Search Results (1,298)

Sepsis is a life-threatening condition caused by a dysregulated immune response to infection, characterized by an initial hyperinflammatory phase frequently followed by compensatory immunosuppression (CARS). Regulatory T cells (Tregs) play a critical, biphasic role: inadequate suppression during early hyperinflammation fails to control cytokine storms, while excessive/persistent activity in late-phase immunosuppression drives immune paralysis and secondary infection susceptibility. This review explores advances in targeting Treg immunoregulation across bacterial, viral, and fungal sepsis, where pathogenic type critically influenced the types of immunoresponses, shaping Treg heterogeneity in terms of phenotype, survival, and function. Understanding this multifaceted Treg biology offers novel therapeutic avenues, highlighting the need to decipher functional heterogeneity and develop precisely timed, pathogen-tailored immunomodulation to safely harness beneficial Treg roles while mitigating detrimental immunosuppression. Full article

Considering the high plasticity of FoxP3⁺ regulatory T (Treg) cells and Interleukin (IL)-17-producing Th17 cells, we hypothesized that a Th17 inflammatory milieu may impair the functional properties of Treg cells in chronic inflammatory arthritides. Therefore, a cross-sectional explorative analysis was set up in patients with psoriatic arthritis (PsoA), rheumatoid arthritis, or spondyloarthritis to investigate the features of Th17 and Treg cells. T cell subpopulation counts, FOXP3 mRNA expression, CpG methylation of the FOXP3 gene, and the suppressive capacity of isolated Treg cells were determined. Ex vivo analysis of PsoA-derived peripheral blood lymphocytes showed a Th17-mediated inflammation. It was accompanied by demethylation of the FOXP3 promotor and Treg-specific demethylated region (TSDR) in Treg cells which, however, resulted neither in elevated FOXP3 mRNA expression nor in increased suppressive Treg cell capacity. To clarify this conundrum, in vitro stimulation of isolated Treg cells with Th17-inducing cytokines (IL-1β, IL-6, IL-23, TGFβ), recombinant IL-17, or the anti-IL-17A antibody secukinumab was performed, demonstrating that cell culture conditions polarizing towards Th17, but not IL-17 itself, impair the suppressive function of Treg cells, accompanied by diminished FOXP3 mRNA expression due to hypermethylation of the FOXP3 promotor and TSDR. This potential causal relationship between Th17 inflammation and impaired Treg cell function requires attention regarding the development of immunomodulatory therapies. Full article

Disruption of the gut microenvironment is a hallmark of HIV infection, where regulatory T cells (Tregs) play a critical role in maintaining gut homeostasis. However, the mechanisms by which gut Tregs contribute to immune reconstitution failure in HIV-infected individuals remain poorly understood. In this study, we employed single-cell RNA sequencing (scRNA-seq) to analyze gut Treg populations across three cohorts: eight immunological responders (IRs), three immunological non-responders (INRs), and four HIV-negative controls (NCs). Our findings revealed that INRs exhibit an increased proportion of gut Tregs but with significant functional impairments, including reduced suppressive capacity and heightened apoptotic activity. Notably, these Tregs underwent metabolic reprogramming in INRs, marked by an upregulation of glycolysis-related genes and a downregulation of the oxidative phosphorylation (OXPHOS) pathway. Additionally, both the abundance of short-chain fatty acid (SCFA)-producing bacteria and SCFA concentrations were reduced in INRs. In vitro SCFA supplementation restored Treg function by enhancing suppressive capacity, reducing early apoptosis, and rebalancing cellular energy metabolism from glycolysis to OXPHOS. These findings provide a comprehensive characterization of gut Treg dysfunction in INRs and underscore the therapeutic potential of targeting gut Tregs through microbiota and metabolite supplementation to improve immune reconstitution in HIV-infected individuals. Full article

