TLR2 Directing PD-L2 Expression Inhibit T Cells Response in Schistosoma japonicum Infection

Toll-like receptor 2 (TLR2) was shown to be an important immune receptor involved in the recognition of schistosome antigens, especially soluble egg antigen (SEA). In mice models with Schistosoma japonicum acute infection, we observed enhanced T cell-mediated immune responses in TLR2 knock out (TLR2^−/−) mice compared with B6 mice. In Schistosoma japonicum chronic infection models, programmed death ligand 1 (PD-L1) and programmed death ligand 2 (PD-L2) expression as well as TLR2 expression gradually increased in B6 mice, while only PD-L2 expression significantly decreased in TLR2^−/− mice. Meanwhile, Programmed Death 1(PD-1) expression on CD4⁺T cells was down-regulated in TLR2^−/− mice after a large number of egg appeared. We also found that stimulation with schistosome antigens, especially SEA, could up-regulate PD-L2 expression on BMDCs in a TLR2-dependent manner in vitro. Schistosome antigens primed-BMDCs with impaired expression of TLR2 or PD-L2 could induce CD4⁺T cells to produce low level of IL-10 or high level of IFN-γ. Our results indicated that TLR2 signaling can direct PD-L2 expression on DCs, which binds to PD-1 mainly on CD4⁺T cells, to help inhibit T cells response in Schistosoma japonicum infection.     

Myeloid-derived suppressor cells regulate the immunosuppressive functions of PD-1−PD-L1+ Bregs through PD-L1/PI3K/AKT/NF-κB axis in breast cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of myeloid cells that are closely related to tumor immune escape, but the mechanism by which MDSCs regulate B cells has not been elucidated. Our previous studies revealed that breast cancer-derived MDSCs could induce a group of PD-1⁻PD-L1⁺ Bregs with immunosuppressive functions. Here, we reported that blocking PD-1/PD-L1 interaction between MDSCs and B cells could reverse the immunosuppressive functions of PD-1⁻PD-L1⁺ Bregs. The activation of PI3K/AKT/NF-κB signaling pathway is essential for PD-1⁻PD-L1⁺ Bregs to exert immunosuppressive effects. MDSCs activated the PI3K/AKT/NF-κB pathway in B cells via the PD-1/PD-L1 axis. Furthermore, inhibition of PD-1/PD-L1 or PI3K/AKT signaling suppressed both tumor growth and the immunosuppressive functions of PD-1⁻PD-L1⁺ Bregs. Dual suppression of PD-1/PD-L1 and PI3K/AKT exerted better antitumor effect. Finally, MDSCs and PD-1⁻PD-L1⁺ Bregs were colocalized in breast cancer tissues and PD-1⁻PD-L1⁺ Bregs were positively correlated with poor prognosis. Thus, MDSC-educated PD-1⁻PD-L1⁺ Bregs and their regulatory mechanisms could contribute to the immunosuppressive tumor microenvironment. Our study proposes a novel mechanism for MDSC-mediated regulation of B cell immunity, which might shed new light on tumor immunotherapy.⁺Subject terms: Breast cancer, Cancer microenvironment     

PD-L1 signaling on human memory CD4+ T cells induces a regulatory phenotype

Programmed cell death protein 1 (PD-1) is expressed on T cells upon T cell receptor (TCR) stimulation. PD-1 ligand 1 (PD-L1) is expressed in most tumor environments, and its binding to PD-1 on T cells drives them to apoptosis or into a regulatory phenotype. The fact that PD-L1 itself is also expressed on T cells upon activation has been largely neglected. Here, we demonstrate that PD-L1 ligation on human CD25-depleted CD4⁺ T cells, combined with CD3/TCR stimulation, induces their conversion into highly suppressive T cells. Furthermore, this effect was most prominent in memory (CD45RA⁻CD45RO⁺) T cells. PD-L1 engagement on T cells resulted in reduced ERK phosphorylation and decreased AKT/mTOR/S6 signaling. Importantly, T cells from rheumatoid arthritis patients exhibited high basal levels of phosphorylated ERK and following PD-L1 cross-linking both ERK signaling and the AKT/mTOR/S6 pathway failed to be down modulated, making them refractory to the acquisition of a regulatory phenotype. Altogether, our results suggest that PD-L1 signaling on memory T cells could play an important role in resolving inflammatory responses; maintaining a tolerogenic environment and its failure could contribute to ongoing autoimmunity.

