NOD proteins: regulators of inflammation in health and disease

Lactobacillus intestinalis facilitates tumor-derived CCL5 to recruit dendritic cell and suppress colorectal tumorigenesis

Gut microbes play a crucial role in regulating the tumor microenvironment (TME) of colorectal cancer (CRC). Nevertheless, the deep mechanism between the microbiota-TME interaction has not been well explored. In this study, we for the first time discovered that Lactobacillus intestinalis (L. intestinalis) effectively suppressed tumor growth both in the AOM/DSS-induced CRC model and the ApcMin/+ spontaneous adenoma model. Our investigation revealed that L. intestinalis increased the infiltration of immune cells, particularly dendritic cells (DC), in the TME. Mechanically, the tumor-derived CCL5 induced by L. intestinalis recruited DC chemotaxis through the NOD1/NF-κB signaling pathway. In clinical samples and datasets, we found positive correlation between L. intestinalis, CCL5 level, and the DC-related genes. Our study provided a new strategy for microbial intervention for CRC and deepened the understanding of the interaction between tumor cells and the immune microenvironment modulated by gut microbes.

Regulation of gene expression under temperature stress and genome-wide analysis of heat shock protein family in Eriocheir sinensis

The growth of the Chinese mitten crab (Eriocheir sinensis) is significantly influenced by environmental temperature variations. However, there is limited research on the molecular mechanisms through which extreme temperatures induce adverse effects in E. sinensis. In this study, the effects of low and high temperatures on gene expression in E. sinensis were analyzed. Differential expression analysis of the transcriptome revealed that several differentially expressed genes (DEGs) were associated with heat shock responses within the organism. Additionally, numerous DEGs were linked to immune responses and oxidative stress pathways. Gene Ontology (GO) enrichment analysis of key modules identified through weighted correlation network analysis (WGCNA) similarly highlighted multiple GO terms related to heat shock proteins (HSPs). Based on the crucial functions of the HSP gene family in various organisms, such as facilitating protein folding, enhancing cellular resistance to stress, regulating immune responses, and contributing to cell development and environmental adaptation, we conducted a genome-wide identification and analysis of hsps in E. sinensis (Eshsps). A total of 56 Eshsps were identified, and phylogenetic analyses revealed that tandem duplication events occurred in the hsp40 of the E. sinensis, with a significantly higher number compared to closely related species. This study provides essential insights for further exploration into the response mechanisms of HSPs in crustaceans exposed to external stimuli. Our research provides valuable insights into how extreme temperatures affect crabs, proposes alternative molecular markers for crab breeding programs, and ultimately helps address the challenges encountered in aquaculture practices.

DUBA sustains the stability of NOD2 and RIPK2 to enhance innate immune responses

Nucleotide-binding oligomerization domain containing 2 (NOD2) detects conserved fragments of bacterial peptidoglycan in the cytosol and induces innate immune responses. Here, we found that the NOD2 signaling pathway was critically regulated by the deubiquitinating enzyme DUBA. DUBA-deficient macrophages were defective in NOD2 signaling and produced significantly lower amounts of cytokines and chemokines in response to muramyl dipeptide (MDP). DUBA potentiated NOD2-mediated signal transduction by maintaining the protein levels of NOD2 and receptor-interacting protein kinase 2 (RIPK2). Mechanistically, DUBA interacted with NOD2 and RIPK2 and removed K48-linked polyubiquitin chains from them through enzymatic activity, thereby inhibiting the proteasomal degradation of NOD2 and RIPK2. Macrophage-specific ablation of DUBA attenuated MDP-induced systematic inflammation and liver injury in mice. In addition, DUBA deficiency in macrophages rendered mice hypersensitive to DSS-induced colitis and eliminated the protective effect of MDP treatment in colitis. Thus, DUBA acts as an important regulator of NOD2-mediated signaling and innate immune responses.

Molecular Identification and Expression Analysis of NOD1/2 and TBK1 in Response to Viral or Bacterial Infection in the Spotted Knifejaw (Oplegnathus punctatus)

This study investigates the role of the Opnod1, Opnod2, and Optbk1 genes in antiviral and antibacterial immunity of spotted knifejaw (Oplegnathus punctatus). The expression patterns of these genes were analyzed using qRT-PCR in different tissues and at different time points. The open reading frame (ORF) of the Opnod1 gene was 2757 bp in length and encoded 918 amino acids, the ORF of the Opnod2 gene was 2970 bp in length and encoded 990 amino acids, while the Optbk1 gene was 2172 bp in length and encoded 723 amino acids. The Opnod1 and Opnod2 proteins contained three conserved domains (CARD, NOD, and LRR), and Optbk1 contained an STKc domain. The Opnod1, Opnod2, and Optbk1 genes were mainly expressed in immune-related tissues of spotted knifejaw, with the highest relative expression of the Opnod1 in the skin, the Opnod2 in the gill, and the Optbk1 in the liver. The expression of these genes changed significantly in the immune tissues following infection with SKIV-SD and Vibrio harveyi. In kidney cells, the Opnod1, Opnod2, and Optbk1 expression was up-regulated after stimulation by poly I:C and LPS in vitro. The results suggest that the NOD1/2-TBK1 signal pathway may play an important role in the resistance of the spotted knifejaw to virus and bacteria, providing valuable insights for disease-resistant breeding.

Gut Microbiota Involved in the Immunopathogenesis of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP), which is considered the pancreatic expression of a systemic immunoglobulin G4-related disease, is characterized by excessive infiltration of plasmacytes bearing immunoglobulin G4 and a unique form of fibrosis in multiple organs. This relatively new disease entity has garnered great attention from clinicians, but its pathophysiology remains poorly understood. Recent discoveries indicate that plasmacytoid dendritic cell activation followed by robust production of type I interferon and interleukin-33 plays a key role in driving chronic fibro-inflammatory responses in both murine and human AIP. Furthermore, the compositional alterations in the gut microbiota, known as intestinal dysbiosis, triggered plasmacytoid dendritic cell-driven pathogenic type I interferon responses. Intestinal dysbiosis is associated with a breakdown in intestinal barrier function; thus, we examined whether the latter condition affects the development of experimental AIP. Our recent research has revealed that intestinal barrier disruption worsens experimental AIP by facilitating the translocation of pathogenic bacteria, such as Staphylococcus sciuri, to the pancreas from the gut. These results indicate the "gut-pancreas axis" underlies the immunopathogenesis of AIP, and the maintenance of intestinal barrier integrity can prevent the worsening of AIP by inhibiting pancreatic colonization by harmful gut bacteria. In this mini review, the interactions between AIP development and gut microbiota are discussed with the aim of providing useful information not only for researchers but also for clinicians.

Gut microbial-derived N-acetylmuramic acid alleviates colorectal cancer via the AKT1 pathway

BACKGROUND

Gut microbial metabolites are recognised as critical effector molecules that influence the development of colorectal cancer (CRC). Peptidoglycan fragments (PGFs) produced by microbiota play a crucial role in maintaining intestinal homeostasis, but their role in CRC remains unclear.

OBJECTIVE

Here, we aimed to explore the potential contribution of PGFs in intestinal tumourigenesis.

