Retrospective Analyses of PD-L1, LAG-3, TIM-3, OX40L Expressions and MSI Status in Gastroenteropancreatic Neuroendocrine Neoplasms.

We investigated expressions of PD-L1, LAG-3, TIM-3, and OX40L as immune checkpoint proteins, and MSI (repetitive short-DNA-sequences due to defective DNA-repair system) status were analyzed with immunohistochemistry from tissue blocks. Of 83 patients, PD-L1 expression was observed in 18.1% (n = 15) of the patients. None of the patients exhibited LAG-3 expression. TIM-3 expression was 4.9% (n = 4), OX40L was 22.9% (n = 19), and 8.4% (n = 7) of the patients had MSI tumor. A low-to-intermediate positive correlation was observed between PD-L1 and TIM-3 expressions (rho: 0.333, p < 0.01). Although PD-L1 expression was higher in grade 3 NET/NEC, MSI status was prominent in grade 1/2 NET.

Comparative evaluation of antitumor effects of TNF superfamily costimulatory ligands delivered by mesenchymal stem cells.

Stimulation of costimulatory receptors serves as an alternative immunotherapeutic strategy other than checkpoint inhibition. However, systemic administration of the agonistic antibodies is associated with severe toxicities, which is one of the major obstacles for their clinical application. This study aimed to develop a mesenchymal stem cell (MSC)-based system for tumor-targeted delivery of TNF superfamily ligands and assess their potential in enhancing antitumor immunity. Here we established an MSC-based system for tumor-targeted delivery of TNF superfamily ligands, including TNFSF4, 9 and 18. The TNFSF receptors (TNFRSFs) were evaluated in mouse models and patient samples for lung and colorectal cancers. TNFRSFs were all expressed at various levels on tumor-infiltrated lymphocytes, with TNFRSF18 being the most prevalent receptor. Human umbilical cord-derived MSCs expressing these costimulatory ligands (MSC-TNFSFs) effectively activated lymphocytes in vitro and elicited antitumor immunity in mice. TNFSF4 showed the least antitumor efficacy in both LLC1 and CT26 tumor models. MSC-TNFSF9 showed the most potent tumor-inhibiting effect in the LLC1 tumor model, while MSCs expressing TNFSF18 in combination with CXCL9 most significantly repressed CT26 tumor growth. Overall, TNFSF9 and TNFSF18 exhibited stronger lymphocyte-stimulating and antitumor activities than TNFSF4. Our study provides evidence that antitumor effects of agonism of different costimulatory receptors may vary in different tumor types and presents a promising approach for targeted delivery of TNF superfamily costimulatory ligands to avoid the systemic toxicities and side effects associated with immune agonist antibodies.

Amygdalin Improves Allergic Asthma via the Thymic Stromal Lymphopoietin-dendritic Cell-OX40 Ligand Axis in a Mouse Model.

Asthma, characterized by persistent inflammation and increased sensitivity of the airway, is the most common chronic condition among children. Novel, safe, and reliable treatment strategies are the focus of current research on pediatric asthma. Amygdalin, mainly present in bitter almonds, has anti-inflammatory and immunoregulatory potential, but its effect on asthma remains uninvestigated. Here, the impact of amygdalin on the thymic stromal lymphopoietin (TSLP)-dendritic cell (DC)-OX40L axis was investigated. A BALB/c mouse model for allergic asthma was established using the ovalbumin-sensitization method. Amygdalin treatment was administered between days 21 and 27 of the protocol. Cell numbers and hematoxylin and eosin (H&E) staining in bronchoalveolar lavage fluid (BALF) were used to observe the impact of amygdalin on airway inflammation. TSLP, IL-4, IL-5, IL-13, and IFN-γ concentrations were determined via Enzyme-linked immunosorbent assay (ELISA). TSLP, GATA-3, and T-bet proteins were measured using western blotting. Cell-surface receptor expression on DCs (MHC II, CD80, and CD86) was assessed via flow cytometry. OX40L mRNA and protein levels were detected using western blotting and qRT-PCR, respectively. Amygdalin treatment attenuated airway inflammation decreased BALF TSLP levels, inhibited DC maturation, restrained TSLP-induced DC surface marker expression (MHCII, CD80, and CD86), and further decreased OX40L levels in activated DCs. This occurred together with decreased Th2 cytokine levels (IL-4, IL-5, and IL-13) and GATA3 expression, whereas Th1 cytokine (IFN-γ) levels and T-bet expression increased. Amygdalin thus regulates the Th1/Th2 balance through the TSLP-DC-OX40L axis to participate in inflammation development in the airways, providing a basis for potential allergic asthma treatments.

