Spatio-temporal dynamics of the human small intestinal microbiome and its response to a synbiotic.

Although fecal microbiota composition is considered to preserve relevant and representative information for distal colonic content, it is evident that it does not represent microbial communities inhabiting the small intestine. Nevertheless, studies investigating the human small intestinal microbiome and its response to dietary intervention are still scarce. The current study investigated the spatio-temporal dynamics of the small intestinal microbiome within a day and over 20 days, as well as its responses to a 14-day synbiotic or placebo control supplementation in 20 healthy subjects. Microbial composition and metabolome of luminal content of duodenum, jejunum, proximal ileum and feces differed significantly from each other. Additionally, differences in microbiota composition along the small intestine were most pronounced in the morning after overnight fasting, whereas differences in composition were not always measurable around noon or in the afternoon. Although overall small intestinal microbiota composition did not change significantly within 1 day and during 20 days, remarkable, individual-specific temporal dynamics were observed in individual subjects. In response to the synbiotic supplementation, only the microbial diversity in jejunum changed significantly. Increased metabolic activity of probiotic strains during intestinal passage, as assessed by metatranscriptome analysis, was not observed. Nevertheless, synbiotic supplementation led to a short-term spike in the relative abundance of genera included in the product in the small intestine approximately 2 hours post-ingestion. Collectively, small intestinal microbiota are highly dynamic. Ingested probiotic bacteria could lead to a transient spike in the relative abundance of corresponding genera and ASVs, suggesting their passage through the entire gastrointestinal tract. This study was registered to http://www.clinicaltrials.gov, NCT02018900.

Back to the Future: Immune Protection or Enhancement of Future Coronaviruses.

Before the emergence of SARS-CoV-1, MERS-CoV, and most recently, SARS-CoV-2, four other coronaviruses (the alpha coronaviruses NL63 and 229E and the beta coronaviruses OC43 and HKU1) had already been circulating in the human population. These circulating coronaviruses all cause mild respiratory illness during the winter seasons, and most people are already infected in early life. Could antibodies and/or T cells, especially against the beta coronaviruses, have offered some form of protection against (severe) COVID-19 caused by infection with SARS-CoV-2? Related is the question of whether survivors of SARS-CoV-1 or MERS-CoV would be relatively protected against SARS-CoV-2. More importantly, would humoral and cellular immunological memory generated during the SARS-CoV-2 pandemic, either by infection or vaccination, offer protection against future coronaviruses? Or rather than protection, could antibody-dependent enhancement have taken place, a mechanism by which circulating corona antibodies enhance the severity of COVID-19? Another related phenomenon, the original antigenic sin, would also predict that the effectiveness of the immune response to future coronaviruses would be impaired because of the reactivation of memory against irrelevant epitopes. The currently available evidence indicates that latter scenarios are highly unlikely and that especially cytotoxic memory T cells directed against conserved epitopes of human coronaviruses could at least offer partial protection against future coronaviruses.

The long and winding road of faecal microbiota transplants to targeted intervention for improvement of immune checkpoint inhibition therapy.

INTRODUCTION: Immune checkpoint inhibition (ICI) therapy has revolutionized the treatment of cancer. Inhibitory molecules, either on the tumor or on cells of the immune system, are blocked, allowing the immune system of the patient to attack and eradicate the tumor. Not all patients respond to ICI therapy, and response or non-response has been associated with composition of gut microbiota. AREA COVERED: Fecal microbiota transplantation (FMT) is used as adjunctive therapy in order to improve the outcome of ICI. ClinicalTrials.gov, and other databases were searched (October 2022) for studies dealing with gut microbiota modification and the outcome of ICI. EXPERT OPINION: There is ample evidence for the beneficial effect of FMT on the outcome of ICI therapy for cancer, especially melanoma. Progress is being made in the unraveling of the mechanisms by which microbiota and their metabolites (butyrate and the tryptophan metabolite indole-3-aldehyde) interact with the mucosal immune system of the host. A better understanding of the mechanisms involved will allow the identification of key bacterial species which mediate the effect of FMT. Promising species are Faecalibacterium prausnitzii, Eubacterium rectale, Bifidobacterium adolescentis, B. bifidum, and B. longum, because they are important direct and indirect butyrate producers.