This study shows that programmed death cell receptor ligand 1 (PD-L1) signaling in memory CD4+ T cells from healthy individuals induces a regulatory phenotype; this mechanism seems to be defective in equivalent T cells from rheumatoid arthritis patients and could be in part responsible for the pathology.     

Crystal clear: visualizing the intervention mechanism of the PD-1/PD-L1 interaction by two cancer therapeutic monoclonal antibodies

Antibody-based PD-1/PD-L1 blockade therapies have taken center stage in immunotherapies for cancer, with multiple clinical successes. PD-1 signaling plays pivotal roles in tumor-driven T-cell dysfunction. In contrast to prior approaches to generate or boost tumor-specific T-cell responses, antibody-based PD-1/PD-L1 blockade targets tumor-induced T-cell defects and restores preexisting T-cell function to modulate antitumor immunity. In this review, the fundamental knowledge on the expression regulations and inhibitory functions of PD-1 and the present understanding of antibody-based PD-1/ PD-L1 blockade therapies are briefly summarized. We then focus on the recent breakthrough work concerning the structural basis of the PD-1/PD-Ls interaction and how therapeutic antibodies, pembrolizumab targeting PD-1 and avelumab targeting PD-L1, compete with the binding of PD-1/PD-L1 to interrupt the PD-1/PD-L1 interaction. We believe that this structural information will benefit the design and improvement of therapeutic antibodies targeting PD-1 signaling.     

Interaction of PD-L1 on tumor cells with PD-1 on tumor-specific T cells as a mechanism of immune evasion: implications for tumor immunotherapy

Programmed death receptor ligand 1 (PD-L1, also called B7-H1) is a recently described B7 family member. In contrast to B7-1 and B7-2, PD-L1 does not interact with either CD28 or CTLA-4. To date, one specific receptor has been identified that can be ligated by PD-L1. This receptor, programmed death receptor 1 (PD-1), has been shown to negatively regulate T-cell receptor (TCR) signaling. Upon ligating its receptor, PD-L1 has been reported to decrease TCR-mediated proliferation and cytokine production. PD-1 gene–deficient mice developed autoimmune diseases, which early led to the hypothesis of PD-L1 regulating peripheral tolerance. In contrast to normal tissues, which show minimal surface expression of PD-L1 protein, PD-L1 expression was found to be abundant on many murine and human cancers and could be further up-regulated upon IFN- stimulation. Thus, PD-L1 might play an important role in tumor immune evasion. This review discusses the currently available data concerning negative T-cell regulation via PD-1, the blockade of PD-L1/PD-1 interactions, and the implications for adoptive T-cell therapies.     

Lack of PD-L1 Expression by iNKT Cells Improves the Course of Influenza A Infection

There is evidence indicating that invariant Natural Killer T (iNKT) cells play an important role in defense against influenza A virus (IAV). However, the effect of inhibitory receptor, programmed death-1 (PD-1), and its ligands, programmed death ligand (PD-L) 1 and 2 on iNKT cells in protection against IAV remains to be elucidated. Here we investigated the effects of these co-stimulatory molecules on iNKT cells in the response to influenza. We discovered that compare to the wild type, PD-L1 deficient mice show reduced sensitivity to IAV infection as evident by reduced weight loss, decreased pulmonary inflammation and cellular infiltration. In contrast, PD-L2 deficient mice showed augmented weight loss, pulmonary inflammation and cellular infiltration compare to the wild type mice after influenza infection. Adoptive transfer of iNKT cells from wild type, PD-L1 or PD-L2 deficient mice into iNKT cell deficient mice recapitulated these findings. Interestingly, in our transfer system PD-L1^−/−-derived iNKT cells produced high levels of interferon-gamma whereas PD-L2^−/−-derived iNKT cells produced high amounts of interleukin-4 and 13 suggesting a role for these cytokines in sensitivity to influenza. We identified that PD-L1 negatively regulates the frequency of iNKT cell subsets in the lungs of IAV infected mice. Altogether, these results demonstrate that lack of PD-L1 expression by iNKT cells reduces the sensitivity to IAV and that the presence of PD-L2 is important for dampening the deleterious inflammatory responses after IAV infection. Our findings potentially have clinical implications for developing new therapies for influenza.     

