Actin-binding proteins play a critical role in regulating the dynamic rearrangement of the actin cytoskeleton, which is essential for maintaining cellular homeostasis and facilitating various processes in eukaryotic cells. Cofilin-1 (Cfl1), an actin-binding protein, promotes the severing and depolymerization of actin filaments. To investigate the function of Cfl1 in mast cells, we generated Mcpt5-Cre-nf-Cfl1fl/fl knock-in mice, expressing a non-functional form of Cfl1 (nf-Cfl1) instead of wildtype Cfl1 under the control of the connective tissue mast cell (CTMC)-specific promoter mast cell protease 5 (Mcpt5). Expression of nf-Cfl1 resulted in the complete absence of CTMCs. Notably, normal numbers of basophils were observed, in contrast to other mast cell-deficient mice. Interestingly, an inducible knock-in of nf-Cfl1 in mature mast cells did not affect the survival of mature mast cells. The Mcpt5-Cre-nf-Cfl1fl/fl mice lacking CTMCs showed impaired induction of systemic anaphylaxis. However, they remained fully susceptible to 1-fluoro-2,4-dinitrobenzene-induced contact hypersensitivity and imiquimod-induced psoriasis-like dermatitis. In addition, clearance of vaccinia virus skin infection was unaltered. Thus, this study demonstrates that CTMCs are not essential in these inflammatory skin diseases. Deviating results in some other mast cell-deficient models suggest that the concomitant lack of basophils or residual CTMCs in these mouse models influence disease outcome. Taken together, the complete absence of CTMCs and the preserved presence of basophils in Mcpt5-Cre-nf-Cfl1fl/fl mice establishes this model as a valuable tool for studying the specific role of CTMCs in different diseases.

Bone marrow (BM) harbors a large repertoire of regulatory T (Treg) cells, which are essential in hematopoiesis and peripheral tolerance. Treg cell accumulation in BM has been viewed as a consequence of preferential immigration of thymus-derived Treg cells. Here we report a subset of antigen presenting cells, which expresses the autoimmune regulator (Aire). These BM Aire-expressing cells resemble a subset of CD138 + B220 − TACI + Blimp-1 + MHC-II + plasma cells ( p lasma c ell-like b one m arrow A ire expressing c ells, pc -BMACs) and express tissue-restricted self-antigens. pc -BMACs present self-antigens to naïve CD4 + T cells and can efficiently convert these into functionally competent CD25 + Foxp3 + bona fide peripheral Treg cells (pTregs) capable of exerting immune suppression in vitro and in vivo . Aire expression may contribute to the tolerogenic function of pc -BMACs as it regulates the expression of genes involved in pTreg induction and function, including Icosl and retinoic acid synthesis-related genes. Our data demonstrate an Aire-expressing APC subset in the BM capable to promote peripheral tolerance by ectopically expressing tissue-restricted self-antigens and generating pTregs.

Chimeric antigen receptor (CAR)-T cell therapy has achieved remarkable clinical success in B cell malignancies. However, its efficacy in solid tumors remains limited, in part due to suboptimal expansion, persistence, and restrained effector function. Strategies that promote durable CAR-T cell fitness are therefore required to overcome these barriers. In this study, we generated HER2-CAR-T cells targeting human breast cancer cells and evaluated the impact of different cytokine supplementation strategies on CAR-T cell phenotype and function. We analyzed gene expression patterns and performed repetitive tumor killing assays to assess the ability of CAR-T cells expanded with IL-2 + IL-7 + IL-15 compared with IL-2 alone to maintain proliferation and cytotoxic function across multiple rounds of tumor cell exposure. Compared with IL-2 alone, supplementation with IL-7 and IL-15 significantly enhanced CAR-T cell expansion, preserved stem cell-like features prior to antigen encounter, and promoted superior proliferative capacity. Moreover, CAR-T cells cultured with IL-7+15 or IL-2+7+15 maintained sustained cytotoxicity and exhibited increased antitumor cytokine production during repeated tumor challenges. Notably, IL-7 and IL-15 supplementation induced a CD57+ CAR-T cell population that, unlike the immunosenescent CD57+ cells reported previously, retained full proliferative and cytotoxic capacity, with CD57 expression being dynamically downregulated upon antigen stimulation. Collectively, these findings demonstrate that incorporation of IL-7 and IL-15 into CAR-T cell manufacturing protocols substantially improves expansion, persistence, and effector function, supporting their use as a strategy to enhance CAR-T cell performance against solid tumors.