Background/Objectives: Restored CD4 absolute counts (CD4AC) and CD4/CD8 ratio in the setting of continuous antiretroviral treatment (ART) do not exclude a low-level immune activation associated with HIV reservoirs, microbial translocation, or the side effects of ART itself, which accelerates the aging of people living with HIV (PLHIV). To delineate biomarkers of incomplete immune restoration in PLHIV on successful ART, we evaluated T-lymphocyte mitochondrial parameters in relation to phenotypic markers of immune exhaustion and senescence. Methods: PLHIV with sustained viral suppression, CD4AC > 500 and CD4/CD8 ratio >0.9 on ART (n = 39) were compared to age-matched ART-naïve donors (n = 27) and HIV(–) healthy controls (HC, n = 35). CD4 and CD8 differentiation and effector subsets (CCR7/CD45RA and CD27/CD28), activation, exhaustion, and senescence markers (CD38, CD39 Treg, CD57, TIGIT, and PD-1) were determined by flow cytometry. Mitochondrial mass (MM) and membrane potential (MMP) of CD8 and CD4 T cells were evaluated with MitoTracker Green and Red flow cytometry dyes. Results: ART+PLHIV differed from HC by increased CD4 TEMRA (5.3 (2.1–8.8) vs. 3.2 (1.6–4.4), p < 0.05), persistent TIGIT+CD57–CD27+CD28– CD8+ subset (53.9 (45.5–68.9) vs. 40.1 (26.7–58.5), p < 0.05), and expanding preapoptotic TIGIT–CD57+CD8+ effectors (9.2 (4.3–21.8) vs. 3.0 (1.5–7.3), p < 0.01) in correlation with increased CD8+ MMP (2527 (1675–4080) vs.1477 (1280–1691), p < 0.01). These aberrations were independent of age, time to ART, or ART duration, and were combined with increasing CD4 T cell MMP and MM. Conclusions: In spite of recovered CD4AC and CD4/CD8 ratio, the increased CD8+ MMP, combined with elevated markers of exhaustion and senescence in ART+PLHIV, signals a malfunction of the CD8 effector pool that may compromise viral reservoir latency. Full article

Objective: The interactions between the central nervous system (CNS) and the immune system suggest that immune mechanisms may be effective in the pathogenesis of epilepsy and epileptic seizures. Although studies on the natural immune response and epilepsy are continuing, it is not yet clear whether the interaction of the current immune system is due to epilepsy itself or antiepileptic drugs (AEDs), since epileptic patients also use AEDs There are a limited number of studies that have reported an increased incidence of upper respiratory tract infections (URTIs) in patients during levetiracetam (LEV) treatment. Therefore, we aimed to report our experience regarding the effect of LEV monotherapy on the complete blood count (CBC), immunoglobulin (Ig) levels, and lymphocyte subgroups in the interictal period in children and adolescents with epilepsy. Methods: This study enrolled 31 children who presented with epilepsy and underwent LEV monotherapy for at least one year (patient group) and 43 healthy children (control group). The CBC parameters (hemoglobin (hb), lymphocytes, leukocytes, neutrophils, and platelets), Ig levels (IgA, IgM, IgG, and IgE), and lymphocyte subsets (CD3, CD4, CD8, CD4/CD8 ratio, CD19, CD56, NKT cells, and Treg cells) were measured and compared between the two groups. The patients were also investigated regarding the frequency and types of infections that they experienced in the first month and first year of the study, and these data were compared between the patient group and the control group. In addition, the same parameters and the frequency of infection were compared among the patient subgroups (focal and generalized seizures). Results: The results of the present study indicate that there were no significant differences in the CBC parameters, lymphocyte subsets, or Ig levels between the patient group and the control group. The comparison among the patient subgroups was similar; however, the CD4/CD8 ratio was lower in the patient subgroup with focal seizures. In addition, there were no significant differences in the frequency or type of infections experienced one month and one year of the study between the patient group and the control group, and likewise for the patient subgroups (focal and generalized seizures). Conclusions: The present study demonstrated that LEV monotherapy did not increase the incidence of infection, and there were no significant effects on the CBC or on the humoral or cellular immune system in epileptic children. These findings also suggest that the CD4/CD8 ratio among lymphocyte subgroups is lower in patients with focal seizures. However, the epilepsy subgroups had a relatively small sample size; therefore, further prospective studies involving a larger patient population are needed to establish the association between LEV monotherapy and lymphocyte subgroups in patients with epilepsy. Full article

