Malt1 inactivation attenuates experimental colitis through the regulation of Th17 and Th1/17 cells

Animal models of inflammatory bowel disease: category and evaluation indexes

Inflammatory bowel disease (IBD) research often relies on animal models to study the etiology, pathophysiology, and management of IBD. Among these models, rats and mice are frequently employed due to their practicality and genetic manipulability. However, for studies aiming to closely mimic human pathology, non-human primates such as monkeys and dogs offer valuable physiological parallels. Guinea pigs, while less commonly used, present unique advantages for investigating the intricate interplay between neurological and immunological factors in IBD. Additionally, New Zealand rabbits excel in endoscopic biopsy techniques, providing insights into mucosal inflammation and healing processes. Pigs, with their physiological similarities to humans, serve as ideal models for exploring the complex relationships between nutrition, metabolism, and immunity in IBD. Beyond mammals, non-mammalian organisms including zebrafish, Drosophila melanogaster, and nematodes offer specialized insights into specific aspects of IBD pathology, highlighting the diverse array of model systems available for advancing our understanding of this multifaceted disease. In this review, we conduct a thorough analysis of various animal models employed in IBD research, detailing their applications and essential experimental parameters. These include clinical observation, Disease Activity Index score, pathological assessment, intestinal barrier integrity, fibrosis, inflammatory markers, intestinal microbiome, and other critical parameters that are crucial for evaluating modeling success and drug efficacy in experimental mammalian studies. Overall, this review will serve as a valuable resource for researchers in the field of IBD, offering insights into the diverse array of animal models available and their respective applications in studying IBD.

Chemical Probes for Profiling of MALT1 Protease Activity

The paracaspase MALT1 is a key regulator of the human immune response. It is implicated in a variety of human diseases. For example, deregulated protease activity drives the survival of malignant lymphomas and is involved in the pathophysiology of autoimmune/inflammatory diseases. Thus, MALT1 has attracted attention as promising drug target. Although many MALT1 inhibitors have been identified, molecular tools to study MALT1 activity, target engagement and inhibition in complex biological samples, such as living cells and patient material, are still scarce. Such tools are valuable to validate MALT1 as a drug target in vivo and to assess yet unknown biological roles of MALT1. In this review, we discuss the recent literature on the development and biological application of molecular tools to study MALT1 activity and inhibition.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 exaggerates multiple organ injury, inflammation, and immune cell imbalance by activating the NF-κB pathway in sepsis

Objective

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates the inflammatory immune response and organ dysfunction, which are closely implicated in sepsis pathogenesis and progression. This study aimed to explore the role of MALT1 in sepsis-induced organ injury, immune cell dysregulation, and inflammatory storms.

Methods

Septic mice were constructed by intraperitoneal injection of lipopolysaccharide, followed by overexpression or knockdown of MALT1 by tail vein injection of the corresponding lentivirus. Mouse naïve CD4⁺ T cells and bone marrow-derived macrophages were treated with MALT1 overexpression/knockdown lentivirus plus lipopolysaccharide.

Results

In the lungs, livers, and kidneys of septic mice, MALT1 overexpression exaggerated their injuries, as shown by hematoxylin and eosin staining (all p < 0.05), elevated cell apoptosis, as reflected by the TUNEL assay and cleaved caspase-3 expression (p < 0.05 in the lungs and kidneys), and promoted macrophage infiltration, as illustrated by CD68 immunofluorescence (p < 0.05 in the lungs and kidneys). Meanwhile, in the blood, MALT1 overexpression reduced T-helper (Th)1/Th2 cells, increased Th17/regulatory T-cell ratios (both p < 0.05), promoted systematic inflammation, as revealed by tumor necrosis factor-α, interleukin-6, interleukin-1β, and C-reactive protein (all p < 0.05), elevated oxidative stress, as shown by nitric oxide (p < 0.05), superoxide dismutase, and malondialdehyde (p < 0.05), and enhanced liver and kidney dysfunction, as revealed by an automatic animal biochemistry analyzer (all p < 0.05 except for aspartate aminotransferase). However, MALT1 knockdown exerted the opposite effect as MALT1 overexpression. Ex vivo experiments revealed that MALT1 overexpression promoted the polarization of M1 macrophages and naïve CD4⁺ T cells toward Th2 and Th17 cells (all p < 0.05), while MALT1 knockdown attenuated these effects (all p < 0.05). Mechanistically, MALT1 positively regulated the nuclear factor-κB (NF-κB) pathway both in vivo and ex vivo (p < 0.05).

