Engineering cytokines and cytokine circuits

Polyethylene microplastics impair chicken growth through gut microbiota-induced hepatic fatty acid metabolism dysfunction

Microplastics (MPs) negatively impact various terrestrial animals, but their comprehensive effects on Gallus gallus domesticus, key agricultural and ecological species connecting people and the environment, are not well-documented. This study investigates the effects of polyethylene (PE) MPs and phthalate esters (PAEs) on chicken growth, liver metabolism, and gut microbiota using multi-omics and 16S rRNA sequencing technology. Results show that PE MPs, particularly those containing PAEs, significantly reduced body weight gain and hepatic triglyceride levels by up to 71.2 % and 50.1 %, respectively (p < 0.05). The clean MPs affected energy metabolism, while PAE-spiked MPs disrupted fatty acid metabolism and triggered immune and inflammatory responses in the liver. Key genes related to fatty acid metabolism such as FAN, SCD and ELOVL5 were significantly downregulated, leading to imbalances in lipid metabolism. These disruptions in PAE-spiked MPs exposure were associated with the altered gut microbiota balance, including increased Firmicutes/Bacteroidetes ratios and changes in Actinobacteriota and Proteobacteria abundance. Totally, the study highlights a "Trojan Horse" effect, where MPs act as carriers for PAEs, intensifying toxicity through gut-liver axis interactions. The findings emphasize the role of gut microbiota in mediating liver dysfunction and impaired growth.

Changes in Macrophages in Pulmonary Hypertension: A Focus on High-altitude Pulmonary Hypertension

High-altitude pulmonary hypertension (HAPH) is a condition characterized by elevated pulmonary arterial pressure exceeding normal physiological values, resulting from a combination of high-altitude low-pressure, hypoxic environments, genetic susceptibility, immune dysfunction, and neurogenic disturbances. This condition predominantly manifests as right heart failure, severely impacting quality of life and life expectancy. Macrophages, as one of the most prevalent innate immune cells, have been increasingly recognized for their crucial role in the pathogenesis of HAPH. The low-pressure and hypoxic environment, along with other etiological factors, lead to metabolic abnormalities in tissue cells and the microenvironment. This results in increased secretion of chemokines, cytokines, and growth factors in the microenvironment, which promote the proliferation of tissue-resident macrophages and the differentiation of monocytes recruited from the blood into macrophages. This exacerbates the inflammatory cascade, further promoting cell proliferation, tissue repair, and inhibition of apoptosis. These processes contribute to the migration and proliferation of pulmonary arterial smooth muscle cells, endothelial cells, and fibroblasts, leading to vascular remodeling and ultimately the development of pulmonary arterial hypertension. This review examines the role of macrophage-mediated immune responses in high-altitude pulmonary arterial hypertension, with a focus on hypoxia as a key feature.

Synthetic transmembrane DNA receptors enable engineered sensing and actuation

In living organisms, cells synergistically couple cascade reaction pathways to achieve inter- and intracellular signal transduction by transmembrane protein receptors. The construction and assembly of synthetic receptor analogs that can mimic such biological processes is a central goal of synthetic biochemistry and bionanotechnology to endow receptors with user-defined signal transduction effects. However, designing artificial transmembrane receptors with the desired input, output, and performance parameters are challenging. Here we show that the dimerization of synthetic transmembrane DNA receptors executes a systematically engineered sensing and actuation cascade in response to external molecular signals. The synthetic DNA receptors are composed of three parts, including an extracellular signal reception part, a lipophilic transmembrane anchoring part, and an intracellular signal output part. Upon the input of external signals, the DNA receptors can form dimers on the cell surface triggered by configuration changes, leading to a series of downstream cascade events including communication between donor and recipient cells, gene transcription regulation, protein level control, and cell apoptosis. We believe this work establishes a flexible cell surface engineering strategy that is broadly applicable to implement sophisticated biological functions.

