MEFV and NLRP3 Inflammasome Expression Is Attributed to Immature Macrophages and Correlates with Serum Inflammatory Proteins in Crohn´s Disease Patients

A novel genetic association of IL32 with tuberculosis

AIM

IL32 is a pleiotropic intracellular cytokine with an emergent role in tuberculosis. The different isoforms of IL32: α, β, γ and δ have varying pro and anti-inflammatory potentials. We studied the role of genetic variants of IL32 and its isoforms in susceptibility to tuberculosis using a case-household contact association study.

METHODOLOGY

Using a targeted sequencing approach, IL32 (+1kb) gene was sequenced in 64 pairs of culture positive TB cases and their culture negative household contacts. Subsequently the identified variants were validated in an independent cohort of cases and household contacts using TaqMan genotyping assay. Regulatory role of the associated variants was assessed using GTExPortal, RegulomeDB score, HaploReg and ENCODE histone ChIP-seq data. Expression of IL32 and its isoforms was evaluated by RT-PCR in PBMC from unexposed healthy controls (N = 25) with different genotype background and stimulated with TB antigens ESAT6 and CFP10. ∼ 200 bp around the associated variant was cloned into pGL3 promoter vector to assess enhancer activity by dual luciferase assay in cell lines.

RESULTS

Intronic variant rs9927163(G/T) was found associated with pulmonary TB, T being the risk allele (OR = 2.3(1.40-3.83, p = 0.03)), while G is the protective allele. This finding was validated in independent set of TB cases and household contacts (p = 0.0435). rs9927163 is an eQTL for the genes IL32 (p = 4.1e-10) and BICDL2 (p = 2.1e-7) in whole blood and interrupts an AP-1 binding site. ENCODE histone ChIP-seq data shows rs9927163 residing within T cell specific H3K4me3 peak. The G allele is associated with greater enhancer activity in a T cell line (2.12 fold, p = 0.0059). The TT genotype showed greater normalized expression of IL32δ, a less proinflammatory isoform compared to the GT and GG genotypes together following ESAT6 (p = 0.02288) and CFP10 (p = 0.04595) treatment. This indicates that greater expression of a potentially less protective IL32 isoform within individuals with the TT genotype might be a risk factor for developing TB.

The improvement of a refractory enterocutaneous fistula with colchicine in a patient with Crohn's disease who had an MEFV gene mutation

Enterocutaneous fistulas (ECFs) occurring in the setting of Crohn's disease (CD) are difficult to cure with medical treatment alone and affects a patient's quality of life. A 39-year-old man was diagnosed with an ileocolitis-type CD in 2007. His inflammation was insufficiently controlled despite the administration of an anti-tumor necrosis factor-alpha antibody. Therefore, he underwent subtotal colectomy, terminal ileal resection, and ileostomy for multiple colon and anal stenoses in Dec 2015. The patient subsequently received ustekinumab; however, purulent discharge was observed from a postoperative scar around the umbilicus in July 2019. In July 2021, enteroscopy and magnetic resonance imaging (MRI) showed an ECF extending from the small intestine to the umbilicus. Upon referral to our hospital, laboratory data showed elevated C-reactive protein (CRP) and serum amyloid A (SAA). After receiving colchicine, his purulent discharge disappeared, and his CRP and SAA levels rapidly decreased. Enteroscopy and MRI performed 1 year and 5 months after the administration of colchicine revealed ECF closure. Genetic analysis revealed that the patient harbored an MEFV exon 1 (E84K) mutation.

Fecal Supernatants from Patients with Crohn's Disease Induce Inflammatory Alterations in M2 Macrophages and Fibroblasts

Intestinal macrophages and fibroblasts act as microenvironmental sentinels mediating inflammation and disease progression in Crohn's disease (CD). We aimed to establish the effects of fecal supernatants (FSs) from patients with CD on macrophage and fibroblast phenotype and function. FS were obtained by ultracentrifugation, and the metabolites were analyzed. Monocyte-derived M2 macrophages and fibroblasts were conditioned with FS, and secreted proteins, surface proteins and gene expression were analyzed. M2 macrophage efferocytosis was evaluated. Patients with CD (n = 15) had a skewed fecal metabolite profile compared to healthy subjects (HS, n = 10). FS from CD patients (CD-FS) induced an anti-inflammatory response in M2 macrophages with higher expression of IL-10, IL1RA and CD206 as compared to healthy FS (HS-FS) while the efferocytotic capacity was unaltered. CD-FS did not affect extracellular matrix production from fibroblasts, but increased expression of the pro-inflammatory proteins IL-6 and MCP-1. Conditioned media from M2 macrophages treated with CD-FS modulated gene expression in fibroblasts for TGFβ superfamily members and reduced IL-4 expression compared to HS-FS. We show that M2 macrophages and fibroblasts react abnormally to the fecal microenvironment of CD patients, resulting in altered protein expression related to inflammation but not fibrosis. This implies that the gut microbiota and its metabolites have an important role in the generation and/or perpetuation of inflammation in CD.

Plasma Proteomics Unveil Novel Immune Signatures and Biomarkers upon SARS-CoV-2 Infection

Several elements have an impact on COVID-19, including comorbidities, age and sex. To determine the protein profile changes in peripheral blood caused by a SARS-CoV-2 infection, a proximity extension assay was used to quantify 1387 proteins in plasma samples among 28 Finnish patients with COVID-19 with and without comorbidities and their controls. Key immune signatures, including CD4 and CD28, were changed in patients with comorbidities. Importantly, several unreported elevated proteins in patients with COVID-19, such as RBP2 and BST2, which show anti-microbial activity, along with proteins involved in extracellular matrix remodeling, including MATN2 and COL6A3, were identified. RNF41 was downregulated in patients compared to healthy controls. Our study demonstrates that SARS-CoV-2 infection causes distinct plasma protein changes in the presence of comorbidities despite the interpatient heterogeneity, and several novel potential biomarkers associated with a SARS-CoV-2 infection alone and in the presence of comorbidities were identified. Protein changes linked to the generation of SARS-CoV-2-specific antibodies, long-term effects and potential association with post-COVID-19 condition were revealed. Further study to characterize the identified plasma protein changes from larger cohorts with more diverse ethnicities of patients with COVID-19 combined with functional studies will facilitate the identification of novel diagnostic, prognostic biomarkers and potential therapeutic targets for patients with COVID-19.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Intestinal cellular heterogeneity and disease development revealed by single-cell technology

The intestinal epithelium is responsible for food digestion and nutrient absorption and plays a critical role in hormone secretion, microorganism defense, and immune response. These functions depend on the integral single-layered intestinal epithelium, which shows diversified cell constitution and rapid self-renewal and presents powerful regeneration plasticity after injury. Derailment of homeostasis of the intestine epithelium leads to the development of diseases, most commonly including enteritis and colorectal cancer. Therefore, it is important to understand the cellular characterization of the intestinal epithelium at the molecular level and the mechanisms underlying its homeostatic maintenance. Single-cell technologies allow us to gain molecular insights at the single-cell level. In this review, we summarize the single-cell RNA sequencing applications to understand intestinal cell characteristics, spatiotemporal evolution, and intestinal disease development.