[This corrects the article DOI: 10.3389/fimmu.2025.1655212.].

The immune system is central to the prevention and control of cancer, yet tumors evolve multiple strategies to subvert immune surveillance. Checkpoint inhibitors targeting CTLA-4, PD-1, and PD-L1 have revolutionized oncology by demonstrating that therapeutic restoration of T cell activity can yield durable remissions. However, their efficacy remains limited by the profoundly immunosuppressive tumor microenvironment (TME), where regulatory immune cells, suppressive cytokines, and metabolic stressors converge to dampen effector function. As interest in integrative and complementary approaches grows, plant-derived compounds - long used in traditional medicine - have been identified as bioactive agents capable of modulating immune function. This review focuses on three key phytochemicals: piperlongumine, berberine, and epigallocatechin gallate (EGCG). Piperlongumine, a pro-oxidative alkaloid from Piper longum, suppresses T cell activation and promotes regulatory T cell differentiation, suggesting potential for chronic inflammation but raising caution in oncology. Berberine, an isoquinoline alkaloid from Berberis vulgaris, reduces PD-L1 expression via CSN5 inhibition, thereby mimicking checkpoint blockade and enhancing cytotoxic T cell activity in preclinical models. EGCG, the major polyphenol in green tea, downregulates PD-L1 expression and augments anti-tumor immunity in murine melanoma. We critically assess the promise and pitfalls of these compounds in cancer immunotherapy, emphasizing mechanistic insights, pharmacokinetics, translational hurdles, and potential risks of interfering with established therapies. A precision immunology framework - integrating immune monitoring, patient stratification, and controlled clinical trials - will be essential to determine whether phytochemicals can be safely and effectively incorporated into oncology. Far from being benign, plant-derived agents exert potent immune effects that could either complement or compromise modern immunotherapy, underscoring the need for rigorous evaluation.

Arnica montana L. (Arnica) has a long history of use in treating inflammation and soft tissue injury, yet its immunomodulatory mechanisms remain largely unexplored. In this study, we investigated the effects of distinct Arnica extracts - derived from different plant parts (root or whole plant) and manufacturing processes - on primary human T cells. We also compared their effects with those of the pure compounds helenalin and thymol. All extracts inhibited T cell activation and proliferation. This could be traced back to reduced IL-2 responsiveness due to decreased CD25 (IL–2Rα chain) expression, accompanied by reduced IL-2 production. Transcriptomic analysis (nCounter) and gene set enrichment revealed that the extracts target key T cell receptor (TCR) signaling pathways. Mechanistically, the hydroethanolic root extract selectively inhibited NFκB DNA binding, while the aqueous fermented extract predominantly suppressed NFAT-dependent gene expression. The hydroethanolic whole plant extract exerted a moderate effect on both pathways. These findings identify Arnica extracts as promising modulators of human TCR signaling and support their potential in regulating T cell-driven inflammatory responses, with implications for muscle healing and chronic inflammatory diseases.

