TL1A/DR3 Signaling Axis in Autoimmune Diseases: Inflammatory Amplification and Targeted Intervention
TL1A/DR3 Signaling Axis in Autoimmune Diseases: Inflammatory Amplification and Targeted Intervention
TL1A amplifies Th1/Th17 immune responses through DR3 and participates in intestinal mucosal inflammation, synovial injury, psoriatic lesions, and intestinal wall fibrosis. It has become an important target for autoimmune disease mechanism research and antibody drug development.
Keywords: TL1A; TNFSF15; DR3; TNFRSF25; Th1 cells; Th17 cells; inflammatory bowel disease; rheumatoid arthritis; psoriasis; tissue fibrosis
1 Molecular Structure and Immunoregulatory Features of TL1A
1.1 Molecular Forms of TL1A
TL1A (TNF-like ligand 1A) is encoded by the TNFSF15 gene and belongs to the tumor necrosis factor ligand superfamily. Its initial form is a type II transmembrane protein. The extracellular region contains a TNF homology domain and can form receptor-binding homotrimers.
(1) Membrane-bound TL1A
Membrane-bound TL1A retains the transmembrane structure and mainly mediates local signaling between adjacent cells. It can continuously stimulate DR3-positive cells at immune cell contact sites.
(2) Soluble TL1A
Membrane-bound TL1A can be processed by proteolysis to form soluble TL1A, which is present in tissue fluid, blood, and culture supernatants. It is also the main target for patient sample detection and antibody blockade studies.
Both forms can activate DR3, but their action range, local concentration, and receptor clustering efficiency may differ. When recombinant TL1A is used for cell stimulation, biological activity, trimeric conformation, and tag format should be considered in addition to protein purity.
1.2 DR3 and DcR3 Constitute the TL1A Receptor System
(1) DR3
DR3, also known as TNFRSF25, is the main functional receptor for TL1A and contains an intracellular death domain. DR3 is mainly expressed on activated T cells, NK cells, regulatory T cells, and innate lymphoid cells, and some fibroblasts may also express DR3.
Although DR3 belongs to the death receptor family, in autoimmune inflammation, TL1A/DR3 signaling mainly promotes cell survival, proliferation, and inflammatory cytokine production rather than directly inducing apoptosis.
(2) DcR3
DcR3 is a soluble decoy receptor lacking a transmembrane region and intracellular signaling domain. It can competitively bind TL1A, reducing the opportunity for TL1A to bind DR3 and form effective signaling.
1.3 Immunoregulatory Positioning of TL1A
TL1A is not a cytokine that independently determines T cell differentiation direction, but a co-stimulatory and amplifying factor in inflammatory environments.
(1) It enhances responses of T cells that have received T-cell receptor stimulation and strengthens NK-cell and innate lymphoid-cell responses driven by cytokines or activating receptors.
(2) It cooperates with cytokines such as IL-12, IL-18, or IL-23 to increase the production of IFN-γ, IL-17, and IL-22.
(3) It affects both immune cells and fibroblasts, linking chronic inflammation with tissue remodeling and fibrosis.
2 Regulation of TL1A Expression in the Inflammatory Microenvironment
2.1 Main TL1A-Expressing Cells
(1) Monocytes
Circulating monocytes can express TL1A after stimulation by inflammatory cytokines, immune complexes, or pattern recognition receptor signals. After entering diseased tissues, monocyte-derived TL1A can enhance local T cell and innate lymphoid cell responses.
(2) Macrophages
Tissue macrophages are an important source of TL1A in chronic inflammatory environments. Microbial components, tissue damage signals, and immune complexes can all induce macrophages to produce TL1A, maintaining inflammatory interactions between myeloid cells and lymphocytes.
(3) Dendritic cells
Dendritic cells can express TL1A during antigen uptake and presentation. Together with other co-stimulatory signals, TL1A can enhance antigen-specific T cell expansion and cytokine production.
(4) Vascular endothelial cells
Vascular endothelial cells can upregulate TL1A after stimulation by inflammatory cytokines such as TNF and IL-1β, participating in local vascular inflammation and immune cell recruitment into diseased tissues.
(5) Activated lymphocytes
Some activated T cells can express membrane-bound TL1A and act on neighboring DR3-positive cells at cell contact sites, strengthening local co-stimulatory signals.
2.2 Main Inducing Signals for TL1A Expression
(1) Inflammatory cytokines
TNF and IL-1β can induce TL1A expression in endothelial cells and some myeloid cells. After TL1A is produced, it can further enhance TNF-, IFN-γ-, and IL-17-related responses.