DESIGN

The relative abundance of peptidoglycan synthase and hydrolase genes was assessed by metagenomic analysis. Specific PGFs in the faeces and serum of CRC patients were quantified using targeted mass spectrometry. The effects of PGF on intestinal tumourigenesis were systematically evaluated using various murine models of CRC and organoids derived from CRC patients. Downstream molecular targets were screened and evaluated using proteome microarray, transcriptome sequencing and rescue assays.

RESULTS

Metagenomic analysis across seven independent cohorts (n=1121) revealed a comprehensive reduction in peptidoglycan synthase gene relative abundance in CRC patients. Targeted mass spectrometry identified significant depletion of a specific PGF, N-acetylmuramic acid (NAM) in CRC patients, which decreased as tumours progressed (p<0.001). NAM significantly inhibits intestinal tumourigenesis in various models, including Apc Min/+, AOM/DSS-treated and MC38 tumour-bearing mice. Additionally, NAM inhibits the growth of patient-derived CRC organoids in a concentration-dependent manner. Mechanistically, NAM inhibits the activation of AKT1 by directly binding to it and blocking its phosphorylation, which is a partial mediator of NAM's anticancer effects.

CONCLUSION

The PGF NAM protects against intestinal tumourigenesis by targeting the AKT1 signalling pathway. NAM may serve as a novel potential preventive and therapeutic biomarker against CRC.

The changes of NLRs family members in the brain of AD mouse model and AD patients

Introduction

Alzheimer's disease (AD), a prevalent neurodegenerative disease, is primarily characterized by progressive neuron loss and memory impairment. NOD-like receptors (NLRs) are crucial for immune regulation and maintaining cellular homeostasis. Recently, NLRs have been identified as important contributors to neuroinflammation, thus presenting a potential approach for reducing inflammation and slowing AD progression.

Methods

We use quantitative RT-PCR to detect levels of NLR family members in AD mouse model. Additionally, we use immunofluorescence to detect NLRP3 expressions in microglia surrounding Aβ plaques in AD mouse model and human AD patients.

Results

In this study, we examined the expression of NLR family members in the human AD database, and found increased levels of CIITA, NOD1, NLRC5, NLRP1, NLRP3, NLRP7, NLRP10, NLRP12, and NLRP13 in hippocampus tissue in patients with AD, along with increased levels of NOD1, NLRC5, NLRX1, NLRP3, and NLRP7 levels in frontal cortex tissue. Furthermore, through detecting their levels in AD mouse model, we found that NLRP3 levels were significantly increased. Additionally, we found that NLRP3 expressions were mainly elevated in microglia surrounding Aβ plaques in AD mouse model and human AD patients.

Discussion

These findings highlight the potential important role of NLRP3 in AD pathology, offering new therapeutic targets and interventions.

BCL-2 inhibitors in hematological malignancies: biomarkers that predict response and management strategies

Apoptosis is an essential characteristic of cancer and its dysregular promotes tumor growth, clonal evolution, and treatment resistance. B-cell lymphoma-2 (BCL-2) protein family members are key to the intrinsic, mitochondrial apoptotic pathway. The inhibition of the BCL-2 family pro-survival proteins, which are frequently overexpressed in B-cell malignancies and pose a fundamental carcinogenic mechanism has been proposed as a promising therapeutic option, with venetoclax (ABT-199) being the first FDA-approved BCL-2 inhibitor. Unfortunately, although BCL-2 inhibition has shown remarkable results in a range of B-cell lymphoid cancers as well as acute myeloid leukemia (AML), the development of resistance significantly reduces response rates in specific tumor subtypes. In this article, we explain the role of BCL-2 family proteins in apoptosis and their mechanism of action that justifies their inhibition as a potential treatment target in B-cell malignancies, including chronic lymphocytic leukemia, multiple myeloma, B-cell lymphomas, but also AML. We further analyze the tumor characteristics that result in the development of intrinsic or inherited resistance to BCL-2 inhibitors. Finally, we focus on the biomarkers that can be used to predict responses to treatment in the name of personalized medicine, with the goal of exploring alternative strategies to overcome resistance.

NOD1: a metabolic modulator

Nucleotide-binding oligomerization domain 1 (NOD1) is an intracellular pattern recognition receptor that detects injury signals and initiates inflammatory responses and host defense. Furthermore, NOD1 serves as a metabolic mediator by influencing the metabolism of various tissues, including adipose tissue, liver, cardiovascular tissue, pancreatic β cells, adrenal glands, and bones through diverse mechanisms. It has been discovered that activated NOD1 is associated with the pathological mechanisms of certain metabolic diseases. This review presents a comprehensive summary of the impact of NOD1 on tissue-specific metabolism.

Revealing NOD1-Activating Gram-Positive Gut Microbiota via in Vivo Labeling with a meso-Diaminopimelic Acid Probe

As an important receptor in a host's immune and metabolic systems, NOD1 is usually activated by Gram-negative bacteria having meso-diaminopimelic acid (m-DAP) in their peptidoglycan (PGN). But some atypical Gram-positive bacteria also contain m-DAP in their PGN, giving them the potential to activate NOD1. The prevalence of m-DAP-type Gram-positive bacteria in the gut, however, remains largely unknown. Here, we report a stem-peptide-based m-DAP-containing tetrapeptide probe for labeling and identifying m-DAP-type Gram-positive microbiota. The probe was synthesized via a five-step convergent approach and demonstrated moderate selectivity toward m-DAP-type bacteria in vitro. In vivo labeling revealed that ∼13.7% of the mouse gut microbiota (mostly Gram-positive) was selectively labeled. We then identified Oscillibacter and several other Gram-positive genera in this population, most of which were previously unknown m-DAP-type bacteria. The following functional assay showed that Oscillibacter's PGN could indeed activate NOD1, suggesting an overlooked NOD1-activating role for these Gram-positive bacteria. These findings deepen our understanding of the structural diversity of gut microbes and their interactions with the host's immune system.

Peptidoglycan accumulates in distinct brain regions and cell types over lifetime but is absent in newborns

Peptidoglycan (PGN) is a large complex polymer critical to structure and function of all bacterial species. Intact PGN and its fragments are inflammatory, contributing to infectious and autoimmune disease. Recent studies show that PGN physiologically contributes to immune setpoints, and importantly also to mouse brain development and behavior. However, for the human brain, it remains unknown whether PGN and its fragments differentially gain access to distinct brain regions, which cell types accumulate it, and whether PGN brain load varies with age. Therefore, we investigated human postmortem brain samples of donors with an extensive age range, from newborns to nonagenarians. We examined two monoclonal antibodies against PGN which were validated using dot blot analysis, competition assays and immunofluorescence experiments on bacteria sacculi, which jointly showed specific detection of Gram-positive PGN. As positive reference tissue, brain tissue from sepsis patients, and human liver were used, both showing the expected high PGN levels. In adult brain tissue of different age (34- to 94-year-old) and sex, we detected PGN signals in seven different brain regions, with highest loads in the occipital cortex, hippocampal formation, frontal cortex, the periventricular region and the olfactory bulb. Age-dependent increase of signals was not evident by microscopic observations and only weak correlation was found by statistical analysis in this cohort. PGN was found intracellularly in the cytoplasm surrounding the cell nucleus in astrocytes, oligodendrocytes, neurons, and endothelial cells, but not in macrophages like microglia. PGN was absent in brain tissues of three human newborns (stillbirth to four weeks old). For comparison, three brain regions from non-human primates of varying age (newborn to 21 years) were immunohistochemically stained. The highest PGN-load was observed in brain tissue from 18- to 21-year-old macaques. This first systematic evaluation of PGN in human postmortem brain suggests that PGN accumulates during lifetime until it reaches a plateau by homeostatic turnover and highlights the ubiquitous presence of PGN in human brain tissues, and their ability to participate in physiological as well as pathological processes throughout life.