Background: Regulatory T cells (Tregs) are the main suppressor cells that maintain immune tolerance and prevent autoimmunity. Changes in Treg number or function are implicated in a wide range of autoimmune and inflammatory (AI/I) diseases, with or without underlying inborn errors of immunity (IEI). Understanding the phenotypic profiles of Treg subsets and their associations with immune dysregulation is crucial to identifying potential robust and holistic biomarkers for disease activity. Methods: We examined peripheral blood mononuclear cells from 40 patients diagnosed with various autoimmune/inflammatory diseases, including those with genetically confirmed inborn errors of immunity (IEIs), and compared these samples to those from 38 healthy controls of the same age. Utilizing multiparametric flow cytometry, we measured multiple Treg sub-populations and investigated their correlations with lymphocyte subset profiles and the diversity of autoantibodies. We applied advanced statistical and machine learning techniques, such as t-SNE, k-means clustering, and ROC analysis, to analyze immunophenotypic patterns in the patients. Results: Among all Treg sub-populations, only CD4⁺CD127^lowCD25^highFOXP3⁺ Tregs showed a significant decrease in patients compared to healthy controls (p < 0.05), while other Treg phenotypes did not differ. FOXP3 expression showed reduced intensity in patients and demonstrated diagnostic potential (AUC = 0.754). Notably, this Treg subset negatively correlated with CD19⁺ B cell percentages and positively correlated with the diversity of circulating autoantibodies. Unsupervised clustering revealed three distinct immunophenotypic profiles, highlighting heterogeneity among patients and underlining FOXP3-centered immune dysregulation. Conclusions: Our results presented that patients have an impairment in the CD4⁺CD127^lowCD25^highFOXP3⁺ regulatory T cell subset, which is identified by significantly decreased frequency and decreased expression of FOXP3. Immunological heterogeneity among patients was further uncovered by unsupervised clustering, highlighting the critical role that FOXP3-centered regulatory failure plays in the pathophysiology of illness. The combined evaluation of these three immunological factors, centered around FOXP3, holds promise as an integrative tool for monitoring disease progression across various autoimmune and immunodeficient contexts. Full article

Background: Boiling histotripsy (BH) uses high-amplitude, short-pulse focused ultrasound to disrupt tissue mechanically. Oncolytic virotherapy using reovirus has shown modest clinical benefit in pancreatic cancer patients. Here, reovirus and BH were used to treat pancreatic tumours, and their effects on the immune transcriptome of these tumours were characterised. Methods: Orthotopic syngeneic murine pancreatic KPC tumours grown in immune-competent subjects, were allocated to control, reovirus, BH and combined BH and reovirus treatment groups. Acoustic cavitation was monitored using a passive broadband cavitation sensor. Treatment effects were assessed histologically with hematoxylin and eosin staining. Single-cell multi-omics combining whole-transcriptome analysis with the expression of surface-expressed immune proteins was used to assess the effects of treatments on tumoural leukocytes. Results: Acoustic cavitation was detected in all subjects exposed to BH, causing cellular disruption in tumours 6 h after treatment. Distinct cell clusters were identified in the pancreatic tumours 24 h post-treatment. These included neutrophils and cytotoxic T cells overexpressing genes associated with an N2-like and an exhaustion phenotype, respectively. Reovirus decreased macrophages, and BH decreased regulatory T cells compared to controls. The combined treatments increased neutrophils and the ratio of various immune cells to Treg. All treatments overexpressed genes associated with an innate immune response, while ultrasound treatments downregulated genes associated with the transporter associated with antigen processing (TAP) complex. Conclusions: Our results show that the combined BH and reovirus treatments maximise the overexpression of genes associated with the innate immune response compared to that seen with each individual treatment, and illustrate the anti-immune phenotype of key immune cells in the pancreatic tumour microenvironment. Full article

