Cell density plays a critical role in ex vivo expansion of T cells for adoptive immunotherapy

Isolation of tumour-reactive lymphocytes from peripheral blood via microfluidic immunomagnetic cell sorting

The clinical use of tumour-infiltrating lymphocytes for the treatment of solid tumours is hindered by the need to obtain large and fresh tumour fractions, which is often not feasible in patients with unresectable tumours or recurrent metastases. Here we show that circulating tumour-reactive lymphocytes (cTRLs) can be isolated from peripheral blood at high yield and purity via microfluidic immunomagnetic cell sorting, allowing for comprehensive downstream analyses of these rare cells. We observed that CD103 is strongly expressed by the isolated cTRLs, and that in mice with subcutaneous tumours, tumour-infiltrating lymphocytes isolated from the tumours and rapidly expanded CD8+CD103+ cTRLs isolated from blood are comparably potent and respond similarly to immune checkpoint blockade. We also show that CD8+CD103+ cTRLs isolated from the peripheral blood of patients and co-cultured with tumour cells dissociated from their resected tumours resulted in the enrichment of interferon-γ-secreting cell populations with T-cell-receptor clonotypes substantially overlapping those of the patients' tumour-infiltrating lymphocytes. Therapeutically potent cTRLs isolated from peripheral blood may advance the clinical development of adoptive cell therapies.

Three-Dimensional Spheroid Culture of Human Mesenchymal Stem Cells: Offering Therapeutic Advantages and In Vitro Glimpses of the In Vivo State

As invaluable as the standard 2-dimensional (2D) monolayer in vitro cell culture system has been, there is increasing evidence that 3-dimensional (3D) non-adherent conditions are more relevant to the in vivo condition. While one of the criteria for human mesenchymal stem cells (MSCs) has been in vitro plastic adherence, such 2D culture conditions are not representative of in vivo cell-cell and cell-extracellular matrix (ECM) interactions, which may be especially important for this progenitor/stem cell of skeletal and connective tissues. The 3D spheroid, a multicellular aggregate formed under non-adherent 3D in vitro conditions, may be particularly suited as an in vitro method to better understand MSC physiological processes, since expression of ECM and other adhesion proteins are upregulated in such a cell culture system. First used in embryonic stem cell in vitro culture to recapitulate in vivo developmental processes, 3D spheroid culture has grown in popularity as an in vitro method to mimic the 3-dimensionality of the native niche for MSCs within tissues/organs. In this review, we discuss the relevance of the 3D spheroid culture for understanding MSC biology, summarize the biological outcomes reported in the literature based on such this culture condition, as well as contemplate limitations and future considerations in this rapidly evolving and exciting area.

Live-cell imaging and mathematical analysis of the “community effect” in apoptosis

As a cellular intrinsic mechanism leading to cellular demise, apoptosis was thoroughly characterized from a mechanistic perspective. Nowadays there is an increasing interest in describing the non-cell autonomous or community effects of apoptosis, especially in the context of resistance to cancer treatments. Transitioning from cell-centered to cell population-relevant mechanisms adds a layer of complexity for imaging and analyzing an enormous number of apoptotic events. In addition, the community effect between apoptotic and living cells is difficult to be taken into account for complex analysis. We describe here a robust and easy to implement method to analyze the interactions between cancer cells, while under apoptotic pressure. Using this approach we showed as proof-of-concept that apoptosis is insensitive to cellular density, while the proximity to apoptotic cells increases the probability of a given cell to undergo apoptosis.

Microfluidic T Cell Selection by Cellular Avidity

No T cell receptor (TCR) T cell therapies have obtained clinical approval. The lack of strategies capable of selecting and recovering potent T cell candidates may be a contributor to this. Existing protocols for selecting TCR T cell clones for cell therapies such as peptide multimer methods have provided effective measurements on TCR affinities. However, these methods lack the ability to measure the collective strength of intercellular interactions (i.e., cellular avidity) and markers of T cell activation such as immunological synapse formation. This study describes a novel microfluidic fluid shear stress-based approach to identify and recover highly potent T cell clones based on the cellular avidity between living T cells and tumor cells. This approach is capable of probing approximately up to 10 000 T cell-tumor cell interactions per run and can recover potent T cells with up to 100% purity from mixed populations of T cells within 30 min. Markers of cytotoxicity, activation, and avidity persist when recovered high cellular avidity T cells are subsequently exposed to fresh tumor cells. These results demonstrate how microfluidic probing of cellular avidity may fast track the therapeutic T cell selection process and move the authors closer to precision cancer immunotherapy.