RRS1 knockdown inhibits the proliferation of neuroblastoma cell via PI3K/Akt/NF-κB pathway

BACKGROUND

RRS1 plays an important role in regulating ribosome biogenesis. Recently, RRS1 has emerged as an oncoprotein involved in tumorigenicity of some cancers. However its role in neuroblastoma remains unknown.

METHODS

RRS1 expression was detected in pediatric neuroblastoma patients' tissues and cell lines. The effects of RRS1 knockdown on proliferation, apoptosis, and cell cycle were evaluated in neuroblastoma cell lines. RRS1-related survival pathway was analyzed by co-immunoprecipitation (Co-IP), mass spectrometry, reverse transcription-quantitative real-time PCR (RT-qPCR), and western blot. Protein-protein interaction (PPI) network was constructed using Cytoscape software and the STRING databases.

RESULTS

Increased RRS1 level was found in neuroblastoma cases (35.6%) and cell lines. High RRS1 expression levels were associated with poor prognosis. RRS1 knockdown inhibited cell proliferation, induced apoptosis, and caused cell cycle arrest in SK-N-AS and SH-SY5Y cells. Co-IP and mass spectrometry analysis showed that RRS1 affects PI3K/Akt and nuclear factor κB (NF-κB) pathways. RT-qPCR and western blot results revealed that RRS1 knockdown inhibited the PI3K/Akt/NF-κB pathway through dephosphorylation of key proteins. In PPI network, AKT, PI3K, and P65 connected RRS1 with differentially expressed proteins more closely.

CONCLUSIONS

This study suggests RRS1 knockdown may inhibit neuroblastoma cell proliferation by the PI3K/Akt/NF-κB pathway. Therefore, RRS1 may be a potential target for neuroblastoma treatment.

IMPACT

RRS1 is involved in the progression of neuroblastoma. Knockdown of RRS1 contributes to inhibit the survival of neuroblastoma cells. RRS1 is associated with the PI3K/Akt/NF-κB signaling pathway in neuroblastoma cells. RRS1 may be a promising target for neuroblastoma therapy.

New insight in treating autoimmune diseases by targeting autophagy

Autophagy is a highly conserved biological process in eukaryotes, which degrades cellular misfolded proteins, damaged organelles and invasive pathogens in the lysosome-dependent manner. Autoimmune diseases caused by genetic elements, environments and aberrant immune responses severely impact patients' living quality and even threaten life. Recently, numerous studies have reported autophagy can regulate immune responses, and play an important role in autoimmune diseases. In this review, we summarised the features of autophagy and autophagy-related genes, enumerated some autophagy-related genes involved in autoimmune diseases, and further overviewed how to treat autoimmune diseases through targeting autophagy. Finally, we outlooked the prospect of relieving and curing autoimmune diseases by targeting autophagy pathway.

Mesenchymal stem cell-derived exosomes ameliorate diabetic kidney disease through NOD2 signaling pathway

BACKGROUND AND AIMS

Diabetic kidney disease (DKD) is one of the most common complications of diabetes. It is reported that mesenchymal stem cells (MSCs) derived exosomes (MSCs-Exo) may have great clinical application potential for the treatment of DKD, but the underlying mechanism has not been illustrated. To clarify the effect of MSC-Exo on NOD2 signaling pathway in podocytes under high glucose (HG) and DKD, we conduct this study.

METHODS

We co-cultured podocytes and MSCs-Exo under 30 mM HG and injected MSCs-Exo into DKD mice, then we detected the NOD2 signaling pathway by western blot, qRT-PCT, immunofluorescence, transmission electron microscopy and immunohistochemistry both in vitro and in vivo.

RESULTS

In vitro, HG lead to the apoptosis, increased the ROS level and activated the NOD2 signaling pathway in podocytes, while MSCs-Exo protected podocytes from injury reduced the expression of inflammatory factors including TNF-α, IL-6, IL-1β, and IL-18 and alleviated the inflammatory response, inhibited the activation of NOD2 signaling pathway and the expression of it's downstream protein p-P65, p-RIP2, prevented apoptosis, increased cell viability in podocytes caused by HG. In vivo, MSCs-Exo alleviated renal injury in DKD mice, protected renal function, decreased urinary albumin excretion and inhibited the activation of NOD2 signaling pathway as well as the inflammation in renal tissue.

CONCLUSION

MSCs-Exo protected the podocytes and DKD mice from inflammation by mediating NOD2 pathway, MSCs-Exo may provide a new target for the treatment of DKD.

Synergistic immune augmentation enabled by covalently conjugating TLR4 and NOD2 agonists

Enhancing the efficacy of subunit vaccines relies significantly on the utilization of potent adjuvants, particularly those capable of triggering multiple immune pathways. To achieve synergistic immune augmentation by Toll-like receptor 4 agonist (TLR4a) and nucleotide-binding oligomerization-domain-containing protein 2 agonist (NOD2a), in this work, we conjugated RC529 (TLR4a) and MDP (NOD2a) to give RC529-MDP, and evaluated its adjuvanticity for OVA antigen. Compared to the unconjugated RC529+MDP, RC529-MDP remarkably enhanced innate immune responses with 6.8-fold increase in IL-6 cytokine, and promoted the maturation of antigen-presenting cells (APCs), possibly because of the conjugation of multiple agonists ensuring their delivery to the same cell and activation of various signaling pathways within that cell. Furthermore, RC529-MDP improved OVA-specific antibody response, T cells response and the memory T cells ratio relative to the unconjugated mixture. Therefore, covalently conjugating TLR4 agonist and NOD2 agonist was an effective strategy to enhance immune responses, providing the potential to design and develop more effective vaccines.

Prognostic model for gastric cancer patients with COVID-19 and network pharmacology study on treatment by lentinan

Patients with gastric cancer (GC) are more susceptible to coronavirus disease 2019 (COVID-19), which further worsens their already challenging prognosis. However, there are no effective treatment options for these patients. Lentinan is a potent bioactive component with antiviral and antitumor effects. We hypothesized that lentinan might exert powerful pharmacological effects in patients with GC and COVID-19. In this study, a prognostic model of patients with GC/COVID-19 was constructed and used to apply a network pharmacology approach to reveal biological functions, drug targets, and molecular mechanisms of the action of lentinan against GC/COVID-19. Clinical analysis revealed key prognostic genes in patients with GC/COVID-19. The results of network pharmacology analysis suggested that the therapeutic effect of lentinan on GC/COVID-19 mainly involves the modulation of several neutrophil-related biological processes, as well as the nucleotide-binding and oligomerization domain-like receptor and interleukin-17 signaling pathways. In addition, C-X-C motif chemokine ligand 8, vascular endothelial growth factor A, ribonuclease 3, and F2 were identified as key genes of lentinan against GC/COVID-19. Key prognostic genes were identified in patients with GC/COVID-19 through the construction of a prognostic model. Pharmacological functions and signaling pathways of lentinan against GC/COVID-19 were revealed. These included the regulation of neutrophils and NOD-like receptor signaling pathways. The findings provide the first published evidence of the potential value of lentinan as a complementary therapy for GC/COVID-19.