Background/Objectives: In gastric cancer, only a subset of patients benefit clinically from neoadjuvant chemoimmunotherapy, underscoring the need for robust biomarkers that can predict treatment responses and guide personalized immunotherapy. This study aimed to characterize the immune microenvironment of gastric tumors and identify predictive markers associated with therapeutic efficacy. Methods: We prospectively enrolled 16 patients with histologically confirmed, PD-L1–positive (CPS ≥ 1) gastric adenocarcinoma (T_2–4N_0–1M₀). All patients received eight cycles of FLOT chemotherapy combined with pembrolizumab. Treatment response was assessed by Mandard tumor regression grading. Spatial transcriptomic profiling (10x Genomics Visium) and multiplex immunofluorescence were used to evaluate tumor-infiltrating immune cell subsets and PD-1 expression at baseline and after treatment. Results: Transcriptomic analysis differentiated the immune landscapes of responders from non-responders. Responders exhibited elevated expression of IL1B, CXCL5, HMGB1, and IFNGR2, indicative of an inflamed tumor microenvironment and type I/II interferon signaling. In contrast, non-responders demonstrated upregulation of immunosuppressive genes such as LGALS3, IDO1, and CD55, along with enrichment in oxidative phosphorylation and antigen presentation pathways. Multiplex immunofluorescence confirmed a higher density of FoxP3⁺ regulatory T cells in non-responders (median 5.36% vs. 2.41%; p = 0.0032). Notably, PD-1⁺ CD8⁺ T cell and PD-1⁺ FoxP3⁺ Treg frequencies were significantly elevated in non-responders, suggesting that PD-1 expression within cytotoxic and regulatory compartments may contribute to immune evasion. No substantial differences were observed in PD-L1 CPS or PD-1⁺ B cells and PD-1⁺ macrophages. Conclusions: Our findings identify PD-1⁺ CD8⁺ T cells and PD-1⁺ FoxP3⁺ Tregs as potential biomarkers of resistance to neoadjuvant chemoimmunotherapy in gastric cancer. Transcriptional programs centered on IL1B/CXCL5 and LGALS3/IDO1 define distinct immune phenotypes that may guide future combination strategies targeting both effector and suppressive arms of the tumor immune response. Full article

Regulatory T cells (Tregs) have multiple roles in the tumor microenvironment (TME), which maintain a balance between autoimmunity and immunosuppression. This research aimed to investigate the interaction between cancer stemness and Regulatory T cells (Tregs) in the breast cancer tumor immune microenvironment. Breast cancer stemness was calculated using one-class logistic regression. Twelve main cell clusters were identified, and the subsequent three subsets of Regulatory T cells with different differentiation states were identified as being closely related to immune regulation and metabolic pathways. A prognostic risk model including MEA1, MTFP1, PASK, PSENEN, PSME2, RCC2, and SH2D2A was generated through the intersection between Regulatory T cell differentiation-related genes and stemness-related genes using LASSO and univariate Cox regression. The patient’s total survival times were predicted and validated with AUC of 0.96 and 0.831 in both training and validation sets, respectively; the immunotherapeutic predication efficacy of prognostic signature was confirmed in four ICI RNA-Seq cohorts. Seven drugs, including Ethinyl Estradiol, Epigallocatechin gallate, Cyclosporine, Gentamicin, Doxorubicin, Ivermectin, and Dronabinol for prognostic signature, were screened through molecular docking and found a synergistic effect among drugs with deep learning. Our prognostic signature potentially paves the way for overcoming immune resistance, and blocking the interaction between cancer stemness and Tregs may be a new approach in the treatment of breast cancer. Full article