The Impact of SARS-CoV-2 Immune Status and Societal Restrictions in Controlling COVID-19 across the World.

To control the COVID-19 pandemic, many countries implemented vaccination and imposed societal restrictions both at the national level and for international travel. As a check of corona status, COVID passes have been issued. A COVID pass could be obtained when either fully vaccinated against COVID-19, or after recovering from a documented COVID-19 episode, or after a recent (24-48 h) negative SARS-CoV-2 antigen test. A global analysis of SARS-CoV-2 immune status determined by past infection and/or vaccination, vaccination rates, as well as societal restrictions in controlling the COVID-19 pandemic is presented. The data show that across the world, vaccination was more effective in reducing SARS-CoV-2 infections with the delta variant than the omicron variant. Strict societal restrictions could control spread of the virus, but relief of the restrictions was associated with an increase in omicron infections. No significant difference in SARS-CoV-2 infections were found when comparing countries or territories which did or did not implement a COVID pass.

Antigen Presentation of mRNA-Based and Virus-Vectored SARS-CoV-2 Vaccines.

Infection with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19), which has reached pandemic proportions. A number of effective vaccines have been produced, including mRNA vaccines and viral vector vaccines, which are now being implemented on a large scale in order to control the pandemic. The mRNA vaccines are composed of viral Spike S1 protein encoding mRNA incorporated in a lipid nanoparticle and stabilized by polyethylene glycol (PEG). The mRNA vaccines are novel in many respects, including cellular uptake and the intracellular routing, processing, and secretion of the viral protein. Viral vector vaccines have incorporated DNA sequences, encoding the SARS-CoV-2 Spike protein into (attenuated) adenoviruses. The antigen presentation routes in MHC class I and class II, in relation to the induction of virus-neutralizing antibodies and cytotoxic T-lymphocytes, will be reviewed. In rare cases, mRNA vaccines induce unwanted immune mediated side effects. The mRNA-based vaccines may lead to an anaphylactic reaction. This reaction may be triggered by PEG. The intracellular routing of PEG and potential presentation in the context of CD1 will be discussed. Adenovirus vector-based vaccines have been associated with thrombocytopenic thrombosis events. The anti-platelet factor 4 antibodies found in these patients could be generated due to conformational changes of relevant epitopes presented to the immune system.

A Polymorphism in C-C Chemokine Receptor 5 (CCR5) Associates with Löfgren's Syndrome and Alters Receptor Expression as well as Functional Response.

C-C chemokine receptor 5 (CCR5) and polymorphisms in CCR5 gene are associated with sarcoidosis and Löfgren's syndrome. Löfgren's syndrome is an acute and usually self-remitting phenotype of sarcoidosis. We investigated whether the single nucleotide polymorphism (SNP) rs1799987 is associated with susceptibility for Löfgren's syndrome and has an effect on CCR5 expression on monocytes and function of CCR5. A total of 106 patients with Löfgren's syndrome and 257 controls were genotyped for rs1799987. Expression of CCR5 on monocytes was measured by flowcytometry. We evaluated calcium influx kinetics following stimulation upon N-formylmethionyl-leucyl-phenylalanine (fMLP) and macrophage inflammatory protein-1α (MIP-1α) on monocytes by measuring the median fluorescence intensity (MFI). The frequency of the G allele of rs1799987 was significantly higher in Löfgren's syndrome than in healthy controls (p = 0.0015, confidence interval (CI) 1.22-2.32, odds ratio (OR) 1.680). Patients with a GG genotype showed higher CCR5 expression on monocytes than patients with the AA genotype (p = 0.026). A significantly (p = 0.027) lower count of patients with the GG genotype showed a calcium influx reaction to simulation upon MIP-1 α, compared with patients with the AA genotype. The rs1799987 G allele in CCR5 gene is associated with susceptibility to Löfgren's syndrome and with quantitative and qualitative changes in CCR5, potentially effecting the inflammatory response.