Genetic and epigenetic dysregulation of innate immune mechanisms in autoinflammatory diseases

Dysregulation and hyperactivation of innate immune responses can lead to the onset of systemic autoinflammatory diseases. Monogenic autoinflammatory diseases are caused by inborn genetic errors and based on molecular mechanisms at play, can be divided into inflammasomopathies, interferonopathies, relopathies, protein misfolding, and endogenous antagonist deficiencies. On the other hand, more common autoinflammatory diseases are multifactorial, with both genetic and non-genetic factors playing an important role. During the last decade, long-term memory characteristics of innate immune responses have been described (also called trained immunity) that in physiological conditions provide enhanced host protection from pathogenic re-infection. However, if dysregulated, induction of trained immunity can become maladaptive, perpetuating chronic inflammatory activation. Here, we describe the mechanisms of genetic and epigenetic dysregulation of the innate immune system and maladaptive trained immunity that leads to the onset and perpetuation of the most common and recently described systemic autoinflammatory diseases.

Innate immunity gene Nod2 protects mice from orthotopic breast cancer

BACKGROUND

Nod2 is involved in innate immune responses to bacteria, regulation of metabolism, and sensitivity to cancer. A Nod2 polymorphism is associated with breast cancer, but the role of Nod2 in the development and progression of breast cancer is unknown.

METHODS

Here, we tested the hypothesis that Nod2 protects mice from breast cancer using the 4T1 orthotopic model of mammary tumorigenesis. WT and Nod2-/- mice were injected with 4T1 mammary carcinoma cells and the development of tumors was monitored. A detailed analysis of the tumor transcriptome was performed and genes that were differentially expressed and pathways that were predicted to be altered between WT and Nod2-/- mice were identified. The activation of key signaling molecules involved in metabolism and development of cancer was studied.

RESULTS

Our data demonstrate that Nod2-/- mice had a higher incidence and larger tumors than WT mice. Nod2-/- mice had increased expression of genes that promote DNA replication and cell division, and decreased expression of genes required for lipolysis, lipogenesis, and steroid biosynthesis compared with WT mice. Nod2-/- mice also had lower expression of genes required for adipogenesis and reduced levels of lipids compared with WT mice. The tumors in Nod2-/- mice had decreased expression of genes associated with PPARα/γ signaling, increased activation of STAT3, decreased activation of STAT5, and no change in the activation of ERK compared with WT mice.

CONCLUSIONS

We conclude that Nod2 protects mice from the 4T1 orthotopic breast tumor, and that tumors in Nod2-/- mice are predicted to have increased DNA replication and cell proliferation and decreased lipid metabolism compared with WT mice.

Lactic Acid Bacteria-Gut-Microbiota-Mediated Intervention towards Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), arises from intricate interactions involving genetics, environment, and pharmaceuticals with an ambiguous pathogenic mechanism. Recently, there has been an increasing utilization of lactic acid bacteria (LAB) in managing IBD, attributed to their ability to enhance intestinal barrier function, mitigate inflammatory responses, and modulate gut microbiota. This review initiates by elucidating the pathogenesis of IBD and its determinants, followed by an exploration of the mechanisms underlying LAB therapy in UC and CD. Special attention is directed towards their influence on intestinal barrier function and homeostasis regulated by gut microbiota. Furthermore, the review investigates the complex interplay among pivotal gut microbiota, metabolites, and pathways associated with inflammation. Moreover, it underscores the limitations of LAB in treating IBD, particularly in light of their varying roles in UC and CD. This comprehensive analysis endeavors to offer insights for the optimized application of LAB in IBD therapy.

The Role of Host Genetics and Intestinal Microbiota and Metabolome as a New Insight into IBD Pathogenesis

Inflammatory bowel disease (IBD) is an incurable, chronic disorder of the gastrointestinal tract whose incidence increases every year. Scientific research constantly delivers new information about the disease and its multivariate, complex etiology. Nevertheless, full discovery and understanding of the complete mechanism of IBD pathogenesis still pose a significant challenge to today's science. Recent studies have unanimously confirmed the association of gut microbial dysbiosis with IBD and its contribution to the regulation of the inflammatory process. It transpires that the altered composition of pathogenic and commensal bacteria is not only characteristic of disturbed intestinal homeostasis in IBD, but also of viruses, parasites, and fungi, which are active in the intestine. The crucial function of the microbial metabolome in the human body is altered, which causes a wide range of effects on the host, thus providing a basis for the disease. On the other hand, human genomic and functional research has revealed more loci that play an essential role in gut homeostasis regulation, the immune response, and intestinal epithelial function. This review aims to organize and summarize the currently available knowledge concerning the role and interaction of crucial factors associated with IBD pathogenesis, notably, host genetic composition, intestinal microbiota and metabolome, and immune regulation.

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

Role of novel protein acylation modifications in immunity and its related diseases

The cross-regulation of immunity and metabolism is currently a research hotspot in life sciences and immunology. Metabolic immunology plays an important role in cutting-edge fields such as metabolic regulatory mechanisms in immune cell development and function, and metabolic targets and immune-related disease pathways. Protein post-translational modification (PTM) is a key epigenetic mechanism that regulates various biological processes and highlights metabolite functions. Currently, more than 400 PTM types have been identified to affect the functions of several proteins. Among these, metabolic PTMs, particularly various newly identified histone or non-histone acylation modifications, can effectively regulate various functions, processes and diseases of the immune system, as well as immune-related diseases. Thus, drugs aimed at targeted acylation modification can have substantial therapeutic potential in regulating immunity, indicating a new direction for further clinical translational research. This review summarises the characteristics and functions of seven novel lysine acylation modifications, including succinylation, S-palmitoylation, lactylation, crotonylation, 2-hydroxyisobutyrylation, β-hydroxybutyrylation and malonylation, and their association with immunity, thereby providing valuable references for the diagnosis and treatment of immune disorders associated with new acylation modifications.

NOD1 and NOD2: Essential Monitoring Partners in the Innate Immune System

Nucleotide-binding oligomerization domain containing 1 (NOD1) and NOD2 are pivotal cytoplasmic pattern-recognition receptors (PRRs) that exhibit remarkable evolutionary conservation. They possess the ability to discern specific peptidoglycan (PGN) motifs, thereby orchestrating innate immunity and contributing significantly to immune homeostasis maintenance. The comprehensive understanding of both the structure and function of NOD1 and NOD2 has been extensively elucidated. These receptors proficiently recognize an array of damage-associated molecular patterns (DAMPs) as well as pathogen-associated molecular patterns (PAMPs), subsequently mediating inflammatory responses and autophagy. In recent years, emerging evidence has highlighted the crucial roles played by NOD1 and NOD2 in regulating infectious diseases, metabolic disorders, cancer, and autoimmune conditions, among others. Perturbation in either their loss or excessive activation can detrimentally impact immune homeostasis. This review offers a comprehensive overview of the structural characteristics, subcellular localization, activation mechanisms, and significant roles of NOD1 and NOD2 in innate immunity and related disease.

