Recent breakthroughs have substantially advanced our understanding of chemokine-receptor networks in immune cell migration. Kryukova et al. identified a 16-mer peptide “HD2” via phage display that simultaneously binds and inhibits CCL/CXCL chemokines, serving as a blueprint for pan-chemokine inhibitor design (68). In parallel, quantitative structure-activity relationship (QSAR) analysis and molecular docking have facilitated the discovery of novel CXCR7 inhibitors, enabling precise targeting of tumor angiogenesis and metastasis (69). Additionally, biased signaling in G-protein-coupled receptor (GPCR) transduction has emerged as a critical concept: by designing small molecules that selectively activate β-arrestin while sparing G protein pathways, more effective and safer therapeutics can be developed (70).

Chemokines, a specialized class of cytokine polypeptides, critically regulate immune cell migration through GPCR activation (71, 72). Classical chemokine-receptor pairs such as CXCL10/CXCR3, CCL2/CCR2, and CCL5/CCR5 are well-characterized under both physiological and inflammatory conditions (73). During inflammation, chemokines enhance leukocyte adhesion to vascular endothelium and promote endothelial gap formation, facilitating immune cell extravasation. Their rapid action and subset specificity allow precise spatiotemporal control of leukocyte trafficking (74, 75). Chemokine receptors on leukocyte surfaces serve as “migratory passports”, guiding specific cell subpopulations through tissue barrier checkpoints (75).

The CCL19/21–CCR7 axis exemplifies this mechanism: during antigen exposure or vaccination, CCR7-mediated chemotaxis directs dendritic cells (DCs) from peripheral tissues to lymph nodes, thereby initiating T cell responses (76, 77). Recent studies show that CCL21 provides a spatial gradient for DC lymphatic entry, whereas CCL19 establishes self-generated chemokine gradients via CCR7 internalization, synchronizing DC–T cell interactions (77). Moreover, boosting CCL19/21 signaling (e.g., with adjuvants or focused ultrasound) enhances DC vaccine efficacy by improving lymph node homing and antitumor immunity (78, 79). Zhang et al. reviewed chemokine-GPCR pathways and their modulatory roles in inflammation (80). Hu et al. summarized the role of cell adhesion molecules in fibrotic diseases, suggesting that targeting adhesion pathways may complement chemokine inhibition in inflammatory settings (81). These findings underscore the clinical potential of chemokine-targeted strategies in cancer, vaccination, and inflammatory disorders. However, challenges such as pathway redundancy, compensatory mechanisms, and safety concerns highlight the need for more selective and context-specific therapeutic approaches. Future efforts should prioritize developing next-generation chemokine modulators that achieve precise immune control while minimizing systemic toxicity.

Cell adhesion molecules (CAMs), particularly selectins, integrins, and mucin-associated hyaluronate receptors, mediate essential cell-cell and extracellular matrix (ECM) interactions that critically regulate immune cell trafficking during inflammatory responses (81). These molecules provide precise spatiotemporal control of leukocyte adhesion and migration, forming the molecular basis for targeted immune surveillance.

L-selectin, expressed predominantly by circulating immune cells, binds vascular sulfated sialoglycoproteins to initiate leukocyte rolling adhesion. While indispensable for tissue repair and immune surveillance, dysregulated L-selectin activity contributes to pathological inflammation and tissue damage in infectious and inflammatory diseases (82).

Integrins, a family of heterodimeric proteins composed of α and β subunits, represent another critical class of CAMs governing immune cell migration. The β1 integrin subfamily, including VLA-1, VLA-2, VLA-4, VLA-5, and VLA-6, regulates leukocyte passage across the vascular basement membrane, through the ECM, and into stromal and endothelial layers. By mediating adhesion and spreading on ECM proteins, these integrins enable tissue infiltration during inflammatory responses (83).