Oncolytic Newcastle disease virus expressing the co-stimulator OX40L as immunopotentiator for colorectal cancer therapy.

NDV as an attractive candidate for oncolytic immunotherapy selectively lyses tumor cells but shows limited anti-tumor immunity. Immune co-stimulator OX40 ligand (OX40L) boosts anti-tumor immunity response by delivering a potent costimulatory signal to CD4+ and CD8+ T cells. To improve the anti-tumor immunity of NDV, the recombinant NDV expressing the murine OX40L (rNDV-mOX40L) was engineered. The viral growth kinetics was examined in CT26 cell lines. The ability of rNDV-mOX40L to express mOX40L was detected in the infected tumor cells and tumor tissues. The anti-tumor activity of rNDV-mOX40L was studied in the CT26 animal model. Tumor-specific CD4+, CD8+ and OX40+ T cells were examined by immunohistochemistry staining. The virus growth curve showed that the insertion of the mOX40L gene did not affect the growth kinetics of NDV. rNDV-mOX40L expresses mOX40L and effectively inhibits the growth of CT26 colorectal cancer in vivo. The tumor inhibition rate of the rNDV-mOX40L-treated group was increased by 15.8% compared to that of  NDV-treated group in the CT26 model. Furthermore, immunohistochemistry staining of tumor tissues removed from the CT26 model revealed that intense infiltration of tumor-specific CD4+, CD8+ T cells, especially OX40+ T cells were found in the rNDV-mOX40L-treated group. FACS showed that rNDV-mOX40L significantly enhanced the number of CD4+ and CD8+ T cells in spleen. Moreover, compared to the NDV-treated group, the level of mouse IFN-γ protein in the tumor site increased significantly in the rNDV-mOX40L-treated group. Taken together, rNDV-mOX40L exhibited superior anti-tumor immunity by stimulating tumor-specific T cells and may be a promising agent for cancer immunotherapy.

In Situ Reprogramming of Tumors for Activating the OX40/OX40 Ligand Checkpoint Pathway and Boosting Antitumor Immunity.

OX40 (CD134, TNFRSF4) is a member of the tumor necrosis factor receptor superfamily that can be activated by its cognate ligand OX40L (CD252, TNFSF4) and functions as a pair of T cell costimulatory molecules. The interaction between OX40 and OX40L (OX40/OX40L) plays a critical role in regulating antitumor immunity, including promoting effector T cells expansion and survival, blocking natural regulatory T cells (Treg) activity, and antagonizing inducible Treg generation. However, current OX40 agonists including anti-OX40 monoclonal antibodies (aOX40) have serious side effects after systemic administration, which limits their clinical success and application. Herein, we propose a strategy to reprogram tumor cells into OX40L-expressing "artificial" antigen-presenting cells (APCs) by OX40L plasmid-loaded nanoparticles for boosting antitumor immunity in situ. A novel gene transfection carrier was prepared by a modular hierarchical assembly method, which could efficiently transfect various tumor cells and express OX40L proteins on their surface. These surface-decorated OX40L proteins were proved to stimulate T cell proliferation in vitro while stimulating strong antitumor immune responses in vivo. Importantly, this in situ reprogramming strategy did not induce any toxicity as observed in aOX40 treatment, thus providing a novel method for immune checkpoint stimulator application.

Potential biomarkers for predicting the overall survival outcome of kidney renal papillary cell carcinoma: an analysis of ferroptosis-related LNCRNAs.