Conclusion

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 amplifies multiple organ injury, inflammation, oxidative stress, and imbalance of macrophages and CD4⁺ T cells by activating the NF-κB pathway in sepsis.

MALT1 reflects inflammatory cytokines, disease activity, and its chronological change could estimate treatment response to infliximab in Crohn's disease patients

Background

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) mediates the immunity and inflammatory response in multiple ways to be intimately involved in the progression of autoimmune diseases. This study intended to explore the linkage of MALT1 with inflammation, disease activity, and its change with infliximab treatment response in Crohn's disease (CD) patients.

Methods

MALT1 in peripheral blood mononuclear cell samples from 72 active CD patients (at baseline, 2 weeks [W2], W6, and W12 after infliximab treatment), 20 remissive CD patients (after enrollment), and 20 healthy controls (after enrollment) were detected by RT‐qPCR.

Results

MALT1 was highest in active CD patients, followed by remissive CD patients, and lowest in healthy controls (p < 0.001). MALT1 was positively linked with C‐reactive protein (p = 0.001), erythrocyte sedimentation rate (p = 0.014), clinical disease activity index (p = 0.003), tumor necrosis factor (TNF)‐α (p = 0.006), interleukin (IL)‐1β (p = 0.049), and IL‐17A (p = 0.004), but not other clinical characteristics (all p > 0.05) in active CD patients. After infliximab treatment, MALT1 was decreased from baseline to W12 in active CD patients (p < 0.001), especially in responders (p < 0.001), but not in nonresponders (p = 0.053). The reduction of MALT1 at W6 (p = 0.049) and W12 (p = 0.004) was associated with a good treatment response to infliximab in active CD patients. Moreover, the response rate or MALT1 at any time point was not different between active CD patients with and without TNFi history (all p > 0.05).

Conclusion

MALT1 reflects aggravated inflammation and disease activity. Meanwhile, the decrement of MALT1 from baseline to W12 could reflect infliximab treatment response in CD patients.

MALT1 regulates Th2 and Th17 differentiation via NF-κB and JNK pathways, as well as correlates with disease activity and treatment outcome in rheumatoid arthritis

Objective

MALT1 regulates immunity and inflammation in multiple ways, while its role in rheumatoid arthritis (RA) is obscure. This study aimed to investigate the relationship of MALT1 with disease features, treatment outcome, as well as its effect on Th1/2/17 cell differentiation and underlying molecule mechanism in RA.

Methods

Totally 147 RA patients were enrolled. Then their blood Th1, Th2, and Th17 cells were detected by flow cytometry. Besides, PBMC MALT1 expression was detected before treatment (baseline), at week (W) 6, W12, and W24. PBMC MALT1 in 30 osteoarthritis patients and 30 health controls were also detected. Then, blood CD4⁺ T cells were isolated from RA patients, followed by MALT1 overexpression or knockdown lentivirus transfection and Th1/2/17 polarization assay. In addition, IMD 0354 (NF-κB antagonist) and SP600125 (JNK antagonist) were also added to treat CD4⁺ T cells.