Recent insights of PROTAC developments in inflammation-mediated and autoimmune targets: a critical review

According to the mounting evidence in the literature, pro-inflammatory mediators/targets activate multiple signalling pathways to trigger illnesses that are ultimately responsible for acute pain, chronic inflammatory diseases, and several auto-immune disorders. Conventional drugs have been ruled out since proteolysis-targeting chimeras (PROTACs) are poised to overcome the limitations of traditional therapies. These heterobifunctional molecules help to degrade the targeted proteins of interest through ubiquitination. This review encompasses current and future aspects of PROTACs in inflammation-mediated and autoimmune targets. Different key points are highlighted and discussed, such as why PROTACs are preferred in this disease area, drawbacks and lessons learnt from the past, the role of linkers in establishing crucial degradation, in vitro findings, pharmacokinetics, in silico parameters, limitations of PROTACs in clinical settings, and future outcomes.

Microbiota-associated mechanisms in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, ranking third in terms of incidence and second as a cause of cancer-related death. There is growing scientific evidence that the gut microbiota plays a key role in the initiation and development of CRC. Specific bacterial species and complex microbial communities contribute directly to CRC pathogenesis by promoting the neoplastic transformation of intestinal epithelial cells or indirectly through their interaction with the host immune system. As a result, a protumoural and immunosuppressive environment is created conducive to CRC development. On the other hand, certain bacteria in the gut microbiota contribute to protection against CRC. In this chapter, we analysed the relationship of the gut microbiota to CRC and the associations identified with specific bacteria. Microbiota plays a key role in CRC through various mechanisms, such as increased intestinal permeability, inflammation and immune system dysregulation, biofilm formation, genotoxin production, virulence factors and oxidative stress. Exploring the interaction between gut microbiota and tumourigenesis is essential for developing innovative therapeutic approaches in the fight against CRC.

PPARdelta: A key modulator in the pathogenesis of diabetes mellitus and Mycobacterium tuberculosis co-morbidity

The interplay between lipid metabolism and immune response in macrophages plays a pivotal role in various infectious diseases, notably tuberculosis (TB). Herein, we illuminate the modulatory effect of heat-killed Mycobacterium tuberculosis (HKMT) on macrophage lipid metabolism and its implications on the inflammatory cascade. Our findings demonstrate that HKMT potently activates the lipid scavenger receptor, CD36, instigating lipid accumulation. While CD36 inhibition mitigated lipid increase, it unexpectedly exacerbated the inflammatory response. Intriguingly, this paradoxical effect was linked to an upregulation of PPARδ. Functional analyses employing PPARδ modulation revealed its central role in regulating both lipid dynamics and inflammation, suggesting it as a potential therapeutic target. Moreover, primary monocytic cells from diabetic individuals, a demographic at amplified risk of TB, exhibited heightened PPARδ expression and inflammation, further underscoring its pathological relevance. Targeting PPARδ in these cells effectively dampened the inflammatory response, offering a promising therapeutic avenue against TB.

FOCUS on NOD2: Advancing IBD Drug Discovery with a User-Informed Machine Learning Framework

In this study, we introduce the Framework for Optimized Customizable User-Informed Synthesis (FOCUS), a generative machine learning model tailored for drug discovery. FOCUS integrates domain expertise and uses Proximal Policy Optimization (PPO) to guide Monte Carlo Tree Search (MCTS) to efficiently explore chemical space. It generates SMILES representations of potential drug candidates, optimizing for druggability and binding efficacy to NOD2, PEP, and MCT1 receptors. The model is highly interpretive, allowing for user-feedback and expert-driven adjustments based on detailed cycle reports. Employing tools like SHAP and LIME, FOCUS provides a transparent analysis of decision-making processes, emphasizing features such as docking scores and interaction fingerprints. Comparative studies with Muramyl Dipeptide (MDP) demonstrate improved interaction profiles. FOCUS merges advanced machine learning with expert insight, accelerating the drug discovery pipeline.

Unconventional posttranslational modification in innate immunity

Pattern recognition receptors (PRRs) play a crucial role in innate immunity, and a complex network tightly controls their signaling cascades to maintain immune homeostasis. Within the modification network, posttranslational modifications (PTMs) are at the core of signaling cascades. Conventional PTMs, which include phosphorylation and ubiquitination, have been extensively studied. The regulatory role of unconventional PTMs, involving unanchored ubiquitination, ISGylation, SUMOylation, NEDDylation, methylation, acetylation, palmitoylation, glycosylation, and myristylation, in the modulation of innate immune signaling pathways has been increasingly investigated. This comprehensive review delves into the emerging field of unconventional PTMs and highlights their pivotal role in innate immunity.

The Role of Bacterial Extracellular Membrane Nanovesicles in Atherosclerosis: Unraveling a Potential Trigger

PURPOSE OF REVIEW

In this review, we explore the intriguing and evolving connections between bacterial extracellular membrane nanovesicles (BEMNs) and atherosclerosis development, highlighting the evidence on molecular mechanisms by which BEMNs can promote the athero-inflammatory process that is central to the progression of atherosclerosis.

RECENT FINDINGS

Atherosclerosis is a chronic inflammatory disease primarily driven by metabolic and lifestyle factors; however, some studies have suggested that bacterial infections may contribute to the development of both atherogenesis and inflammation in atherosclerotic lesions. In particular, the participation of BEMNs in atherosclerosis pathogenesis has attracted special attention. We provide some general insights into how the immune system responds to potential threats such as BEMNs during the development of atherosclerosis. A comprehensive understanding of contribution of BEMNs to atherosclerosis pathogenesis may lead to the development of targeted interventions for the prevention and treatment of the disease.

Two cosmoses, one universe: a narrative review exploring the gut microbiome's role in the effect of urban risk factors on vascular ageing

In the face of rising global urbanisation, understanding how the associated environment and lifestyle impact public health is a cornerstone for prevention, research, and clinical practice. Cardiovascular disease is the leading cause of morbidity and mortality worldwide, with urban risk factors contributing greatly to its burden. The current narrative review adopts an exposome approach to explore the effect of urban-associated physical-chemical factors (such as air pollution) and lifestyle on cardiovascular health and ageing. In addition, we provide new insights into how these urban-related factors alter the gut microbiome, which has been associated with an increased risk of cardiovascular disease. We focus on vascular ageing, before disease onset, to promote preventative research and practice. We also discuss how urban ecosystems and social factors may interact with these pathways and provide suggestions for future research, precision prevention and management of vascular ageing. Most importantly, future research and decision-making would benefit from adopting an exposome approach and acknowledging the diverse and boundless universe of the microbiome.

When pyro(ptosis) meets palm(itoylation)

Pyroptosis, a programmed cell death process, is vital for the immune response against microbial infections and internal danger signals. Recent studies have highlighted the importance of protein palmitoylation, a modification that involves attaching palmitate to cysteine residues, in regulating key proteins involved in pyroptosis. Palmitoylation of cGAS at residue C474 by ZDHHC18 affects its enzymatic activity and DNA binding ability. Similarly, ZDHHC9 promotes cGAS activity through palmitoylation at residues C404/405. NLRP3 palmitoylation at residue C844, mediated by ZDHHC12, impacts its stability and interactions with other proteins, crucial for activating the NLRP3 inflammasome and triggering inflammation. However, the role of ZDHHC5 in NLRP3 palmitoylation remains uncertain due to conflicting findings. Palmitoylation at C88/91 is essential for STING activation and induction of type I interferons. It modulates the formation of multimeric complexes and downstream signaling pathways. GSDMD palmitoylation at C191 is necessary for pore formation and membrane translocation, while GSDME palmitoylation at C407/408 is associated with drug-induced pyroptosis. Moreover, palmitoylation of NOD1 and NOD2 influences their membrane recruitment and immune signaling pathways in response to bacterial peptidoglycans, acting as upstream regulators of pyroptosis. This review summarizes the important roles for palmitoylation in regulating the function of key pyroptosis-related proteins, shedding light on the intricate mechanisms governing immune responses and inflammation.