Foxp3+ Regulatory T Cells among Tuberculosis Patients: Impact on Prognosis and Restoration of Antigen Specific IFN-γ Producing T Cells

CD4⁺CD25⁺Foxp3⁺ Regulatory T cells (Treg) and programmed death-1 (PD-1) molecules have emerged as pivotal players in immune suppression of chronic diseases. However, their impact on the disease severity, therapeutic response and restoration of immune response in human tuberculosis remains unclear. Here, we describe the possible role of Treg cells, their M. tuberculosis driven expansion and contribution of PD-1 pathway to the suppressive function of Treg cells among pulmonary tuberculosis (PTB) patients. Multicolor flow cytometry, cell culture, cells sorting and ELISA were employed to execute the study. Our results showed significant increase in frequency of antigen-reactive Treg cells, which gradually declined during successful therapy and paralleled with decline of M. tuberculosis–specific IL-10 along with elevation of IFN-γ production, and raising the IFN-γ/IL-4 ratio. Interestingly, persistence of Treg cells tightly correlated with MDR tuberculosis. Also, we show that blocking PD-1/PD-L1 pathway abrogates Treg-mediated suppression, suggesting that the PD-1/PD-L1 pathway is required for Treg-mediated suppression of the antigen-specific T cells. Treg cells possibly play a role in dampening the effector immune response and abrogating PD-1 pathway on Treg cells significantly rescued protective T cell response, suggesting its importance in immune restoration among tuberculosis patients.     

Deubiquitinating enzyme OTUB1 promotes cancer cell immunosuppression via preventing ER-associated degradation of immune checkpoint protein PD-L1

Upregulation of programmed death ligand 1 (PD-L1) helps tumor cells escape from immune surveillance, and therapeutic antibodies targeting PD-1/PD-L1 have shown better patient outcomes only in several types of malignancies. Recent studies suggest that the clinical efficacy of anti-PD-1/PD-L1 treatments is associated with PD-L1 levels; however, the underlying mechanism of high PD-L1 protein levels in cancers is not well defined. Here, we report that the deubiquitinase OTUB1 positively regulates PD-L1 stability and mediates cancer immune responses through the PD-1/PD-L1 axis. Mechanistically, we demonstrate that OTUB1 interacts with and removes K48-linked ubiquitin chains from the PD-L1 intracellular domain in a manner dependent on its deubiquitinase activity to hinder the degradation of PD-L1 through the ERAD pathway. Functionally, depletion of OTUB1 markedly decreases PD-L1 abundance, reduces PD-1 protein binding to the tumor cell surface, and causes increased tumor cell sensitivity to human peripheral blood mononuclear cells (PBMCs)-mediated cytotoxicity. Meanwhile, OTUB1 ablation-induced PD-L1 destabilization facilitates more CD8⁺ T cells infiltration and increases the level of IFN-γ in serum to enhance antitumor immunity in mice, and the tumor growth suppression by OTUB1 silencing could be reversed by PD-L1 overexpression. Furthermore, we observe a significant correlation between PD-L1 abundance and OTUB1 expression in human breast carcinoma. Our study reveals OTUB1 as a deubiquitinating enzyme that influences cancer immunosuppression via regulation of PD-L1 stability and may be a potential therapeutic target for cancer immunotherapy.Subject terms: Proteins, Immune evasion     

PD-1 and PD-L1 Expression in NSCLC Indicate a Favorable Prognosis in Defined Subgroups

Background

Immunotherapy can become a crucial therapeutic option to improve prognosis for lung cancer patients. First clinical trials with therapies targeting the programmed cell death receptor PD-1 and its ligand PD-L1 have shown promising results in several solid tumors. However, in lung cancer the diagnostic, prognostic and predictive value of these immunologic factors remains unclear.

Method

The impact of both factors was evaluated in a study collective of 321 clinically well-annotated patients with non-small lung cancer (NSCLC) using immunohistochemistry.