Characterization and functional analysis of interleukin-6 and its receptor subunits (IL-6Rα and IL-6Rβ) in the yellow drum, Nibea alibiflora

Interleukin 6 (IL-6) is one of the cytokines found to be multifunctional and biologically effective, regulating immune and inflammatory response by interacting with receptors to transmit signals. In this study, the full-length cDNAs of IL-6 (named as NaIL-6) and its receptors IL-6R and gp130 (named as NaIL-6Rα and NaIL-6Rβ) of Nibea albiflora were acquired and they possessed the typical symbolic motifs similar to its teleost orthologues in multiple sequence comparisons. The phylogenetic trees showed that NaIL-6 and its receptors clustered with their counterparts in bony fish, and had the closest affinity to Larimichthys crocea. Real-time PCR indicated that NaIL-6, NaIL-6Rα and NaIL-6Rβ were widely expressed in different tissues, among which NaIL-6 was highly expressed in the liver, NaIL-6Rα showed the highest expression in the kidney and NaIL-6Rβ was reflected in the liver. Following stimulation by Vibrio parahaemolyticus, Vibrio alginolyticus, or Polyinosinic-polycytidylic acid (Poly (I:C)) infection, the mRNA expression of all three genes were greatly up-regulated over time. The cell localization analysis showed that NaIL-6 distributed in cytoplasm and cell membrane, and NaIL-6Rα located on the cell membrane. After co-transfection of NaIL-6- mCherry and NaIL-6Rα-EGFP, they co-expressed as orange at the same position for their possibility of spatial interactions on the cellular membrane. By GST-Pull down with the purified target proteins, the association between NaIL-6-His and NaIL-6Rα-GST was confirmed, which may be utilized for further functional study. Taken together, the results indicated that the biological functions of NaIL-6 and its receptors NaIL-6Rα and NaIL-6Rβ involved in the immunologic mechanism in N.albiflora, which would provide a basis for the research of immune functions and signaling pathway of IL-6 and its receptors in fish.

Engineering synthetic suppressor T cells that execute locally targeted immunoprotective programs

Immune homeostasis requires a balance of inflammatory and suppressive activities. To design cells potentially useful for local immune suppression, we engineered conventional CD4+ T cells with synthetic Notch (synNotch) receptors driving antigen-triggered production of anti-inflammatory payloads. Screening a diverse library of suppression programs, we observed the strongest suppression of cytotoxic T cell attack by the production of both anti-inflammatory factors (interleukin-10, transforming growth factor-β1, programmed death ligand 1) and sinks for proinflammatory cytokines (interleukin-2 receptor subunit CD25). Engineered cells with bespoke regulatory programs protected tissues from immune attack without systemic suppression. Synthetic suppressor T cells protected transplanted beta cell organoids from cytotoxic T cells. They also protected specific tissues from unwanted chimeric antigen receptor (CAR) T cell cross-reaction. Synthetic suppressor T cells are a customizable platform to potentially treat autoimmune diseases, organ rejection, and CAR T cell toxicities with spatial precision.

Role of Non-Binding T63 Alteration in IL-18 Binding

Engineered interleukin-18 (IL-18) has attracted interest as a cytokine-based treatment. However, knowledge-based mutagenesis of IL-18 has been reported for only a few regions of the protein structures, including binding sites I and II. When coupled with the binding region mutant (E6K), the non-binding residue of IL-18, Thr63 (T63), has been shown to increase the flexibility of the binding loop. Nevertheless, the function of Thr63 in conformational regulation is still unknown. Using homology modeling, molecular dynamics simulation, and structural analysis, we investigated the effects of Thr63 alteration coupling with E6K on conformational change pattern, binding loop flexibility, and the hydrogen bond network. The results indicate that the 63rd residue was significantly associated with hydrogen-bond relaxation at the core β-barrel binding sites I and II Glu85-Ile100 loop. This result provided conformational and flexible effects to binding sites I and III by switching their binding loops and stabilizing the 63rd residue cavity. These findings may pave the way for the conceptualization of a new design for IL-18 proteins by modifying non-binding residues for structure-based drug development.