(2) Immune complexes
Immune complexes formed by antigens and antibodies can activate monocytes, macrophages, and dendritic cells through Fcγ receptors, promoting TL1A expression. This mechanism is relatively important in autoantibody-associated diseases such as rheumatoid arthritis.
(3) Pattern recognition receptor signals
After Toll-like receptors recognize microbial components or damage-associated molecules, they can induce TL1A expression in myeloid cells, allowing infection, intestinal microbiota changes, and tissue injury to further influence adaptive immune responses.
3 TL1A/DR3 Signal Transduction and Inflammatory Effects
3.1 DR3 Receptor Signaling Complex
After trimeric TL1A binds DR3, it can promote clustering of multiple DR3 molecules and recruit signaling molecules such as TRADD, TRAF2, and RIPK1 through the intracellular death domain. After the receptor-proximal complex forms, signals are mainly transmitted to the NF-κB and MAPK pathways.
DR3 signaling output is strongly cell-context dependent. In activated lymphocytes, this pathway mainly enhances cell survival, expansion, and inflammatory cytokine expression. Under specific stress and signaling imbalance conditions, it may also participate in cell death regulation.
3.2 NF-κB Signaling Pathway
TL1A/DR3 can promote IκBα phosphorylation and degradation, allowing NF-κB p65 to enter the nucleus and regulate inflammatory cytokines, chemokines, and cell survival-related genes.
NF-κB signaling mainly participates in:
(1) Enhancing survival and proliferation of activated lymphocytes.
(2) Promoting expression of inflammatory cytokines and chemokines.
(3) Maintaining immune cell recruitment into diseased tissues.
3.3 MAPK and AP-1 Signaling Pathways
(1) ERK
ERK participates in cell activation, proliferation, and expression of some inflammation-related genes.
(2) JNK/c-Jun
JNK/c-Jun participates in cellular stress and AP-1-mediated transcriptional regulation and can cooperate with NF-κB to enhance inflammatory responses.
(3) p38 MAPK
p38 MAPK participates in inflammatory cytokine transcription, mRNA stability, and regulation of effector cell functions.
Activation of NF-κB or MAPK only indicates initiation of downstream signaling. Cell proliferation and cytokine production should also be assessed to determine the actual immune effects of TL1A/DR3.
3.4 Regulatory Factors of TL1A/DR3 Signaling
(1) DR3 expression level on target cell surfaces.
(2) Competitive binding of TL1A by DcR3.
(3) T cell receptor signaling and cooperative signals such as IL-12, IL-18, and IL-23.
(4) Trimeric conformation and receptor-crosslinking capacity of TL1A protein.
4 Amplification of Th1/Th17 Immune Responses by TL1A
4.1 Th1-Type Immune Response
TL1A can enhance T cell activation after T cell receptor stimulation and cooperate with IL-12 and IL-18 to promote IFN-γ production by T cells, NK cells, and other cells. In this process, TL1A mainly provides co-stimulatory signaling rather than independently initiating Th1 cell differentiation.
Increased IFN-γ can enhance macrophage activation, antigen presentation, and chemokine expression, and promote the entry of monocytes and T cells into diseased tissues.
4.2 Th17 Cell Expansion and Effector Maintenance
DR3 can be expressed in effector Th17 cells, and TL1A can enhance their expansion and effector function. In the presence of signals such as IL-23, TL1A can increase the production of IL-17A, IL-17F, and IL-22.
TL1A mainly enhances already formed Th17 responses. Initial differentiation of naïve CD4⁺ T cells into Th17 cells mainly depends on cytokines such as IL-6, IL-1β, and TGF-β, whereas IL-23 primarily promotes Th17-cell expansion, stabilization, and maintenance of pathogenic effector functions.
4.3 Tissue Inflammation Mediated by Th1 and Th17 Responses
(1) IFN-γ-related responses
These mainly enhance macrophage activation, antigen presentation, and cellular immune responses.
(2) IL-17-related responses
These promote epithelial cells, endothelial cells, keratinocytes, and fibroblasts to produce chemokines, enhancing neutrophil recruitment.
(3) IL-22-related responses
These affect epithelial barriers, tissue hyperplasia, and damage repair, and may show protective or pathological effects depending on tissue context.