Results

PD-1 expression by tumor infiltrating lymphocytes (TILs) was found in 22%, whereas tumor cell associated PD-L1 expression was observed in 24% of the NSCLC tumors. In Fisher’s exact test a positive correlation was found for PD-L1 and Bcl-xl protein expression (p = 0.013). Interestingly, PD-L1 expression on tumor cells was associated with improved overall survival in pulmonary squamous cell carcinomas (SCC, p = 0.042, log rank test), with adjuvant therapy (p = 0.017), with increased tumor size (pT2-4, p = 0.039) and with positive lymph node status (pN1-3, p = 0.010). These observations were confirmed by multivariate cox regression models.

Conclusion

One major finding of our study is the identification of a prognostic implication of PD-L1 in subsets of NSCLC patients with pulmonary SCC, with increased tumor size, with a positive lymph node status and NSCLC patients who received adjuvant therapies. This study provides first data for immune-context related risk stratification of NSCLC patients. Further studies are necessary both to confirm this observation and to evaluate the predictive value of PD-1 and PD-L1 in NSCLC in the context of PD-1 inhibition.     

Secretion of human soluble programmed cell death protein 1 by chimeric antigen receptor-modified T cells enhances anti-tumor efficacy

Background aimsChimeric antigen receptor (CAR) T cells have achieved favorable responses in patients with hematologic malignancies, but the outcome has been far from satisfactory in the treatment of tumors with high expression of immunosuppressive molecules. To overcome this limitation, we modified CAR T cells to secrete types of human soluble programmed cell death protein 1 (PD-1) called sPD-1 CAR T cells.MethodsTo compare the effector function between second (conventional second-generation CAR targeting CD19) and sPD-1 CAR T cells, we measured cytotoxicity, cytokine secretion and activation markers incubated with or without tumor cells expressing CD19 and/or programmed cell death ligand 1 (PD-L1). Furthermore, the anti-tumor efficacy of second and sPD-1 CAR T cells was determined using an NSG mouse model bearing NALM-6-PD-L1. Finally, the underlying mechanism was investigated by metabolic parameters and RNA sequencing analysis of different CAR T cells.ResultsCompared with second CAR T cells, sPD-1 CAR T cells enhanced killing efficiency toward CD19⁺PD-L1⁺ tumor cells in vitro. Furthermore, sPD-1 CAR T cells reduced the tumor burden and prolonged overall survival of the NSG (NOD-SCID-IL2rg) mice bearing NALM-6-PD-L1. To explore the effect of soluble PD-1 on CAR T cells, we found that sPD-1 CAR T cells exhibited higher levels of activation and ameliorative profiles of differentiation, exhaustion, glycolysis and apoptosis.ConclusionsWith constitutive soluble PD-1 secretion, sPD-1 CAR T cells have tended to eradicate tumors with a high expression of PD-L1 more effectively than second CAR T cells. This may be due to soluble PD-1 enhancing apoptosis resistance, aerobic metabolism and a more “stem” differentiation of CAR T cells. Overall, our study presents a feasible strategy to increase the efficacy of CAR T cells.     

Dendritic Cells in Chronic Mycobacterial Granulomas Restrict Local Anti-Bacterial T Cell Response in a Murine Model

Background

Mycobacterium-induced granulomas are the interface between bacteria and host immune response. During acute infection dendritic cells (DCs) are critical for mycobacterial dissemination and activation of protective T cells. However, their role during chronic infection in the granuloma is poorly understood.

Methodology/Principal Findings

We report that an inflammatory subset of murine DCs are present in granulomas induced by Mycobacteria bovis strain Bacillus Calmette-guerin (BCG), and both their location in granulomas and costimulatory molecule expression changes throughout infection. By flow cytometric analysis, we found that CD11c⁺ cells in chronic granulomas had lower expression of MHCII and co-stimulatory molecules CD40, CD80 and CD86, and higher expression of inhibitory molecules PD-L1 and PD-L2 compared to CD11c⁺ cells from acute granulomas. As a consequence of their phenotype, CD11c⁺ cells from chronic lesions were unable to support the reactivation of newly-recruited, antigen 85B-specific CD4⁺IFNγ⁺ T cells or induce an IFNγ response from naïve T cells in vivo and ex vivo. The mechanism of this inhibition involves the PD-1:PD-L signaling pathway, as ex vivo blockade of PD-L1 and PD-L2 restored the ability of isolated CD11c⁺ cells from chronic lesions to stimulate a protective IFNγ T cell response.