De novo functional discovery of peptide-MHC restricted CARs from recombinase-constructed large-diversity monoclonal T cell libraries

Chimeric antigen receptors (CAR) that mimic T cell receptors (TCR) on eliciting peptide-major histocompatibility complex (pMHC) specific T cell responses hold great promise in the development of immunotherapies against solid tumors, infections, and autoimmune diseases. However, broad applications of TCR-mimic (TCRm) CARs are hindered to date largely due to lack of a facile approach for the effective isolation of TCRm CARs. Here, we establish a highly efficient process for de novo discovery of TCRm CARs from human naïve antibody repertories by combining recombinase-mediated large-diversity monoclonal library construction with T cell activation-based positive and negative screenings. Panels of highly functional TCRm CARs with peptide-specific recognition, minimal cross-reactivity, and low tonic signaling were rapidly identified towards MHC-restricted intracellular tumor-associated antigens MAGE-A3, NY-ESO-1, and MART-1. Transduced TCRm CAR-T cells exhibited pMHC-specific functional avidity, potent cytokine release, and efficacious and persistent cytotoxicity. The developed approach could be used to generate safe and potent immunotherapies targeting MHC-restricted antigens.

Advancements and challenges in immunocytokines: A new arsenal against cancer

Immunocytokines, employing targeted antibodies to concentrate cytokines at tumor sites, have shown potential advantages such as prolonged cytokine half-lives, mitigated adverse effects, and synergistic antitumor efficacy from both antibody and cytokine components. First, we present an in-depth analysis of the advancements of immunocytokines evaluated in preclinical and clinical applications. Notably, anti-PD-1-based immunocytokines can redirect cytokines to intratumoral CD8+ T cells and reinvigorate them to elicit robust antitumor immune responses. Then, we focus on their molecular structures and action mechanisms, striving to elucidate the correlations between diverse molecular structures and their antitumor efficacy. Moreover, our exploration extends to the realm of novel cytokines, including IL-10, IL-18, and IL-24, unraveling their potential in the construction of immunocytokines. However, safety concerns remain substantial barriers to immunocytokines' development. To address this challenge, we explore potential strategies, such as cytokine engineering and prodrug design, which can foster next-generation immunocytokines development. Overall, this review concentrates on the design of molecular structures in immunocytokines, underscoring the direction and focus of ongoing efforts to improve safety profiles while maximizing therapeutic efficacy.

Integrating Computational Design and Experimental Approaches for Next-Generation Biologics

Therapeutic protein engineering has revolutionized medicine by enabling the development of highly specific and potent treatments for a wide range of diseases. This review examines recent advances in computational and experimental approaches for engineering improved protein therapeutics. Key areas of focus include antibody engineering, enzyme replacement therapies, and cytokine-based drugs. Computational methods like structure-based design, machine learning integration, and protein language models have dramatically enhanced our ability to predict protein properties and guide engineering efforts. Experimental techniques such as directed evolution and rational design approaches continue to evolve, with high-throughput methods accelerating the discovery process. Applications of these methods have led to breakthroughs in affinity maturation, bispecific antibodies, enzyme stability enhancement, and the development of conditionally active cytokines. Emerging approaches like intracellular protein delivery, stimulus-responsive proteins, and de novo designed therapeutic proteins offer exciting new possibilities. However, challenges remain in predicting in vivo behavior, scalable manufacturing, immunogenicity mitigation, and targeted delivery. Addressing these challenges will require continued integration of computational and experimental methods, as well as a deeper understanding of protein behavior in complex physiological environments. As the field advances, we can anticipate increasingly sophisticated and effective protein therapeutics for treating human diseases.

