David Bernardo

• PhD
• Fellow at University of Valladolid

Background Human intestinal conventional dendritic cells (cDC) maintain the mechanisms of immune tolerance in health. However, their specific contribution to the development of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn´s disease (CD) remains elusive Methods Human intestinal cDC were identified by flow cytometry...

Background Crohn's disease (CD) is a chronic inflammatory condition of the gastrointestinal tract, with a globally rising incidence. It may result from a complex interaction among genetic predisposition, environmental influences, and alterations in gut microbiota, leading to dysregulation of both innate and adaptive immune responses. Despite advanc...

Purpose SARS-CoV-2 causes a severe inflammatory syndrome (COVID-19) leading, in many cases, to bilateral pneumonia, severe dyspnea and in ~5% of these, death. DNA methylation is known to play an important role in the regulation of the immune processes behind COVID-19 progression, however it has not been studied in depth. In this study, we aim to ev...

Here we describe the results of a genome-wide study conducted in 11 939 COVID-19 positive cases with an extensive clinical information that were recruited from 34 hospitals across Spain (SCOURGE consortium). In sex-disaggregated genome-wide association studies for COVID-19 hospitalization, genome-wide significance (p < 5x10−8) was crossed for varia...

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is the coronavirus strain causing the respiratory pandemic COVID-19 (coronavirus disease 2019). To understand the pathobiology of SARS-CoV-2 in humans it is necessary to unravel the metabolic changes that are produced in the individuals once the infection has taken place. The goal of this...

Background Crohn’s disease (CD) is a chronic inflammation of the human gastrointestinal tract. Intestinal conventional dendritic cells (cDC) maintain the balance between immunity against pathogens and tolerance towards nutrients and commensals. However, there is not much information about DC composition, phenotype and function in the human gut in C...

Background Inflammatory bowel disease (IBD) is an idiopathic and chronic disorder that include ulcerative colitis (UC) and Crohn’s disease (CD). Both diseases are different but show an uncontrolled intestinal immune response that generate tissue inflammation. Monocytes (Φ) play a key role in the tolerogenic maintenance in the gastrointestinal mucos...

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences b...

SARS-CoV-2 causes a severe inflammatory syndrome (COVID-19) leading, in many cases, to bilateral pneumonia, severe dyspnea and in ∼5% of these, death. DNA methylation is known to play an important role in the regulation of the immune processes behind COVID-19 progression, however it has not been studied in depth, yet. In this study, we aim to evalu...

Severe status of coronavirus disease 2019 (COVID-19) is extremely associated to cytokine release. Moreover, it has been suggested that blood group is also associated with the prevalence and severity of this disease. However, the relationship between the cytokine profile and blood group remains unclear in COVID-19 patients. In this sense, we prospec...

Background: There is considerable variability in COVID-19 outcomes amongst younger adults-and some of this variation may be due to genetic predisposition. Methods: We combined individual level data from 13,888 COVID-19 patients (N=7,185 hospitalized) from 17 cohorts in nine countries to assess the association of the major common COVID-19 genetic...

Murine dendritic cells, when pulsed with heat-killed Burkholderia pseudomallei and used to immunise naïve mice, have previously been shown to induce protective immunity in vivo. We have now demonstrated the in vitro priming of naïve human T cells against heat-killed B. pseudomallei, by co-culture with syngeneic B. pseudomallei-pulsed dendritic cell...

Antigen tests or polymerase chain reaction (PCR) amplification are currently COVID-19 diagnostic tools. However, developing complementary diagnosis tools is mandatory. Thus, we performed a plasma cytokine array in COVID-19 patients to identify novel diagnostic biomarkers. A discovery–validation study in two independent prospective cohorts was perfo...

Pneumonia is the leading cause of hospital admission and mortality in coronavirus disease 2019 (COVID-19). We aimed to identify the cytokines responsible for lung damage and mortality. We prospectively recruited 108 COVID-19 patients between March and April 2020 and divided them into four groups according to the severity of respiratory symptoms. Tw...

Introduction Lunasin is a soybean bioactive peptide with a variety of beneficial properties against chronic disorders. However, its effect in human primary intestinal cells remains unknown. Hence, this study aims to characterize its ex vivo biological activity in the human intestinal mucosa. Methods and Results Human intestinal biopsies, obtained...

