A protein microarray assay for serological determination of antigen-specific antibody responses following Clostridium difficile infection

We provide a detailed overview of a novel high-throughput protein microarray assay for the determination of anti-C. difficile antibody levels in human sera and in separate preparations of polyclonal IVIg. The protocol describes the methodological steps involved in sample preparation, printing of arrays, assay procedure and data analysis. In addition, this protocol could be further developed to incorporate diverse clinical samples including plasma and cell culture supernatants. Herein, a combination of isotype (IgG, IgA IgM), subclass (IgG1, IgG2, IgG3, IgG4, IgA1, IgA2), and strain-specific antibodies to highly purified whole C. difficile toxins A and B (toxinotype 0, strain VPI 10463, ribotype 087), toxin B from a C. difficile toxin-B-only expressing strain (CCUG 20309), precursor form of B fragment of binary toxin, pCDTb, ribotype-specific whole surface layer proteins (SLPs; 001, 002, 027) and control proteins (Tetanus toxoid and Candida albicans) were determined by protein microarray. Microarrays were probed with sera from individuals with C. difficile infection (CDI), cystic fibrosis (CF) without diarrhea, healthy controls and individuals pre- and post-IVIg therapy for treatment of CDI, combined immunodeficiency disorder and chronic inflammatory demyelinating polyradiculopathy. Significant differences in toxin neutralization efficacies and multi-isotype specific antibody levels were seen between patient groups, commercial preparations of IVIg and sera before and following IVIg administration. A significant correlation was observed between microarray and enzyme-linked immunosorbent assay (ELISA) for antitoxin IgG levels in serum samples. These results suggest that microarray could become a promising tool for profiling antibody responses to C. difficile antigens in vaccinated or infected humans. With further refinement of antigen panels and a reduction in production costs, it is anticipated that microarray technology may help optimize and select the most clinically useful immunotherapies for C. difficile infection in a patient-specific manner

Plant-Derived Products with Therapeutic Potential against Gastrointestinal Bacteria

The rising burden of antimicrobial resistance and increasing infectious disease outbreaks, including the recent COVID-19 pandemic, has led to a growing demand for the development of natural products as a valuable source of leading medicinal compounds. There is a wide variety of active constituents found in plants, making them an excellent source of antimicrobial agents with therapeutic potential as alternatives or potentiators of antibiotics. The structural diversity of phytochemicals enables them to act through a variety of mechanisms, targeting multiple biochemical pathways, in contrast to traditional antimicrobials. Moreover, the bioactivity of the herbal extracts can be explained by various metabolites working in synergism, where hundreds to thousands of metabolites make up the extract. Although a vast amount of literature is available regarding the use of these herbal extracts against bacterial and viral infections, critical assessments of their quality are lacking. This review aims to explore the efficacy and antimicrobial effects of herbal extracts against clinically relevant gastrointestinal infections including pathogenic Escherichia coli, toxigenic Clostridioides difficile, Campylobacter and Salmonella species. The review will discuss research gaps and propose future approaches to the translational development of plant-derived products for drug discovery purposes for the treatment and prevention of gastrointestinal infectious diseases

Orbital inflammatory complications of Crohn’s disease: a rare case series

Orbital inflammatory disease is a rare ophthalmic manifestation of Crohn’s disease. Inflammation is characteristically non-specific, involving one or multiple structures of the orbit. Mechanisms of disease and optimal methods of treatment are poorly understood. The aim of this report is to present three cases of orbital involvement in Crohn’s disease. A retrospective case note review of patients with orbital inflammatory disease and Crohn’s disease was performed at our academic centre to determine the clinical, imaging and histopathological features of this condition and its relationship to intestinal Crohn’s disease. Three patients were identified with orbital inflammatory manifestations complicating Crohn’s disease. All patients described were female with active intestinal disease and had a history of treatment with immunosuppressive therapies. Similarities were observed in clinical presentations with variance noted in radiological and histopathological findings. In all cases, symptoms improved with oral corticosteroids or non-steroidal drugs in combination with anti-tumour necrosis factor (anti-TNF) agents. Inflammatory bowel disease-related orbital complications are rare but potentially vision-threatening. It is important to consider mimics of orbital inflammatory disease such as systemic inflammatory disease, malignancy, congenital malformations, infection and trauma when formulating a comprehensive differential diagnosis. Therapeutic intervention is directed towards preservation of vision and orbital function and reducing the acute inflammatory process. Corticosteroids are typically the initial treatment of choice for moderate-to-severe disease, although several classes of immunomodulatory agents have been variably useful in treating this condition. Heightened awareness and close cooperation between gastroenterologists and ophthalmologists is mandatory