Results

MALT1 was increased in RA patients compared to osteoarthritis patients and healthy controls. Meanwhile, MALT1 positively related to CRP, ESR, DAS28 score, Th17 cells, negatively linked with Th2 cells, but did not link with other features or Th1 cells in RA patients. Notably, MALT1 decreased longitudinally during treatment, whose decrement correlated with RA treatment outcome (treatment response, low disease activity, or disease remission). In addition, MALT1 overexpression promoted Th17 differentiation, inhibited Th2 differentiation, less affected Th1 differentiation, activated NF-κB and JNK pathways in RA CD4⁺ T cells; while MALT1 knockdown exhibited the opposite effect. Besides, IMD 0354 and SP600125 addition attenuated MALT1’s effect on Th2 and Th17 differentiation.

Conclusion

MALT1 regulates Th2 and Th17 differentiation via NF-κB and JNK pathways, as well as correlates with disease activity and treatment outcome in RA.

Pharmacological Inhibition of MALT1 Ameliorates Autoimmune Pathogenesis and Can Be Uncoupled From Effects on Regulatory T-Cells

MALT1 forms part of a central signaling node downstream of immunoreceptor tyrosine-based activation motif (ITAM)-containing receptors, across a broad range of immune cell subsets, and regulates NF-κB driven transcriptional responses via dual scaffolding-protease activity. Allosteric inhibition of MALT1 activity has demonstrated benefit in animal models of inflammation. However, development of MALT1 inhibitors to treat autoimmune and inflammatory diseases (A&ID) has been hindered by reports linking MALT1 inhibition and genetic loss-of-function to reductions in regulatory T-cell (Treg) numbers and development of auto-inflammatory syndromes. Using an allosteric MALT1 inhibitor, we investigated the consequence of pharmacological inhibition of MALT1 on proinflammatory cells compared to regulatory T-cells. Consistent with its known role in ITAM-driven responses, MALT1 inhibition suppressed proinflammatory cytokine production from activated human T-cells and monocyte-derived macrophages, and attenuated B-cell proliferation. Oral administration of a MALT1 inhibitor reduced disease severity and synovial cytokine production in a rat collagen-induced arthritis model. Interestingly, reduction in splenic Treg numbers was less pronounced in the context of inflammation compared with naïve animals. Additionally, in the context of the disease model, we observed an uncoupling of anti-inflammatory effects of MALT1 inhibition from Treg reduction, with lower systemic concentrations of inhibitor needed to reduce disease severity compared to that required to reduce Treg numbers. MALT1 inhibition did not affect suppressive function of human Tregs in vitro. These data indicate that anti-inflammatory efficacy can be achieved with MALT1 inhibition without impacting the number or function of Tregs, further supporting the potential of MALT1 inhibition in the treatment of autoimmune disease.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 in rheumatoid arthritis: Longitudinal change after treatment and correlation with treatment efficacy of tumor necrosis factor inhibitors

Background

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) correlates with treatment outcomes in inflammatory bowel disease and rheumatoid arthritis (RA). This study aimed to further evaluate the MALT1 longitudinal change and its relationship with tumor necrosis factor inhibitors (TNFi) response in RA patients.

Methods

Seventy‐one RA patients receiving TNFi [etanercept (n = 42) or adalimumab (n = 29)] were enrolled. MALT1 was detected by RT‐qPCR in peripheral blood samples of RA patients before treatment (W0), at week (W)4, W12, and W24 after treatment. RA patients were divided into response/non‐response, remission/non‐remission patients according to their treatment outcome at W24. Meanwhile, MALT1 was also detected by RT‐qPCR in 30 osteoarthritis patients and 30 healthy controls (HCs).

Results

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 was elevated in RA patients compared with HCs (Z=−6.392, p < 0.001) and osteoarthritis patients (Z = −5.020, p < 0.001). In RA patients, MALT1 was positively correlated with C‐reactive protein (r_s = 0.347, p = 0.003), but not other clinical characteristics, treatment history, or current TNFi category. Meanwhile, MALT1 decreased from W0 to W12 in total RA patients (x² = 86.455, p < 0.001), etanercept subgroup (x² = 46.636, p < 0.001), and adalimumab subgroup (x² = 41.291, p < 0.001). Moreover, MALT1 at W24 (p = 0.012) was decreased in response patients compared with non‐response patients; MALT1 at W12 (p = 0.027) and W24 (p = 0.010) were reduced in remission patients than non‐remission patients. In etanercept subgroup, MALT1 at W24 (p = 0.013) was decreased in response patients compared with non‐response patients. In adalimumab subgroup, MALT1 at W24 (p = 0.015) was lower in remission patients than non‐remission patients.