In addition, L-selectin, P-selectin glycoprotein ligand-1 (PSGL-1), and α4 integrin cooperate to mediate immune cell adhesion to vascular endothelial cells (13). Initially, L-selectin and P-selectin promote rolling interactions that slow leukocytes and allow transient attachment, a prerequisite for sensing chemotactic cues from inflamed tissues. From a translational perspective, α4-integrin blockade has emerged as an effective therapeutic strategy in multiple sclerosis: natalizumab, a monoclonal antibody against α4-integrin, significantly reduces relapse rates and delays disability progression (84). Vedolizumab, a selective α4β7 integrin inhibitor, has demonstrated efficacy in ulcerative colitis and Crohn’s disease and is FDA-approved for these indications (85, 86), underscoring the therapeutic relevance of α4-integrin biology.

Mechanistically, E-selectin and α4 integrins further decelerate rolling leukocytes, enabling chemokines to rapidly activate β2 and/or α4 integrins on the immune cell surface. This activation induces firm adhesion to the endothelium, a prerequisite for transendothelial migration (87). Ultimately, immune cells extravasate into the surrounding tissue, orchestrating the inflammatory response. However, dysregulated CAM activity can lead to excessive infiltration and drive the pathogenesis of various inflammatory disorders. Thus, elucidating the molecular mechanisms underlying selectins, integrins, and related CAMs is critical for developing targeted strategies to modulate immune cell migration (13).

In summary, CAMs not only underpin the molecular logic of immune surveillance and inflammation but also represent actionable therapeutic targets in autoimmune and inflammatory diseases. Nevertheless, context-specific regulation of CAMs remains insufficiently understood, representing a key research gap for advancing their clinical translation.

Functioning as proteolytic enzymes, proteases critically regulate immune responses through protein cleavage and modification (88, 89). However, current descriptions often fail to distinguish between the proteases mediating neutrophil, monocyte, and T cell migration. For example, MMP-9 plays a central role in neutrophil extravasation (90, 91), whereas MMP-2 is primarily associated with T cell infiltration. Clarifying such distinctions would enhance both mechanistic clarity and therapeutic relevance.

In the context of immune cell migration, proteases degrade extracellular matrix (ECM) components, enabling cellular transit through tissues to inflammatory or infected sites. These proteases comprise both secretory and cell-surface-associated subtypes. The most well-studied secretory proteases are matrix metalloproteins (MMPs) and urokinase-type plasminogen activator (uPA). MMPs cleave key ECM proteins, including collagen, elastin, and fibronectin, thereby facilitating immune cell infiltration (92). uPA promotes migration by converting plasminogen to plasmin, which degrades fibrin and other ECM components (93). Cell-surface proteases, expressed on endothelial and immune cells, serve dual functions as both ectoenzymes and adhesion receptors, regulating cell-ECM interactions through substrate cleavage and soluble factor generation. While proteases facilitate immune cell migration, their pleiotropic nature complicates therapeutic targeting. Given their diverse biological roles, protease inhibition risks off-target effects that may compromise immune function or tissue homeostasis. For example, inhibiting MMPs could potentially disrupt wound healing, tissue remodeling (94), or even the recruitment of non-inflammatory cells necessary for tissue repair. These challenges highlight the need for more targeted therapeutic strategies. A promising therapeutic approach involves developing tissue-specific drug delivery systems, such as antibody-conjugated nanoparticles that target inflamed endothelium, thereby minimizing systemic effects (95).

Notably, certain immune cells, such as lymphocytes and monocytes, can migrate independently of protease activity by physically deforming to traverse ECM spaces without enzymatic degradation (96). This protease-independent mechanism suggests that some immune cells rely on mechanical properties and interactions with other cellular structures, such as the actin cytoskeleton, to facilitate their movement. This finding underscores the complexity of leukocyte migration and highlights the importance of considering both enzymatic and mechanical mechanisms in therapeutic design.