Figure 1. TL1A/DR3 axis-mediated immune cell interactions and inflammatory responses
5 TL1A-Driven Intestinal Mucosal Inflammation and Intestinal Wall Fibrosis
5.1 TNFSF15 Genetic Variants and IBD Susceptibility
TNFSF15 is an important susceptibility gene for inflammatory bowel disease. Some genetic variants are associated with disease susceptibility, lesion location, and fibrostenotic phenotypes, suggesting that the TL1A pathway may participate in both mucosal immunity and long-term tissue remodeling.
TNFSF15 genotype reflects genetic risk and cannot directly represent current TL1A pathway activity in patients. It should be analyzed together with mucosal TL1A expression, DR3 levels, and clinical phenotype.
5.2 Intestinal Mucosal Immune Inflammation
Intestinal macrophages and dendritic cells can produce TL1A after stimulation by microbial products, immune complexes, and tissue damage signals.
The main roles of TL1A in intestinal mucosa include:
(1) Enhancing IFN-γ responses of Th1 cells and NK cells.
(2) Maintaining IL-17 and IL-22 responses of Th17 cells and innate lymphoid cells.
(3) Promoting recruitment of inflammatory cells into the intestinal mucosa.
(4) Affecting the intestinal epithelial barrier, goblet cells, and mucosal repair.
5.3 Fibroblast Activation and Intestinal Wall Remodeling
Crohn’s disease-associated fibrostenosis involves fibroblast expansion, myofibroblast activation, and persistent extracellular matrix deposition. TL1A may participate in this process through two routes:
(1) Inflammation-mediated indirect effects
TL1A enhances lymphocyte and myeloid cell responses, causing repeated tissue injury and repair in the intestinal wall and promoting persistent fibroblast activation.
(2) Stromal cell-mediated direct effects
Some intestinal fibroblasts can express DR3. TL1A can directly affect their migration, activation, and extracellular matrix production.
Improvement of fibrosis indicators in experimental models cannot be directly equated with reversal of established intestinal strictures in patients.
6 TL1A in Synovial Immune Regulation in Rheumatoid Arthritis
6.1 Immune Complex-Induced TL1A Expression
Immune complexes formed by rheumatoid factor and other autoantibodies can activate monocytes, macrophages, and dendritic cells through Fcγ receptors, promoting TL1A expression.
TL1A then acts on DR3-positive memory T cells and effector T cells, enhancing the production of inflammatory cytokines such as TNF, IFN-γ, and IL-17, thereby further converting autoantibody-associated responses into persistent synovial inflammation.
6.2 TL1A and the TNF Inflammatory Network
TNF can induce endothelial cells and myeloid cells to express TL1A, while TL1A can enhance TNF-related responses in T cells and myeloid cells. The two may jointly maintain synovial inflammation.
A decrease in TL1A levels after anti-TNF treatment may reflect weakened TNF-related inflammation, but it does not prove that TL1A is merely a passive downstream indicator of TNF. Whether TL1A has independent therapeutic value requires observation of whether its blockade can further improve synovitis and structural joint damage.
6.3 Synovitis and Joint Structural Damage
TL1A can promote synovial immune cell infiltration, inflammatory cytokine release, and synovial hyperplasia. In animal arthritis models, enhanced TL1A signaling is associated with disease aggravation, and TL1A blockade can reduce inflammation and bone erosion.
Current evidence in rheumatoid arthritis mainly comes from patient samples and animal models, and the clinical benefit of anti-TL1A therapy still requires further validation.
7 TL1A in the IL-23/IL-17 Inflammatory Network of Psoriasis
7.1 TL1A and the IL-23/IL-17 Axis
The IL-23/IL-17 axis is an important immunopathological pathway in psoriasis. TL1A can enhance IL-23-driven Th17 and γδT17 cell responses, but TL1A stimulation alone is usually insufficient to produce IL-17 output of the same intensity.
Its main effects include:
(1) Enhancing the response of Th17 and γδT17 cells to IL-23.
(2) Promoting IL-17 and IL-22 production.
(3) Enhancing keratinocyte proliferation and inflammatory mediator expression.
(4) Promoting neutrophil and other inflammatory cell entry into skin lesions.
7.2 γδT17 Cells and Keratinocytes
Skin γδT17 cells are important sources of IL-17 and IL-22. They can express DR3 and respond to TL1A-mediated co-stimulation. After IL-17 and IL-22 act on keratinocytes, they can promote chemokine and antimicrobial peptide expression as well as abnormal proliferation, forming pathological changes such as epidermal thickening, scaling, and neutrophil infiltration.