IntroductionThe use of Complementary and Integrative Medicine (CIM) is very popular among the general population in Germany. However, international studies show that nurses, physicians, and other health care professionals (HCPs) at hospitals often do not feel sufficiently informed about different CIM approaches. Moreover, they do not feel trained enough to counsel their patients appropriately. In the German-speaking context, particularly within university hospitals, research on this subject is scarce. Therefore, the aim of this explorative study was to evaluate attitudes, subjective knowledge, and needs regarding CIM among HCPs with direct patient interaction across all four university hospitals in the federal state of Baden-Württemberg, Germany (Tübingen, Ulm, Freiburg, Heidelberg).MethodsThe multicenter, cross-sectional, anonymous full survey was conducted online using a self-developed, semi-structured, web-based questionnaire. Recruitment took place via all-inclusive e-mail distribution lists of all four university hospitals.ResultsA total of n = 2,026 participants (response rate varied by location from about 5 to 14%) fully answered the questionnaire. Nurses constituted the largest professional group (n = 1,196; 59%), followed by physicians (n = 567; 28%), physiotherapists (n = 54), psychologists (n = 48), midwives (n = 37), and other professions (n = 124). More than two-thirds (71%, n = 1,437) of the participants were female and 14% (n = 286) reported additional training in CIM. The overall attitude toward CIM (10-point Likert scale, 10 = “very favorable”) was clearly positive (M ± SD: 7.43 ± 2.33), with notable differences between professional groups: midwives (9.05 ± 1.18), physiotherapists (8.44 ± 1.74), and nurses (8.08 ± 1.95) expressed the highest support, whereas physicians (5.80 ± 2.39) the lowest. 42% of the participants incorporated CIM in patient care (from 33% of physicians to 86% of midwives). Overall, relaxation therapy (n = 1,951; 96%), external applications (n = 1,911; 94%), massage (n = 1,836; 91%), and meditation/mindfulness (n = 1,812; 89%) were rated as useful or rather useful for patients. The average self-assessed knowledge level about CIM was moderate (M ± SD: 5.83 ± 2.03). Most of the participants found CIM training at university hospitals important and saw research about CIM as one of the tasks of university hospitals. The participants expressed the highest interest in education for acupuncture/acupressure, relaxation therapies, and manual medicine.DiscussionThis comprehensive survey of health care professionals (HCPs) at university hospitals in Germany reveals a clearly positive disposition toward CIM, aligning with findings from other hospital-based surveys and highlighting differences among professional groups. While most therapies deemed beneficial for patient care are supported by positive evidence, further research is required for others. Given the average self-reported knowledge of CIM, targeted education is essential to meet the needs of both HCPs and patients and to ensure the provision of evidence-based information on the risks and benefits of CIM.

IntroductionChronic inflammation is a hallmark of chronic wounds and inflammatory skin diseases. Due to a hyperactive and prolonged inflammation triggered by proinflammatory immune cells, transitioning to the repair and healing phase is halted. T cells may exacerbate the proinflammatory milieu by secreting proinflammatory cytokines. Chamomilla recutita L. (chamomile) has been suggested for use in several inflammatory diseases, implying a capability to modulate T cells. Here, we have characterized and compared the effects of differently prepared chamomile extracts and characteristic pure compounds on the T cell redox milieu as well as on the migration, activation, proliferation, and cytokine production of primary human T cells.MethodsPhytochemical analysis of the extracts was carried out by LC-MS/MS. Primary human T cells from peripheral blood (PBTs) were pretreated with aqueous or hydroethanolic chamomile extracts or pure compounds. Subsequently, the effects on intracellular ROS levels, SDF-1α induced T cell migration, T cell activation, proliferation, and cytokine production after TCR/CD3 and CD28 costimulation were determined. Gene expression profiling was performed using nCounter analysis, followed by ingenuity pathway analysis, and validation at protein levels.ResultsThe tested chamomile extracts and pure compounds differentially affected intracellular ROS levels, migration, and activation of T cells. Three out of five differently prepared extracts and two out of three pure compounds diminished T cell proliferation. In line with these findings, LC-MS/MS analysis revealed high heterogeneity of phytochemicals among the different extracts. nCounter based gene expression profiling identified several genes related to T cell functions associated with activation and differentiation to be downregulated. Most prominently, apigenin significantly reduced granzyme B induction and cytotoxic T cell activity.ConclusionOur results demonstrate an anti-inflammatory effect of chamomile- derived products on primary human T cells. These findings provide molecular explanations for the observed anti-inflammatory action of chamomile and imply a broader use of chamomile extracts in T cell driven chronic inflammatory diseases such as chronic wounds and inflammatory skin diseases. Importantly, the mode of extract preparation needs to be considered as the resulting different phytochemicals can result in differential effects on T cells.