Therapeutic potential of miRNAs in Clostridioides difficile infection

Treating Clostridioides difficile infection with miRNAs alone or combined with live biotherapeutic products may augment therapeutic efficacy and help counteract drug resistance in the future

High prevalence of subclass-specific binding and neutralizing antibodies against Clostridium difficile toxins in adult cystic fibrosis sera: possible mode of immunoprotection against symptomatic C. difficile infection

Objectives: Despite multiple risk factors and a high rate of colonization for Clostridium difficile, the occurrence of C. difficile infection in patients with cystic fibrosis is rare. The aim of this study was to compare the prevalence of binding C. difficile toxin-specific immunoglobulin (Ig)A, IgG and anti-toxin neutralizing antibodies in the sera of adults with cystic fibrosis, symptomatic C. difficile infection (without cystic fibrosis) and healthy controls. Methods: Subclass-specific IgA and IgG responses to highly purified whole C. difficile toxins A and B (toxinotype 0, strain VPI 10463, ribotype 087), toxin B from a C. difficile toxin-B only expressing strain (CCUG 20309) and precursor form of B fragment of binary toxin, pCDTb, were determined by protein microarray. Neutralizing antibodies to C. difficile toxins A and B were evaluated using a Caco-2 cell-based neutralization assay. Results: Serum IgA anti-toxin A and B levels and neutralizing antibodies against toxin A were significantly higher in adult cystic fibrosis patients (n=16) compared with healthy controls (n=17) and patients with symptomatic C. difficile infection (n=16); p≤0.05. The same pattern of response prevailed for IgG, except that there was no difference in anti-toxin A IgG levels between the groups. Compared with healthy controls (toxins A and B) and patients with C. difficile infection (toxin A), sera from cystic fibrosis patients exhibited significantly stronger protective anti-toxin neutralizing antibody responses. Conclusion: A superior ability to generate robust humoral immunity to C. difficile toxins in the cystic fibrosis population is likely to confer protection against symptomatic C. difficile infection. This protection may be lost in the post-transplantation setting, where sera-monitoring of anti-C. difficile toxin antibody titers may be of clinical value

Profiling humoral immune responses to Clostridium difficile-specific antigens by protein microarray analysis

Clostridium difficile is an anaerobic, Gram-positive, and spore-forming bacterium that is the leading worldwide infective cause of hospital-acquired and antibiotic-associated diarrhea. Several studies have reported associations between humoral immunity and the clinical course of C. difficile infection (CDI). Host humoral immune responses are determined using conventional enzyme-linked immunosorbent assay (ELISA) techniques. Herein, we report the first use of a novel protein microarray assay to determine systemic IgG antibody responses against a panel of highly purified C. difficile-specific antigens, including native toxins A and B (TcdA and TcdB, respectively), recombinant fragments of toxins A and B (TxA4 and TxB4, respectively), ribotypespecific surface layer proteins (SLPs; 001, 002, 027), and control proteins (tetanus toxoid and Candida albicans). Microarrays were probed with sera from a total of 327 individuals with CDI, cystic fibrosis without diarrhea, and healthy controls. For all antigens, precision profiles demonstrated<10% coefficient of variation (CV). Significant correlation was observed between microarray and ELISA in the quantification of antitoxin A and antitoxin B IgG. These results indicate that microarray is a suitable assay for defining humoral immune responses to C. difficile protein antigens and may have potential advantages in throughput, convenience, and cost

Effective fecal microbiota transplantation for recurrent Clostridioides difficile infection in humans is associated with increased signalling in bile acid-farnesoid X receptor-fibroblast growth factor pathway

The mechanisms of efficacy for fecal microbiota# transplantation (FMT) in treating recurrent Clostridioides difficile infection (rCDI) remain poorly defined, with restored gut microbiota-bile acid interactions representing one possible explanation. Furthermore, the potential implications for host physiology of these FMT-related changes in gut bile acid metabolism are also not well explored. In this study, we investigated the impact of FMT for rCDI upon signalling through the farnesoid X receptor (FXR)-fibroblast growth factor (FGF) pathway. Herein, we identify that in addition to restoration of gut microbiota and bile acid profiles, FMT for rCDI is accompanied by a significant, sustained increase in circulating levels of FGF19 and reduction in FGF21. These FGF changes were associated with weight gain post-FMT, to a level not exceeding the pre-rCDI baseline. Collectively, these data support the hypothesis that the restoration of gut microbial communities by FMT for rCDI is associated with an upregulated FXR-FGF pathway, and highlight the potential systemic effect of FMT