Network pharmacology and experimental verification of the mechanism of licochalcone A against Staphylococcus aureus pneumonia

Staphylococcus aureus strains cause the majority of pneumonia cases and are resistant to various antibiotics. Given this background, it is very important to discover novel host-targeted therapies. Licochalcone A (LAA), a natural plant product, has various biological activities, but its primary targets in S. aureus pneumonia remain unclear. Therefore, the purpose of this study was to identify its molecular target against S. aureus pneumonia. Network pharmacology analysis, histological assessment, enzyme-linked immunosorbent assays, and Western blotting were used to confirm the pharmacological effects. Network pharmacology revealed 33 potential targets of LAA and S. aureus pneumonia. Enrichment analysis revealed that these potential genes were enriched in the Toll-like receptor and NOD-like receptor signaling pathways. The results were further verified by experiments in which LAA alleviated histopathological changes, inflammatory infiltrating cells and inflammatory cytokines (TNF, IL-6, and IL-1β) in the serum and bronchoalveolar lavage fluid in vivo. Moreover, LAA treatment effectively reduced the expression levels of NF-κB, p-JNK, p-p38, NLRP3, ASC, caspase 1, IL-1β, and IL-18 in lung tissue. The in vitro experimental results were consistent with the in vivo results. Thus, our findings demonstrated that LAA exerts anti-infective effects on S. aureus-induced lung injury via suppression of the Toll-like receptor and NOD-like receptor signaling pathways, which provides a theoretical basis for understanding the function of LAA against S. aureus pneumonia and implies its potential clinical application.

Peptidoglycan fragment release and NOD activation by commensal Neisseria species from humans and other animals

Neisseria gonorrhoeae, a human restricted pathogen, releases inflammatory peptidoglycan (PG) fragments that contribute to the pathophysiology of pelvic inflammatory disease. The genus Neisseria is also home to multiple species of human- or animal-associated Neisseria that form part of the normal microbiota. Here we characterized PG release from the human-associated nonpathogenic species Neisseria lactamica and Neisseria mucosa and animal-associated Neisseria from macaques and wild mice. An N. mucosa strain and an N. lactamica strain were found to release limited amounts of the proinflammatory monomeric PG fragments. However, a single amino acid difference in the PG fragment permease AmpG resulted in increased PG fragment release in a second N. lactamica strain examined. Neisseria isolated from macaques also showed substantial release of PG monomers. The mouse colonizer Neisseria musculi exhibited PG fragment release similar to that seen in N. gonorrhoeae with PG monomers being the predominant fragments released. All the human-associated species were able to stimulate NOD1 and NOD2 responses. N. musculi was a poor inducer of mouse NOD1, but ldcA mutation increased this response. The ability to genetically manipulate N. musculi and examine effects of different PG fragments or differing amounts of PG fragments during mouse colonization will lead to a better understanding of the roles of PG in Neisseria infections. Overall, we found that only some nonpathogenic Neisseria have diminished release of proinflammatory PG fragments, and there are differences even within a species as to types and amounts of PG fragments released.

Gut permeability among Astronauts during Space missions

The space environment poses substantial challenges to human physiology, including potential disruptions in gastrointestinal health. Gut permeability has only recently become widely acknowledged for its potential to cause adverse effects on a systemic level, rendering it a critical factor to investigate in the context of spaceflight. Here, we propose that astronauts experience the onset of leaky gut during space missions supported by transcriptomic and metagenomic analysis of human and murine samples. A genetic map contributing to intestinal permeability was constructed from a systematic review of current literature. This was referenced against our re-analysis of three independent transcriptomic datasets which revealed significant changes in gene expression patterns associated with the gut barrier. Specifically, in astronauts during flight, we observed a substantial reduction in the expression genes that are crucial for intestinal barrier function, goblet cell development, gut microbiota modulation, and immune responses. Among rodent spaceflight studies, differential expression of cytokines, chemokines, and genes which regulate mucin production and post-translational modifications suggest a similar dysfunction of intestinal permeability. Metagenomic analysis of feces from two murine studies revealed a notable reduction probiotic, short chain fatty acid-producing bacteria and an increase in the Gram-negative pathogens, including Citrobacter rodentium, Enterobacter cloacea, Klebsiella aerogenes, and Proteus hauseri which promote LPS circulation, a recipe for barrier disruption and systemic inflammatory activation. These findings emphasize the critical need to understand the underlying mechanisms and develop interventions to maintain gastrointestinal health in space.

The role of glycans in health and disease: Regulators of the interaction between gut microbiota and host immune system

The human gut microbiota is home to a diverse collection of microorganisms that has co-evolved with the host immune system in which host-microbiota interactions are essential to preserve health and homeostasis. Evidence suggests that the perturbation of this symbiotic host-microbiome relationship contributes to the onset of major diseases such as chronic inflammatory diseases including Inflammatory Bowel Disease. The host glycocalyx (repertoire of glycans/sugar-chains at the surface of gut mucosa) constitutes a major biological and physical interface between the intestinal mucosa and microorganisms, as well as with the host immune system. Glycans are an essential niche for microbiota colonization and thus an important modulator of host-microorganism interactions both in homeostasis and in disease. In this review, we discuss the role of gut mucosa glycome as an instrumental pathway that regulates host-microbiome interactions in homeostasis but also in health to inflammation transition. We also discuss the power of mucosa glycosylation remodelling as an attractive preventive and therapeutic strategy to preserve gut homeostasis.

A cross-disease, pleiotropy-driven approach for therapeutic target prioritization and evaluation

Cross-disease genome-wide association studies (GWASs) unveil pleiotropic loci, mostly situated within the non-coding genome, each of which exerts pleiotropic effects across multiple diseases. However, the challenge "W-H-W" (namely, whether, how, and in which specific diseases pleiotropy can inform clinical therapeutics) calls for effective and integrative approaches and tools. We here introduce a pleiotropy-driven approach specifically designed for therapeutic target prioritization and evaluation from cross-disease GWAS summary data, with its validity demonstrated through applications to two systems of disorders (neuropsychiatric and inflammatory). We illustrate its improved performance in recovering clinical proof-of-concept therapeutic targets. Importantly, it identifies specific diseases where pleiotropy informs clinical therapeutics. Furthermore, we illustrate its versatility in accomplishing advanced tasks, including pathway crosstalk identification and downstream crosstalk-based analyses. To conclude, our integrated solution helps bridge the gap between pleiotropy studies and therapeutics discovery.

Erosive Hand Osteoarthritis: Recent Advances and Future Treatments

PURPOSE OF THE REVIEW

Erosive hand osteoarthritis (EHOA) is an aggressive form of hand osteoarthritis that leads to significant disability, and recent data suggests that it is increasing in prevalence. This review provides an update of our current understanding of epidemiology, genetic associations, biomarkers, pathogenesis, and treatment of EHOA, with particular focus on studies published within the last 5 years.