Human leukocyte extract (HLE), a non-immunogenic dialyzable leukocyte preparation (<10 kDa), may serve as a safe adjuvant in immunotherapy. We investigated the effects of albendazole (ABZ), HLE, and their combination in Mesocestoides vogae infected mice, focusing on lymphoid cells in the peritoneal cavity, the site of larval proliferation and parasite-induced immunosuppression. Peritoneal lymphoid cells were analysed by flow cytometry and qPCR. Cells proliferative responses to ConA, LPS, and parasite excretory/secretory (E/S) antigens, cytokine production (ELISA), IgM and IgG isotypes in exudates and parasite antigen recognition (Western blot) were assessed. Efficacy was measured by larval burden and 14-3-3 gene expression in larvae. HLE combined with ABZ enhanced larval clearance and suppressed 14-3-3 gene expression in larvae. HLE and combination therapy increased CD3⁺ T cell frequencies, especially CD3^+high, reduced regulatory CD3+/IL-10 Tregs and expression of Foxp3⁺. All treatments diminished CD19⁺/IL-10⁺ Bregs, correlating with lower CD9 and Atf3 mRNA levels compared to infected mice. Transcription factors T-bet expression was strongly upregulated, while GATA3 was moderately elevated. IFN-γ production and T/B cell proliferation were restored after HLE and combination therapy, partially, even in the presence of E/S antigens. IgM and total IgG levels against parasite antigens declined, while Th1-associated IgG2a increased in ABZ+HLE and HLE-treated groups. Albendazole failed to reverse the immunosuppressive Treg-type immunity but was more effective in reducing Breg populations and their functions. HLE enhanced ABZ efficacy by restoring Th1 responsiveness, reducing Treg/Breg activity, and modulating antibody profiles. It represents a promising immunomodulatory adjuvant in the treatment of the infections associated with Th2/Treg-driven immunosuppression. Full article

Background/Objectives: CD318 (also known as CDCP1) is a transmembrane protein that is overexpressed in many cancers and contributes to tumor progression, invasion, and metastasis by activating SRC family kinases through phosphorylation. Emerging evidence also suggests that CD318 plays a role in modulating the tumor immune microenvironment, although its precise mechanism in tumor progression is still not well understood. Methods: To investigate this, we analyzed the expression and immune-related functions of CD318 using the publicly available data from The Cancer Genome Atlas (TCGA) across colorectal adenocarcinoma (COAD), cervical squamous cell carcinoma (CESC), lung adenocarcinoma (LUAD), and pancreatic adenocarcinoma (PAAD). Results: All four cancers exhibited a high level of CD318 expression. Notably, in CESC, LUAD, and PAAD, plasmin-mediated cleavage of CD318 leads to phosphorylation of SRC and protein kinase C delta (PKCδ), which activates HIF1α and/or p38 MAPK. These downstream effectors translocate to the nucleus and promote the transcriptional upregulation of TGFβ1, fostering an immunosuppressive tumor microenvironment through Treg cell recruitment. In contrast, this signaling cascade appears to be absent in COAD. Instead, our analysis indicate that intact CD318 in COAD interacts with the surface receptors CD96 and CD160, which are found on CD8⁺ T cells and NK cells. Conclusions: This interaction enhances cytotoxic immune responses in COAD by promoting CD8⁺ T cell and NK cell activity, offering a possible explanation for the favorable prognosis associated with high CD318 expression in COAD, compared to the poorer outcomes observed in CESC, LUAD, and PAAD. Full article

Background/Objectives: Organ transplantation is a life-saving intervention for patients with terminal organ failure, but long-term success is hindered by graft rejection and dependence on lifelong immunosuppressants. These drugs pose risks such as opportunistic infections and malignancies. Chimeric antigen receptor (CAR) technology, originally developed for cancer immunotherapy, has been adapted to regulatory T cells (Tregs) to enhance their antigen-specific immunosuppressive function. This systematic review evaluates the preclinical development of CAR-Tregs in promoting graft tolerance and suppressing graft-versus-host disease (GvHD). Methods: A systematic review following PROSPERO guidelines (CRD420251073207) was conducted across PubMed, Scopus, and Web of Science for studies published from 2015 to 2024. After screening 105 articles, 17 studies involving CAR-Tregs in preclinical or in vivo transplant or GvHD models were included. Results: CAR-Tregs exhibited superior graft-protective properties compared to unmodified or polyclonal Tregs. HLA-A2-specific CAR-Tregs consistently improved graft survival, reduced inflammatory cytokines, and suppressed immune cell infiltration across skin, heart, and pancreatic islet transplant models. The inclusion of CD28 as a co-stimulatory domain enhanced Treg function and FOXP3 expression. However, challenges such as Treg exhaustion, tonic signaling, and reduced in vivo persistence were noted. Some studies reported synergistic effects when CAR-Tregs were combined with immunosuppressants like rapamycin or tacrolimus. Conclusions: CAR-Tregs offer a promising strategy for inducing targeted immunosuppression in allogeneic transplantation. While preclinical findings are encouraging, further work is needed to optimize CAR design, ensure in vivo stability, and establish clinical-scale manufacturing before translation to human trials. Full article