Conclusions/Significance

Our data suggest that DCs in chronic lesions may facilitate latent infection by down-regulating protective T cell responses, ultimately acting as a shield that promotes mycobacterium survival. This DC shield may explain why mycobacteria are adapted for long-term survival in granulomatous lesions.     

Influence of Macrocyclic Chelators on the Targeting Properties of 68Ga-Labeled Synthetic Affibody Molecules: Comparison with 111In-Labeled Counterparts

Affibody molecules are a class of small (7 kDa) non-immunoglobulin scaffold-based affinity proteins, which have demonstrated substantial potential as probes for radionuclide molecular imaging. The use of positron emission tomography (PET) would further increase the resolution and quantification accuracy of Affibody-based imaging. The rapid in vivo kinetics of Affibody molecules permit the use of the generator-produced radionuclide ⁶⁸Ga (T_1/2 = 67.6 min). Earlier studies have demonstrated that the chemical nature of chelators has a substantial influence on the biodistribution properties of Affibody molecules. To determine an optimal labeling approach, the macrocyclic chelators 1,4,7,10-tetraazacylododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-N,N,N-triacetic acid (NOTA) and 1-(1,3-carboxypropyl)-1,4,7- triazacyclononane-4,7-diacetic acid (NODAGA) were conjugated to the N-terminus of the synthetic Affibody molecule Z_HER2:S1 targeting HER2. Affibody molecules were labeled with ⁶⁸Ga, and their binding specificity and cellular processing were evaluated. The biodistribution of ⁶⁸Ga-DOTA-Z_HER2:S1, ⁶⁸Ga-NOTA-Z_HER2:S1 and ⁶⁸Ga-NODAGA-Z_HER2:S1, as well as that of their ¹¹¹In-labeled counterparts, was evaluated in BALB/C nu/nu mice bearing HER2-expressing SKOV3 xenografts. The tumor uptake for ⁶⁸Ga-DOTA-Z_HER2:S1 (17.9±0.7%IA/g) was significantly higher than for both ⁶⁸Ga-NODAGA-Z_HER2:S1 (16.13±0.67%IA/g) and ⁶⁸Ga-NOTA-Z_HER2:S1 (13±3%IA/g) at 2 h after injection. ⁶⁸Ga-NODAGA-Z_HER2:S1 had the highest tumor-to-blood ratio (60±10) in comparison with both ⁶⁸Ga-DOTA-Z_HER2:S1 (28±4) and ⁶⁸Ga-NOTA-Z_HER2:S1 (42±11). The tumor-to-liver ratio was also higher for ⁶⁸Ga-NODAGA-Z_HER2:S1 (7±2) than the DOTA and NOTA conjugates (5.5±0.6 vs.3.3±0.6). The influence of chelator on the biodistribution and targeting properties was less pronounced for ⁶⁸Ga than for ¹¹¹In. The results of this study demonstrate that macrocyclic chelators conjugated to the N-terminus have a substantial influence on the biodistribution of HER2-targeting Affibody molecules labeled with ⁶⁸Ga.This can be utilized to enhance the imaging contrast of PET imaging using Affibody molecules and improve the sensitivity of molecular imaging. The study demonstrated an appreciable difference of chelator influence for ⁶⁸Ga and ¹¹¹In.     

Characterization of PD-1/PD-L1 immune checkpoint expression in soft tissue sarcomas

