16/0015/0018-REEM); by a collaboration agreement with Inmunotek; by Atresmedia (Constantes y Vitales prize); by Fundacio´ La Marato´ de TV3 (201723); and by Fondo Solidario Juntos (Banco Santander). The CNIC is supported by the Instituto de Salud Carlos III, the MICINN, and the Pro CNIC Foundation.S

Microbiota Sensing by Mincle-Syk Axis in Dendritic Cells Regulates Interleukin-17 and -22 Production and Promotes Intestinal Barrier Integrity

We are grateful to members of the D.S. laboratory and Dr. E. Fernández-Malavé for discussions and critical reading of the manuscript. We appreciate the support of A. Tomás-Loba, G. Sabio, P. Martín, A. Tsilingiri, A.R. Ramiro, C.L. Abram, C.A. Lowell, J.M. García-Lobo, M. Molina, and M.C. Rodríguez for providing reagents and support. We thank the staff at the Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) facilities for technical support. M.M.-L. received a Formación de Personal Universitario (FPU) fellowship (AP2010-5935) from the Spanish Ministerio de Educación. S.I. is funded by grant SAF2015-74561-JIN from the Spanish Ministerio de Ciencia, Innovación, y Universidades (MCIU) and Fondos Europeos de Desarrollo Regional (FEDER). G.D.B and D.M.R. are supported by the Wellcome Trust and the MRC Centre for Medical Mycology at the University of Aberdeen. S.L.L. is supported by the Swiss National Science Foundation (PP00P3_150758). Work in the D.S. laboratory is funded by the CNIC and grant SAF2016-79040-R from MCIU, the Agencia Estatal de Investigación, and FEDER; B2017/BMD-3733 Immunothercan-CM from Comunidad de Madrid; RD16/0015/0018-REEM from FIS-Instituto de Salud Carlos III, MCIU, and FEDER; the Acteria Foundation; the Constantes y Vitales prize (Atresmedia); La Marató de TV3 Foundation (201723); the European Commission (635122-PROCROP H2020), and the European Research Council (ERC-2016-Consolidator Grant 725091). The CNIC is supported by the MCIU and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).Peer reviewedPublisher PD

Flexible Signaling of Myeloid C-Type Lectin Receptors in Immunity and Inflammation

Myeloid C-type lectin receptors (CLRs) are important sensors of self and non-self that work in concert with other pattern recognition receptors (PRRs). CLRs have been previously classified based on their signaling motifs as activating or inhibitory receptors. However, specific features of the ligand binding process may result in distinct signaling through a single motif, resulting in the triggering of non-canonical pathways. In addition, CLR ligands are frequently exposed in complex structures that simultaneously bind different CLRs and other PRRs, which lead to integration of heterologous signaling among diverse receptors. Herein, we will review how sensing by myeloid CLRs and crosstalk with heterologous receptors is modulated by many factors affecting their signaling and resulting in differential outcomes for immunity and inflammation. Finding common features among those flexible responses initiated by diverse CLR-ligand partners will help to harness CLR function in immunity and inflammation

Trained Immunity Based-Vaccines as a Prophylactic Strategy in Common Variable Immunodeficiency. A Proof of Concept Study

Background. A major concern in the care of common variable immunodeficiency (CVID) patients is the persistence of subclinical or recurrent respiratory tract infections (RRTI) despite adequate trough IgG levels, which impacts the quality of life (QoL) and morbidity. Therefore, the development of new approaches to prevent and treat infection, especially RRTI, is necessary. Objectives. We conducted a clinical observational study from May, 2016 to December, 2017 in 20 CVID patients; ten of these patients had a history of RRTI and received the polybacterial preparation MV130, a trained immunity-based vaccine (TIbV) to assess its impact on their QoL and prognosis. Methods. Subjects with RRTI received MV130 for 3 months and were followed up to 12 months after initiation of the treatment. The primary endpoint was a reduction in RRTI at the end of the study. We analyzed the pharmacoeconomic impact on the RRTI group before and after immunotherapy by estimating the direct and indirect costs, and assessed CVID-QoL and cytokine profile. Specific antibody responses to the bacteria contained in MV130 were measured. Results. The RRTI-group treated with TIbV MV130 showed a significant decrease in infection rate (p = 0.006) throughout the 12 months after initiation of the treatment. A decrease in antibiotic use and unscheduled outpatient visits was observed (p = 0.005 and p = 0.002, respectively). Significant increases in anti-pneumococcus and anti-MV130 IgA antibodies (p = 0.039 both) were detected after 12 months of MV130. Regarding the CVID QoL questionnaire, an overall decrease in the score by more than 50% was observed (p &lt; 0.05) which demonstrated that patients experienced an improvement in their QoL. The pharmacoeconomic analysis showed that the real annual direct costs decreased up to 4 times per patient with the prophylactic intervention (p = 0.005). Conclusion. The sublingual administration of the TIbV MV130 significantly reduced the rate of respiratory infections, antibiotic use and unscheduled visits, while increasing specific IgA responses in CVID patients. Additionally, the CVID population felt that their QoL was improved, and a decrease in expenses derived from health care was predicted

DNGR-1 in dendritic cells limits tissue damage by dampening neutrophil recruitment