Controlled Refolding of Denatured IL-12 Using In Situ Antigen-Capturing Nanochaperone Remarkably Reduces the Systemic Toxicity and Enhances Cancer Immunotherapy

Cytokines are powerful in cancer immunotherapy, however, their therapeutic potential is limited by the severe systemic toxicity. Here a potent strategy to reduce the toxicity of systemic cytokine therapy by delivering its denatured form using a finely designed nanochaperone, is described. It is demonstrated that even if the denatured protein cargos are occasionally released under normal physiological conditions they are still misfolded, while can effectively refold into native states and release to function in tumor microenvironment. Consequently, the systemic toxicity of cytokines is nearly completely overcome. Moreover, an immunogenic cell death (ICD)-inducing chemotherapeutic is further loaded and delivered to tumor using this nanochaperone to trigger the release of tumor-associated antigens (TAAs) that are subsequently captured in situ by nanochaperone and then reflows into lymph nodes (LNs) to promote antigen cross-presentation. This optimized personalized nanochaperone-vaccine demonstrates unprecedented suppressive effects against large, advanced tumors, and in combination with immune checkpoint blockade (ICB) therapy results in a significant abscopal effect and inhibition of postoperative tumor recurrence and metastasis. Hence, this approach provides a simple and universal delivery strategy to reduce the systemic toxicities of cytokines, as well as provides a robust personalized cancer vaccination platform, which may find wide applications in cancer immunotherapy.

In vivo macrophage engineering reshapes the tumor microenvironment leading to eradication of liver metastases

Liver metastases are associated with poor response to current pharmacological treatments, including immunotherapy. We describe a lentiviral vector (LV) platform to selectively engineer liver macrophages, including Kupffer cells and tumor-associated macrophages (TAMs), to deliver type I interferon (IFNα) to liver metastases. Gene-based IFNα delivery delays the growth of colorectal and pancreatic ductal adenocarcinoma liver metastases in mice. Response to IFNα is associated with TAM immune activation, enhanced MHC-II-restricted antigen presentation and reduced exhaustion of CD8+ T cells. Conversely, increased IL-10 signaling, expansion of Eomes CD4+ T cells, a cell type displaying features of type I regulatory T (Tr1) cells, and CTLA-4 expression are associated with resistance to therapy. Targeting regulatory T cell functions by combinatorial CTLA-4 immune checkpoint blockade and IFNα LV delivery expands tumor-reactive T cells, attaining complete response in most mice. These findings support a promising therapeutic strategy with feasible translation to patients with unmet medical need.

A synthetic biology approach to engineering circuits in immune cells

A synthetic circuit in a biological system involves the designed assembly of genetic elements, biomolecules, or cells to create a defined function. These circuits are central in synthetic biology, enabling the reprogramming of cellular behavior and the engineering of cells with customized responses. In cancer therapeutics, engineering T cells with circuits have the potential to overcome the challenges of current approaches, for example, by allowing specific recognition and killing of cancer cells. Recent advances also facilitate engineering integrated circuits for the controlled release of therapeutic molecules at specified locations, for example, in a solid tumor. In this review, we discuss recent strategies and applications of synthetic receptor circuits aimed at enhancing immune cell functions for cancer immunotherapy. We begin by introducing the concept of circuits in networks at the molecular and cellular scales and provide an analysis of the development and implementation of several synthetic circuits in T cells that have the goal to overcome current challenges in cancer immunotherapy. These include specific targeting of cancer cells, increased T-cell proliferation, and persistence in the tumor microenvironment. By harnessing the power of synthetic biology, and the characteristics of certain circuit architectures, it is now possible to engineer a new generation of immune cells that recognize cancer cells, while minimizing off-target toxicities. We specifically discuss T-cell circuits for antigen density sensing. These circuits allow targeting of solid tumors that share antigens with normal tissues. Additionally, we explore designs for synthetic circuits that could control T-cell differentiation or T-cell fate as well as the concept of synthetic multicellular circuits that leverage cellular communication and division of labor to achieve improved therapeutic efficacy. As our understanding of cell biology expands and novel tools for genome, protein, and cell engineering are developed, we anticipate further innovative approaches to emerge in the design and engineering of circuits in immune cells.