Inhibitors of the programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) immune checkpoint system are used for treating various malignancies. However, evidence on their use in soft tissue sarcomas (STS) is limited. This study aimed to retrospectively investigate the relationship between the expression of PD-1/PD-L1 and related antigens in STS, and their association with clinical characteristics. Immunostaining for CD4, CD8, PD-1, PD-L1, IL-2, and IFN-γ was performed using pathological specimens harvested at the time of biopsy from 10 patients with undifferentiated pleomorphic sarcoma (UPS), nine with myxofibrosarcoma (MFS), and three with malignant peripheral nerve sheath tumor (MPNST) who were treated at our hospital. Subsequently, the positive immunostaining cell rates were calculated. We also examined the correlation between each immune positive cell rate and age, tissue grade, size, and maximum standardized uptake (SUV-max) values. The 3-year event-free survival (EFS) and overall survival (OS) rates were compared between the positive and negative groups (positive rate >10%; negative <10%) for various immune stains. The positive rates were also compared between the presence and absence of events groups. There was positive staining for the immune checkpoint molecules in every STS type except for PD-1 in MPNST. CD4, CD8, and PD-1 stained lymphocytes in close proximity to the tumor in adjacent tissue sections. A positive correlation was observed between the positive cell rates of each immune component including inflammatory cytokines such as IL-2 and IFN-γ. Additionally, the clinical features positively correlated with the positive PD-1/PD-L1 expression rates. No significant differences in the 3-EFS and OS rates were observed between the PD-1/PD-L1 positive and negative groups. Our results suggest that an inducible immune checkpoint mechanism may be involved in UPS, MFS, and MPNST.Key words: Immune checkpoint inhibitors, PD-1/PD-L1, soft tissue sarcoma, programmed death-1, programmed death-ligand 1     

KRAS G12V mutation upregulates PD-L1 expression via TGF-β/EMT signaling pathway in human non-small-cell lung cancer

Although clinical data suggest remarkable promise for targeting programmed cell death protein-1 (PD-1) and ligand (PD-L1) signaling in non-small-cell lung cancer (NSCLC), it is still largely undetermined which subtype of patients will be responsive to checkpoint blockade. In the present study, we explored whether PD-L1 was regulated by mutant Kirsten rat sarcoma viral oncogene homolog (KRAS), which is frequently mutated in NSCLC and results in poor prognosis and low survival rates. We verified that PD-L1 levels were dramatically increased in KRAS mutant cell lines, particularly in NCI-H441 cells with KRAS G12V mutation. Overexpression of KRAS G12V remarkably elevated PD-L1 messenger RNA and protein levels, while suppression of KRAS G12V led to decreased PD-L1 levels in NCI-H441 cells. Consistently, higher levels of PD-L1 were observed in KRAS-mutated tissues as well as tumor tissues-derived CD4⁺ and CD8⁺ T cells using a tumor xenograft in B-NDG mice. Mechanically, both in vitro and in vivo assays found that KRAS G12V upregulated PD-L1 via regulating the progression of epithelial-to-mesenchymal transition (EMT). Moreover, pembrolizumab activated the antitumor activity and decreased tumor growth with KRAS G12V mutated NSCLC. This study demonstrates that KRAS G12V mutation could induce PD-L1 expression and promote immune escape via transforming growth factor-β/EMT signaling pathway in KRAS-mutant NSCLC, providing a potential therapeutic approach for NSCLC harboring KRAS mutations.     

The Pekin duck programmed death ligand-2: cDNA cloning,genomic structure,molecular characterization and expression analysis

Programmed death-1 (PD-1), upon engagement by its ligands, programmed death ligand-1 (PD-L1) and programmed death ligand-2 (PD-L2), provides signals that attenuate adaptive immune responses. Here we describe the identification of the Pekin duck PD-L2 (duPD-L2) and its gene structure. The duPD-L2 cDNA encodes a 321 amino acid protein that has an amino acid identity of 76% and 35% with chicken and human PD-L2, respectively. Mapping of the duPD-L2 cDNA with duck genomic sequences revealed an exonic structure similar to that of the human Pdcd1lg2 gene. Homology modelling of the duPD-L2 protein was compatible with the murine PD-L2 ectodomain structure. Residues known to be important for PD-1 receptor binding of murine PD-L2 were mostly conserved in duPD-L2 within sheets A and G and partially conserved within sheets C and F. DuPD-L2 mRNA was constitutively expressed in all tissues examined with highest expression levels in lung, spleen, cloaca, bursa, cecal tonsil, duodenum and very low levels of expression in muscle, kidney and brain. Lipopolysaccharide treatment of adherent duck PBMC upregulated duPD-L2 mRNA expression. Our work shows evolutionary conservation of the PD-L2 ectodomain structure and residues important for PD-1 binding in vertebrates including fish. The information provided will be useful for further investigation of the role of duPD-L2 in the regulation of duck adaptive immunity and exploration of PD-1-targeted immunotherapies in the duck hepatitis B infection model.     