Overall, although proteases are crucial regulators of immune cell migration, their varying functions across different immune cell types and tissue contexts highlight the complexity of this process. Future research should prioritize developing highly specific protease inhibitors or alternative strategies that selectively target pathological migration while minimizing side effects. However, despite promising preclinical evidence, several clinical trials targeting MMPs have failed. For instance, Sparano et al. conducted a randomized phase III trial of marimastat versus placebo in metastatic breast cancer and found no improvement in overall survival or PFS, along with significantly higher rates of musculoskeletal toxicity (63% vs 22%) (97). Similarly, Bissett et al. reported that the MMP inhibitor prinomastat failed to improve outcomes in advanced non-small-cell lung cancer, and was associated with frequent joint-related adverse events, leading to premature trial termination (98). Although these trials primarily investigated cancer rather than inflammatory diseases, their outcomes reveal fundamental challenges in targeting proteases therapeutically.

In summary, proteases are indispensable yet complex regulators of immune cell migration. Their cell type–specific and context-dependent roles underscore both their therapeutic potential and the difficulties in developing selective inhibitors. A deeper understanding of protease regulation in inflammatory versus homeostatic settings remains a major research gap, and addressing this will be crucial for advancing clinical translation.

The dual role of immune cell migration in both protective immunity and pathological inflammation has made it a compelling therapeutic target (99, 100). Current therapeutic strategies target various stages of the migratory cascade, utilizing both small-molecule inhibitors and biologic agents (101, 102). Sphingosine-1-phosphate (S1P) receptor modulators exemplify this approach. By binding S1P₁ on lymphocytes, agents such as siponimod and ozanimod prevent lymph node egress, thereby reducing inflammatory infiltration into the CNS. Beyond immunomodulation, siponimod penetrates the blood-brain barrier and confers neuroprotective benefits, including remyelination and reduced gray matter atrophy. In phase III clinical trials, significant reductions in relapse rates and delayed disability progression have been demonstrated in multiple sclerosis (103–105).

Integrin inhibitors represent another clinically validated approach, with natalizumab serving as the prototype. This monoclonal antibody targets α4 integrins, blocking both VCAM-1 interactions in the CNS and MadCAM-1 binding in the gut. While effective in multiple sclerosis and Crohn’s disease, its association with progressive multifocal leukoencephalopathy highlights the risks of broad immune cell sequestration (106, 107). Vedolizumab, a selective α4β7 integrin inhibitor, has proven particularly effective in ulcerative colitis and Crohn’s disease. Phase III GEMINI I/II trials confirmed the therapeutic benefit of vedolizumab, leading to FDA approval for both UC and CD (108).

Emerging precision strategies aim to redirect beneficial immune subsets rather than broadly suppress immunity. Low-dose IL-2 selectively expands Tregs and has demonstrated clinical benefit in autoimmune conditions such as systemic lupus erythematosus (109). Engineered IL-2 muteins further improve specificity and pharmacokinetics, sustaining Treg expansion in preclinical models (110). In inflammatory bowel disease, low-dose IL-2 and cytokine-delivery nanoparticles have been shown to reduce colitis and restore mucosal tolerance (111). Nanoparticle-based approaches also enable chemokine modulation, such as CCL22 delivery promotes Treg recruitment and improves outcomes in experimental autoimmune encephalomyelitis (EAE) (112). Combination strategies targeting chemokine receptors have also been explored. For instance, CCR2-deficient mice are largely resistant to EAE, highlighting CCR2’s central role in monocyte recruitment to the CNS. Additionally, preclinical studies have investigated CCR1 and CCR2 blockade as therapeutic strategies to limit neuroinflammation in EAE and multiple sclerosis models (113). Collectively, these findings indicate that modulating immune cell trafficking provides therapeutic benefit while preserving immune surveillance. The field is moving toward precision strategies that separate pathological from protective migration.