BACKGROUND: Kidney renal papillary cell carcinoma (KIRP) is a dangerous cancer, which accounts for 15-20% of all kidney malignancies. Ferroptosis is a rare kind of cell death that overcomes medication resistance. Ferroptosis-related long non-coding RNAs (LNCRNAs) in KIRP, remain unknown. METHOD: We wanted to express how ferroptosis-related LNCRNAs interact with immune cell infiltration in KIRP. Gene set enrichment analysis in the GO and KEGG databases were used to explore gene expression enrichment. The prognostic model was constructed using Lasso regression. In addition, we also analyzed the modifications in the tumor microenvironment (TME) and immunological association. RESULT: The expression of LNCRNA was closely connected to the ferroptosis, according to co-expression analyses. CASC19, AC090197.1, AC099850.3, AL033397.2, LINC00462, and B3GALT1-AS1 were found to be significantly increased in the high-risk group, indicating that all of these markers implicates the malignancy processes for KIRP patients and may be cancer-promoting variables. LNCTAM34A and AC024022.1 were shown to be significantly elevated in the low-risk group; these might represent as the KIRP tumor suppressor genes. According to the TCGA, CCR, and inflammation-promoting genes were considered to be significantly different between the low-risk and high-risk groups. The expression of CD160, TNFSF4, CD80, BTLA, and TNFRSF9 was different in the two risk groups. CONCLUSION: LNCRNAs associated with ferroptosis were linked to the occurrence and progression of KIRP. Ferroptosis-related LNCRNAs and immune cell infiltration in the TME may be potential biomarkers in KIRP that should be further investigated.

Expression of the immune checkpoint modulator OX40 indicates poor survival in acute myeloid leukemia.

Despite therapeutic advances, mortality of Acute Myeloid Leukemia (AML) is still high. Currently, the determination of prognosis which guides treatment decisions mainly relies on genetic markers. Besides molecular mechanisms, the ability of malignant cells to evade immune surveillance influences the disease outcome and, among others, the expression of checkpoints modulators contributes to this. In AML, functional expression of the checkpoint molecule OX40 was reported, but the prognostic relevance of OX40 and its ligand OX40L axis has so far not been investigated. Here we described expression and prognostic relevance of the checkpoint modulators OX40 and OX40L, analyzed on primary AML cells obtained from 92 therapy naïve patients. Substantial expression of OX40 and OX40L on AML blasts was detected in 29% and 32% of the investigated subjects, respectively, without correlation between the expression of the receptor and its ligand. Whereas OX40L expression was not associated with different survival, patients with high expression levels of the receptor (OX40high) on AML blasts survived significantly shorter than OX40low patients (p = 0.009, HR 0.46, 95% CI 0.24-0.86), which identifies OX40 as novel prognostic marker and a potential therapeutic target in AML patients.

ZBTB46 defines and regulates ILC3s that protect the intestine.

RORγt is a lineage-specifying transcription factor that is expressed by immune cells that are enriched in the gastrointestinal tract and promote immunity, inflammation and tissue homeostasis1-15. However, fundamental questions remain with regard to the cellular heterogeneity among these cell types, the mechanisms that control protective versus inflammatory properties and their functional redundancy. Here we define all RORγt+ immune cells in the intestine at single-cell resolution and identify a subset of group 3 innate lymphoid cells (ILC3s) that expresses ZBTB46, a transcription factor specifying conventional dendritic cells16-20. ZBTB46 is robustly expressed by CCR6+ lymphoid-tissue-inducer-like ILC3s that are developmentally and phenotypically distinct from conventional dendritic cells, and its expression is imprinted by RORγt, fine-tuned by microbiota-derived signals and increased by pro-inflammatory cytokines. ZBTB46 restrains the inflammatory properties of ILC3s, including the OX40L-dependent expansion of T helper 17 cells and the exacerbated intestinal inflammation that occurs after enteric infection. Finally, ZBTB46+ ILC3s are a major source of IL-22, and selective depletion of this population renders mice susceptible to enteric infection and associated intestinal inflammation. These results show that ZBTB46 is a transcription factor that is shared between conventional dendritic cells and ILC3s, and identify a cell-intrinsic function for ZBTB46 in restraining the pro-inflammatory properties of ILC3s and a non-redundant role for ZBTB46+ ILC3s in orchestrating intestinal health.

Interaction between BEND5 and RBPJ suppresses breast cancer growth and metastasis via inhibiting Notch signaling.