Conclusion

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 reduction after treatment is associated with response and remission to TNFi in RA patients.

Aberrant blood MALT1 and its relevance with multiple organic dysfunctions, T helper cells, inflammation, and mortality risk of sepsis patients

Background

MALT1 is linked with multiple organic dysfunctions, inflammatory storm, and T helper (Th) cell differentiation. Herein, the current study aimed to investigate the correlation of peripheral blood mononuclear cell (PBMC) MALT1 with Th1 cells, Th17 cells, and prognosis of sepsis patients.

Methods

In general, 78 sepsis patients and 40 health controls (HCs) were enrolled. MALT1 expression was detected in PBMCs from all subjects by RT‐qPCR. Besides, Th1 and Th17 cells were measured in PBMCs from sepsis patients by flow cytometry; interleukin 17A (IL‐17A) and interferon gamma (IFN‐γ) were determined in serum from sepsis patients by ELISA.

Results

MALT1 expression was higher in sepsis patients than HCs (p < 0.001). MALT1 expression was positively correlated with Th17 cells (r_s = 0.291, p = 0.038) and IL‐17A (r_s = 0.383, p = 0.001), but not with Th1 cells (r_s = 0.204, p = 0.151) or IFN‐γ (r_s = 0.175, p = 0.125) in sepsis patients. MALT1 expression was positively correlated with APACHE II score (r_s = 0.275, p = 0.015), C‐reactive protein (CRP) (r_s = 0.257, p = 0.023), and sequential organ failure assessment (SOFA) score (r_s = 0.306, p = 0.006) (MALT1 expression was positively correlated with SOFA respiratory system score (r_s = 0.348, p = 0.002), and SOFA liver score (r_s = 0.260, p = 0.021), but not with SOFA scores in nervous system, cardio vascular system, coagulation, and renal system (all p > 0.05)). MALT1 expression (p = 0.010), Th1 cells (p = 0.010), Th17 cells (p = 0.038), and IL‐17A (p = 0.012), except for IFN‐γ (p = 0.102), elevated in sepsis deaths compared with sepsis survivors.

Conclusion

PBMC MALT1 is highly expressed in sepsis patients with its overexpression associated with multiple organic dysfunctions, elevated Th17 cells, and increased mortality risk.

Blood MALT1, Th1, and Th17 cells are dysregulated, inter-correlated, and correlated with disease activity in rheumatoid arthritis patients; meanwhile, MALT1 decline during therapy relates to treatment outcome

Objective

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) participates in inflammatory and autoimmune diseases via activating various signaling pathways and promoting the differentiation of T‐helper (Th) 1 and Th17 cells; however, it is rarely reported in rheumatoid arthritis (RA). This study aimed to assess the correlation of MALT1 with Th1 and Th17 cells and evaluate its potential as a biomarker for evaluating disease activity and treatment outcomes in RA patients.

Methods

This study enrolled 139 RA patients and 45 health controls (HCs); then, blood MALT1, Th1, and Th17 cells were determined. For RA patients only, blood MALT1 at week (W) 6 and W12 after treatment was also detected. Additionally, clinical response and remission of RA patients were assessed at W12.

Results

MALT1 (p < 0.001), Th1 (p = 0.011), and Th17 (p < 0.001) cells were all increased in RA patients than HCs; meanwhile, increased MALT1 was associated with elevated Th1 (p = 0.003) and Th17 (p < 0.001) cells in RA patients. Besides, MALT1, Th1, and Th17 cells were positively correlated with parts of disease activity indexes in RA patients (all p < 0.050). In addition, MALT1 was gradually declined from W0 to W12 (p < 0.001) in RA patients. Specifically, MALT1 at W6 and W12 was lower in response patients than no response patients (both p < 0.010), also in remission patients than no remission patients (both p < 0.050).