RECENT FINDINGS

New studies of EHOA have identified new genetic loci associated with disease, including variants in genes involved in inflammation and bone remodeling. Preclinical studies implicate pathways of innate immunity, including some that may be causal in the condition. Recent novel studies showed that inflammatory features identified by ultrasound and MRI are associated with development of erosive lesions over time on conventional radiography. In the future, these imaging modalities may be useful in identifying patients at risk of adverse outcomes. Promising new findings in genetics, biomarkers, and treatment targets will hopefully allow for future therapeutic options for this debilitating condition.

Role of the nucleotide-binding oligomerization domain-containing protein 1 pathway in the development of periodontitis

OBJECTIVES

During innate immune defense, host pattern recognition receptors, including toll-like receptors and nucleotide-binding oligomerization domain-like receptors (NLRs), can activate downstream pathways by recognizing pathogen-associated molecular patterns produced by microorganisms, triggering immune responses. NOD1, an important cell membrane protein in the NLR-like receptor protein family, exerts anti-infective effects through γ-D-glutamyl-meso-diaminopimelic acid (iE-DAP) recognition. Oral epithelial cells resist bacterial invasion through iE-DAP-induced interleukin (IL)-8 production, recruiting neutrophils to sites of inflammation in response to bacterial threats to periodontal tissues. To date, the regulatory mechanisms of iE-DAP in gingival epithelial cells (GECs) are poorly understood. This study was conducted to investigate the role of the NOD1 pathway in the development of periodontitis by examining the effect of iE-DAP on IL-8 production in Ca9-22 cells.

METHODS

IL-8 production by iE-DAP-stimulated-Ca9-22 cells was assessed using an enzyme-linked immunosorbent assay. Phosphorylation levels of intracellular signaling molecules were evaluated using western blot analyses.

RESULTS

iE-DAP induced NOD1 receptor expression in Ca9-22 cells. Additionally, iE-DAP induced expression of pro-IL-1β protein without extracellular secretion. Our results suggest that iE-DAP regulates IL-8 production by activating p38 mitogen-activated protein kinase (MAPK) and ERK1/2 signaling pathways. iE-DAP also promoted nuclear factor kappa-B p65 phosphorylation, facilitating its nuclear translocation. Notably, p38 MAPK and ERK1/2 inhibitors suppressed iE-DAP-stimulated IL-8 production, suggesting that JNK is not involved in this mechanism.

CONCLUSIONS

Our results indicate that p38 MAPK and ERK1/2, but not JNK, are involved in innate immune responses in GECs.

Discovery of 2,3-Diaminoindole Derivatives as a Novel Class of NOD Antagonists

NOD1 and NOD2 are members of the pattern recognition receptors involved in the innate immune response. Overactivation of NOD1 is implicated in inflammatory disorders, multiple sclerosis, and cancer cell metastases. NOD1 antagonists would represent valuable pharmacological tools to gain further insight into protein roles, potentially leading to new therapeutic strategies. We herein report the expansion of the chemical space of NOD1 antagonists via a multicomponent synthetic approach affording a novel chemotype, namely, 2,3-diaminoindoles. These efforts resulted in compound 37, endowed with low micromolar affinity toward NOD1. Importantly, a proof-of-evidence of direct binding to NOD1 of Noditinib-1 and derivative 37 is provided here for the first time. Additionally, the combination of computational studies and NMR-based displacement assays enabled the characterization of the binding modality of 37 to NOD1, thus providing key unprecedented knowledge for the design of potent and selective NOD1 antagonists.

A closer look at ligand specificity for cellular activation of NOD2 with synthetic muramyl dipeptide analogues

To further understand the specificity of muramyl dipeptide (MDP) sensing by NOD2, we evaluated the compatibility of synthetic MDP analogues for cellular uptake and NAGK phosphorylation, the pre-requisite steps of intracellular NOD2 activation. Our results revealed that these two prior steps do not confer ligand stereoselectivity; yet NAGK strictly discriminates against the disaccharide NOD2 agonists for phosphorylation in vitro, despite it being indispensable for the cellular NOD2-stimulating effects of these analogues, implying potential glycosidase cleavage as a novel intermediate step for cellular activation of NOD2.

Contribution of Nucleotide-Binding Oligomerization Domain-like (NOD) Receptors to the Immune and Metabolic Health

Nucleotide-binding oligomerization domain-like (NOD) receptors rely on the interface between immunity and metabolism. Dietary factors constitute critical players in the activation of innate immunity and modulation of the gut microbiota. The latter have been involved in worsening or improving the control and promotion of diseases such as obesity, type 2 diabetes, metabolic syndrome, diseases known as non-communicable metabolic diseases (NCDs), and the risk of developing cancer. Intracellular NODs play key coordinated actions with innate immune 'Toll-like' receptors leading to a diverse array of gene expressions that initiate inflammatory and immune responses. There has been an improvement in the understanding of the molecular and genetic implications of these receptors in, among others, such aspects as resting energy expenditure, insulin resistance, and cell proliferation. Genetic factors and polymorphisms of the receptors are determinants of the risk and severity of NCDs and cancer, and it is conceivable that dietary factors may have significant differential consequences depending on them. Host factors are difficult to influence, while environmental factors are predominant and approachable with a preventive and/or therapeutic intention in obesity, T2D, and cancer. However, beyond the recognition of the activation of NODs by peptidoglycan as its prototypical agonist, the underlying molecular response(s) and its consequences on these diseases remain ill-defined. Metabolic (re)programming is a hallmark of NCDs and cancer in which nutritional strategies might play a key role in preventing the unprecedented expansion of these diseases. A better understanding of the participation and effects of immunonutritional dietary ingredients can boost integrative knowledge fostering interdisciplinary science between nutritional precision and personalized medicine against cancer. This review summarizes the current evidence concerning the relationship(s) and consequences of NODs on immune and metabolic health.

Nod-like receptors in inflammatory arthritis

Nod-like receptors (NLRs) are innate immune receptors that play a key role in sensing components from pathogens and from damaged cells or organelles. NLRs form signaling complexes that can lead to activation of transcription factors or effector caspases - by means of inflammasome activation -Inflammatory arthritis (IA) culminating in promoting inflammation. An increasing body of research supports the role of NLRs in driving pathogenesis of IA, a collection of diseases that include rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis, and pediatric arthritis. In this review, we briefly discuss the main drivers of IA diseases and dive into the evidence for - and against - various NLRs in driving these diseases. We also review the studies examining the use of NLR and inflammasome inhibitors as potential therapies for IA.

NLRX1: Versatile functions of a mitochondrial NLR protein that controls mitophagy

NLRX1 is a member of the of the Nod-like receptor (NLR) family, and it represents a unique pattern recognition molecule (PRM) as it localizes to the mitochondrial matrix in resting conditions. Over the past fifteen years, NLRX1 has been proposed to regulate multiple cellular processes, including antiviral immunity, apoptosis, reactive oxygen species (ROS) generation and mitochondrial metabolism. Similarly, in vivo models have shown that NLRX1 was associated with the control of a number of diseases, including multiple sclerosis, colorectal cancer and ischemia-reperfusion injury. This apparent versatility in function hinted that a common and general overarching role for NLRX1 may exist. Recent evidence has suggested that NLRX1 controls mitophagy through the detection of a specific "danger signal", namely the defective import of proteins into mitochondria, or mitochondrial protein import stress (MPIS). In this review article, we propose that mitophagy regulation may represent the overarching process detected by NLRX1, which could in turn impact on a number of diseases if dysfunctional.