In-situ scalable manufacturing of Epstein-Barr virus-specific T-cells using bioreactor with an expandable culture area (BECA)

The ex-vivo expansion of antigen-specific T-cells for adoptive T-cell immunotherapy requires active interaction between T-cells and antigen-presenting cells therefore culture density and environment become important variables to control. Maintenance of culture density in a static environment is traditionally performed by the expansion of the culture area through splitting of culture from a single vessel into multiple vessels-a highly laborious process. This study aims to validate the use and efficacy of a novel bioreactor, bioreactor with an expandable culture area-dual chamber (BECA-D), that was designed and developed with a cell chamber with expandable culture area (12-108 cm²) and a separate media chamber to allow for in-situ scaling of culture with maintenance of optimum culture density and improved nutrient and gas exchange while minimizing disturbance to the culture. The performance of BECA-D in the culture of Epstein-Barr virus-specific T-cells (EBVSTs) was compared to the 24-well plate. BECA-D had 0.9-9.7 times the average culture yield of the 24-well plates across 5 donor sets. BECA-D was able to maintain the culture environment with relatively stable glucose and lactate levels as the culture expanded. This study concludes that BECA-D can support the culture of ex-vivo EBVSTs with lower manufacturing labour and time requirements compared to the use of the 24-well plate. BECA-D and its adaptation into a closed system with an automated platform (currently being developed) provides cell therapy manufacturers and developers with a closed scale-out solution to producing adoptive cell therapy for clinical use.

Efficient recovery of potent tumour-infiltrating lymphocytes through quantitative immunomagnetic cell sorting

Adoptive cell therapies require the recovery and expansion of highly potent tumour-infiltrating lymphocytes (TILs). However, TILs in tumours are rare and difficult to isolate efficiently, which hinders the optimization of therapeutic potency and dose. Here we show that a configurable microfluidic device can efficiently recover potent TILs from solid tumours by leveraging specific expression levels of target cell-surface markers. The device, which is sandwiched by permanent magnets, balances magnetic forces and fluidic drag forces to sort cells labelled with magnetic nanoparticles conjugated with antibodies for the target markers. Compared with conventional cell sorting, immunomagnetic cell sorting recovered up to 30-fold higher numbers of TILs, and the higher levels and diversity of the recovered TILs accelerated TIL expansion and enhanced their therapeutic potency. Immunomagnetic cell sorting also allowed us to identify and isolate potent TIL subpopulations, in particular TILs with moderate levels of CD39 (a marker of T-cell reactivity to tumours and T-cell exhaustion), which we found are tumour-specific, self-renewable and essential for the long-term success of adoptive cell therapies.

Production and Characterization of SIV-Specific CAR/CXCR5 T Cells

HIV-specific chimeric antigen receptor (CAR) T cells that target lymphoid follicles have the potential to functionally cure HIV infection. CD8⁺ T cells, NK cells, or peripheral blood mononuclear cells (PBMC) may be modified to express HIV-specific CARs as well as follicular homing molecules such as CXCR5 to target the virally infected T follicular helper cells that concentrate within B cell follicles during HIV infection. This chapter outlines methods utilizing a simian immunodeficiency virus (SIV) rhesus macaque model of HIV to produce transduced T cells from primary PBMCs. Methods are presented for production of an SIV-specific CAR/CXCR5-encoding retrovirus used to transduce primary rhesus macaque PBMCs. Procedures to evaluate the functionality of the expanded CAR/CXCR5 T cells in vitro and ex vivo are also presented. An in vitro migration assay determines the ability of the T cells expressing CAR/CXCR5 to migrate to the CXCR5 ligand CXCL13, while an ex vivo migration assay allows measurement of the transduced T cell migration into the B cell follicle. Antiviral activity of the CAR/CXCR5 transduced T cells is determined using a viral suppression assay. These methods can be used to produce T cells for immunotherapy in SIV-infected rhesus macaques and to evaluate the functionality of the cells prior to infusion. Similar procedures can be used to produce HIV-specific CAR/CXCR5 T cells.

Microfluidic transfection of mRNA into human primary lymphocytes and hematopoietic stem and progenitor cells using ultra-fast physical deformations

Messenger RNA (mRNA) delivery provides gene therapy with the potential to achieve transient therapeutic efficacy without risk of insertional mutagenesis. Amongst other applications, mRNA can be employed as a platform to deliver gene editing molecules, to achieve protein expression as an alternative to enzyme replacement therapies, and to express chimeric antigen receptors (CARs) on immune cells for the treatment of cancer. We designed a novel microfluidic device that allows for efficient mRNA delivery via volume exchange for convective transfection (VECT). In the device, cells flow through a ridged channel that enforces a series of ultra-fast and large intensity deformations able to transiently open pores and induce convective transport of mRNA into the cell. Here, we describe efficient delivery of mRNA into T cells, natural killer (NK) cells and hematopoietic stem and progenitor cells (HSPCs), three human primary cell types widely used for ex vivo gene therapy applications. Results demonstrate that the device can operate at a wide range of cell and payload concentrations and that ultra-fast compressions do not have a negative impact on T cell function, making this a novel and competitive platform for the development of ex vivo mRNA-based gene therapies and other cell products engineered with mRNA.