Conclusion

MALT1, Th1, and Th17 cells are dysregulated, inter‐correlated, and correlated with disease activity in RA patients; meanwhile, the decline of MALT1 expression can partly reflect RA treatment response and remission.

MALT1 positively correlates with Th1 cells, Th17 cells, and their secreted cytokines and also relates to disease risk, severity, and prognosis of acute ischemic stroke

Background

This study aimed to explore the association of mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) with acute ischemic stroke (AIS) risk and also to explore its association with T helper type 1 (Th1) cells, Th17 cells, disease severity, and prognosis in AIS patients.

Methods

One hundred twenty first‐episode AIS patients and 120 non‐AIS patients with high‐stroke‐risk factors (as controls) were recruited. Besides, in the cluster of differentiation 4‐positive (CD4⁺) T cells, the MALT1 gene expression was detected by reverse transcription quantitative polymerase chain reaction; meanwhile, Th1 and Th17 were detected by flow cytometry. Moreover, serum interferon (IFN)‐γ and interleukin (IL)‐17 were determined by enzyme‐linked immunosorbent assay.

Results

MALT1 expression was increased in AIS patients compared with controls and also it could differentiate AIS patients from controls, with an area under curve of 0.905 (95% confidence interval: 0.869–0.941). In AIS patients, MALT1 positively correlated with Th1 cells, Th17 cells, IFN‐γ, and IL‐17. Besides, MALT1 positively correlated with the National Institutes of Health Stroke Scale score. Furthermore, the Kaplan‐Meier curve and univariate Cox's regression analyses showed no correlation of MALT1 high expression with recurrence‐free survival (RFS) in AIS patients, although after adjustment using multivariant Cox's regression, high MALT1 expression independently correlated with worse RFS in AIS patients.

Conclusion

MALT1 expression is increased and positively correlates with disease severity, Th1 cells, and Th17 cells, whose high expression severs as an independent risk factor for worse RFS in AIS patients.

Human MALT1 deficiency and predisposition to infections

Human germline MALT1 deficiency is an inborn error of immunity characterized by recurrent bacterial, viral, and fungal infections, periodontal disease, enteropathy, dermatitis, and failure to thrive. The number of identified MALT1-deficient patients have greatly increased in the past two years, which has significantly improved our understanding of the clinical features of this disorder. Patients frequently experience infections affecting the respiratory, skin, gastrointestinal, and blood systems. The most frequently detected pathogens are Staphylococcus aureus, Candida albicans, and cytomegalovirus. Enhanced susceptibility to S. aureus and C. albicans is likely due to impaired Th17 immunity, similar to STAT3 and IL-17 pathway deficiencies.

MALT1 targeting suppresses CARD14-induced psoriatic dermatitis in mice

CARD14 gain-of-function mutations cause psoriasis in humans and mice. Together with BCL10 and the protease MALT1, mutant CARD14 forms a signaling node that mediates increased NF-κB signaling and proinflammatory gene expression in keratinocytes. However, it remains unclear whether psoriasis in response to CARD14 hyperactivation is keratinocyte-intrinsic or requires CARD14 signaling in other cells. Moreover, the in vivo effect of MALT1 targeting on mutant CARD14-induced psoriasis has not yet been documented. Here, we show that inducible keratinocyte-specific expression of CARD14^E138A in mice rapidly induces epidermal thickening and inflammation as well as increased expression of several genes associated with psoriasis in humans. Keratinocyte-specific MALT1 deletion as well as oral treatment of mice with a specific MALT1 protease inhibitor strongly reduces psoriatic skin disease in CARD14^E138A mice. Together, these data illustrate a keratinocyte-intrinsic causal role of enhanced CARD14/MALT1 signaling in the pathogenesis of psoriasis and show the potential of MALT1 inhibition for the treatment of psoriasis.