Background: Pneumonia is the leading cause of hospital admission and mortality in coronavirus disease 2019 (COVID-19), attributed to a cytokine storm. The objective of our study is to characterize this profile to identify the cytokines responsible for lung damage and mortality. Methods: Plasma samples of 108 prospectively recruited COVID-19 patient...

Eosinophilic esophagitis (EoE) is a chronic, immune-mediated inflammatory esophageal disease triggered by food antigens. Cumulative evidence supports the implication of microbiota and the innate immune system in the pathogenesis of EoE. Changes in the esophageal microbiome were investigated by applying 16S rRNA gene sequencing on esophageal biopsie...

Background: Growth arrest-specific factor 6 (GAS6) and the Tyro3, AXL, and MERTK (TAM) receptors counterbalance pro-inflammatory responses. AXL is a candidate receptor for SARS-CoV-2, particularly in the respiratory system, and the GAS6/AXL axis is targeted in current clinical trials against COVID-19. However, GAS6 and TAMs have not been evaluated...

Background: There is considerable variability in COVID-19 outcomes amongst younger adults and some of this variation may be due to genetic predisposition. We characterized the clinical implications of the major genetic risk factor for COVID-19 severity, and its age-dependent effect, using individual-level data in a large international multi-centre...

Dendritic cells (DC) and macrophages (Mϕ) constitute the most abundant antigen presenting cells in the human intestinal mucosa. In resting conditions, they are essential to maintain the mechanisms of immune tolerance toward food antigens and commensals, at the time that they keep the capacity to initiate and maintain antigen-specific pro-inflammato...

Abstract Adipose tissue secretes molecules that can promote activity in Crohn’s disease. We aimed to evaluate the role of serum adipokines as possible biomarkers in Crohn’s disease. Serum samples were obtained from 40 patients with endoscopically active or quiescent Crohn’s disease and 36 healthy controls. Serum leptin, ghrelin, resistin and adipon...

Here we present an easy flow cytometry protocol to study the viability of Helicobacter pylori which also enables the detection of even low live bacteria densities. This protocol has potential utility for a fast and accurate assessment of experimental eradication methods against H. pylori.

Burkholderia pseudomallei is a Gram-negative bacterium that causes melioidosis, an infectious disease endemic to south-east Asia. As B. pseudomallei is antibiotic-resistant, the need for cell-based vaccines and therapies is crucial to managing melioidosis. Dendritic cells (DC) provide the first line of defense to infection and direct downstream imm...

Background Intestinal dendritic cells (DC) and macrophages drive disease progression in patients with inflammatory bowel disease (IBD). We aimed to characterize the activation and homing profile of human circulating DC and monocyte subsets in healthy control patients (CP) and IBD patients. Methods Eighteen CP and 64 patients with IBD were categori...

Aims: The aims of this study were (a) to know the kinetics of antitumor necrosis factor (TNF) drug serum levels during the induction phase in patients with Crohn's disease; (b) to identify variables associated with these levels; and (c) to assess the relation between these levels and short-term effectiveness in Crohn's disease patients. Methods:...

Introduction: celiac disease (CD) patients have a specific pattern of lymphocytic infiltrate in the duodenal mucosa. Flow cytometry is a complementary tool for the diagnosis of CD, which allows the quantification and characterization of intraepithelial lymphocytes (IELs) by what is commonly called a lymphogram. Here we describe our experience with...

Scope Circulating dendritic cell (DC) and monocyte subsets contribute to the pool of intestinal DC and macrophages in celiac disease (CeD), an autoimmune gut disorder triggered by dietary gluten. Here, this study aims to characterize these circulating subsets in CeD and assess the effect of different gliadin‐derived peptides on conventional DC (cDC...

Background Our aim was to identify novel biomarkers and molecular pathways that may be involved in the development or progression of inflammatory bowel diseases (IBD) by the comparison of serum extracellular vesicles (EVs) proteomic profile between healthy controls (HC), Crohn’s disease (CD) [active (aCD) and quiescent (qCD)] and ulcerative colitis...