Host injury triggers feedback mechanisms that limit tissue damage. Conventional type 1 dendritic cells (cDC1s) express dendritic cell natural killer lectin group receptor-1 (DNGR-1), encoded by the gene Clec9a, which senses tissue damage and favors cross-presentation of dead-cell material to CD8+ T cells. Here we find that DNGR-1 additionally reduces host-damaging inflammatory responses induced by sterile and infectious tissue injury in mice. DNGR-1 deficiency leads to exacerbated caerulein-induced necrotizing pancreatitis and increased pathology during systemic Candida albicans infection without affecting fungal burden. This effect is B and T cell–independent and attributable to increased neutrophilia in DNGR-1–deficient settings. Mechanistically, DNGR-1 engagement activates SHP-1 and inhibits MIP-2 (encoded by Cxcl2) production by cDC1s during Candida infection. This consequently restrains neutrophil recruitment and promotes disease tolerance. Thus, DNGR-1–mediated sensing of injury by cDC1s serves as a rheostat for the control of tissue damage, innate immunity, and immunopathology.C.d.F. is supported by the AECC Foundation as the recipient of an “Ayuda Fundación Científica AECC a personal investigador en cancer.” P.S.-L. is funded by grant BES-2015-072699 from the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU). M.E. is the recipient of a CNIC International Ph.D. Programme fellowship “la Caixa”-Severo Ochoa OSLC-CNIC-2013-04. S.K.W. is supported by a European Molecular Biology Organization (EMBO) Long-Term Fellowship (grant ALTF 438-2016) and a CNIC-International Postdoctoral Programme Fellowship (grant 17230-2016). Work in the D.S. laboratory is funded by the CNIC and grant SAF2016-79040-R from MCIU, Agencia Estatal de Investigación, and Fondos Europeos de Desarrollo Regional (FEDER); B2017/BMD-3733 Immunothercan-CM from Comunidad de Madrid; RD16/0015/0018-REEM from FIS-Instituto de Salud Carlos III, MICINN, and FEDER; Acteria Foundation; Constantes y Vitales prize (Atresmedia); La Marató de TV3 Foundation (201723); the European Commission (635122-PROCROP H2020); and the European Research Council (ERC-2016-Consolidator Grant 725091). The CNIC is supported by the MCIU and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).Peer reviewe

IVIg promote cross-tolerance against inflammatory stimuli in vitro and in vivo

12 p.-7 fig.IVIg is an approved therapy for immunodeficiency and for several autoimmune and inflammatory diseases. However, the molecular basis for the IVIg anti-inflammatory activity remains to be fully explained and cannot be extrapolated from studies on animal models of disease. We now report that IVIg impairs the generation of human monocyte-derived anti-inflammatory macrophages by inducing JNK activation and activin A production and limits proinflammatory macrophage differentiation by inhibiting GM-CSF-driven STAT5 activation. In vivo, IVIg provokes a rapid increase in peripheral blood activin A, CCL2, and IL-6 levels, an effect that can be recapitulated in vitro on human monocytes. On differentiating monocytes, IVIg promotes the acquisition of altered transcriptional and cytokine profiles, reduces TLR expression and signaling, and upregulates negative regulators of TLR-initiated intracellular signaling. In line with these effects, in vivo IVIg infusion induces a state tolerant toward subsequent stimuli that results in reduced inflammatory cytokine production after LPS challenge in human peripheral blood and significant protection from LPS-induced death in mice. Therefore, IVIg conditions human macrophages toward the acquisition of a state of cross-tolerance against inflammatory stimuli, an effect that correlates with the net anti-inflammatory action of IVIg in vivo.This work was supported by grants from the Ministerio de Economía y Competitividad (SAF2014-23801), the Instituto de Salud Carlos III (La Red de Investigación en Inflamación y Enfermedades Reumáticas, RIER RD12/009), and the Comunidad Autónoma de Madrid/FEDER (S2010/BMD-2350, RAPHYME Program) to A.L.C. and M.A.V. and by Instituto de Salud Carlos III Grant PI16/01428 to S.S.-R.Peer reviewe

Bioavailability of Oniria^®, a melatonin prolonged-release formulation, versus immediate-release melatonin in healthy volunteers

Background: Melatonin is an endogenous substance which plays a key role in sleep induction by reducing sleep onset latency; it has been approved by the European Food Safety Authority as a food supplement for exogenous administration. Oniria® is a food supplement formulated as 1.98 mg of prolonged-release melatonin tablets; it displays a dual dissolution profile in vitro. Objectives: The main objective of the present study was to evaluate the relative oral bioavailability of Oniria®, in comparison with immediate-release tablets (IRT) with a similar melatonin content as a reference. We also attempted to characterize the circadian rhythm of endogenous melatonin. Methods: We performed an open-label, cross-over, randomized, phase I clinical study with two sequences and three periods involving 14 healthy volunteers. We characterized the endogenous melatonin circadian profile (period 1) and pharmacokinetics (PK) of both Oniria® and the reference melatonin (periods 2 and 3). Results: Two phases were clearly differentiated in the PK profile of Oniria®. An initial one, from dosing up to 2 h, and a delayed one from 2 to 11 h post-administration. During the initial phase, both melatonin formulations were equivalent, with a Cmax value close to 4000 pg/mL. However, in the delayed phase, Oniria® showed significantly higher melatonin concentrations than the IRT (three times higher at 4–6 h post-administration). Moreover, Oniria® exhibited concentrations above the endogenous melatonin peak of 80 pg/mL for up to 2.5 h versus the reference formulation, potentially suggesting an effect of Oniria®, not only in the induction of sleep, but also in the maintenance. Conclusion: Oniria® could be a highly promising food supplement, not only for sleep induction but also for the maintenance of sleepThe study was funded by the sponsor ITF Research Pharma S.L.