AbstractPolymorphonuclear neutrophils (PMNs) can differentiate into distinct states, which can either exacerbate or resolve inflammation. Our study shows that mice challenged with TLR agonists exhibited PMN differentiation along two major paths characterized by the expression of CCR5 or PD-L1. Similar differentiation was observed in the blood of severe COVID-19 patients and the synovial fluid of osteoarthritis patients. Prolongedin vitropriming of human PMNs modeled the differentiation paths. Actin disassembly favored CCR5 upregulation, while NF-kB activation stabilized the actin cytoskeleton and suppressed the development of CCR5+PMNs. Additionally, PD-L1 upregulation was triggered by STAT3 signaling and NF-kB activation. Functionally, CCR5 expressing PMNs were pro-NETotic, while PD-L1+PMNs showed immunosuppressive functions by inhibiting T cell proliferation via PD1. Together, PMN differentiation depended on the priming conditions, and the balance between actin disassembly and NF-kB/STAT3 activation translated the present micro-milieu into phenotypic and functional diversification of PMNs.SynopsisNeutrophils underwent phenotypical and functional diversification bothin vivoandin vitro. Actin disassembly led to the generation of CCR5highneutrophils with increased spontaneous NETosis, whereas NF-kB and STAT3 induced PD-L1 expression with T-cell suppressive properties as a deviation from the default pathway.PMN of mice challenged with TLR agonists develop two distinct phenotypes, CCR5highand PD-L1high.CCR5 and PD-L1-defined neutrophil phenotypes were found in blood of patients with severe COVID-19 and in the synovial fluid of osteoarthritis patients.In vitropriming induced a similar bifurcation of PMN phenotypes marked by either CCR5 or PD-L1.Actin disassembly preceded canonical development of CCR5+PMN.NF-kB halted actin disassembly by LPL regulation.During neutrophil priming, STAT3 aided NF-kB in the expression of PD-L1.Graphical abstract

Cytokines released during chronic inflammatory diseases induce pro-inflammatory properties in polymorphonuclear neutrophils (PMN). Here we show that in vitro cytokine treatment leads to the development of a subgroup of human PMN expressing CCR5, termed CCR5 + cytokine-induced PMN (CCR5 + cPMN). Auto/paracrine TNF signaling increases intracellular neutrophil elastase (ELANE) abundance and induces NETosis in CCR5 + cPMN. Triggering of CCR5 amplifies NETosis. Membranous TNF (mTNF) outside-in signaling induces the formation of reactive oxygen species, a known activator of NETosis. In vivo , we find an increased number of CCR5 + cPMN in the peripheral blood and inflamed lamina propria of patients with ulcerative colitis (UC) but not Crohn’s disease (CD). Notably, failure of anti-TNF therapy is associated with higher frequencies of CCR5 + cPMN. In conclusion, we identify a phenotype of pro-NETotic, CCR5 positive PMN present in inflamed tissue in vivo and inducible in vitro . These cells may reflect an important component of tissue damage during chronic inflammation and could be of diagnostic value.

Background Complementary medicine (CM) is frequently used by patients, but little is known about the usage of CM in surgical patients. The study aimed to elucidate the relevance of CM in surgery. Methods This cross-sectional, multi-center survey utilized a paper-based questionnaire consisting of 21 questions to capture CM usage and interest as well as CM communication in visceral and thoracic surgical patients being hospitalized at the corresponding departments of surgery at the University Medical Centers in Freiburg, Heidelberg und Ulm, Germany. Results Overall, 151 patients consented to the survey. On average, current CM usage was stated by 44% of patients. Most frequently used CM approaches were physical exercise (63%), nutritional supplements (59%) and herbal medicine (56%). Strong interest in CM counselling was stated by 51% of patients. Almost 80% of patients wanted to be treated in a holistic manner and desired for reliable information about CM as well as CM informed physicians. Only 12% of patients communicated CM usage and interest with their attending physician. Review of literature revealed similar results showing an overall CM usage of 43%, preferring nutritional supplements and herbal medicine. Conclusion The results of our cross-sectional study indicate a high percentage of CM users and a strong interest in CM among surgical patients. Indeed, the current communication about CM between patients and surgeons is poor. With respect to safety and quality reasons, but also to pay attention to patients’ demands, physicians should be aware of patients’ CM usage in surgery. Trial registration German Clinical Trial register (DRKS00015445).