Vaccination and their importance for lung transplant recipients in a COVID-19 world.

INTRODUCTION: Lung transplant patients are immunocompromised because of the medication they receive to prevent rejection, and as a consequence are susceptible to (respiratory) infections. Adequate vaccination strategies, including COVID-19 vaccination, are therefore needed to minimize infection risks. AREAS COVERED: The international vaccination guidelines for lung transplant patients are reviewed, including the data on immunogenicity and effectivity of the vaccines. The impact on response to vaccination of the various categories of immunosuppressive drugs, used in the posttransplant period, on response to vaccination is described. A number of immunosuppressive and/or anti-inflammatory drugs also is used for controlling the immunopathology of severe COVID-19. Current available COVID-19 vaccines, both mRNA or adenovirus based are recommended for lung transplant patients. EXPERT OPINION: In order to improve survival and quality of life, infections of lung transplant patients should be prevented by vaccination. When possible, vaccination should start already during the pre-transplantation period when the patient is on the waiting list. Booster vaccinations should be given post-transplantation, but only when immunosuppression has been tapered. Vaccine design based on mRNA technology could allow the design of an array of vaccines against other respiratory viruses, offering a better protection for lung transplant patients.

The clinical relevance of IgM and IgA anti-pneumococcal polysaccharide ELISA assays in patients with suspected antibody deficiency.

Unlike immunoglobulin (Ig)G pneumococcal polysaccharide (PnPS)-antibodies, PnPS IgA and IgM-antibodies are not routinely determined for the assessment of immunocompetence. It is not yet known whether an isolated inability to mount a normal IgM or IgA-PnPS response should be considered a relevant primary antibody deficiency (PAD). We studied the clinical relevance of anti-PnPS IgM and IgA-assays in patients with suspected primary immunodeficiency in a large teaching hospital in 's-Hertogenbosch, the Netherlands. Serotype-specific-PnPS IgG assays were performed; subsequently, 23-valent-PnPS IgG assays (anti-PnPS IgG assays), and later anti-PnPS IgA and IgM assays, were performed in archived material (240 patients; 304 samples). Eleven of 65 pre- and six of 10 post-immunization samples from good responders to PnPS serotype-specific IgG testing had decreased anti-PnPS IgA and/or IgM titres. Of these, three pre- and no post-immunization samples were from patients previously classified as 'no PAD'. Determination of anti-PnPS IgA and IgM in addition to anti-PnPS IgG did not reduce the need for serotype-specific PnPS IgG testing to assess immunocompetence [receiver operating characteristic (ROC) analysis of post-immunization samples: anti-PnPS IgA + IgG area under the curve (AUC) = 0.80, 95% confidence interval (CI) = 0.63-0.97; anti-PnPS IgM + IgG AUC 0.80, 95% CI = 0.62-0.98; anti-PnPS IgA + IgG + IgM AUC = 0.71, 95% CI = 0.51-0.91; anti-PnPS IgG AUC = 0.93, 95% CI = 0.85-1.00]. Our data show that patients classified as having an intact antibody response based on measurement of serotype-specific PnPS IgG can still display impaired anti-PnPS IgM and IgA responses, and that the additional measurement of anti-PnPS IgA and IgM could not reduce the need for serotype-specific IgG testing. Future studies are needed to investigate the clinical relevance of potential 'specific IgA or IgM antibody deficiency' in patients with recurrent airway infections in whom no PAD could be diagnosed according to the current definitions.

Adjunctive treatment with oral dexamethasone in non-ICU patients hospitalised with community-acquired pneumonia: a randomised clinical trial.