Background Plasma cells (PCs) and B lymphocytes (BLs) are a source of immunoglobulins (Ig), being IgA essential for intestinal homeostasis. An unbalanced intestinal Ig production has been described in inflammatory bowel disease (IBD). Nevertheless little is known about the role of mucosal Ig-producing BL and PC in IBD, reason why we decided to stud...

Background Adipose tissue wrapping the gastrointestinal tract is a risk factor for disease activity in Crohn’s disease (CD). Indeed, adipokines associated to lipid metabolism can modulate local immune responses. However, few studies have investigated the possible association between adipokines and CD. Here, we aimed to evaluate the role of serum ad...

Background Intestinal dendritic cells (DCs) and macrophages govern the mechanisms of immune homeostasis having a role in inflammatory bowel disease (IBD) onset. However, the profile of their circulating precursors (DC and monocytes) in IBD has not been previously described in depth. Our aim was to characterise blood DC and monocyte subsets in healt...

Intraepithelial immune response can be studied by flow cytometry. The proportion of CD3+ cells differs between Crohn’s disease and ulcerative colitis.

Celiac disease (CeD) and inflammatory bowel disease (IBD) are chronic gastrointestinal disorders of inflammatory origin that develop in response to environmental triggers in genetically predisposed individuals. CeD localizes in the duodenal mucosa, where intolerance develops to dietary gluten from wheat, barley, rye, and some varieties of oats. IBD...

Bioactive peptides secreted by probiotic Bifidobacterium longum (peptide B7) and opportunistic pathogen Bacteroides fragilis (peptide B12) modulate the intestinal cytokine milieu in health. Here, we characterized their capacity to modulate both the mucosal cytokine production and the phenotype of circulating antigen presenting cells (APCs) in activ...

Background and aims: To evaluate the clinical outcomes in patients with IBD after switching from Remicade® to CT-P13 in comparison with patients who maintain Remicade®. Methods: Patients under Remicade® who were in clinical remission with standard dosage at study entry were included. The 'switch cohort' [SC] comprised patients who made the switc...

Background The effect of low-frequency functional variation on anti-tumor necrosis factor alpha (TNF) response in Crohn’s disease (CD) patients remains unexplored. The objective of this study was to investigate the impact of functional rare variants in clinical response to anti-TNF therapy in CD. Methods CD anti-TNF naïve patients starting anti-TN...

Introduction: The only available effective treatment for celiac disease (CD) is strict and long-term compliance with a gluten-free diet. Dietary gluten restriction must be strict and long term, but is difficult to achieve in many cases and alternative dietary strategies have been investigated in the past few years. Areas covered: This review highli...

Objectives (a) To evaluate the diagnostic accuracy of anti-TNF trough levels to predict mucosal healing in inflammatory bowel disease (IBD); (b) to determine the best cut-off point to predict mucosal healing in IBD patients treated with anti-TNF. Methods This is a multicenter, prospective study. IBD patients under anti-TNF treatment for at least 6...

Background: Inflammatory bowel disease (IBD) comprises a group of chronic inflammatory disorders of the gastrointestinal tract which precise aetiology remains unknown. Diet is one of the main environmental factors involved in IBD as it modulates both the gut microbiota and the mucosal immune system. The gastrointestinal tract is therefore the main...

Production of interleukin-17 (IL-17) and IL-22 by T helper 17 (Th17) cells and group 3 innate lymphoid cells (ILC3s) in response to the gut microbiota ensures maintenance of intestinal barrier function. Here, we examined the mechanisms whereby the immune system detects microbiota in the steady state. A Syk-kinase-coupled signaling pathway in dendri...

Background Loss-of-function (LoF) variants are one of the most interesting forms of rare functional genetic variations as they impair the function of a gene and are more likely to lead to extreme phenotypes. Our aim was to know the impact of functional rare variants in clinical response to anti-TNF therapy in Crohn’s disease (CD). Methods CD anti-...

Background Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammation of the human gastrointestinal (GI) tract. Intestinal dendritic cells (DC) are essential to maintain the balance between immunity against pathogens and tolerance towards nutrients and commensals. However, there is not mu...