Nebivolol alleviates liver damage caused by methotrexate via AKT1/Hif1α/eNOS signaling

Despite the wide clinical indications, methotrexate (MTX) use is limited because of serious side effects including liver toxicity. MTX was shown to cause tissue damage by mainly oxidative stress and also inflammation and apoptosis. Thus, Nebivolol (NEB) which has antioxidant and antiapoptotic properties were thought to be effective against MTX-induced injury. This study aimed to evaluate the effects of NEB on MTX-induced liver toxicity via AKT/Hypoxia-Inducible Factor 1 Alpha (HIF1α)/Endothelial Nitric Oxide Synthase (eNOS) signaling pathways. Rats were divided into three groups as control, MTX, and NEB. A single dose of MTX (20 mg/kg intraperitoneally) was given to the rats on the first day of the experiment and NEB (10 mg/kg, daily by oral gavage) was given to the treatment group for a week. At the end of the experiment, bloods were taken for aspartate transaminase (AST), alanine aminotransferase (ALT), and total bilirubin (T-BIL) analyses. Liver tissues were harvested for biochemical (total oxidant status (TOS) and total antioxidant status (TAS), genetic (PCR analyses for AKT1, eNOS, and HIF1a), and histological (Hemotoxylin-Eosin, Masson Trichome, Periodic Acid Schiff-Asien Blue, reticulin for histological, and CD3 for immunohistochemical staining) analyses. MTX increased the levels of TOS values, AST, ALT, T-BIL levels and decreased the expressions of AKT/HIF1α/eNOS. NEB treatment reversed all these changes markedly via decreasing inflammation by nitric oxid (NO) production. In conclusion, NEB treatment significantly preserves the liver by decreasing oxidant levels and inflammatory parameters through HIF1α/eNOS signaling. Due to the antioxidant properties of NEB, it can be used in other liver injury models sharing the same pathway.

Primary culture of immature, naïve mouse CD4+ T cells

Primary T-cell culture is an invaluable model for investigating mechanisms underlying T-cell differentiation and function in health and disease. However, different culture conditions are required for immature versus mature CD4⁺ T cells. Here, we provide an improved culture protocol for immature naïve mouse CD4⁺ T cells, including details for splenocyte isolation, naïve CD4⁺ T-cell purification and differentiation, and functional evaluation via flow cytometry. This protocol can also be applied for immature human CD4⁺ T cells. For complete details on the execution of this protocol, please refer to Wang et al. (2019).

Optimizing interleukin-2 concentration, seeding density and bead-to-cell ratio of T-cell expansion for adoptive immunotherapy

Background

The successful ex vivo expansion of T-cells in great numbers is the cornerstone of adoptive cell therapy. We aimed to achieve the most optimal T-cell expansion condition by comparing the expansion of T-cells at various seeding densities, IL-2 concentrations, and bead-to-cell ratios. we first expanded the peripheral blood mononuclear cells (PBMCs) of a healthy donor at a range of 20 to 500 IU/mL IL-2 concentrations, 125 × 10³ to 1.5 × 10⁶ cell/mL, and 1:10 to 10:1 B:C (Bead-to-cell) ratios and compared the results. We then expanded the PBMC of three healthy donors using the optimized conditions and examined the growth kinetics. On day 28, CD3, CD4, and CD8 expression of the cell populations were analyzed by flow cytometry.

Results

T-cells of the first donor showed greater expansion results in IL-2 concentrations higher than 50 IU/mL compared to 20 IU/mL (P = 0.02). A seeding density of 250 × 10³ cell/mL was superior to higher or lower densities in expanding T-cells (P = 0.025). Also, we witnessed a direct correlation between the B:C ratio and T-cell expansion, in which, in 5:1 and 10:1 B:C ratios T-cell significantly expanded more than lower B:C ratios. The results of PBMC expansions of three healthy donors were similar in growth kinetics. In the optimized condition, 96–98% of the lymphocyte population expressed CD3. While the majority of these cells expressed CD8, the mean expression of CD4 in the donors was 19.3, 16.5, and 20.4%.

Conclusions

Our methodology demonstrates an optimized culture condition for the production of large quantities of polyclonal T-cells, which could be useful for future clinical and research studies.

The Redox-Metabolic Couple of T Lymphocytes: Potential Consequences for Hypertension

Significance: T lymphocytes, as part of the adaptive immune system, possess the ability to activate and function in extreme cellular microenvironments, which requires these cells to remain highly malleable. One mechanism in which T lymphocytes achieve this adaptability is by responding to cues from both reactive oxygen and nitrogen species, as well as metabolic flux, which together fine-tune the functional fate of these adaptive immune cells. Recent Advances: To date, examinations of the redox and metabolic effects on T lymphocytes have primarily investigated these biological processes as separate entities. Given that the redox and metabolic environments possess significant overlaps of pathways and molecular species, it is inevitable that perturbations in one environment affect the other. Recent consideration of this redox-metabolic couple has demonstrated the strong link and regulatory consequences of these two systems in T lymphocytes. Critical Issues: The redox and metabolic control of T lymphocytes is essential to prevent dysregulated inflammation, which has been observed in cardiovascular diseases such as hypertension. The role of the adaptive immune system in hypertension has been extensively investigated, but the understanding of how the redox and metabolic environments control T lymphocytes in this disease remains unclear. Future Directions: Herein, we provide a discussion of the redox and metabolic control of T lymphocytes as separate entities, as well as coupled to one another, to regulate adaptive immunity. While investigations examining this pair together in T lymphocytes are sparse, we speculate that T lymphocyte destiny is shaped by the redox-metabolic couple. In contrast, disrupting this duo may have inflammatory consequences such as hypertension.