BACKGROUND: Adjunctive intravenous corticosteroid treatment has been shown to reduce length of stay (LOS) in adults hospitalised with community-acquired pneumonia (CAP). We aimed to assess the effect of oral dexamethasone on LOS and whether this effect is disease severity dependent. METHODS: In this multicentre, stratified randomised, double-blind, placebo-controlled trial, immunocompetent adults with CAP were randomly assigned (1:1 ratio) to receive oral dexamethasone (6 mg once daily) or placebo for 4 days in four teaching hospitals in the Netherlands. Randomisation (blocks of four) was stratified by CAP severity (pneumonia severity index class I-III and IV-V). The primary outcome was LOS. RESULTS: Between December 2012 and November 2018, 401 patients were randomised to receive dexamethasone (n=203) or placebo (n=198). Median LOS was shorter in the dexamethasone group (4.5 days, 95% CI 4.0-5.0 days) than in the placebo group (5.0 days, 95% CI 4.6-5.4 days; p=0.033). Within both CAP severity subgroups, differences in LOS between treatment groups were not statistically significant. The secondary ICU admission rate was lower in the dexamethasone arm (5 (3%) versus 14 (7%); p=0.030); 30-day mortality did not differ between groups. In the dexamethasone group the rate of hospital readmission tended to be higher (20 (10%) versus 9 (5%); p=0.051) and hyperglycaemia (14 (7%) versus 1 (1%); p=0.001) was more prevalent. CONCLUSION: Oral dexamethasone reduced LOS and ICU admission rate in adults hospitalised with CAP. It remains unclear for which patients the risk-benefit ratio is optimal.

The "original antigenic sin" and its relevance for SARS-CoV-2 (COVID-19) vaccination.

Imprinting of the specific molecular image of a given protein antigen into immunological memory is one of the hallmarks of immunity. A later contact with a related, but different antigen should not trigger the memory response (because the produced antibodies would not be effective). The preferential expansion of cross-reactive antibodies, or T-lymphocytes for that matter, by a related antigen has been termed the original antigenic sin and was first described by Thomas Francis Jr. in 1960. The phenomenon was initially described for influenza virus, but also has been found for dengue and rotavirus. The antibody dependent enhancement observed in feline coronavirus vaccination also may be related to the original antigenic sin. For a full interpretation of the effectivity of the immune response against SARS-CoV-2, as well as for the success of vaccination, the role of existing immunological memory against circulating corona viruses is reviewed and analyzed.

Data on global analysis of clinical trials with probiotics.

Data on characteristics of clinical trials with probiotics, registered at ClinicalTrials.gov were retrieved from the registry . Data on the registration process itself (moment of registration of the trial in relation to date of inclusion of first participant, data of completion of the study) as well as the number of participants were analysed. A trend analysis (over the period 2000-2020) was made of the number of participants in clinical trials with probiotics on gastrointestinal conditions and diseases. A comparison was made between conditions and diseases studied in completed clinical trials with those trials not yet recruiting participants. The data can be used and reused for assessment of the quality of clinical studies with probiotics and to identify future trends in applications of probiotics.

Global analysis of clinical trials with probiotics.

Over 1,000 clinical studies with probiotics, registered at ClinicalTrials.gov and/or the International Clinical Trials Registry Platform (ICTRP) of the World Health Organization, have addressed over 700 different diseases and conditions. The average size of a clinical trial with probiotics (74 participants) is comparable to the overall average of all studies in ClincialTrials.gov. Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis ssp. lactis BB12 are the probiotic strains studied most. The exact composition of the product which is used, including the dosage, is not always indicated in the registry. The majority of probiotics studies at ClinicalTrials.gov is registered in the USA or Europe (56%). The data from ICTRP show the rapid expansion of clinical studies with probiotics in Asia, notably Iran and China.