High frequent metastasis is the major cause of breast cancer (BC) mortality among women. However, the molecular mechanisms underlying BC metastasis remain largely unknown. Here, we identified six hub BC metastasis driver genes (BEND5, HSD11B1, NEDD9, SAA2, SH2D2A and TNFSF4) through bioinformatics analysis, among which BEND5 is the most significant gene. Low BEND5 expression predicted advanced stage and shorter overall survival in BC patients. Functional experiments showed that BEND5 could suppress BC growth and metastasis in vitro and in vivo. Mechanistically, BEND5 inhibits Notch signaling via directly interacting with transcription factor RBPJ/CSL. BEN domain of BEND5 interacts with the N-terminal domain (NTD) domain of RBPJ, thus preventing mastermind like transcriptional coactivator (MAML) from forming a transcription activation complex with RBPJ. Our study provides a novel insight into regulatory mechanisms underlying Notch signaling and suggests that BEND5 may become a promising target for BC therapy.

Clinical Significance of OX40 and OX40 Ligand in the Peripheral Blood of Patients with Myasthenia Gravis.

Background: A previous study on thymomas in myasthenia gravis (MG) patients indicated that OX40 expression may be upregulated in thymic tissues adjacent to germinal centers (GCs) and thymomas, and OX40 may interact with OX40L in GCs to enhance anti-acetylcholine receptor antibody production. However, little is known about the clinical significance of the expression of OX40 and OX40L in the peripheral blood of patients with MG. We aimed to characterize the expression of membrane-bound and soluble OX40 and OX40L in the peripheral blood of patients with MG and to identify their clinical significance. Methods: For membrane molecules, we collected peripheral blood (PB) from 39 MG patients at baseline, 22 patients in relapse, and 42 patients in remission, as well as from 36 healthy participants as controls. For soluble molecules, plasma from 37 MG patients at baseline, 34 patients in relapse, and 30 patients in remission, as well as plasma from 36 healthy controls (HC), was retrospectively collected from the sample bank of the First Hospital of Soochow University. The expression of membrane-bound OX40 and OX40L (mOX40 and mOX40L) by immune cells was measured using flow cytometry. Plasma levels of soluble OX40 and OX40L (sOX40 and sOX40L) were measured by ELISA. Results: (1) The expression of OX40 on CD4+ T cells and that of OX40L on B cells and monocytes were significantly increased, and the levels of sOX40 were significantly decreased in MG patients at baseline compared with HC, while the expression of sOX40L was not significantly different between the two groups. (2) Dynamic observation of the molecules showed significantly higher expression of OX40 on CD4+ T cells and higher levels of sOX40 in MG patients in relapse than in MG patients at baseline and MG patients in remission. Furthermore, the expression levels of sOX40 were significantly elevated in MG patients in remission compared with MG patients at baseline, and the expression of sOX40L was significantly lower in MG patients in remission than in MG patients at baseline and MG patients in relapse. (3) Plasma levels of sOX40 and sOX40L were significantly decreased in 13 patients with relapsed MG after immunosuppressive treatment compared with those before treatment. (4) Correlation analysis showed that the expression of OX40 on CD4+ T cells in patients with relapsed MG was positively correlated with the concentration of acetylcholine receptor antibodies (AchR-Ab), whereas the expression of OX40L on CD19+ B cells and CD14+ monocytes was negatively correlated with disease duration. (5) Binary regression analysis showed that patients with high CD4+ OX40 expression and high sOX40L levels had an increased risk of relapse. Conclusions: OX40 and OX40L are abnormally expressed in the peripheral blood of patients with MG and may be closely associated with disease status and treatment. The OX40/OX40L pathway may be involved in the immunopathological process of MG and may play a role mainly in the later stage of MG.