Oxidative stress in common variable immunodeficiency

Common variable immunodeficiency (CVID) is a heterogenous group of immunologic disorders of unknown etiology. Alterations of the normal cellular balance due to an increase in reactive oxygen species and/or decrease in antioxidant defense may lead to increased oxidative stress. We aimed to evaluate the levels of oxidative stress biomarkers in patients with CVID who had different presentations. We investigated the serum catalase (CAT), erythrocyte superoxide dismutase (SOD), erythrocyte reduced glutathione as antioxidants and serum malondialdehyde levels as lipid peroxidation marker in patients with CVID in Uludag University Hospital Department of Pediatric Allergy and Immunology’s outpatient clinics. In the analysis, there were 21 patients and 27 matched healthy controls. The median levels of CAT in patients with CVID was significantly lower than in healthy controls ( p = 0.04). Among the patients with CVID, 19% had autoimmune disease, one had Sjögren’s syndrome, one had autoimmune alopecia, one had juvenile rheumatoid arthritis, and one had chronic inflammatory demyelinating polyneuropathy. Patients with autoimmune complications had significantly lower CAT levels compared to the ones without autoimmune diseases ( p = 0.03). The patients without non-infectious complications (NICs) had lower SOD levels than the patients with NICs ( p = 0.05). The analysis of oxidative stress markers in the patients with CVID suggested a series of abnormalities in the anti-oxidant system. The clinical syndrome associations may be a useful tool for future studies to set prediction markers for the prognosis of patients with CVID.

Eryptosis and Malaria: New Experimental Guidelines and Re-Evaluation of the Antimalarial Potential of Eryptosis Inducers

Erythrocytes possess an unusual programmed cell death mechanism termed eryptosis, and several compounds have been previously claimed to induce eryptosis in vitro. Malaria parasites (genus Plasmodium) reside in erythrocytes during the pathogenic part of their life cycle, and the potential of several eryptosis inducers to act as antimalarials has been tested in recent years. However, the eryptosis-inducing capacity of these compounds varies significantly between eryptosis-focused studies and malaria investigations. Here, we investigated the reasons for these discrepancies, we developed a protocol to investigate eryptosis in malaria cultures and we re-evaluated the potential of eryptosis inducers as antimalarials. First, we showed that eryptosis read-out in vitro is dependent on culture conditions. Indeed, conditions that have consistently been used to study eryptosis do not support P. falciparum growth and prime erythrocytes for eryptosis. Next, we defined culture conditions that allow the detection of eryptosis while supporting P. falciparum survival. Finally, we selected six eryptosis-inducers based on their clinical use, molecular target and antimalarial activities, and re-evaluated their eryptosis inducing capacities and their potential as antimalarials. We demonstrate that none of these compounds affect the viability of naïve or P. falciparum-infected erythrocytes in vitro. Nevertheless, three of these compounds impair parasite development, although through a mechanism unrelated to eryptosis and yet to be elucidated. We conclude that careful consideration of experimental set up is key for the accurate assessment of the eryptosis-inducing potential of compounds and their evaluation as potential antimalarials.

Cryopreservation as a Key Element in the Successful Delivery of Cell-Based Therapies-A Review

Cryopreservation is a key enabling technology in regenerative medicine that provides stable and secure extended cell storage for primary tissue isolates and constructs and prepared cell preparations. The essential detail of the process as it can be applied to cell-based therapies is set out in this review, covering tissue and cell isolation, cryoprotection, cooling and freezing, frozen storage and transport, thawing, and recovery. The aim is to provide clinical scientists with an overview of the benefits and difficulties associated with cryopreservation to assist them with problem resolution in their routine work, or to enable them to consider future involvement in cryopreservative procedures. It is also intended to facilitate networking between clinicians and cryo-researchers to review difficulties and problems to advance protocol optimization and innovative design.

Rapid Transduction and Expansion of Transduced T Cells with Maintenance of Central Memory Populations

Chimeric antigen receptor (CAR)-T cells show great promise in treating cancers and viral infections. However, most protocols developed to expand T cells require relatively long periods of time in culture, potentially leading to progression toward populations of terminally differentiated effector memory cells. Here, we describe in detail a 9-day protocol for CAR gene transduction and expansion of primary rhesus macaque peripheral blood mononuclear cells (PBMCs). Cells produced and expanded with this method show high levels of viability, high levels of co-expression of two transduced genes, retention of the central memory phenotype, and sufficient quantity for immunotherapeutic infusion of 1-2 × 108 cells/kg in a 10 kg rhesus macaque. This 9-day protocol may be broadly used for CAR-T cell and other T cell immunotherapy approaches to decrease culture time and increase maintenance of central memory populations.

Modeling cell-cell communication for immune systems across space and time

Communicating is crucial for cells to coordinate their behaviors. Immunological processes, involving diverse cytokines and cell types, are ideal for developing frameworks for modeling coordinated behaviors of cells. Here, we review recent studies that combine modeling and experiments to reveal how immune systems use autocrine, paracrine, and juxtacrine signals to achieve behaviors such as controlling population densities and hair regenerations. We explain that models are useful because one can computationally vary numerous parameters, in experimentally infeasible ways, to evaluate alternate immunological responses. For each model, we focus on the length-scales and time-scales involved and explain why integrating multiple length-scales and time-scales in a model remain challenging. We suggest promising modeling strategies for meeting this challenge and their practical consequences.