Harnessing type I interferon-mediated immunity to target malignant brain tumors

Type I interferons have long been appreciated as a cytokine family that regulates antiviral immunity. Recently, their role in eliciting antitumor immune responses has gained increasing attention. Within the immunosuppressive tumor microenvironment (TME), interferons stimulate tumor-infiltrating lymphocytes to promote immune clearance and essentially reshape a "cold" TME into an immune-activating "hot" TME. In this review, we focus on gliomas, with an emphasis on malignant glioblastoma, as these brain tumors possess a highly invasive and heterogenous brain TME. We address how type I interferons regulate antitumor immune responses against malignant gliomas and reshape the overall immune landscape of the brain TME. Furthermore, we discuss how these findings can translate into future immunotherapies targeting brain tumors in general.

Molecular and cellular factors determining the functional pleiotropy of cytokines

Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.

Tumor Microenvironment in Gliomas: A Treatment Hurdle or an Opportunity to Grab?

Gliomas are the most frequent central nervous system (CNS) primary tumors. The prognosis and clinical outcomes of these malignancies strongly diverge according to their molecular alterations and range from a few months to decades. The tumor-associated microenvironment involves all cells and connective tissues surrounding tumor cells. The composition of the microenvironment as well as the interactions with associated neoplastic mass, are both variables assuming an increasing interest in these last years. This is mainly because the microenvironment can mediate progression, invasion, dedifferentiation, resistance to treatment, and relapse of primary gliomas. In particular, the tumor microenvironment strongly diverges from isocitrate dehydrogenase (IDH) mutated and wild-type (wt) tumors. Indeed, IDH mutated gliomas often show a lower infiltration of immune cells with reduced angiogenesis as compared to IDH wt gliomas. On the other hand, IDH wt tumors exhibit a strong immune infiltration mediated by several cytokines and chemokines, including CCL2, CCL7, GDNF, CSF-1, GM-CSF, etc. The presence of several factors, including Sox2, Oct4, PD-L1, FAS-L, and TGF β2, also mediate an immune switch toward a regulatory inhibited immune system. Other important interactions are described between IDH wt glioblastoma cells and astrocytes, neurons, and stem cells, while these interactions are less elucidated in IDH-mutated tumors. The possibility of targeting the microenvironment is an intriguing perspective in terms of therapeutic drug development. In this review, we summarized available evidence related to the glioma microenvironment, focusing on differences within different glioma subtypes and on possible therapeutic development.

Recent progress of gene circuit designs in immune cell therapies

The success of chimeric antigen receptor (CAR) T cell therapy against hematological cancers has convincingly demonstrated the potential of using genetically engineered cells as therapeutic agents. Although much progress has been achieved in cell therapy, more beneficial capabilities have yet to be fully explored. One of the unique advantages afforded by cell therapies is the possibility to implement genetic control circuits, which enables diverse signal sensing and logical processing for optimal response in the complex tumor microenvironment. In this perspective, we will first outline design considerations for cell therapy control circuits that address clinical demands. We will compare and contrast key design features in some of the latest control circuits developments and conclude by discussing potential future directions.

Intratumoral nanobody-IL-2 fusions that bind the tumor extracellular matrix suppress solid tumor growth in mice

Confining cytokine exposure to the tumors would greatly enhance cancer immunotherapy safety and efficacy. Immunocytokines, cytokines fused to tumor-targeting antibodies, have been developed with this intention, but without significant clinical success to date. A critical limitation is uptake by receptor-expressing cells in the blood, that decreases the dose at the tumor and engenders toxicity. Small-format immunocytokines, constructed with antibody fragments, are hypothesized to improve tumor specificity due to rapid systemic clearance. However, effective design criteria for small-format immunocytokines need further examination. Here, we engineer small interleukin-2 (IL-2) immunocytokines fused to nanobodies with nanomolar to picomolar affinities for the tumor-specific EIIIB domain of fibronectin (also known as EDB). Upon intravenous delivery into immunocompetent mice, such immunocytokines led to similar tumor growth delay as size-matched untargeted IL-2. Intratumoral (i.t.) delivery imparted improved survival dependent on affinity to EIIIB. I.t. administration offers a promising avenue to deliver small-format immunocytokines, given effective affinity for the tumor microenvironment.