Differences in Antibody Kinetics and Functionality Between Severe and Mild Severe Acute Respiratory Syndrome Coronavirus 2 Infections.

We determined and compared the humoral immune response in patients with severe (hospitalized) and mild (nonhospitalized) coronavirus disease 2019 (COVID-19). Patients with severe disease (n = 38) develop a robust antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including immunoglobulin G and immunoglobulin A antibodies. The geometric mean 50% virus neutralization titer is 1:240. SARS-CoV-2 infection was found in hospital personnel (n = 24), who developed mild symptoms necessitating leave of absence and self-isolation, but not hospitalization; 75% developed antibodies, but with low/absent virus neutralization (60% with titers <1:20). While severe COVID-19 patients develop a strong antibody response, mild SARS-CoV-2 infections induce a modest antibody response. Long-term monitoring will show whether these responses predict protection against future infections.

Pneumococcal Conjugate Vaccination Followed by Pneumococcal Polysaccharide Vaccination in Lung Transplant Candidates and Recipients.

BACKGROUND: Pneumococcal conjugate vaccination as well as pneumococcal polysaccharide vaccination are recommended for lung transplant candidates and recipients, but the combination of these vaccines has not been extensively studied in these specific populations. METHODS: Lung transplant candidates and recipients were vaccinated with a 13-valent pneumococcal conjugate vaccine, followed 8 weeks later by a pneumococcal polysaccharide vaccine. Pneumococcal antibody levels against 13 pneumococcal serotypes were measured and followed up after 1 year in the transplant recipients. These values were compared with a historical control group vaccinated with the polysaccharide vaccine alone. RESULTS: Twenty-five lung transplant candidates and 23 lung transplant recipients were included. For the majority of serotypes, there was no significant increase in antibody levels after additional vaccination with the polysaccharide vaccine in both patient groups. When compared with the historical control group, the antibody response in lung transplant recipients 1 year after vaccination did not seem to have improved by vaccination with both vaccines instead of the polysaccharide vaccine alone. CONCLUSIONS: Serologic vaccination responses in lung transplant candidates and recipients were not improved by giving a 23-valent pneumococcal polysaccharide vaccine after a 13-valent pneumococcal conjugate vaccine. The benefit of this vaccination schedule in lung transplant recipients seems to differ from other immunocompromised populations. The optimal vaccination schedule for lung transplant candidates and recipients remains to be determined.

Genetic Variation in CCL18 Gene Influences CCL18 Expression and Correlates with Survival in Idiopathic Pulmonary Fibrosis: Part A.

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic disease, characterized by fibroblast proliferation and extracellular matrix deposition. CC-chemokine ligand 18 (CCL18) upregulates the production of collagen by lung fibroblasts and is associated with mortality. This study was designed to evaluate the influence of single nucleotide polymorphisms (SNPs) in the CCL18 gene on CCL18 expression and survival in IPF. Serum CCL18 levels and four SNPs in the CCL18 gene were analyzed in 77 Dutch IPF patients and 349 healthy controls (HCs). CCL18 mRNA expression was analyzed in peripheral blood mononuclear cells (PBMCs) from 18 healthy subjects. Survival analysis was conducted, dependent on CCL18-levels and -genotypes and validated in two German IPF cohorts (Part B). IPF patients demonstrated significantly higher serum CCL18 levels than the healthy controls (p < 0.001). Both in IPF patients and HCs, serum CCL18 levels were influenced by rs2015086 C > T genotype, with the highest CCL18-levels with the presence of the C-allele. Constitutive CCL18 mRNA-expression in PBMCs was significantly increased with the C-allele and correlated with serum CCL18-levels. In IPF, high serum levels correlated with decreased survival (p = 0.02). Survival was worse with the CT-genotype compared to the TT genotype (p = 0.01). Concluding, genetic variability in the CCL18-gene accounts for differences in CCL18 mRNA-expression and serum-levels and influences survival in IPF.