A PBMC-Based System to Assess Human T Cell Responses to Influenza Vaccine Candidates In Vitro

Vaccine development is an expensive and time-consuming process that heavily relies on animal models. Yet, vaccine candidates that have previously succeeded in animal experiments often fail in clinical trials questioning the predictive value of animal models. Alternative assay systems that can add to the screening and evaluation of functional characteristics of vaccines in a human context before embarking on costly clinical trials are therefore urgently needed. In this study, we have established an in vitro system consisting of long-term cultures of unfractionated peripheral blood mononuclear cells (PBMCs) from healthy volunteers to assess (recall) T cell responses to vaccine candidates. We observed that different types of influenza vaccines (whole inactivated virus (WIV), split, and peptide vaccines) were all able to stimulate CD4 and CD8 T cell responses but to different extents in line with their reported in vivo properties. In-depth analyses of different T cell subsets revealed that the tested vaccines evoked mainly recall responses as indicated by the fact that the vast majority of the responding T cells had a memory phenotype. Furthermore, we observed vaccine-induced activation of T follicular helper cells, which are associated with the induction of humoral immune responses. Our results demonstrate the suitability of the established PBMC-based system for the in vitro evaluation of memory T cell responses to vaccines and the comparison of vaccine candidates in a human immune cell context. As such, it can help to bridge the gap between animal experiments and clinical trials and assist in the selection of promising vaccine candidates, at least for recall antigens.

Enhanced metabolic activities for ATP production and elevated metabolic flux via pentose phosphate pathway contribute for better CIK cells expansion

Objective

Ex vivo expansion is an effective way to produce cytokine‐induced killer (CIK) cells needed for clinical trials. Here, ex vivo expansion and metabolism characters of CIK cells in static and dynamic cultures and the relationship between cell expansion and metabolism were investigated.

Materials and methods

Oxygen transfer efficiency was assessed by computational fluid dynamics technique. Cell phenotype, apoptosis and of transporter expression were determined by flow cytometry and Western blotting. Metabolites and enzyme activities were assessed by biochemical methods.

Results

Dynamic cultures favoured better CIK cell expansion without impairing their phenotype and cytotoxicity, enhanced oxygen transfer efficiency. The glucose metabolism flux of cells in dynamic cultures was enhanced by upregulating surface glucose transporter 1 expression and phosphofructokinase activity. Moreover, pentose phosphate pathway (PPP) metabolic flux was enhanced through upregulating glucose‐6‐phosphate dehydrogenase activity. Glutaminolysis was also accelerated via boosting glutamine transporters expression, glutaminase (GLS) and glutamate dehydrogenase activities. Together with higher oxygen consumption rate and extracellular acidification rate, it was suggested that cells in dynamic cultures were in a more vigorous metabolic state for ATP production.

Conclusion

Dynamic cultures accelerated glucose and glutamine metabolic flux to promote ATP production, elevated glucose metabolic flux through PPP to promote biosynthesis for better cell expansion. These findings may provide the basis for ex vivo CIK cell expansion process optimization.

A dual neutrophil-T cell purification procedure and methodological considerations in studying the effects of estrogen on human Th17 cell differentiation

New procedures are required to optimize the use of blood samples to study different cell types. The purification of neutrophils and T cells from the same blood sample is not commonly described. We have previously used PolymorphPrep™ (P) or LymphoPrep™ (L) for purifying neutrophils or T cells, respectively. In this study, we describe a new method for purifying both of these cells using P and L from the same sample, and methodological considerations required to obtain consistent Th17 differentiation results. For T cell studies, we first isolated mononuclear cells from peripheral blood of healthy humans using either P alone, L alone or sequential isolation with P and then L (P + L). CD3⁺ lymphocytes comprise up to 73% of peripheral blood mononuclear cells (PBMCs) obtained by sequential isolation, with 29% and 36% for P and L, respectively. T lymphocyte subsets, Th1, Th17 or double-positive (Th17/1), were then amplified. Four days of amplification culture after isolation by P alone led to over-expression of Th17/1 cells and of Th17 cells in comparison to cells isolated by L or by sequential P + L. Th17/1 cells comprised 11.0 ± 6.8% (P alone) vs 1.2 ± 0.28% (L alone) vs 0.45 ± 0.11% (P + L) and Th17 cells comprised 2.8 ± 0.4% (P alone) 0.88 ± 0.15% (L alone) vs 0.86 ± 0.14% (P + L). As the second step, we examined T cell purification and differentiation. A higher purity of 97.1 ± 0.44% naïve CD4⁺ T cell was reached after P + L followed by immunomagnetic bead sorting in comparison to 70 ± 9.3% (L) vs 21.0 ± 8.5% (P). These cells grew well in the density range of 25, 000 to 100, 000 cells per well in 96-well plates during Th17 cell differentiation; higher or lower cell density did not support Th17 cell differentiation. Lastly, to investigate the effect of estrogen on Th17 cell differentiation, serum-free AIM V medium without phenol red was chosen to minimize the hormonal effects of the medium. We found that exogenous estrogen (1 nM) inhibited Th17 cell differentiation in this medium. Taken together, we devised a method to isolate both neutrophils and T cells from the same blood sample and show that high PBMC purity, selected culture medium and an optimal cell density of the initial cell culture produced the most robust and consistent results for Th17 differentiation.