Targeted inducible delivery of immunoactivating cytokines reprograms glioblastoma microenvironment and inhibits growth in mouse models

Glioblastoma multiforme (GBM) is the most common and lethal brain tumor characterized by a strongly immunosuppressive tumor microenvironment (TME) that represents a barrier also for the development of effective immunotherapies. The possibility to revert this hostile TME by immunoactivating cytokines is hampered by the severe toxicity associated with their systemic administration. Here, we exploited a lentiviral vector–based platform to engineer hematopoietic stem cells ex vivo with the aim of releasing, via their tumor-infiltrating monocyte/macrophage progeny, interferon-α (IFN-α) or interleukin-12 (IL-12) at the tumor site with spatial and temporal selectivity. Taking advantage of a syngeneic GBM mouse model, we showed that inducible release of IFN-α within the TME achieved robust tumor inhibition up to eradication and outperformed systemic treatment with the recombinant protein in terms of efficacy, tolerability, and specificity. Single-cell RNA sequencing of the tumor immune infiltrate revealed reprogramming of the immune microenvironment toward a proinflammatory and antitumoral state associated with loss of a macrophage subpopulation shown to be associated with poor prognosis in human GBM. The spatial and temporal control of IL-12 release was critical to overcome an otherwise lethal hematopoietic toxicity while allowing to fully exploit its antitumor activity. Overall, our findings demonstrate a potential therapeutic approach for GBM and set the bases for a recently launched first-in-human clinical trial in patients with GBM.

Mitigating Host Burden of Genetic Circuits by Engineering Autonegatively Regulated Parts and Improving Functional Prediction

Mitigating unintended interferences between circuits and host cells is key to realize applications of synthetic regulatory systems both for bacteria and mammalian cells. Here, we demonstrated that growth burden and circuit dysregulation occurred in a concentration-dependent manner for specific transcription factors (CymR*/CymR) in E.coli, and direct negative feedback modules were able to control the concentration of CymR*/CymR, mitigate growth burden, and restore circuit functions. A quantitative design scheme was developed for circuits embedded with autorepression modules. Four key parameters were theoretically identified to determine the performance of autoregulated switches and were experimentally modified by fine-tuning promoter architectures and cooperativity. Using this strategy, we synthesized a number of switches and demonstrated its improvement of product titers and host growth controlling the complex deoxyviolacein biosynthesis pathway. Furthermore, we restored functions of a dysregulated multilayer NOR gate by integrating autorepression modules. Our work provides a blueprint for engineering host-adaptable synthetic systems.

Systemic sterile induced-co-expression of IL-12 and IL-18 drive IFN-γ-dependent activation of microglia and recruitment of MHC-II-expressing inflammatory monocytes into the brain

The development of neuroinflammation, as well as the progression of several neurodegenerative diseases, has been associated with the activation and mobilization of the peripheral immune system due to systemic inflammation. However, the mechanism by which this occurs remains unclear. Here, we addressed the effect of systemic sterile induced-co-expression of IL-12 and IL-18, in the establishment of a novel cytokine-mediated model of neuroinflammation. Following peripheral hydrodynamic shear of IL-12 plus IL-18 cDNAs in C57BL/6 mice, we induced systemic and persistent level of IL-12, which in turn promoted the elevation of circulating pro-inflammatory cytokines TNF-α and IFN-γ, accompanied with splenomegaly. Moreover, even though we identified an increased gene expression of both TNF-α and IFN-γ in the brain, we observed that only IFN-γ, but not TNF-α signaling through its type I receptor, was required to induce both the trafficking of leukocytes from the periphery toward the brain and upregulate MHC-II in microglia and inflammatory monocytes. Therefore, only TNF-α was shown to be dispensable, revealing an IFN-γ-dependent activation of microglia and recruitment of leukocytes, particularly of highly activated inflammatory monocytes. Taken together, our results argue for a systemic cytokine-mediated establishment and development of neuroinflammation, having identified IFN-γ as a potential target for immunomodulation.