Background The gastrointestinal mucosa represents the main interface between dietary components and the organism. Lunasin is a 43-amino acid peptide naturally present in soybean protein with a variety of biological functions demonstrated by in vitro assays, cell cultures and animal models. Nevertheless, its physiological relevance in human primary...

Peptides encrypted in the intestinal microbial-exoproteome mediate the host-microbiota crosstalk, which is disrupted in inflammatory bowel disease (IBD). Here, the MAHMI database was used for the identification of 20 novel intestinal bacterial peptides. Our results revealed that serum IgA levels directed towards the peptides, but not IgG, discrimin...

Background The gastrointestinal tract harbors the largest microbiota load in the human body, hence maintaining a delicate balance between immunity against invading pathogens and tolerance toward commensal. Such immune equilibrium, or intestinal homeostasis, is conducted by a tight regulation and cooperation of the different branches of the immune s...

Although macrophages (Mϕ) maintain intestinal immune homoeostasis, there is not much available information about their subset composition, phenotype and function in the human setting. Human intestinal Mϕ (CD45+HLA-DR+CD14+CD64+) can be divided into subsets based on the expression of CD11c, CCR2 and CX3CR1. Monocyte-like cells can be identified as C...

Objectives: Esophageal microbiota and regulation of adaptive immunity are increasingly being investigated in eosinophilic esophagitis (EoE). Toll-like receptors (TLRs) play a central role in the initiation and maintenance of innate immune activity. Our objective was to characterize the esophageal and duodenal innate immune response in EoE and its...

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a serious, costly and persistent health problem with an estimated prevalence in Western countries around 0.5% of the general population; its socioeconomic impact is comparable with that for chronic diseases such as diabetes. Conventional treatment involves escala...

Background Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is thought to be driven by an exacerbated immune response to the commensal microbiota. Macrophages (MΦ) are the most abundant mononuclear phagocytes in the gastrointestinal tract, where they are critical at shaping the type of immune elicited to...

Background Inflammatory bowel disease (IBD) is thought to be associated with an abnormal immune response towards commensal microbiota in genetically predisposed individuals, being the host-microbiota crosstalk dysrupted in IBD patients. Bacterial secreted peptides encrypted in the intestinal microbial exoproteome are key mediators of this dialogue,...

Background and aims: Fibrosis is a common complication of Crohn's disease, and is related with dysregulated tissular repair following inflammation, in which macrophages play a central role. We have previously observed that STAT6-/- mice present delayed mucosal recovery after TNBS-induced colitis due to a deficiency in reparatory IL4/STAT6-dependen...

Introduction Colorectal cancer (CRC) is a major cause of mortality. Dendritic cells (DC) promote tumour immunity or tolerance dictated by tissue microenvironment. Proximal colon (right-sided) CRC has lower incidence but poorer prognosis than distal colon (left-sided) CRC. This may be due to immunological differences between the proximal and distal...

Background: Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is thought to be driven by an exacerbated immune response to the commensal microbiota. Macrophages (MΦ) are the most abundant mononuclear phagocytes in the gastrointestinal tract, where they are critical at shaping the type of immune elicited t...

Celiac disease is the most common oral intolerance in Western countries. It results from an immune response towards gluten proteins from certain cereals in genetically predisposed individuals (HLA-DQ2 and/or HLA-DQ8). Its pathogenesis involves the adaptive (HLA molecules, transglutaminase 2, dendritic cells, and CD4+ T-cells) and the innate immunit...

Probiotic bacteria are widely used in functional foods or as dietary supplements. However, the signalling pathways by which they promote beneficial effects on the immune system are not fully understood. The effects of six different probiotics on monocyte-derived dendritic cells (MoDCs) were examined in this study. We found that Lactobacillus rhamno...

Dendritic cells (DCs) are antigen-presenting cells that can acquire tumour antigens and initiate cytotoxic T cell reactions. Obesity has been proposed as a cause for tumours escaping immune surveillance, but few studies investigate the impact of other body composition parameters. We examined the relationship of DC phenotype with computer tomography...

Background: Dendritic cells (DC) determine initiation, type and location of immune responses and, in adults, show decreased Toll-like receptors and some increased cytokine levels on ageing. Few studies in children have characterised DC or explored DC-related mechanisms producing age-related immune changes. Results: The pDC marker BDCA2 (but not...