Significant translational challenges remain, which can be divided into three principal barriers: compensatory migratory mechanisms that circumvent single-target strategies, the translational gap between preclinical findings and clinical application, and interspecies differences in receptor expression such as CCR5 and α4β7 (114, 115). Patients with elevated CCR5 expression, notably in HIV, multiple sclerosis, and IBD, may benefit from CCR5 antagonists such as maraviroc. In mice, oral maraviroc attenuated intestinal inflammation by reducing CCR5⁺ leukocyte recruitment, underscoring its therapeutic potential in IBD (116). Conversely, patients with predominant α4β7 integrin expression respond preferentially to vedolizumab. Accumulating evidence links α4β7⁺ lymphocyte abundance and transcriptional signatures of regulatory T cells to favorable treatment outcomes (117–119).

Bridging these receptor-specific insights into broadly effective therapies will require next-generation translational platforms, including humanized mouse models, functionally competent organoids, and organ-on-a-chip microfluidic systems (120–122). When combined with comprehensive multi-omics profiling, these technologies will enable systematic mapping of conserved migratory networks, strengthening target validation and supporting the rational design of precision immunotherapies. In addition to integrin antagonists and chemokine receptor inhibitors, S1P receptor modulators (e.g., fingolimod and siponimod) represent an important class of small-molecule therapies that restrict lymphocyte egress from lymph nodes, thereby limiting central nervous system infiltration in multiple sclerosis (105). Beyond blocking pathogenic cell entry, tolerance-inducing strategies are emerging, including low-dose IL-2, engineered IL-2 muteins, and CAR-Treg therapies can selectively expand Tregs, reduce inflammation, and provide long-term immune regulation (123–125).

In summary, therapies targeting immune cell migration have demonstrated clear efficacy in MS, IBD, and related inflammatory conditions. However, receptor redundancy, interspecies variability, and safety concerns underscore a key research gap: the urgent need for more selective, context-specific, and clinically translatable therapeutic platforms to fully realize the potential of migration-targeted immunotherapy.

Recent breakthroughs in advanced in vitro systems, including organ-on-a-chip technology, 3D bioprinted tissues, and microfluidic platforms, have greatly improved the ability to mimic physiological microenvironments (126–128). These models provide precise control of chemokine gradients, tissue architecture, and cellular interactions, enabling detailed studies of immune cell chemotaxis under physiologically relevant conditions. Huh et al. and Bhatia et al. demonstrated that organ-on-a-chip devices, which employ microengineered channels lined with living cells, can replicate key structural and functional features of human organs while incorporating dynamic elements such as blood flow and mechanical stress (129, 130). These systems are particularly valuable for investigating immune cell migration across vascular and epithelial barriers. Recent studies, including those by Mazzaglia et al. and Cherukuri et al., demonstrated that 3D bioprinting techniques allow the spatial arrangement of diverse cell populations within extracellular matrices to construct immune-competent tissues, faithfully mimicking specialized niches such as lymphoid structures (131, 132). These platforms are indispensable for dissecting mechanisms of leukocyte guidance and cross-talk in controlled environments. Collectively, these advanced technologies effectively bridge the gap between conventional 2D cultures and animal models, enhancing translational potential while minimizing animal testing. They have been applied to investigate neutrophil swarming, T cell tumor infiltration, and dendritic cell migration. The integration of immune-competent organoids, omics technologies, and machine learning will further improve the precision and predictive value of these in vitro systems, driving advances in immunotherapy development and personalized medicine. Recent advances in BBB-on-a-chip models have also enabled the evaluation of S1P₁ modulators such as siponimod in human-relevant settings (133), while immune-competent organ-on-a-chip platforms-designed to mimic lymphoid tissue microenvironments and cellular cross-talk-offer a promising foundation to investigate mechanisms of Treg recruitment, including chemokine-driven cues such as CCL22 (134).

In summary, advanced in vitro models provide powerful and transformative tools to interrogate immune cell chemotaxis with high precision and translational relevance. By bridging the gap between conventional 2D cultures and animal models, they accelerate the discovery of clinically actionable mechanisms. Nonetheless, achieving standardization, scalability, and clinical validation remains essential to fully integrate these platforms into next-generation drug development and precision immunotherapy.