Enhanced Cancer Therapy Using an Engineered Designer Cytokine Alone and in Combination With an Immune Checkpoint Inhibitor

melanoma differentiation associated gene-7 or Interleukin-24 (mda-7, IL-24) displays expansive anti-tumor activity without harming corresponding normal cells/tissues. This anticancer activity has been documented in vitro and in vivo in multiple preclinical animal models, as well as in patients with advanced cancers in a phase I clinical trial. To enhance the therapeutic efficacy of MDA-7 (IL-24), we engineered a designer cytokine (a "Superkine"; IL-24S; referred to as M7S) with enhanced secretion and increased stability to engender improved "bystander" antitumor effects. M7S was engineered in a two-step process by first replacing the endogenous secretory motif with an alternate secretory motif to boost secretion. Among four different signaling peptides, the insulin secretory motif significantly enhanced the secretion of MDA-7 (IL-24) protein and was chosen for M7S. The second modification engineered in M7S was designed to enhance the stability of MDA-7 (IL-24), which was accomplished by replacing lysine at position K122 with arginine. This engineered "M7S Superkine" with increased secretion and stability retained cancer specificity. Compared to parental MDA-7 (IL-24), M7S (IL-24S) was superior in promoting anti-tumor and bystander effects leading to improved outcomes in multiple cancer xenograft models. Additionally, combinatorial therapy using MDA-7 (IL-24) or M7S (IL-24S) with an immune checkpoint inhibitor, anti-PD-L1, dramatically reduced tumor progression in murine B16 melanoma cells. These results portend that M7S (IL-24S) promotes the re-emergence of an immunosuppressive tumor microenvironment, providing a solid rationale for prospective translational applications of this therapeutic designer cytokine.

The thrombopoietin receptor: revisiting the master regulator of platelet production

Thrombopoietin (TPO) and its receptor, MPL, are the primary regulators of platelet production and critical for hematopoietic stem cell (HSC) maintenance. Since TPO was first cloned in 1994, the physiological and pathological roles of TPO and MPL have been well characterized, culminating in the first MPL agonists being approved for the treatment of chronic immune thrombocytopenia in 2008. Dysregulation of the TPO-MPL signaling axis contributes to the pathogenesis of hematological disorders: decreased expression or function results in severe thrombocytopenia progressing to bone marrow failure, while hyperactivation of MPL signaling, either by mutations in the receptor or associated Janus kinase 2 (JAK2), results in pathological myeloproliferation. Despite its importance, it was only recently that the long-running debate over the mechanism by which TPO binding activates MPL has been resolved. This review will cover key aspects of TPO and MPL structure and function and their importance in receptor activation, discuss how these are altered in hematological disorders and consider how a greater understanding could lead to the development of better-targeted and more efficacious therapies.

Emerging role of interleukin-13 in cardiovascular diseases: A ray of hope

Despite the great progress made in the treatment for cardiovascular diseases (CVDs), the morbidity and mortality of CVDs remains high due to the lack of effective treatment strategy. Inflammation is a central pathophysiological feature of the heart in response to both acute and chronic injury, while the molecular basis and underlying mechanisms remains obscure. Interleukin (IL)-13, a pro-inflammatory cytokine, has been known as a critical mediator in allergy and asthma. Recent studies appraise the role of IL-13 in CVDs, revealing that IL-13 is not only involved in more obvious cardiac inflammatory diseases such as myocarditis but also relevant to acute or chronic CVDs of other origins, such as myocardial infarction and heart failure. The goal of this review is to summarize the advancement in our knowledge of the regulations and functions of IL-13 in CVDs and to discuss the possible mechanisms of IL-13 involved in CVDs. We highlight that IL-13 may be a promising target for immunotherapy in CVDs.