Chronic exposure of the RAW246.7 macrophage cell line to H2O2 leads to increased catalase expression

Altered cellular redox states have been associated with a variety of chronic diseases, especially those correlated with inflammation. One of the primary oxidants generated during the inflammatory response is hydrogen peroxide (H₂O₂). Macrophages in particular are thought to produce large amounts of H₂O₂, however they must somehow protect themselves from the potentially lethal concentrations they produce. To investigate how immune cells protect themselves from H₂O₂ observed in chronic inflammatory diseases, we established an adapted population of macrophages in culture by gradually increasing sub-lethal concentrations of H₂O₂ in the media to typically lethal concentrations over the course of more than a month. The resulting cells were tolerant to very high concentrations of H₂O₂. Further investigation revealed that the cells were able to rapidly neutralize the H₂O₂ added to their culture media due to a dramatic upregulation of catalase. Interestingly, T cells, which are also implicated in chronic inflammation, were unable to adapt to H₂O₂ under the same procedure, however when T cells were cultured in media from adapted macrophages, they were able to survive typically lethal concentrations of H₂O₂. These data support the hypothesis that macrophages are able to protect themselves and neighboring cells during states of chronic inflammation from the oxidizing environment they create.

High-Throughput Screening of Rat Mesenchymal Stem Cell Behavior on Gradient TiO2 Nanotubes

The dimension of TiO₂ nanotubes (TNTs) ranges from several nanometers to hundreds of nanometers. This variety raises the difficulty of screening suitable nanotube dimension for biomedical applications. Herein, we report the use of a simple one-step bipolar anodization method for fabrication of TNT gradients with diameter range from 30 to 100 nm. The gradient TNTs were successfully applied for high-throughput screening of TNT size effect on cell responses, including cell adhesion, proliferation, and differentiation. Results reveal that no significant difference in adherent cell number could be found within the range of 30-87 nm in both the presence and absence of serum proteins. On the contrary, large nanotubes (with outer diameter >87 nm) profoundly reduce cell adhesion in both the presence and absence of serum proteins, indicating TNT size could affect cell adhesion directly without the adsorbed proteins. The size effect on cell behavior becomes prominent with time that cell proliferation and differentiation decrease with increasing nanotube size. This size effect can be comprehended by protein adsorption and the formation of focal adhesion. Another two sample applications of gradient TNTs demonstrate gradient TNTs are promising for high-throughput screening.

Review: Bioengineering strategies to probe T cell mechanobiology

T cells play a major role in adaptive immune response, and T cell dysfunction can lead to the progression of several diseases that are often associated with changes in the mechanical properties of tissues. However, the concept that mechanical forces play a vital role in T cell activation and signaling is relatively new. The endogenous T cell microenvironment is highly complex and dynamic, involving multiple, simultaneous cell-cell and cell-matrix interactions. This native complexity has made it a challenge to isolate the effects of mechanical stimuli on T cell activation. In response, researchers have begun developing engineered platforms that recapitulate key aspects of the native microenvironment to dissect these complex interactions in order to gain a better understanding of T cell mechanotransduction. In this review, we first describe some of the unique characteristics of T cells and the mounting research that has shown they are mechanosensitive. We then detail the specific bioengineering strategies that have been used to date to measure and perturb the mechanical forces at play during T cell activation. In addition, we look at engineering strategies that have been used successfully in mechanotransduction studies for other cell types and describe adaptations that may make them suitable for use with T cells. These engineering strategies can be classified as 2D, so-called 2.5D, or 3D culture systems. In the future, findings from this emerging field will lead to an optimization of culture environments for T cell expansion and the development of new T cell immunotherapies for cancer and other immune diseases.

Vγ9Vδ2 T cell activation by strongly agonistic nucleotidic phosphoantigens

Human Vγ9Vδ2 T cells can sense through their TCR tumor cells producing the weak endogenous phosphorylated antigen isopentenyl pyrophosphate (IPP), or bacterially infected cells producing the strong agonist hydroxyl dimethylallyl pyrophosphate (HDMAPP). The recognition of the phosphoantigen is dependent on its binding to the intracellular B30.2 domain of butyrophilin BTN3A1. Most studies have focused on pyrophosphate phosphoantigens. As triphosphate nucleotide derivatives are naturally co-produced with IPP and HDMAPP, we analyzed their specific properties using synthetic nucleotides derived from HDMAPP. The adenylated, thymidylated and uridylated triphosphate derivatives were found to activate directly Vγ9Vδ2 cell lines as efficiently as HDMAPP in the absence of accessory cells. These antigens were inherently resistant to terminal phosphatases, but apyrase, when added during a direct stimulation of Vγ9Vδ2 cells, abrogated their stimulating activity, indicating that their activity required transformation into strong pyrophosphate agonists by a nucleotide pyrophosphatase activity which is present in serum. Tumor cells can be sensitized with nucleotide phosphoantigens in the presence of apyrase to become stimulatory, showing that this can occur before their hydrolysis into pyrophosphates. Whereas tumors sensitized with HDMAPP rapidly lost their stimulatory activity, sensitization with nucleotide derivatives, in particular with the thymidine derivative, induced long-lasting stimulating ability. Using isothermal titration calorimetry, binding of some nucleotide derivatives to BTN3A1 intracellular domain was found to occur with an affinity similar to that of IPP, but much lower than that of HDMAPP. Thus, nucleotide phosphoantigens are precursors of pyrophosphate antigens which can deliver strong agonists intracellularly resulting in prolonged and strengthened activity.