PCSK9 Suppresses M2-Like Tumor-Associated Macrophage Polarization by Regulating the Secretion of OX40L from Hepatocellular Carcinoma Cells.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) participates in the development of various cancers, including hepatocellular carcinoma (HCC). Here, we attempted to reveal the underlying mechanism of PCSK9 in HCC. METHODS: Tumor tissues and adjacent tissues were separated from HCC patients to detect PCSK9 expression. Then, PCSK9 was overexpressed or silenced in HCC cells (MHCC97H or Huh7), and then the cell supernatant was incubated with THP-1 macrophages. OX40L neutralizing antibody (nAb) was used to inhibit OX40L activity. The expression of macrophage markers was examined by immunohistochemical staining and flow cytometry. Finally, tumor-bearing mouse model was constructed by inoculation of LV-PCSK9 infected MHCC97H cells to verify the role of PCSK in HCC. RESULTS: PCSK9 expression was decreased in tumor tissues of HCC patient specimens. HCC patients displayed M2 macrophage infiltration in tumor tissues. Moreover, PCSK9-silenced Huh7 cell supernatant promoted cell migration, and enhanced the proportion of CD206-positive cells and the expression of M2 macrophage markers IL-10 and ARG-1 in THP-1 macrophages. PCSK9-overexpressing MHCC97H cell supernatant inhibited THP-1 macrophage migration and M2-like tumor-associated macrophage (TAM) polarization, which was abolished by OX40L nAb treatment. PCSK9 overexpression enhanced the expression of OX40L in MHCC97H cells. In tumor-bearing mouse models, PCSK9 overexpression inhibited tumor growth and M2 polarization of TAMs in HCC by promoting OX40L expression. Conclusion: This work demonstrated that PCSK9 suppressed M2-like TAM polarization by regulating the secretion of OX40L from hepatocellular carcinoma cells. This study suggests that PCSK9 may be a potential target for HCC treatment.

March1-overexpressed dendritic cells downregulate Th1/Th2 ratio in asthma through promoting OX40L.

Asthma is an inflammatory disease. Th2 differentiation plays an important role in the pathogenesis of asthma. We explored the role and action mechanism of membrane-associated RING-CH 1 (March1) in the Th2 differentiation regulated by dendritic cells (DCs). Our data showed that the expression of March1 was higher in asthmatic children-derived DCs, asthmatic mice-derived DCs and house dust mites (HDMs)-treated DCs than that in control DCs. Increasing of March1 promoted the production of pro-inflammatory cytokines from HDMs-treated DCs, and enhanced the promotion of HDMs-treated DCs to CD4+T cell proliferation and Th2 differentiation, whereas decreasing of March1 resulted in opposite effects. Furthermore, our data indicated that March1 positively regulated the expression of OX40 ligand (OX40L) and facilitated DCs-induced Th2 differentiation through OX40L. In asthmatic mice, March1-overexpressed DCs significantly aggravated the injury in lung tissues and promoted Th2 differentiation. Overall, our data proved that highly expressed March1 in DCs facilitated asthma development through inducing Th2 differentiation by facilitating OX40L expression. Our data might provide a new idea for the treatment of asthma.

Expansion of cytotoxic natural killer cells in multiple myeloma patients using K562 cells expressing OX40 ligand and membrane-bound IL-18 and IL-21.

BACKGROUND: Natural killer (NK) cell-based immunotherapy is a promising treatment approach for multiple myeloma (MM), but obtaining a sufficient number of activated NK cells remains challenging. Here, we report an improved method to generate ex vivo expanded NK (eNK) cells from MM patients based on genetic engineering of K562 cells to express OX40 ligand and membrane-bound (mb) IL-18 and IL-21. METHODS: K562-OX40L-mbIL-18/-21 cells were generated by transducing K562-OX40L cells with a lentiviral vector encoding mbIL-18 and mbIL-21, and these were used as feeder cells to expand NK cells from peripheral blood mononuclear cells of healthy donors (HDs) and MM patients in the presence of IL-2/IL-15. Purity, expansion rate, receptor expression, and functions of eNK cells were determined over four weeks of culture. RESULTS: NK cell expansion was enhanced by short exposure of soluble IL-18 and IL-21 with K562-OX40L cells. Co-culture of NK cells with K562-OX40L-mbIL-18/-21 cells resulted in remarkable expansion of NK cells from HDs (9,860-fold) and MM patients (4,929-fold) over the 28-day culture period. Moreover, eNK cells showed increased expression of major activation markers and enhanced cytotoxicity towards target K562, U266, and RPMI8226 cells. CONCLUSIONS: Our data suggest that genetically engineered K562 cells expressing OX40L, mbIL-18, and mbIL-21 improve the expansion of NK cells, increase activation signals, and enhance their cytolytic activity towards MM cells.

The immunotherapy candidate TNFSF4 may help the induction of a promising immunological response in breast carcinomas.