A macrophage cell membrane-coated cascade-targeting photothermal nanosystem for combating intracellular bacterial infections

Current antibacterial interventions encounter formidable challenges when confronting intracellular bacteria, attributable to their clustering within phagocytes, particularly macrophages, evading host immunity and resisting antibiotics. Herein, we have developed an intelligent cell membrane-based nanosystem, denoted as MM@DAu NPs, which seamlessly integrates cascade-targeting capabilities with controllable antibacterial functions for the precise elimination of intracellular bacteria. MM@DAu NPs feature a core comprising D-alanine-functionalized gold nanoparticles (DAu NPs) enveloped by a macrophage cell membrane (MM) coating. Upon administration, MM@DAu NPs harness the intrinsic homologous targeting ability of their macrophage membrane to infiltrate bacteria-infected macrophages. Upon internalization within these host cells, exposed DAu NPs from MM@DAu NPs selectively bind to intracellular bacteria through the bacteria-targeting agent, D-alanine present on DAu NPs. This intricate process establishes a cascade mechanism that efficiently targets intracellular bacteria. Upon exposure to near-infrared irradiation, the accumulated DAu NPs surrounding intracellular bacteria induce local hyperthermia, enabling precise clearance of intracellular bacteria. Further validation in animal models infected with the typical intracellular bacteria, Staphylococcus aureus, substantiates the exceptional cascade-targeting efficacy and photothermal antibacterial potential of MM@DAu NPs in vivo. Therefore, this integrated cell membrane-based cascade-targeting photothermal nanosystem offers a promising approach for conquering persistent intracellular infections without drug resistance risks. STATEMENT OF SIGNIFICANCE: Intracellular bacterial infections lead to treatment failures and relapses because intracellular bacteria could cluster within phagocytes, especially macrophages, evading the host immune system and resisting antibiotics. Herein, we have developed an intelligent cell membrane-based nanosystem MM@DAu NPs, which is designed to precisely eliminate intracellular bacteria through a controllable cascade-targeting photothermal antibacterial approach. MM@DAu NPs combine D-alanine-functionalized gold nanoparticles with a macrophage cell membrane coating. Upon administration, MM@DAu NPs harness the homologous targeting ability of macrophage membrane to infiltrate bacteria-infected macrophages. Upon internalization, exposed DAu NPs from MM@DAu NPs selectively bind to intracellular bacteria through the bacteria-targeting agent, enabling precise clearance of intracellular bacteria through local hyperthermia. This integrated cell membrane-based cascade-targeting photothermal nanosystem offers a promising avenue for conquering persistent intracellular infections without drug resistance risks.

A family with ulcerative colitis maps to 7p21.1 and comprises a region with regulatory activity for the aryl hydrocarbon receptor gene

We have mapped a locus on chromosome 7p22.3-7p15.3 spanning a 22.4 Mb region for ulcerative colitis (UC) by whole genome linkage analyses of a large Danish family. The family represent three generations with UC segregating as an autosomal dominant trait with variable expressivity. The whole-genome scan resulted in a logarithm of odds score (LOD score) of Z = 3.31, and a whole genome sequencing (WGS) of two affected excluded disease-causing mutations in the protein coding genes. Two rare heterozygote variants, rs182281985:G>A and rs541426369:G>A, both with low allele frequencies (MAF A:0.0001, gnomAD ver3.1.2), were found in clusters of ChiP-seq transcription factors binding sites close to the AHR (aryl hydrocarbon receptor) gene and the UC associated SNP rs1077773:G>A. Testing the two SNPs in a promoter reporter assay for regulatory activity revealed that rs182281985:G>A influenced the AHR promoter. These results suggest a regulatory region that include rs182281985:G>A close to the UC GWAS SNP rs1077773:G>A and further demonstrate evidence that the AHR gene on the 7p-tel region is a candidate susceptible gene for UC.

Receptor Interacting Ser/Thr-Protein Kinase 2 as a New Therapeutic Target

Receptor interacting serine/threonine protein kinase 2 (RIPK2) is a downstream signaling molecule essential for the activation of several innate immune receptors, including the NOD-like receptors (NOD1 and NOD2). Recognition of pathogen-associated molecular pattern proteins by NOD1/2 leads to their interaction with RIPK2, which induces release of pro-inflammatory cytokines through the activation of NF-κB and MAPK pathways, among others. Thus, RIPK2 has emerged as a key mediator of intracellular signal transduction and represents a new potential therapeutic target for the treatment of various conditions, including inflammatory diseases and cancer. In this Perspective, first, an overview of the mechanisms that underlie RIPK2 function will be presented along with its role in several diseases. Then, the existing inhibitors that target RIPK2 and different therapeutic strategies will be reviewed, followed by a discussion on current challenges and outlook.

NOD1 cooperates with HAX-1 to promote cell migration in a RIPK2- and NF-ĸB-independent manner

The human Nod-like receptor protein NOD1 is a well-described pattern-recognition receptor (PRR) with diverse functions. NOD1 associates with F-actin and its protein levels are upregulated in metastatic cancer cells. A hallmark of cancer cells is their ability to migrate, which involves actin remodelling. Using chemotaxis and wound healing assays, we show that NOD1 expression correlated with the migration rate and chemotactic index in the cervical carcinoma cell line HeLa. The effect of NOD1 in cell migration was independent of the downstream kinase RIPK2 and NF-ĸB activity. Additionally, NOD1 negatively regulated the phosphorylation status of cofilin, which inhibits actin turnover. Co-immunoprecipitation assays identified HCLS1-associated protein X-1 (HAX-1) as a previously unknown interaction partner of NOD1. Silencing of HAX-1 expression reduced the migration behaviour to similar levels as NOD1 knockdown, and simultaneous knockdown of NOD1 and HAX-1 showed no additive effect, suggesting that both proteins act in the same pathway. In conclusion, our data revealed an important role of the PRR NOD1 in regulating cell migration as well as chemotaxis in human cervical cancer cells and identified HAX-1 as a protein that interacts with NOD1 and is involved in this signalling pathway.

Structure shows that the BIR2 domain of E3 ligase XIAP binds across the RIPK2 kinase dimer interface

RIPK2 is an essential adaptor for NOD signalling and its kinase domain is a drug target for NOD-related diseases, such as inflammatory bowel disease. However, recent work indicates that the phosphorylation activity of RIPK2 is dispensable for signalling and that inhibitors of both RIPK2 activity and RIPK2 ubiquitination prevent the essential interaction between RIPK2 and the BIR2 domain of XIAP, the key RIPK2 ubiquitin E3 ligase. Moreover, XIAP BIR2 antagonists also block this interaction. To reveal the molecular mechanisms involved, we combined native mass spectrometry, NMR, and cryo-electron microscopy to determine the structure of the RIPK2 kinase BIR2 domain complex and validated the interface with in cellulo assays. The structure shows that BIR2 binds across the RIPK2 kinase antiparallel dimer and provides an explanation for both inhibitory mechanisms. It also highlights why phosphorylation of the kinase activation loop is dispensable for signalling while revealing the structural role of RIPK2-K209 residue in the RIPK2-XIAP BIR2 interaction. Our results clarify the features of the RIPK2 conformation essential for its role as a scaffold protein for ubiquitination.