An Integrative Computational Approach to Evaluate Genetic Markers for Chronic Lymphocytic Leukemia

Recent studies reported hundreds of genes linked to chronic lymphocytic leukemia (CLL). However, many of these candidate genes were lack of replication and results were not always consistent. Here, we proposed a computational workflow to curate and evaluate CLL-related genes. The method integrates large-scale literature knowledge data, gene expression data, and related pathways/network information for quantitative marker evaluation. Pathway Enrichment, Sub-Network Enrichment, and Gene-Gene Interaction analysis were conducted to study the pathogenic profile of the candidate genes, with four metrics proposed and validated for each gene. By using our approach, a scalable CLL genetic database was developed including CLL-related genes, pathways, diseases and information of supporting references. The CLL case/control classification supported the effectiveness of the four proposed metrics, which successfully identified nine well-studied CLL genes (i.e., TNF, BCL2, TP53, VEGFA, P2RX7, AKT1, SYK, IL4, and MDM2) and highlighted two newly reported CLL genes (i.e., PDGFRA and CSF1R). The computational biology approach and the CLL database developed in this study provide a valuable resource that may facilitate the understanding of the genetic profile of CLL.

Overexpression of zinc-finger protein 777 (ZNF777) inhibits proliferation at low cell density through down-regulation of FAM129A

Krüppel-associated box-containing zinc finger proteins (KRAB-ZFPs) regulate a wide range of cellular processes. KRAB-ZFPs have a KRAB domain, which binds to transcriptional corepressors, and a zinc finger domain, which binds to DNA to activate or repress gene transcription. Here, we characterize ZNF777, a member of KRAB-ZFPs. We show that ZNF777 localizes to the nucleus and inducible overexpression of ZNF777 inhibits cell proliferation in a manner dependent on its zinc finger domain but independent of its KRAB domain. Intriguingly, ZNF777 overexpression drastically inhibits cell proliferation at low cell density but slightly inhibits cell proliferation at high cell density. Furthermore, ZNF777 overexpression decreases the mRNA level of FAM129A irrespective of cell density. Importantly, the protein level of FAM129A strongly decreases at low cell density, but at high cell density the protein level of FAM129A does not decrease to that observed at low cell density. ZNF777-mediated inhibition of cell proliferation is attenuated by overexpression of FAM129A at low cell density. Furthermore, ZNF777-mediated down-regulation of FAM129A induces moderate levels of the cyclin-dependent kinase inhibitor p21. These results suggest that ZNF777 overexpression inhibits cell proliferation at low cell density and that p21 induction by ZNF777-mediated down-regulation of FAM129A plays a role in inhibition of cell proliferation.

Stress-related and homeostatic cytokines regulate Vγ9Vδ2 T-cell surveillance of mevalonate metabolism

The potentially oncogenic mevalonate pathway provides building blocks for protein prenylation and induces cell proliferation and as such is an important therapeutic target. Among mevalonate metabolites, only isopentenyl pyrophosphate (IPP) has been considered to be an immunologically relevant antigen for primate-specific, innate-like Vγ9Vδ2 T cells with antitumor potential. We show here that Vγ9Vδ2 T cells pretreated with the stress-related, inflammasome-dependent cytokine interleukin 18 (IL-18) were potently activated not only by IPP but also by all downstream isoprenoid pyrophosphates that exhibit combined features of antigens and cell-extrinsic metabolic cues. Vγ9Vδ2 T cells induced this way effectively proliferated even under severe lymphopenic conditions and the antioxidant N-acetylcysteine significantly improved reconstitution of γδ T cells predominantly with a central memory phenotype. The homeostatic cytokine IL-15 induced the differentiation of effector cells in an antigen-independent fashion, which rapidly produced abundant interferon γ (IFNγ) upon antigen re-encounter. IL-15 induced effector γδ T cells displayed increased levels of the cytotoxic lymphocyte-associated proteins CD56, CD96, CD161 and perforin. In response to stimulation with isoprenoid pyrophosphates, these effector cells upregulated surface expression of CD107a and exhibited strong cytotoxicity against tumor cells in vitro. Our data clarify understanding of innate immunosurveillance mechanisms and will facilitate the controlled generation of robust Vγ9Vδ2 T cell subsets for effective cancer immunotherapy.