Immune checkpoint blockade, an immunotherapy, has been applied in multiple systemic malignancies and has improved overall survival to a relatively great extent; whether it can be applied in breast cancer remains unknown. We endeavored to explore possible factors that may influence immunotherapy outcomes in breast cancer using several public databases. The possible treatment target TNF superfamily member 4 (TNFSF4) was selected from many candidates based on its abnormal expression profile, survival-associated status, and ability to predict immune system reactions. For the first time, we identified the oncogenic features of TNFSF4 in breast carcinoma. TNFSF4 was revealed to be closely related to treatment that induced antitumor immunity and to interact with multiple immune effector molecules and T cell signatures, which was independent of endocrine status and has not been reported previously. Moreover, the potential immunotherapeutic approach of TNFSF4 blockade showed underlying effects on stem cell expansion, which more strongly and specifically demonstrated the potential effects of applying TNFSF4 blockade-based immunotherapies in breast carcinomas. We identified potential targets that may contribute to breast cancer therapies through clinical analysis and real-world review and provided one potential but crucial tool for treating breast carcinoma that showed effects across subtypes and long-term effectiveness.

Establishment of an ATLL cell line (YG-PLL) dependent on IL-2 and IL-4, which are replaced by OX40-ligand+ HK with poly-L-histidine and dermatan sulfate.

We established an IL-2 and IL-4 (IL2/4) - dependent adult T-cell leukemia/lymphoma (ATLL) cell line (YG-PLL) by adding poly-L-lysine (PLL) to the culture medium. YG-PLL originates from lymphoma cells and contains a defective HTLV-I proviral genome. Although YG-PLL cannot survive without IL-2/4, the follicular dendritic cell (FDC)-like cell line HK expressing OX40-ligand gene (OX40L+HK) inhibited their death in the presence of soluble neutral polymers. After the prevention of cell death, YG-PLL proliferated on OX40L+HK without IL2/4 in the presence of two kinds of positively or negatively charged polymers. In particular, dermatan sulfate and poly-L-histidine supported growth for more than 4 months. Therefore, the original lymphoma cells proliferated transiently in the presence of IL2/4, and their growth arrest was inhibited by the addition of PLL. Furthermore, YG-PLL lost IL2/4 dependency by the following 3-step procedure: preculture with IL2/4 and neutral polymers, 3-day culture with neutral polymer on OX40L+HK to inhibit cell death, and co-culture with OX40L+HK in the presence of the positively and negatively charged polymers. The extracellular environment made by soluble polymers plays a role in the growth of ATLL in vitro.

Dectin-1 Controls TSLP-Induced Th2 Response by Regulating STAT3, STAT6, and p50-RelB Activities in Dendritic Cells.

The epithelium-associated cytokine thymic stromal lymphopoietin (TSLP) can induce OX40L and CCL17 expression by myeloid dendritic cells (mDCs), which contributes to aberrant Th2-type immune responses. Herein, we report that such TSLP-induced Th2-type immune response can be effectively controlled by Dectin-1, a C-type lectin receptor expressed by mDCs. Dectin-1 stimulation induced STAT3 activation and decreased the transcriptional activity of p50-RelB, both of which resulted in reduced OX40L expression on TSLP-activated mDCs. Dectin-1 stimulation also suppressed TSLP-induced STAT6 activation, resulting in decreased expression of the Th2 chemoattractant CCL17. We further demonstrated that Dectin-1 activation was capable of suppressing ragweed allergen (Amb a 1)-specific Th2-type T cell response in allergy patients ex vivo and house dust mite allergen (Der p 1)-specific IgE response in non-human primates in vivo. Collectively, this study provides a molecular explanation of Dectin-1-mediated suppression of Th2-type inflammatory responses and suggests Dectin-1 as a target for controlling Th2-type inflammation.

The OX40/OX40L Axis Regulates T Follicular Helper Cell Differentiation: Implications for Autoimmune Diseases.