Use of chimeric antigen receptor (CAR) T cells to treat B cell lymphoma and leukemia has been remarkably successful. Unfortunately, the therapeutic efficacy of CAR T cells against solid tumors is very limited, with immunosuppression by the pro-oxidative tumor microenvironment (TME) a major contributing factor. High levels of reactive oxygen species are well-tolerated by tumor cells due to their elevated expression of antioxidant proteins; however, this is not the case for T cells, which consequently become hypo-responsive. The aim of this study was to improve CAR T cell efficacy in solid tumors by empowering the antioxidant capacity of CAR T cells against the pro-oxidative TME. To this end, HER2-specific human CAR T cells stably expressing two antioxidant systems: thioredoxin-1 (TRX1), and glutaredoxin-1 (GRX1) were generated and characterized. Thereafter, antitumor functions of CAR T cells were evaluated under control or pro-oxidative conditions. To provide insights into the role of antioxidant systems, gene expression profiles as well as global protein oxidation were analyzed. Our results highlight that TRX1 is pivotal for T cell redox homeostasis. TRX1 expression allows CAR T cells to retain their cytolytic immune synapse formation, cytokine release, proliferation, and tumor cell-killing properties under pro-oxidative conditions. Evaluation of differentially expressed genes and the first comprehensive redoxosome analysis of T cells by mass spectrometry further clarified the underlying mechanisms. Taken together, enhancement of the key antioxidant TRX1 in human T cells opens possibilities to increase the efficacy of CAR T cell treatment against solid tumors.

In psoriasis and other inflammatory skin diseases, keratinocytes (KCs) secrete chemokines that attract T cells, which, in turn, cause epidermal hyperplasia by secreting proinflammatory cytokines. To date, it remains unclear whether skin-homing T cells, particularly memory T cells, can also be activated by direct cell contact with KCs. In this study, we demonstrated the ability of primary human KCs to activate human memory T cells directly by transmitting costimulatory signals through the CD6/CD166/CD318 axis. Interestingly, despite being negative for CD80/CD86, KCs initiate a metabolic shift within T cells. Blockade of the CD6/CD166/CD318 axis prevents mammalian target of rapamycin activation and T cell proliferation but promotes oxidative stress and aerobic glycolysis. In addition, it diminishes formation of central memory T cells. Importantly, although KC-mediated costimulation by CD2/CD58 also activates T cells, it cannot compensate for the lack of CD6 costimulation. Therefore, KCs likely differentially regulate T cell functions in the skin through two distinct costimulatory receptors: CD6 and CD2. This may at least in part explain the divergent effects observed when treating inflammatory skin diseases with antibodies to CD6 versus CD2. Moreover, our findings may provide a molecular basis for selective interference with either CD6/CD166/CD318, or CD2/CD58, or both to specifically treat different types of inflammatory skin diseases.

The integrin LFA-1 is crucial for T-cell/ APC interactions and sensitive recognition of antigens. Precise nanoscale organization and valency regulation of LFA-1 are mandatory for an appropriate function of the immune system. While the inside-out signals regulating the LFA-1 affinity are well described, the molecular mechanisms controlling LFA-1 avidity are still not fully understood. Here, we show that activation of the actin-bundling protein l-plastin (LPL) through phosphorylation at serine-5 enables the formation of clusters containing LFA-1 in high-affinity conformation. Phosphorylation of LPL is induced by an nPKC–MEK–p90RSK pathway and counter-regulated by the serine–threonine phosphatase PP2A. Interestingly, recruitment of LFA-1 into the T-cell/APC contact zone is not affected by LPL phosphorylation. Instead, for this process, activation of the actin-remodeling protein cofilin through dephosphorylation is essential. Together, this study reveals a dichotomic spatial regulation of LFA-1 clustering and microscale movement in T-cells by two different actin-binding proteins, LPL and cofilin.