Clinical Perspectives to Overcome Acquired Resistance to Anti–Programmed Death-1 and Anti–Programmed Death Ligand-1 Therapy in Non-Small Cell Lung Cancer

Immune checkpoint inhibitors have changed the paradigm of treatment options for non-small cell lung cancer (NSCLC). Monoclonal antibodies targeting programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) have gained wide attention for their application, which has been shown to result in prolonged survival. Nevertheless, only a limited subset of patients show partial or complete response to PD-1 therapy, and patients who show a response eventually develop resistance to immunotherapy. This article aims to provide an overview of the mechanisms of acquired resistance to anti–PD-1/PD-L1 therapy from the perspective of tumor cells and the surrounding microenvironment. In addition, we address the potential therapeutic targets and ongoing clinical trials, focusing mainly on NSCLC.     

PD-1, PD-L1 and PD-L2 Gene Expression on T-Cells and Natural Killer Cells Declines in Conjunction with a Reduction in PD-1 Protein during the Intensive Phase of Tuberculosis Treatment

Background

The PD-1 axis is a cell intrinsic immunoregulatory pathway that mediates T cell exhaustion in chronic infection particularly in some viral infections. We hypothesized that PD-1, PD-L1 and PD-L2 would be highly expressed in untreated tuberculosis patients compared to controls due to their chronic infection and would decrease with successful TB treatment.

Materials and Methods

Untreated tuberculosis patients (n = 26) were recruited at diagnosis and followed up during treatment. Household contacts (n = 24) were recruited to establish baseline differences. Blood gene expression ex vivo was investigated using qRT-PCR. Flow cytometry was performed to establish protein expression patterns.

Results

PD-L1 gene expression was found to be elevated in active TB disease; however, this was not observed for PD-1 or PD-L2. The intensive phase of TB treatment was associated with a significant decline in PD-1, PD-L1 and PD-L2 gene expression. PD-1 protein expression on the surface of NK cells, CD8⁺ and CD4⁺ T cells was similar in patients with active TB disease compared to controls but declined with successful TB treatment, with the greatest decline occurring on the NK cells followed by CD8⁺ T cells and then CD4⁺ T cells. Granzyme B/PD-1 co-expression declined with successful intensive phase treatment.

Conclusion

Modulation of PD-1/PD-L1 pathway through TB treatment indicates changes in the peripheral T cell response caused by live Mycobacterium tuberculosis (Mtb) followed by the response to dead bacilli, antigen-release and immuno-pathology resolution. The PD-1 axis could be a host drug target for immunomodulatory treatments in the future.     

Neural and oligodendrocyte progenitor cells: transferrin effects on cell proliferation

NSC (neural stem cells)/NPC (neural progenitor cells) are multipotent and self-renew throughout adulthood in the SVZ (subventricular zone) of the mammalian CNS (central nervous system). These cells are considered interesting targets for CNS neurodegenerative disorder cell therapies, and understanding their behaviour in vitro is crucial if they are to be cultured prior to transplantation. We cultured the SVZ tissue belonging to newborn rats under the form of NS (neurospheres) to evaluate the effects of Tf (transferrin) on cell proliferation. The NS were heterogeneous in terms of the NSC/NPC markers GFAP (glial fibrillary acidic protein), Nestin and Sox2 and the OL (oligodendrocyte) progenitor markers NG2 (nerve/glia antigen 2) and PDGFRα (platelet-derived growth factor receptor α). The results of this study indicate that aTf (apoTransferrin) is able to increase cell proliferation of SVZ-derived cells in vitro, and that these effects were mediated at least in part by the TfRc1 (Tf receptor 1). Since OPCs (oligodendrocyte progenitor cells) represent a significant proportion of the proliferating cells in the SVZ-derived primary cultures, we used the immature OL cell line N20.1 to show that Tf was able to augment the proliferation rate of OPC, either by adding aTf to the culture medium or by overexpressing rat Tf in situ. The culture medium supplemented with ferric iron, together with aTf, increased the DNA content, while ferrous iron did not. The present work provides data that could have a potential application in human cell replacement therapies for neurodegenerative disease and/or CNS injury that require the use of in vitro amplified NPCs.