T Follicular helper (Tfh) cells, a unique subset of CD4+ T cells, play an essential role in B cell development and the formation of germinal centers (GCs). Tfh differentiation depends on various factors including cytokines, transcription factors and multiple costimulatory molecules. Given that OX40 signaling is critical for costimulating T cell activation and function, its roles in regulating Tfh cells have attracted widespread attention. Recent data have shown that OX40/OX40L signaling can not only promote Tfh cell differentiation and maintain cell survival, but also enhance the helper function of Tfh for B cells. Moreover, upregulated OX40 signaling is related to abnormal Tfh activity that causes autoimmune diseases. This review describes the roles of OX40/OX40L in Tfh biology, including the mechanisms by which OX40 signaling regulates Tfh cell differentiation and functions, and their close relationship with autoimmune diseases.

Immunotherapeutic strategy based on anti-OX40L and low dose of IL-2 to prolong graft survival in sensitized mice by inducing the generation of CD4+ and CD8+ Tregs.

Alloreactive memory cells play a critical role after a second transplant and are difficult to suppress. This study investigated the effect of an immunotherapeutic strategy that combines anti-OX40L, rapamycin (Rapa), and a low dose of IL-2 in a memory cell-based adoptive model. In this model, the median survival time (MST) of the grafts of the combined treatment group was significantly extended compared to that of the control group and other treatment groups. A similar effect was observed regarding a reduction in memory T cells (Tm) and inflammatory cytokines production. Also, the percentages of Foxp3+ regulatory T cells (Tregs) increased in our model. In addition, mounting evidence has shown CD8+CD122+ T cells are also Tregs. We found that the group of CD8+CD122+PD1+ T cells was markedly increased in the combined treatment group, especially in the graft. We further demonstrated that CD8+CD122+PD1+ T cells could suppress activated T cells. Our data suggest that anti-OX40L combined with Rapa and a low dose of IL-2 can suppress Tm, modulate CD4 and CD8 Tregs, and induce long-term heart allograft survival in sensitized mice.

Expression and Clinical Significance of OX40 and OX40L mRNA in Hepatocellular Carcinoma.

In a retrospective study, the expression of mRNA of membrane receptor OX40 and its ligand OX40L in liver tissues was analyzed in 34 patients with hepatocellular carcinoma in order to assess their clinical implications and prognostic value. Expression of mRNA was analyzed by reverse transcription PCR and TaqMan probes. Expression of OX40 mRNA was significantly higher in tumor specimens in paired comparison with the samples of adjacent non-tumor tissue or normal liver tissue of control patients. In contrast, expression of OX40L mRNA was lower in tumor tissue in paired comparison with the samples of adjacent non-tumor tissue or normal liver tissue. The clinical and pathological analysis showed that expression of OX40 mRNA significantly correlated with the degree of tumor differentiation; there was an insignificant decreasing trend in the length of recurrence-free period. It was hypothesized that microenvironment of hepatocellular carcinoma can induce immunosuppression due to dysregulation of the expression of OX40 and OX40L in tumor tissue, which promotes tumor growth.

OX40L/OX40 Signal Promotes IL-9 Production by Mucosal MAIT Cells During Helicobacter pylori Infection.

Mucosal associated invariant T (MAIT) cells play a critical role in Helicobacter pylori (H. pylori)-induced gastritis by promoting mucosal inflammation and aggravating mucosal injuries (1, 2). However, the underlying mechanism and key molecules involved are still uncertain. Here we identified OX40, a co-stimulatory molecule mainly expressed on T cells, as a critical regulator to promote proliferation and IL-9 production by MAIT cells and facilitate mucosal inflammation in H. pylori-positive gastritis patients. Serum examination revealed an increased level of IL-9 in gastritis patients. Meanwhile, OX40 expression was increased in mucosal MAIT cells, and its ligand OX40L was also up-regulated in mucosal dendritic cells (DCs) of gastritis patients, compared with healthy controls. Further results demonstrated that activation of the OX40/OX40L pathway promoted IL-9 production by MAIT cells, and MAIT cells displayed a highly-activated phenotype after the cross-linking of OX40 and OX40L. Moreover, the level of IL-9 produced by MAIT cells was positively correlated with inflammatory indexes in the gastric mucosa, suggesting the potential role of IL-9-producing MAIT cells in mucosal inflammation. Taken together, we elucidated that OX40/OX40L axis promoted mucosal MAIT cell proliferation and IL-9 production in H. pylori-induced gastritis, which may provide potential targeting strategies for gastritis treatment.