Background: Oats provide important nutritional and pharmacological properties, although their safety in coeliac patients remains controversial. Previous studies have confirmed that the reactivity of the anti-33-mer monoclonal antibody with different oat varieties is proportional to the immune responses in terms of T-cell proliferation. Although th...

Celiac Disease (CD) is an interferon (IFN)γ-mediated duodenal hypersensitivity to wheat gluten occurring in genetically predisposed individuals. Gluten-free diet (GFD) leads to a complete remission of the disease. Vα24-restricted invariant NKT (iNKT) cells are important to maintain immune homeostasis in the gut mucosa because of their unique capaci...

Background & aims: Most knowledge about gastrointestinal (GI)-tract dendritic cells (DC) relies on murine studies where CD103(+) DC specialize in generating immune tolerance with the functionality of CD11b(+/-) subsets being unclear. Information about human GI-DC is scarce, especially regarding regional specifications. Here, we characterized human...

Faecal microbiota transplantation (FMT) is effective in the treatment of Clostridium difficile infection, where efficacy correlates with changes in microbiota diversity and composition. The effects of FMT on recipient microbiota in inflammatory bowel diseases (IBD) remain unclear. We assessed the effects of FMT on microbiota composition and functio...

Background and Objectives: The host local immune response (LIR) to cancer is a determinant of cancer outcome. Regulation of this local response is largely achieved through chemokine synthesis from the tumor microenvironment such as C-Chemokine-Receptor-7 (CCR7). We examined the LIR measured as CCR7 expression, in colorectal cancers (CRC) and explor...

Resumen Oral tolerance is defined as the lack of a systemic immune response against antigens previously administered through the gastrointestinal tract. Therefore, in an antigen rich environment such as the intestine, the oral tolerance avoids the development of immune responses against food antigens and the commensal microbiota maintaining immune...

Introduction Emerging data support the link between systemic inflammatory response (IR) and body composition alterations in cancer patients but limited information exists on how the local IR to the tumour is associated to these changes. Regulation of the local IR is largely achieved through chemokine synthesis from the tumour microenvironment such...

Introduction Dendritic cells (DC) are potent antigen presenting cells that bridge the innate and adaptive immune systems. Altered function and phenotype of human blood DC has been described in inflammatory bowel diseases including Crohn’s disease (CD), with peripheral blood DC displaying more inflammatory and fewer tolerogenic characteristics in CD...

Dendritic cells (DCs) either boost the immune system (enhancing immunity) or dampen it (leading to tolerance). This dual effect explains their vital role in cancer development and progression. DCs have been tested as a predictor of outcomes for cancer progression. Eight studies evaluated tumour-infiltrating DCs (TIDCs) as a predictor for colorectal...

The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could el...

The gastrointestinal immune system is exposed to a large amount of different products mainly innocuous (derived from “friendly” bacteria and/or food antigens) but sometimes also dangerous and infectious (as invading bacteria or viruses). Despite that, it is effective in discriminating between them and hence maintaining immune tolerance against the...

Dendritic cells (DC) mediate intestinal immune tolerance. Despite striking differences between the colon and the ileum both in function and bacterial load, few studies distinguish between properties of immune cells in these compartments. Furthermore, information of gut DC in humans is scarce. We aimed to characterise human colonic versus ileal DC....

: The pathogenesis of inflammatory bowel disease is incompletely understood but results from a dysregulated intestinal immune response to the luminal microbiota. CD4 T cells mediate tissue injury in the inflammatory bowel disease-associated immune response. Dendritic cells (DC) generate primary T-cell responses and mediate intestinal immune toleran...

Colorectal cancer (CRC) exhibits differences in incidence, pathogenesis, molecular pathways and outcome depending on the location of the tumor. This review focuses on the latest developments in epidemiological and scientific studies, which have enhanced our understanding on the underlying genetic and immunological differences between the proximal (...

Background: Tight junction proteins (TJPs) and dendritic cells (DC) are critical in the pathogenesis of inflammatory bowel diseases. The ileal pouch formed by restorative proctocolectomy provides a unique human model for studying the pathogenesis of inflammatory bowel diseases. Data implicate the microbiota in the pathogenesis of pouchitis, while...