Antibody-mediated rejection (ABMR) caused by donor-specific Abs (DSAs) is still the leading cause of late graft loss following clinical organ transplantation, and effective strategies to combat ABMR are still elusive. We previously showed that rIL-2 complexed with anti-IL-2 mAb clone JES6-1A12 (IL-2 cplx) leads to the selective expansion of regulatory T cells (Tregs) and the prolonged survival of MHC-mismatched skin allografts. Although the grafts were eventually rejected, mice failed to develop DSAs. Here, we investigated the impact of IL-2 cplx on the humoral response and germinal center (GC) reaction during allograft rejection. IL-2 cplx treatment prevents Bcl-6 upregulation, leading to suppressed development of GC T and B cells. The IL-2 cplx-induced impairment of GC development limits IgG allo-Ab production but allows for IgM synthesis. By employing a hapten–carrier system to investigate affinity maturation, we found that IL-2 cplx induces a distinct shift in specific Ab production favoring low-affinity IgM while simultaneously decreasing IgG responses. These findings illuminate the potential of IL-2 cplx therapy for inducing humoral tolerance, potentially paving the way for refining strategies aimed at preventing and treating ABMR. Full article

This study identifies the novel effects of soluble factors derived from murine erythroblasts on lymphoid cell phenotypes. These effects were observed following the treatment of splenic mononuclear cells with erythroblast-conditioned media received from both healthy mice and mice subjected to hematopoiesis-activating conditions (hypoxia, blood loss, and hemolytic anemia), suggesting a common mechanism of action. Using flow cytometry, we elucidated that erythroblast-derived soluble products modulate T cell differentiation by promoting Treg development and increasing PD-1 surface expression on B cells. The immunoregulatory potential of erythroblasts is subpopulation-dependent: CD45+ erythroblasts respond to hemolytic stress by upregulating the surface expression of immunosuppressive molecules PDL1 and Galectin-9, while CD45- erythroblasts primarily increase TGFb production. These findings highlight the regulatory role of erythroblasts in modulating immune responses. Full article

In our previous studies, methylated CpG oligodeoxynucleotides (ODN) derived from Bifidobacterium longum subsp. infantis have demonstrated immunomodulatory effects through the induction of regulatory T cells (Tregs). To define the structural determinants underlying this effect, we synthesized four CpG ODNs varying in methylation degree, CpG motif placement, and backbone length. These include (1) ODN-A (2m-V1), a 20-nucleotide CpG oligodeoxynucleotide incorporating two 5-methylcytosines at positions 4 and 12 within centrally placed CpG motifs; (2) ODN-B (um-V2), a 20-nucleotide CpG oligodeoxynucleotide with a backbone structure identical to ODN-A but unmethylated; (3) ODN-C (2m’-V3), a 20-nucleotide CpG oligodeoxynucleotide with a backbone structure identical to ODN-A, but with two 5-methylcytosines shifted to positions 7 and 15; (4) ODN-D (3m-V4), a 27-nucleotide CpG oligodeoxynucleotide with an extended backbone structure, this time with three 5-methylcytosines at positions 3, 11, and 19. Using a murine model of an OVA-induced allergy, we show that methylated ODN-A (2m-V1) and ODN-D (3m-V4) markedly reduce serum anti-OVA IgE, clinical symptoms, eosinophilic infiltration, and Th2/Th17 responses, while promoting splenic Treg expansion and IL-10 production. In contrast, unmethylated ODN-B (um-V2) and a positionally altered methylated ODN-C (2m’-V3) both failed to suppress allergic inflammation, and, in contrast, enhanced the Th2/Th17 response and induced robust in vitro Toll-like receptors TLR7/8/9 expression in native splenocytes. These findings suggest that both methylation and motif architecture critically influence the immunologic profile of CpG ODNs. Our results provide mechanistic insights into CpG ODN structure/function relationships and support the therapeutic potential of select methylated sequences for restoring immune tolerance in allergic diseases. Full article