7.3 Current Research Evidence
In patient samples, increased circulating TL1A or TNFSF15 expression can be observed. In animal models, TL1A blockade can also reduce some psoriasis-like skin inflammation. However, current evidence is still insufficient to prove that anti-TL1A therapy has achieved clear efficacy in patients with psoriasis.
8 TL1A Biomarkers and Targeted Therapy Research
8.1 Evaluation Levels of TL1A Biomarkers
(1) Genetic biomarkers
TNFSF15 genetic variants can be used to analyze disease susceptibility and some clinical phenotypes, but they cannot reflect the patient’s current pathway activity.
(2) Circulating protein biomarkers
Soluble TL1A in serum or plasma is convenient for dynamic detection and can be used to analyze disease activity and changes before and after treatment, but it is easily affected by systemic inflammation and sample handling conditions.
(3) Tissue biomarkers
TL1A, DR3, and effector cell distribution in diseased tissues are closer to local pathway status, but are limited by sampling and tissue heterogeneity.
TL1A can increase in multiple inflammatory diseases. Its disease specificity as a single marker is limited, and it is more suitable for combined analysis with TNFSF15 genotype, tissue DR3 expression, and disease activity indicators.
8.2 Mechanistic Basis of Anti-TL1A Therapy
Anti-TL1A antibodies block the binding of TL1A to DR3, reducing co-stimulation and inflammatory cytokine output from DR3-positive immune cells.
Their potential effects include:
(1) Simultaneous modulation of Th1, Th17, and innate lymphoid cell responses.
(2) Inhibition of inflammatory amplification maintained by multiple immune cell types.
(3) Potential effects on fibroblast activation and tissue remodeling.
Current clinical development of anti-TL1A drugs is mainly focused on inflammatory bowel disease, while their therapeutic value in rheumatoid arthritis and psoriasis has not been fully validated.
8.3 Key Questions for TL1A-Targeted Therapy
(1) How to identify patients with higher TL1A pathway activity who may obtain greater therapeutic benefit.
(2) Which indicators—circulating TL1A, tissue expression, or TNFSF15 genotype—are more suitable for predicting treatment response.
(3) Whether inflammation relief can further improve structural damage such as intestinal wall fibrosis and strictures.
(4) Whether long-term blockade of TL1A/DR3 affects mucosal immunity, infection defense, and tissue repair.
Table 1. Key Roles of TL1A in Major Autoimmune Diseases
Disease | Main Acting Cells | Core Pathological Links | Research Focus |
Inflammatory bowel disease | Macrophages, dendritic cells, Th1/Th17 cells, innate lymphoid cells, fibroblasts | Mucosal inflammation, epithelial barrier injury, intestinal wall fibrosis | Patient stratification, long-term efficacy, and anti-fibrotic effects |
Rheumatoid arthritis | Monocytes, macrophages, dendritic cells, effector T cells | Immune complex responses, TNF inflammatory network, synovitis, and bone erosion | Independent therapeutic value and protection of joint structure |
Psoriasis | Myeloid cells, Th17 cells, γδT17 cells, keratinocytes | IL-23/IL-17 inflammatory amplification and abnormal epidermal proliferation | Applicable patient subtypes and clinical efficacy validation |
9 Products Related to TL1A/DR3 Signaling Axis and Downstream Effect Research
Research Module | Cat. No. | Product Name | Grade & Purity | Main Application |
TL1A ligand | Recombinant Human TL1A/TNFSF15 Protein | Carrier-free, ActiBioPure™, high performance, ≥95%(SDS-PAGE), expressed in E. coli; see COA | Used for TL1A/DR3 binding analysis and stimulation of human DR3-positive cells | |
TL1A ligand | Recombinant Human TL1A/TNFSF15 Protein | Carrier-free, bioactive, ActiBioPure™, high performance, ≥90%(SDS-PAGE) | Used for functional studies of T cells, NK cells, and other DR3-positive cells | |
TL1A ligand | TL1A | Moligand™ | Used for TL1A-related in vitro signaling and functional research | |
TL1A gene intervention | TNFSF15 Human Pre-designed siRNA Set A |
| Knocks down TNFSF15 to validate the role of endogenous TL1A | |