Sec-containing TrxR1 is essential for self-sufficiency of cells by control of glucose-derived H2O2

It is commonly recognized that diabetic complications involve increased oxidative stress directly triggered by hyperglycemia. The most important cellular protective systems against such oxidative stress have yet remained unclear. Here we show that the selenoprotein thioredoxin reductase 1 (TrxR1), encoded by the Txnrd1 gene, is an essential enzyme for such protection. Individually grown Txnrd1 knockout (Txnrd1^−/−) mouse embryonic fibroblasts (MEFs) underwent massive cell death directly linked to glucose-induced H₂O₂ production. This death and excessive H₂O₂ levels could be reverted by reconstituted expression of selenocysteine (Sec)-containing TrxR1, but not by expression of Sec-devoid variants of the enzyme. Our results show that Sec-containing TrxR1 is absolutely required for self-sufficient growth of MEFs under high-glucose conditions, owing to an essential importance of this enzyme for elimination of glucose-derived H₂O₂. To our knowledge, this is the first time a strict Sec-dependent function of TrxR1 has been identified as being essential for mammalian cells.

Reaction of monocytes to polystyrene and silica nanoparticles in short-term and long-term exposures

Nanoparticles (NPs) are increasingly used in industrial, health and consumer products. In addition to the intended effects, NPs may also cause cell damage. Typical cytotoxicity assays assess short-term effects in adherent cells but do not evaluate longer exposure times and do not focus on cells in suspension. Since NPs are not removed easily from the organism, non-biodegradable NPs may persist in the systemic circulation and affect monocyte function at low concentrations. To mimic this situation, THP-1 monocytes were exposed to low concentrations of plain polystyrene particles (PPP) in different sizes for short (24 h) and prolonged (16 d) time periods. CELLine CL350, a small two-chamber bioreactor, and sub-culturing in flasks were compared regarding prolonged cytotoxicity testing. Uptake rates of the particles, cytotoxicity screening assays, and interleukin secretion were used for the identification of adverse effects. After 24 h, 50 μg ml-1 20 nm PPP did not affect cellular viability and interleukin secretion, while at higher concentrations the cytotoxicity of PPP (20 nm-500 nm) was correlated to surface area. After 16 d of exposure at 50 μg ml-1 20 nm PPP, the decrease in cell number and the increase in interleukins were significant. 200 nm PPP, by contrast, caused only minimal effects. Due to lower reproducibility, CELLine proved to be less suitable for the assessment as compared to sub-culturing in flasks. After prolonged exposure, silica Aerosil OX50 particles also were more cytotoxic towards THP-1 monocytes. The data suggest that prolonged exposure to NPs leads to cytotoxicity at low doses and that induction of cell death may be involved in the observed pro-inflammatory action of NPs.

Redox regulation of T-cell function: from molecular mechanisms to significance in human health and disease

Reactive oxygen species (ROS) are thought to have effects on T-cell function and proliferation. Low concentrations of ROS in T cells are a prerequisite for cell survival, and increased ROS accumulation can lead to apoptosis/necrosis. The cellular redox state of a T cell can also affect T-cell receptor signaling, skewing the immune response. Various T-cell subsets have different redox statuses, and this differential ROS susceptibility could modulate the outcome of an immune response in various disease states. Recent advances in T-cell redox signaling reveal that ROS modulate signaling cascades such as the mitogen-activated protein kinase, phosphoinositide 3-kinase (PI3K)/AKT, and JAK/STAT pathways. Also, tumor microenvironments, chronic T-cell stimulation leading to replicative senescence, gender, and age affect T-cell susceptibility to ROS, thereby contributing to diverse immune outcomes. Antioxidants such as glutathione, thioredoxin, superoxide dismutase, and catalase balance cellular oxidative stress. T-cell redox states are also regulated by expression of various vitamins and dietary compounds. Changes in T-cell redox regulation may affect the pathogenesis of various human diseases. Many strategies to control oxidative stress have been employed for various diseases, including the use of active antioxidants from dietary products and pharmacologic or genetic engineering of antioxidant genes in T cells. Here, we discuss the existence of a complex web of molecules/factors that exogenously or endogenously affect oxidants, and we relate these molecules to potential therapeutics.

High cell density attenuates reactive oxygen species: implications for in vitro assays

In vitro cell-based assays are an essential and universally used step in elucidation of biological processes as well as in drug development. However, results obtained depend on the validity of protocols used. This statement certainly pertains to in vitro assays of oxidative stress. The holy grail of in vitro models is reliability and predictability of outcomes that relate to a single variable like addition of hydrogen peroxide or xanthine oxidase. Without such validated outcomes, comparison of results among different laboratories is not possible. Achieving this goal requires a thorough understanding of the complex interplay between the cells, their environment, and the experimental assays. Furthermore, as this knowledge is attained, it must be disseminated and used to update and standardize existing protocols. Here, we confirm and extend the effect of pyruvate and cell density on in vitro oxidative stress assays. Cell viability was assessed using a colorimetric assay measuring the reduction of a tetrazolium salt (XTT) into a colored formazan dye. Extracellular hydrogen peroxide concentrations were measured using the foxp3 assay. We confirmed a previously reported finding that pyruvate, a common ingredient in cell culture media, acts as an extracellular scavenger of reactive oxygen species. We also demonstrated that cell density directly correlates with resistance to oxidative stress in tissue culture. It is theorized that the protective effect due to cell density predominantly relates to intracellular factors such as reduced glutathione and extracellular factors such as catalase.