TL1A quantification | Human Tumor Necrosis Factor(ligand)Superfamily,Member 15 (TL1A/TNFSF15) ELISA Kit | BioReagent | Quantitatively detects soluble TL1A in human serum, plasma, or culture supernatant | |
DR3 receptor | Recombinant Human DR3/TNFRSF25 Protein | Animal-free, carrier-free, bioactive, ActiBioPure™, azide-free, Fc tag, ≥95%(SDS-PAGE) | Used for TL1A-DR3 binding analysis and screening of blocking molecules | |
DR3 gene intervention | TNFRSF25 Human Pre-designed siRNA Set A |
| Knocks down DR3 to validate TNFRSF25 dependence of TL1A effects | |
Th1 co-stimulation | Recombinant Human IL-12 Protein | Animal-free, carrier-free, bioactive, ActiBioPure™, azide-free, high performance, ≥95%(SDS-PAGE) | Used together with TL1A to stimulate human T cells or NK cells and evaluate Th1-related responses or NK-cell IFN-γ responses, respectively | |
Th1 co-stimulation | Recombinant Human IL-18 Protein | Animal-free, carrier-free, bioactive, ActiBioPure™, azide-free, high performance, ≥95%(SDS-PAGE&HPLC) | Used together with TL1A and IL-12 to study synergistic IFN-γ production | |
Th1 functional detection | Human Interferon Gamma (IFN-γ) ELISA Kit | BioReagent | Detects IFN-γ levels in human-derived cells or samples | |
Th1 functional detection | Mouse Interferon Gamma (IFN-γ) ELISA Kit | BioReagent | Evaluates Th1-type immune responses in mouse inflammatory models | |
Th17 co-stimulation | Recombinant Human IL-23 Protein | Animal-free, carrier-free, bioactive, ActiBioPure™, His tag, ≥90%(SDS-PAGE), expressed in HEK293; see COA | Used together with TL1A to study human Th17 cell expansion and effector enhancement | |
Th17 co-stimulation | Recombinant Mouse IL-23 Protein | Animal-free, carrier-free, bioactive, ActiBioPure™, azide-free, high performance, His tag, ≥95%(SDS-PAGE) | Used for mouse Th17 cells, γδT17 cells, and disease model research | |
Th17 functional detection | Human Interleukin 17A (IL-17A) ELISA Kit | BioReagent | Detects IL-17A levels in human Th17-related experiments | |
Th17 functional detection | Mouse Interleukin 17 A(IL-17A) ELISA Kit | BioReagent | Evaluates IL-17A responses in mouse IBD, arthritis, and psoriasis-like models | |
NF-κB signaling | Recombinant NF-kB p65 Antibody | Recombinant, ExactAb™, KD Validation, validated, high performance, see COA | Detects NF-κB p65 expression downstream of TL1A/DR3 | |
NF-κB signaling | TPCA-1 | Moligand™, ≥98% | Validates whether TL1A-induced inflammatory effects depend on the IKK/NF-κB pathway | |
p38 MAPK signaling | Recombinant Phospho-p38 (T180) Antibody | KD Validation | Detects p38 phosphorylation after TL1A/DR3 stimulation | |
p38 MAPK signaling | Recombinant p38 alpha/MAPK14 Antibody | Recombinant, ExactAb™, validated, high performance, see COA | Detects total p38α and is used with phospho-p38 for analysis | |
p38 MAPK signaling | SB-203580 | Moligand™, ≥98%(HPLC) | Validates dependence of TL1A-related cellular responses on p38 MAPK | |
ERK signaling | Recombinant ERK1/2 Antibody | KD Validation | Detects total ERK1/2 and evaluates ERK pathway downstream of TL1A/DR3 | |
ERK signaling | VX-11e | Moligand™, ≥98% | Analyzes the role of ERK2 in TL1A-mediated cell activation | |
Fibrosis evaluation | Human α-Smooth Muscle Actin(α-SMA) ELISA Kit | BioReagent | Quantitatively evaluates fibroblast activation and α-SMA levels in human-derived systems | |
Fibrosis evaluation | Mouse α-Smooth Muscle Actin (α-SMA) ELISA Kit | BioReagent | Evaluates α-SMA levels in mouse intestinal fibrosis models | |
Fibrosis evaluation | Recombinant Fibronectin Antibody | Recombinant, ExactAb™, KD Validation, validated, see COA | Detects TL1A-related fibroblast activation and Fibronectin expression |
The TL1A/DR3 signaling axis connects myeloid cell activation, Th1/Th17 inflammatory responses, and fibroblast remodeling, making it an important inflammatory amplification pathway in autoimmune diseases. Current evidence is most mature in inflammatory bowel disease, while rheumatoid arthritis and psoriasis still require more clinical validation.
For more related articles, please see below: