Protein Kinase CK2 Controls the Fate between Th17 Cell and Regulatory T Cell Differentiation

T-helper cells flexibility: the possibility of reprogramming T cells fate

Various disciplines cooperate to find novel approaches to cure impaired body functions by repairing, replacing, or regenerating cells, tissues, or organs. The possibility that a stable differentiated cell can reprogram itself opens the door to new therapeutic strategies against a multitude of diseases caused by the loss or dysfunction of essential, irreparable, and specific cells. One approach to cell therapy is to induce reprogramming of adult cells into other functionally active cells. Understanding the factors that cause or contribute to T cell plasticity is not only of clinical importance but also expands the knowledge of the factors that induce cells to differentiate and improves the understanding of normal developmental biology. The present review focuses on the advances in the conversion of peripheral CD4+ T cells, the conditions of their reprogramming, and the methods proposed to control such cell differentiation.

Socs3 expression in myeloid cells modulates the pathogenesis of dextran sulfate sodium (DSS)-induced colitis

Introduction

Myeloid cells play a critical role in the pathogenesis of Inflammatory Bowel Diseases (IBDs), including Ulcerative Colitis (UC) and Crohn's Disease (CD). Dysregulation of the JAK/STAT pathway is associated with many pathological conditions, including IBD. Suppressors Of Cytokine Signaling (SOCS) are a family of proteins that negatively regulate the JAK/STAT pathway. Our previous studies identified that mice lacking Socs3 in myeloid cells developed a hyper-activated phenotype of macrophages and neutrophils in a pre-clinical model of Multiple Sclerosis.

Methods

To better understand the function of myeloid cell Socs3 in the pathogenesis of colitis, mice with Socs3 deletion in myeloid cells (Socs3 ^ΔLysM) were utilized in a DSS-induced colitis model.

Results

Our results indicate that Socs3 deficiency in myeloid cells leads to more severe colitis induced by DSS, which correlates with increased infiltration of monocytes and neutrophils in the colon and increased numbers of monocytes and neutrophils in the spleen. Furthermore, our results demonstrate that the expression of genes related to the pathogenesis and diagnosis of colitis such as Il1β, Lcn2, S100a8 and S100a9 were specifically enhanced in Socs3-deficient neutrophils localized to the colon and spleen. Conversely, there were no observable differences in gene expression in Ly6C⁺ monocytes. Depletion of neutrophils using a neutralizing antibody to Ly6G significantly improved the disease severity of DSS-induced colitis in Socs3-deficient mice.

Discussion

Thus, our results suggest that deficiency of Socs3 in myeloid cells exacerbates DSS-induced colitis and that Socs3 prevents overt activation of the immune system in IBD. This study may provide novel therapeutic strategies to IBD patients with hyperactivated neutrophils.

Regulation and function of poised mRNAs in lymphocytes

Pre-existing but untranslated or 'poised' mRNA exists as a means to rapidly induce the production of specific proteins in response to stimuli and as a safeguard to limit the actions of these proteins. The translation of poised mRNA enables immune cells to express quickly genes that enhance immune responses. The molecular mechanisms that repress the translation of poised mRNA and, upon stimulation, enable translation have yet to be elucidated. They likely reflect intrinsic properties of the mRNAs and their interactions with trans-acting factors that direct poised mRNAs away from or into the ribosome. Here, I discuss mechanisms by which this might be regulated.

PD-1 Deficiency in Regulatory T Cells May be Involved in the Pathogenesis of Takayasu's Arteritis

OBJECTIVES

This study aims to investigate whether PD-1 expressions are abnormal in patients with TAK.

METHODS

PD-1 expression was analyzed by flow cytometry. Serum cytokines IL-10, IL-7, IL-2, IL-15, CCL2, CCL3, and CXCL10 were detected using a cytokine cytometric bead array. Immunohistochemistry staining analysis was used to test PD-1 and programmed death-ligand 1 (PD-L1) expression in the aorta of three patients with TAK and three patients with atherosclerosis as controls.

RESULTS

The mean fluorescence intensity of PD-1 in CD4⁺PD-1⁺ cells was decreased in patients with TAK and the frequency of CD4⁺Foxp3^-PD-1⁺ cells among CD4⁺T cells was also decreased in peripheral blood relative to healthy controls (P < .05). The percentage of CD4⁺CD25⁺Foxp3⁺PD-1⁺ cells in the CD4⁺CD25⁺T cell population was lower in patients with TAK than in healthy control and was lower in active TAK group (P < .05). Comparing PD-1 and PDL-1 expression in aorta tissue showed that patients with TAK tended to have lower levels than patients with atherosclerosis, but the difference was not significant (P > .05). Patients with TAK had higher serum levels of IL-10, IL-7, CCL2, and CCL3 (P < .05).

CONCLUSIONS

Abnormal expression of PD-1 in serum and aorta tissue of patients with TAK may contribute to TAK pathogenesis.

KEY POINTS

PD-1 expression in both peripheral blood and aorta tissue of TAK patients decreased relative to healthy controls, indicating that PD-1 might be involved in TAK pathogenesis.

Emerging role of Protein Kinase CK2 in Tumor immunity

Protein kinase CK2, a conserved serine/threonine-protein kinase, is ubiquitous in cells and regulates various intracellular processes, especially in tumor cells. As one of the earliest discovered protein kinases in humans, CK2 plays a crucial role in phosphorylating or associating with hundreds of substrates to modulate several signaling pathways. Excellent reviews have reported that the overexpression of CK2 could be observed in many cancers and was closely associated with tumor occurrence and development. The elevation of CK2 is also an indicator of a poor prognosis. Recently, increasing attention has been paid to the relationship between CK2 and tumor immunity. However, there is no comprehensive description of how CK2 regulates the immune cells in the tumor microenvironment (TME). Also, the underlying mechanisms are still not very clear. In this review, we systematically summarized the correlation between CK2 and tumor immunity, primarily the effects on various immune cells, both in innate and adaptive immunity in the TME. With the comprehensive development of immunotherapy and the mounting transformation research of CK2 inhibitors from the bench to the clinic, this review will provide vital information to find new treatment options for enhancing the efficacy of immunotherapy.

CK2 and the Hallmarks of Cancer

Cancer is a leading cause of death worldwide. Casein kinase 2 (CK2) is commonly dysregulated in cancer, impacting diverse molecular pathways. CK2 is a highly conserved serine/threonine kinase, constitutively active and ubiquitously expressed in eukaryotes. With over 500 known substrates and being estimated to be responsible for up to 10% of the human phosphoproteome, it is of significant importance. A broad spectrum of diverse types of cancer cells has been already shown to rely on disturbed CK2 levels for their survival. The hallmarks of cancer provide a rationale for understanding cancer’s common traits. They constitute the maintenance of proliferative signaling, evasion of growth suppressors, resisting cell death, enabling of replicative immortality, induction of angiogenesis, the activation of invasion and metastasis, as well as avoidance of immune destruction and dysregulation of cellular energetics. In this work, we have compiled evidence from the literature suggesting that CK2 modulates all hallmarks of cancer, thereby promoting oncogenesis and operating as a cancer driver by creating a cellular environment favorable to neoplasia.

Protein Kinase CK2 Controls CD8+ T Cell Effector and Memory Function during Infection

Protein kinase CK2 is a serine/threonine kinase composed of two catalytic subunits (CK2α and/or CK2α') and two regulatory subunits (CK2β). CK2 promotes cancer progression by activating the NF-κB, PI3K/AKT/mTOR, and JAK/STAT pathways, and also is critical for immune cell development and function. The potential involvement of CK2 in CD8⁺ T cell function has not been explored. We demonstrate that CK2 protein levels and kinase activity are enhanced upon mouse CD8⁺ T cell activation. CK2α deficiency results in impaired CD8⁺ T cell activation and proliferation upon TCR stimulation. Furthermore, CK2α is involved in CD8⁺ T cell metabolic reprogramming through regulating the AKT/mTOR pathway. Lastly, using a mouse Listeria monocytogenes infection model, we demonstrate that CK2α is required for CD8⁺ T cell expansion, maintenance, and effector function in both primary and memory immune responses. Collectively, our study implicates CK2α as an important regulator of mouse CD8⁺ T cell activation, metabolic reprogramming, and differentiation both in vitro and in vivo.

The Role of Protein Kinase CK2 in Development and Disease Progression: A Critical Review

Protein kinase CK2 (CK2) is a ubiquitous holoenzyme involved in a wide array of developmental processes. The involvement of CK2 in events such as neurogenesis, cardiogenesis, skeletogenesis, and spermatogenesis is essential for the viability of almost all organisms, and its role has been conserved throughout evolution. Further into adulthood, CK2 continues to function as a key regulator of pathways affecting crucial processes such as osteogenesis, adipogenesis, chondrogenesis, neuron differentiation, and the immune response. Due to its vast role in a multitude of pathways, aberrant functioning of this kinase leads to embryonic lethality and numerous diseases and disorders, including cancer and neurological disorders. As a result, CK2 is a popular target for interventions aiming to treat the aforementioned diseases. Specifically, two CK2 inhibitors, namely CX-4945 and CIBG-300, are in the early stages of clinical testing and exhibit promise for treating cancer and other disorders. Further, other researchers around the world are focusing on CK2 to treat bone disorders. This review summarizes the current understanding of CK2 in development, the structure of CK2, the targets and signaling pathways of CK2, the implication of CK2 in disease progression, and the recent therapeutics developed to inhibit the dysregulation of CK2 function in various diseases.

Protein Kinase CK2 Maintains Reciprocal Balance Between Th17 and Treg Cells in the Pathogenesis of UC

BACKGROUND

T helper 17 and regulatory T cells balance have crucial effects on the development of ulcerative colitis (UC). Currently, how to break this balance has not yet been found. Protein kinase CK2 is involved in the pathogenesis of immune-related disorders. However, its effects on the development of UC are obscure.

METHODS

The level of CK2 in the colonic tissues of UC patients was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and immune-histochemistry. Peripheral blood CD4+ T cells were treated with CK2 inhibitor CX4945 or transfected with Csnk2-interfering lentivirus; the mRNA expression and protein levels of inflammatory cytokines were detected by qRT-PCR, enzyme-linked immunosorbent assay, and flow cytometry. Moreover, CX4945 was administered to trinitrobenzene sulfonic acid (TNBS)-induced colitis mice model for determining the function of CK2 on the regulation of intestinal inflammation.

RESULTS

The CK2 level was markedly increased in inflamed mucosa of UC and highly expressed in CD4+ T cells. Blockade of CK2 by CX4945 inhibited Th17 but promoted regulatory T-cell (Treg) immune responses in CD4+ T cells from patients with UC. Moreover, CK2 blockade alleviated TNBS-induced colitis in mice. Inhibition of CK2 suppressed Th17 but promoted Treg differentiation by decreasing the phosphorylation level of signal transducer and activator of transcription (STAT) 3 and increasing the phosphorylation level of STAT5. The RNA-Seq and co-immunoprecipitation analysis further showed that CK2 could interact with Sirtuin 1 (SIRT1) and downregulate SIRT1 expression, which participated in Th17 inhibition but promoted Treg differentiation. Sirtuin 1 upregulation ameliorated TNBS-induced colitis, whereas SIRT1 blockade aggravated TNBS-induced colitis in mice.

CONCLUSIONS

CK2 have crucial effects on the development of UC by maintaining reciprocal balance between Th17 and Treg cells. Protein kinase CK2 blockade might be considered as a new therapeutic approach for UC treatment.

The effects of post-translational modifications on Th17/Treg cell differentiation

Regulatory T (Treg) cells and Th17 cells are subsets of CD4⁺ T cells which play an essential role in immune homeostasis and infection. Dysregulation of the Th17/Treg cell balance was shown to be implicated in the development and progression of several disorders such as autoimmune disease, inflammatory disease, and cancer. Multiple factors, including T cell receptor (TCR) signals, cytokines, metabolic and epigenetic regulators can influence the differentiation of Th17 and Treg cells and affect their balance. Accumulating evidence indicates that the activity of key molecules such as forkhead box P3 (Foxp3), the retinoic acid-related orphan receptor gamma t (RORγt), and signal transducer and activator of transcription (STAT)s are modulated by the number of post-translational modifications (PTMs) such as phosphorylation, methylation, nitrosylation, acetylation, glycosylation, lipidation, ubiquitination, and SUMOylation. PTMs might affect the protein folding efficiency and protein conformational stability, and consequently determine protein structure, localization, and function. Here, we review the recent progress in our understanding of how PTMs modify the key molecules involved in the Th17/Treg cell differentiation, regulate the Th17/Treg balance, and initiate autoimmune diseases caused by dysregulation of the Th17/Treg balance. A better understanding of Th17/Treg regulation may help to develop novel potential therapeutics to treat immune-related diseases.

AhR promotes phosphorylation of ARNT isoform 1 in human T cell malignancies as a switch for optimal AhR activity

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a transcription factor present in immune cells as a long and short isoform, referred to as isoforms 1 and 3, respectively. However, investigation into potential ARNT isoform–specific immune functions is lacking despite the well-established heterodimerization requirement of ARNT with, and for the activity of, the aryl hydrocarbon receptor (AhR), a critical mediator of immune homeostasis. Here, using global and targeted transcriptomics analyses, we show that the relative ARNT isoform 1:3 ratio in human T cell lymphoma cells dictates the amplitude and direction of AhR target gene regulation. Specifically, shifting the ARNT isoform 1:3 ratio lower by suppressing isoform 1 enhances, or higher by suppressing isoform 3 abrogates, AhR responsiveness to ligand activation through preprograming a cellular genetic background that directs explicit gene expression patterns. Moreover, the fluctuations in gene expression patterns that accompany a decrease or increase in the ARNT isoform 1:3 ratio are associated with inflammation or immunosuppression, respectively. Molecular studies identified the unique casein kinase 2 (CK2) phosphorylation site within isoform 1 as an essential parameter to the mechanism of ARNT isoform–specific regulation of AhR signaling. Notably, CK2-mediated phosphorylation of ARNT isoform 1 is dependent on ligand-induced AhR nuclear translocation and is required for optimal AhR target gene regulation. These observations reveal ARNT as a central modulator of AhR activity predicated on the status of the ARNT isoform ratio and suggest that ARNT-based therapies are a viable option for tuning the immune system to target immune disorders.

Inhibition of microRNA-448 suppresses CD4+ T cell inflammatory activation via up-regulating suppressor of cytokine signaling 5 in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. MicroRNA-448 (miR-448) has a pro-inflammatory effect in various inflammation-related diseases and is up-regulated in serum of patients with SLE. However, the role of miR-448 in SLE development remains elusive. In our study, we found high expression of miR-448 in peripheral blood mononuclear cells (PBMCs) of SLE patients, and miR-448 level was positively associated with disease severity. Besides, miR-448 level was up-regulated during the growth of MRL/lpr mice. To investigate the function of miR-448 in SLE, we subjected 8-week MRL/lpr mice to injection of lentivirus (LV)-mediated anti-miR-448. Inhibition of miR-448 reduced serum IgG and anti-dsDNA IgG contents, 24 h urine protein and blood urea nitrogen (BUN) levels, increased complement C3 concentration, and ameliorated splenomegaly and lymphadenectasis in MRL/lpr mice. MiR-448 inhibition alleviated renal inflammatory infiltration and glycogen deposition. Moreover, miR-448 inhibition promoted Treg cell activation and inhibited Th17 cell proportion in naïve CD4+ T cells from spleens, along with elevated interleukin (IL)-10 and reduced IL-17A levels. In vitro, miR-448 inhibition diminished CD4+ T cell polarization toward Th17 cells under Th17-polarizing conditions. Further, luciferase reporter assay revealed that miR-448 binds to the 3'UTR of suppressor of cytokine signaling 5 (SOCS5). SOCS5 expression was down-regulated in the spleens of MRL/lpr mice and induced Th17 cells. SOCS5 deficiency partially reversed the role of miR-448 in Th17 differentiation and IL-17A expression in SLE. Taken together, inhibition of miR-448 impedes Th17 cell activation and tissue damages via targeting SOCS5 in SLE.

The Immune Regulatory Role of Protein Kinase CK2 and Its Implications for Treatment of Cancer

Protein Kinase CK2, a constitutively active serine/threonine kinase, fulfills its functions via phosphorylating hundreds of proteins in nearly all cells. It regulates a variety of cellular signaling pathways and contributes to cell survival, proliferation and inflammation. CK2 has been implicated in the pathogenesis of hematologic and solid cancers. Recent data have documented that CK2 has unique functions in both innate and adaptive immune cells. In this article, we review aspects of CK2 biology, functions of the major innate and adaptive immune cells, and how CK2 regulates the function of immune cells. Finally, we provide perspectives on how CK2 effects in immune cells, particularly T-cells, may impact the treatment of cancers via targeting CK2.

Casein Kinase II exacerbates rheumatoid arthritis via promoting Th1 and Th17 cell inflammatory responses

OBJECTIVES

Studies have demonstrated that CK2 is engaged in CD4⁺ T cell proliferation and activation. We investigated the potential involvement of CK2 in the pathogenesis of rheumatoid arthritis (RA).

METHODS

Peripheral blood and synovial fluid mononuclear cells (PBMC and SFMC) of RA patients, as well as splenocytes of collagen-induced arthritis (CIA) mice were treated with different doses of CK2 inhibitor CX4945 in vitro. Then, the Th1, Th2, Th17, and Treg cell responses were analyzed. In addition, CIA mice were administrated with CX4945 via oral gavage. Accordingly, the arthritis scores, bone destruction, tissue damage, and the CD4⁺ T cell subsets were assessed.

RESULTS

The expression of CK2 was upregulated in CD4⁺ T cells under RA circumstance. In vitro CX4945 treatment significantly inhibited the Th1 and Th17 cell responses, while promoted the Th2 cell responses in RA patient PBMC, SFMC and CIA mouse splenocytes, dampening IFN-γ and IL-17A production. Moreover, administration of CX4945 ameliorated the severity of arthritis in CIA mice, along with decreased Th1 and Th17 cells. However, CX4945 seemed to have minimal effect on RA Treg cells.

CONCLUSION

CK2 serves as an important regulator of the Th1 and Th17 cell axes in RA, thus contributing to the disease aggravation.

Oleic acid restores suppressive defects in tissue-resident FOXP3 Tregs from patients with multiple sclerosis

FOXP3+ Tregs rely on fatty acid β-oxidation-driven (FAO-driven) oxidative phosphorylation (OXPHOS) for differentiation and function. Recent data demonstrate a role for Tregs in the maintenance of tissue homeostasis, with tissue-resident Tregs possessing tissue-specific transcriptomes. However, specific signals that establish tissue-resident Treg programs remain largely unknown. Tregs metabolically rely on FAO, and considering the lipid-rich environments of tissues, we hypothesized that environmental lipids drive Treg homeostasis. First, using human adipose tissue to model tissue residency, we identified oleic acid as the most prevalent free fatty acid. Mechanistically, oleic acid amplified Treg FAO-driven OXPHOS metabolism, creating a positive feedback mechanism that increased the expression of FOXP3 and phosphorylation of STAT5, which enhanced Treg-suppressive function. Comparing the transcriptomic program induced by oleic acid with proinflammatory arachidonic acid, we found that Tregs sorted from peripheral blood and adipose tissue of healthy donors transcriptomically resembled the Tregs treated in vitro with oleic acid, whereas Tregs from patients with multiple sclerosis (MS) more closely resembled an arachidonic acid transcriptomic profile. Finally, we found that oleic acid concentrations were reduced in patients with MS and that exposure of MS Tregs to oleic acid restored defects in their suppressive function. These data demonstrate the importance of fatty acids in regulating tissue inflammatory signals.

Understanding Abnormal c-JNK/p38MAPK Signaling Overactivation Involved in the Progression of Multiple Sclerosis: Possible Therapeutic Targets and Impact on Neurodegenerative Diseases

Demyelination, immune dysregulation, and neuroinflammation are the most common triggers of motor neuron disorders such as multiple sclerosis (MS). MS is a chronic demyelinating neurodegenerative disease of the central nervous system caused by abnormal immune activation, which causes myelin sheath damage. Cell signal transduction pathways are required for a variety of physiological and pathological processes in the brain. When these signaling systems become overactive, they can lead to disease progression. In various physiological conditions, abnormal mitogen-activated protein kinase (MAPK) activation is associated with several physiological dysfunctions that cause neurodegeneration. Previous research indicates that c-JNK and p38MAPK signaling play critical roles in neuronal growth and differentiation. c-JNK/p38MAPK is a member of the MAPK family, which regulates metabolic pathways, cell proliferation, differentiation, and apoptosis that control certain neurological activities. During brain injuries, c-JNK/p38MAPK also affects neuronal elastic properties, nerve growth, and cognitive processing. This review systematically linked abnormal c-JNK/p38MAPK signaling activation to multiple neuropathological pathways in MS and related neurological dysfunctions. MS progression is linked to genetic defects, oligodendrocyte destruction, glial overactivation, and immune dysregulation. We concluded that inhibiting both the c-JNK/p38MAPK signaling pathways can promote neuroprotection and neurotrophic effects against the clinical-pathological presentation of MS and influence other neurological disorders. As a result, the potential benefits of c-JNK/p38MAPK downregulation for the development of disease-modifying treatment interventions in the future could include MS prevention and related neurocomplications.

Protein Kinase CK2 Regulates B Cell Development and Differentiation

Protein kinase CK2 (also known as Casein Kinase 2) is a serine/threonine kinase composed of two catalytic subunits (CK2α and/or CK2α') and two regulatory CK2β subunits. CK2 is overexpressed and overactive in B cell acute lymphoblastic leukemia and diffuse large B cell lymphomas, leading to inappropriate activation of the NF-κB, JAK/STAT, and PI3K/AKT/mTOR signaling pathways and tumor growth. However, whether CK2 regulates normal B cell development and differentiation is not known. We generated mice lacking CK2α specifically in B cells (using CD19-driven Cre recombinase). These mice exhibited cell-intrinsic expansion of marginal zone B cells at the expense of transitional B cells, without changes in follicular B cells. Transitional B cells required CK2α to maintain adequate BCR signaling. In the absence of CK2α, reduced BCR signaling and elevated Notch2 signaling activation increased marginal zone B cell differentiation. Our results identify a previously unrecognized function for CK2α in B cell development and differentiation.

Sex-based differences in the activation of peripheral blood monocytes in early Parkinson disease

Increasing evidence supports the role of brain and systemic inflammation in the etiology of Parkinson disease (PD). We used gene expression profiling to examine the activation state of peripheral blood monocytes in 18 patients with early, untreated PD and 16 healthy control (HC) subjects. Monocytes were isolated by negative selection, and gene expression studied by RNA-seq and gene set enrichment analysis. A computational model that incorporated case/control status, sex, and the interaction between case/control status and sex was utilized. We found that there was a striking effect of sex on monocyte gene expression. There was inflammatory activation of monocytes in females with PD, with enrichment of gene sets associated with interferon gamma stimulation. In males, the activation patterns were more heterogeneous. These data point to the importance of systemic monocyte activation in PD, and the importance of studies which examine the differential effects of sex on pathophysiology of the disease.

How can a traffic light properly work if it is always green? The paradox of CK2 signaling

CK2 is a constitutively active protein kinase that assuring a constant level of phosphorylation to its numerous substrates supports many of the most important biological functions. Nevertheless, its activity has to be controlled and adjusted in order to cope with the varying needs of a cell, and several examples of a fine-tune regulation of its activity have been described. More importantly, aberrant regulation of this enzyme may have pathological consequences, e.g. in cancer, chronic inflammation, neurodegeneration, and viral infection. Our review aims at summarizing our current knowledge about CK2 regulation. In the first part, we have considered the most important stimuli shown to affect protein kinase CK2 activity/expression. In the second part, we focus on the molecular mechanisms by which CK2 can be regulated, discussing controversial aspects and future perspectives.

Diverse Roles of Akt in T cells

Akt kinases translate various external cues into intracellular signals that control cell survival, proliferation, metabolism and differentiation. This review discusses the requirement for Akt and its targets in determining the fate and function of T cells. We discuss the importance of Akt at various stages of T cell development including β-selection during which Akt fulfills the energy requirements of highly proliferative DN3 cells. Akt also plays an integral role in CD8 T cell biology where its regulation of Foxo transcription factors and mTORC1 metabolic activity controls effector versus memory CD8 T cell differentiation. Finally, Akt promotes the differentiation of naïve CD4 T cells into Th1, Th17 and Tfh cells but inhibits the development of Treg cells. We also highlight how modulating Akt in T cells is a promising avenue for enhancing cell-based cancer immunotherapy.

Protein kinase 2 (CK2) controls CD4+ T cell effector function in the pathogenesis of colitis

Crohn's disease (CD), one of the major forms of inflammatory bowel disease (IBD), is characterized by chronic inflammation of the gastrointestinal tract and associated with aberrant CD4⁺ T-helper type 1 (Th1) and Th17 responses. Protein kinase 2 (CK2) is a conserved serine-threonine kinase involved in signal transduction pathways, which regulate immune responses. CK2 promotes Th17 cell differentiation and suppresses the generation of Foxp3⁺ regulatory T cells. The function of CK2 in CD4⁺ T cells during the pathogenesis of CD is unknown. We utilized the T cell-induced colitis model, transferring CD45RB^hi-naive CD4⁺ T cells from CK2α^fl/fl controls and CK2α^fl/fldLck-Cre mice into Rag1^-/- mice. CD4⁺ T cells from CK2α^fl/fldLck-Cre mice failed to induce wasting disease and significant intestinal inflammation, which was associated with decreased interleukin-17A-positive (IL-17A⁺), interferon-γ-positive (IFN-γ⁺), and double-positive IL-17A⁺IFN-γ⁺ CD4⁺ T cells in the spleen and colon. We determined that CK2α regulates CD4⁺ T cell proliferation through a cell-intrinsic manner. CK2α is also important in controlling CD4⁺ T cell responses by regulating NFAT2, which is vital for T cell activation and proliferation. Our findings indicate that CK2α contributes to the pathogenesis of colitis by promoting CD4⁺ T cell proliferation and Th1 and Th17 responses, and that targeting CK2 may be a novel therapeutic treatment for patients with CD.

miR-182-5p inhibits the pathogenic Th17 response in experimental autoimmune uveitis mice via suppressing TAF15

BACKGROUND

CD4⁺ T helper 17 (Th17) cells play a contributory role in uveitis and other autoimmune disorders. However, less is understood about the contribution of microRNAs (miRNAs) in regulating the pathogenic Th17 response in uveitis.

METHODS

The in vivo experimental autoimmune uveitis (EAU) model was constructed in female C57BL/6 mice. Primary EAU mouse CD4⁺ T-cells and the murine T-cell line EL4 were used for in vitro experiments. miRNA mimic/inhibitor, lentiviral overexpression plasmids, and small interfering RNAs (siRNAs) were used to modulate miR-182-5p and TAF15 expression. CD4⁺ T-cells from healthy controls (HC, n = 15), active Behçet's disease with uveitis (BD, n = 15), or active sympathetic ophthalmia with uveitis (SO, n = 15) were analyzed for miR-182-5p, TAF15, and Th17 marker gene expression.

RESULTS

miR-182-5p was downregulated in EAU mouse-derived Th17 cells. miR-182-5p negatively regulated Th17 cell development in vitro. miR-182-5p mimic therapy in transplanted Th17 cells ameliorated EAU severity in vivo. Mechanistically, miR-182-5p directly inhibited the transcriptional initiator TATA-binding protein-associated factor 15 (TAF15, TAFII68). miR-182-5p's inhibition of TAF15 negatively regulated Th17 cell development by suppressing STAT3 phosphorylation. TAF15 and Th17 marker expression were positively correlated in CD4⁺ T-cells from BD and SO patients.

CONCLUSION

miR-182-5p mimic therapy inhibits the pathogenic Th17 response in EAU mice. miR-182-5p's inhibition of TAF15 negatively regulates Th17 cell development by suppressing STAT3 phosphorylation. As TAF15 shows a positive relationship with Th17 cell markers in uveitis patients, the miR-182-5p/TAF15 axis shows promise as a therapeutic target for uveitis.

CD5 dynamically calibrates basal NF-κB signaling in T cells during thymic development and peripheral activation

Immature T cells undergo a process of positive selection in the thymus when their new T cell receptor (TCR) engages and signals in response to self-peptides. As the T cell matures, a slew of negative regulatory molecules, including the inhibitory surface glycoprotein CD5, are up-regulated in proportion to the strength of the self-peptide signal. Together these regulators dampen TCR-proximal signaling and help avoid any subsequent peripheral activation of T cells by self-peptides. Paradoxically, antigen-specific T cells initially expressing more CD5 (CD5^hi) have been found to better persist as effector/memory cells after a peripheral challenge. The molecular mechanisms underlying such a duality in CD5 function is not clear. We found that CD5 alters the basal activity of the NF-κB signaling in resting peripheral T cells. When CD5 was conditionally ablated, T cells were unable to maintain higher expression of the cytoplasmic NF-κB inhibitor IκBα. Consistent with this, resting CD5^hi T cells expressed more of the NF-κB p65 protein than CD5^lo cells, without significant increases in transcript levels, in the absence of TCR signals. This posttranslationally stabilized cellular NF-κB depot potentially confers a survival advantage to CD5^hi T cells over CD5^lo ones. Taken together, these data suggest a two-step model whereby the strength of self-peptide-induced TCR signal lead to the up-regulation of CD5, which subsequently maintains a proportional reserve of NF-κB in peripheral T cells poised for responding to agonistic antigen-driven T cell activation.

Effects of CK2β subunit down-regulation on Akt signalling in HK-2 renal cells

The PI3K/Akt pathway is interconnected to protein kinase CK2, which directly phosphorylates Akt1 at S129. We have previously found that, in HK-2 renal cells, downregulation of the CK2 regulatory subunit β (shCK2β cells) reduces S129 Akt phosphorylation. Here, we investigated in more details how the different CK2 isoforms impact on Akt and other signaling pathways. We found that all CK2 isoforms phosphorylate S129 in vitro, independently of CK2β. However, in HK-2 cells the dependence on CK2β was confirmed by rescue experiments (CK2β re-expression in shCK2β HK-2 cells), suggesting the presence of additional components that drive Akt recognition by CK2 in cells. We also found that CK2β downregulation altered the phosphorylation ratio between the two canonical Akt activation sites (pT308 strongly reduced, pS473 slightly increased) in HK-2 cells. Similar results were found in other cell lines where CK2β was stably knocked out by CRISPR-Cas9 technology. The phosphorylation of rpS6 S235/S236, a downstream effector of Akt, was strongly reduced in shCK2β HK-2 cells, while the phosphorylation of two Akt direct targets, PRAS40 T246 and GSK3β S9, was increased. Differently to what observed in response to CK2β down-regulation, the chemical inhibition of CK2 activity by cell treatment with the specific inhibitor CX-4945 reduced both the Akt canonical sites, pT308 and pS473. In CX-4945-treated cells, the changes in rpS6 pS235/S236 and GSK3β pS9 mirrored those induced by CK2β knock-down (reduction and slight increase, respectively); on the contrary, the effect on PRAS40 pT246 phosphorylation was sharply different, being strongly reduced by CK2 inhibition; this suggests that this Akt target might be dependent on Akt pS473 status in HK-2 cells. Since PI3K/Akt and ERK1/2/p90rsk pathways are known to be interconnected and both modulated by CK2, with GSK3β pS9 representing a convergent point, we investigated if ERK1/2/p90rsk signaling was affected by CK2β knock-down and CX-4945 treatment in HK-2 cells. We found that p90rsk was insensitive to any kind of CK2 targeting; therefore, the observation that, similarly, GSK3β pS9 was not reduced by CK2 blockade suggests that GSK3β phosphorylation is mainly under the control of p90rsk in these cells. However, we found that the PI3K inhibitor LY294002 reduced GSK3β pS9, and concomitantly decreased Snail1 levels (a GSK3β target and Epithelial-to-Mesenchymal transition marker). The effects of LY294002 were observed also in CK2β-downregulated cells, suggesting that reducing GSK3β pS9 could be a strategy to control Snail1 levels in any situation where CK2β is defective, as possibly occurring in cancer cells.

Inhibition of Casein Kinase II by CX-4945, But Not Yes-associated protein (YAP) by Verteporfin, Enhances the Antitumor Efficacy of Temozolomide in Glioblastoma

Overcoming temozolomide (TMZ) resistance in glioma cancer cells remains a major challenge to the effective treatment of the disease. Increasing TMZ efficacy for patients with glioblastoma (GBM) is urgently needed because TMZ treatment is the standard chemotherapy protocol for adult patients with glioblastoma. O⁶-methylguanine-DNA-methyltransferase (MGMT) overexpression is associated with TMZ resistance, and low MGMT is a positive response marker for TMZ therapy. Here, we used 3 glioma cell lines (SF767, U373, and LN229), which had different levels of TMZ sensitivity. We found TMZ sensitivity is positively correlated with MGMT expression and multidrug-resistance protein ABC subfamily G member 2 (ABCG2) in these cells. CK2-STAT3 signaling and Hippo-YAP signaling are reported to regulate MGMT expression and ABCG2 expression, respectively. We combined CK2 inhibitor CX-4945 and YAP inhibitor verteporfin with TMZ treatment. We found that CX-4945 but not verteporfin can sensitize TMZ-resistant cells SF767 to TMZ and that CX-4945 and TMZ combinational treatment was effective for glioma treatment in mouse models compared with TMZ alone.

Implications

A combination of CK2 inhibitor with TMZ may improve the therapeutic efficiency of TMZ toward GBM with acquired resistance.

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Inhibition of casein kinase II (CK2) downregulates O⁶-methylguanine-DNA-methyltransferase expression in glioma cells.

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Inhibition of CK2 sensitizes glioma cells to temozolomide (TMZ) treatment.

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Inhibition of ABC subfamily G member 2 has no effects on glioma cells' sensitivity to TMZ.

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CK2 inhibitor CX-4945 addition enhances TMZ efficacy in vivo.

Litopenaeus vannamei CK2 is involved in shrimp innate immunity by modulating hemocytes apoptosis

Protein kinase CK2 (CK2) is a ubiquitous serine/threonine kinase with multiple cellular functions in vertebrates including apoptosis, differentiation, proliferation, survival, tumorigenesis, signal transduction, immune regulation and inflammation. In the current study, the catalytic and regulatory subunit homologs of Litopenaeus vannamei protein kinase CK2 (LvCK2α and LvCK2β) were cloned and characterized. LvCK2α has a full-length cDNA sequence of 1764 bp with a 1053 bp open reading frame (ORF) encoding a putative protein of 351 amino acids, which contains a typical serine/threonine kinase domain. On the other hand, LvCK2β has a 1394 bp full-length cDNA with an ORF of 663 bp encoding a protein with 221 amino acids, which contains a Casein kinase II regulatory subunit domain. Sequence and phylogenetic analysis revealed that LvCK2 was evolutionary related with the CK2 of invertebrates. Quantitative reverse transcription PCR (RT-qPCR) analysis showed that LvCK2α and LvCK2β transcripts were widely expressed in all shrimp tissues tested, and were both induced in hemocytes and hepatopancreas upon challenge with Vibrio parahaemolyticus, Streptoccocus iniae, lipopolysaccharide (LPS), and white spot syndrome virus (WSSV), suggesting their involvement in shrimp immune response. Moreover, RNA interference (RNAi) of LvCK2α resulted in increased hemocytes apoptosis, shown by high caspase 3/7 activity, increased number of apoptotic cells, coupled with an elevation in transcript levels of pro-apoptotic LvCaspase3 and LvCytochrome C, and a reduction in mRNA levels of pro-survival LvBcl2, LvIAP1, and LvIAP2. In addition, LvCK2α knockdown followed by V. parahaemolyticus challenge resulted in higher cumulative mortality of shrimp. Taken together, our current findings suggest that LvCK2 modulates shrimp hemocytes apoptosis as part of the innate immune response to pathogens.

Deficiency of Socs3 leads to brain-targeted EAE via enhanced neutrophil activation and ROS production

Dysregulation of the JAK/STAT signaling pathway is associated with Multiple Sclerosis (MS) and its mouse model, Experimental Autoimmune Encephalomyelitis (EAE). Suppressors Of Cytokine Signaling (SOCS) negatively regulate the JAK/STAT pathway. We previously reported a severe, brain-targeted, atypical form of EAE in mice lacking Socs3 in myeloid cells (Socs3ΔLysM), which is associated with cerebellar neutrophil infiltration. There is emerging evidence that neutrophils are detrimental in the pathology of MS/EAE, however, their exact function is unclear. Here we demonstrate that neutrophils from the cerebellum of Socs3ΔLysM mice show a hyper-activated phenotype with excessive production of reactive oxygen species (ROS) at the peak of EAE. Neutralization of ROS in vivo delayed the onset and reduced severity of atypical EAE. Mechanistically, Socs3-deficient neutrophils exhibit enhanced STAT3 activation, a hyper-activated phenotype in response to G-CSF, and upon G-CSF priming, increased ROS production. Neutralization of G-CSF in vivo significantly reduced the incidence and severity of the atypical EAE phenotype. Overall, our work elucidates that hypersensitivity of G-CSF/STAT3 signaling in Socs3ΔLysM mice leads to atypical EAE by enhanced neutrophil activation and increased oxidative stress, which may explain the detrimental role of G-CSF in MS patients.

The multiple faces of CD5

Since its discovery, over 30 years ago, CD5 has been used as a marker to identify T cells, B1-a cells, and B cell chronic lymphocytic leukemia cells. Throughout the years, many studies have described the functional relevance of CD5 as a modulator of T and B cell receptor signaling. However, it has not been until recent years that CD5 has emerged as a functional receptor in other areas of the immune system. Here, we review some of the most important aspects of CD5 as a modulator of TCR and BCR signaling, cell survival receptor both in T and B cells during health and disease, as well as the newly discovered roles of this receptor in thymocyte selection, T cell effector differentiation, and immune tolerance. CD5 was found to promote T cell survival by protecting autoreactive T cell from activation-induced cell death, to promote de novo induction of regulatory T cells in the periphery, to modulate Th17 and Th2 differentiation, and to modulate immune responses by modulating dendritic cell functions. CD5 is overexpressed in Tregs and Bregs, which are fundamental to maintain immune homeostasis. The newly established roles of CD5 in modulating different aspects of immune responses identify this receptor as an immune checkpoint modulator, and therefore it could be used as a target for immune intervention in different pathologies such as cancer, autoimmune diseases or infections.

Inhibition of Casein Kinase 2 Protects Oligodendrocytes From Excitotoxicity by Attenuating JNK/p53 Signaling Cascade

Oligodendrocytes are highly vulnerable to glutamate excitotoxicity, a central mechanism involved in tissue damage in Multiple Sclerosis (MS). Sustained activation of AMPA receptors in rat oligodendrocytes induces cytosolic calcium overload, mitochondrial depolarization, increase of reactive oxygen species, and activation of intracelular pathways resulting in apoptotic cell death. Although many signals driven by excitotoxicity have been identified, some of the key players are still under investigation. Casein kinase 2 (CK2) is a serine/threonine kinase, constitutively expressed in all eukaryotic tissues, involved in cell proliferation, malignant transformation and apoptosis. In this study, we identify CK2 as a critical regulator of oligodendrocytic death pathways and elucidate its role as a signal inductor following excitotoxic insults. We provide evidence that CK2 activity is up-regulated in AMPA-treated oligodendrocytes and CK2 inhibition significantly diminished AMPA receptor-induced oligodendroglial death. In addition, we analyzed mitogen-activated protein kinase (MAPK) signaling after excitotoxic insult. We observed that AMPA receptor activation induced a rapid increase in c-Jun N-terminal kinase (JNK) and p38 phosphorylation that was reduced after CK2 inhibition. Moreover, blocking their phosphorylation, we enhanced oligodendrocyte survival after excitotoxic insult. Finally, we observed that the tumor suppressor p53 is activated during AMPA receptor-induced cell death and, interestingly, down-regulated by JNK or CK2 inhibition. Together, these data indicate that the increase in CK2 activity induced by excitotoxic insults regulates MAPKs, triggers p53 activation and mediates subsequent oligodendroglial loss. Therefore, targeting CK2 may be a useful strategy to prevent oligodendrocyte death in MS and other diseases involving central nervous system (CNS) white matter.

BCAP links IL-1R to the PI3K-mTOR pathway and regulates pathogenic Th17 cell differentiation

Deason et al. discover a novel signaling adapter in the IL-1R pathway in CD4⁺ T cells that controls the induction of the PI3K–mTOR pathway, downstream of IL-1β, to induce pathogenic Th17 cells involved in the development of autoimmunity.

The toll-like receptor (TLR) and interleukin (IL)–1 family of receptors share several signaling components, including the most upstream adapter, MyD88. We previously reported the discovery of B cell adapter for phosphoinositide 3-kinase (BCAP) as a novel toll–IL-1 receptor homology domain–containing adapter that regulates inflammatory responses downstream of TLR signaling. Here we find that BCAP plays a critical role downstream of both IL-1 and IL-18 receptors to regulate T helper (Th) 17 and Th1 cell differentiation, respectively. Absence of T cell intrinsic BCAP did not alter development of naturally arising Th1 and Th17 lineages but led to defects in differentiation to pathogenic Th17 lineage cells. Consequently, mice that lack BCAP in T cells had reduced susceptibility to experimental autoimmune encephalomyelitis. More importantly, we found that BCAP is critical for IL-1R–induced phosphoinositide 3-kinase–Akt–mechanistic target of rapamycin (mTOR) activation, and minimal inhibition of mTOR completely abrogated IL-1β–induced differentiation of pathogenic Th17 cells, mimicking BCAP deficiency. This study establishes BCAP as a critical link between IL-1R and the metabolic status of activated T cells that ultimately regulates the differentiation of inflammatory Th17 cells.

CK2 Controls Th17 and Regulatory T Cell Differentiation Through Inhibition of FoxO1

Growing evidence demonstrates that the highly conserved serine/threonine kinase CK2 promotes Th17 cell differentiation while suppressing the generation of Foxp3⁺ regulatory T cells (Tregs); however, the exact mechanism by which CK2 regulates the Th17/Treg axis remains unclear. CK2 can be composed of three distinct subunits: two catalytic subunits, CK2α and CK2α', and the regulatory subunit CK2β. We generated mice that lack the major catalytic subunit of CK2, CK2α, specifically in mature T cells using the distal Lck-Cre (CK2α^-/-). Importantly, CK2α deficiency resulted in a significant decrease in the overall kinase activity of CK2. Further, CK2α deficiency resulted in a significant defect in Th17 cell polarization and a reciprocal increase in Tregs both in vitro and in vivo in the context of autoimmune neuroinflammation. The transcription factor forkhead box protein O1 (FoxO1) directly inhibits Th17 cell differentiation and is essential for the generation of Tregs. CK2α^-/- CD4⁺ T cells exhibit less phosphorylated FoxO1 and a corresponding increase in the transcription of FoxO1-regulated genes. Treatment of CK2α^-/- CD4⁺ T cells with the FoxO1 inhibitor AS1842856 or short hairpin RNA knockdown of FoxO1 is sufficient to rescue Th17 cell polarization. Through use of a genetic approach to target CK2 kinase activity, the current study provides evidence of a major mechanism by which CK2 regulates the Th17/Treg axis through the inhibition of FoxO1.

Differential T-cell receptor signals for T helper cell programming

Upon encounter with their cognate antigen, naive CD4 T cells become activated and are induced to differentiate into several possible T helper (Th) cell subsets. This differentiation depends on a number of factors including antigen-presenting cells, cytokines and co-stimulatory molecules. The strength of the T-cell receptor (TCR) signal, related to the affinity of TCR for antigen and antigen dose, has emerged as a dominant factor in determining Th cell fate. Recent studies have revealed that TCR signals of high or low strength do not simply induce quantitatively different signals in the T cells, but rather qualitatively distinct pathways can be induced based on TCR signal strength. This review examines the recent literature in this area and highlights important new developments in our understanding of Th cell differentiation and TCR signal strength.

The Balance of Th17 versus Treg Cells in Autoimmunity

T helper type 17 (Th17) cells and pTreg cells, which share a common precursor cell (the naïve CD4 T cell), require a common tumor growth factor (TGF)-β signal for initial differentiation. However, terminally differentiated cells fulfill opposite functions: Th17 cells cause autoimmunity and inflammation, whereas Treg cells inhibit these phenomena and maintain immune homeostasis. Thus, unraveling the mechanisms that affect the Th17/Treg cell balance is critical if we are to better understand autoimmunity and tolerance. Recent studies have identified many factors that influence this balance; these factors range from signaling pathways triggered by T cell receptors, costimulatory receptors, and cytokines, to various metabolic pathways and the intestinal microbiota. This review article summarizes recent advances in our understanding of the Th17/Treg balance and its implications with respect to autoimmune disease.

Protein Kinase CK2: An Emerging Regulator of Immunity

Although it has historically been studied in the context of cancer, recent literature has highlighted the importance of the highly conserved serine/threonine kinase casein kinase II (CK2) in inflammatory disorders. Most strikingly, CK2 is a major regulator of the Th17-Treg axis relevant to many T cell-driven autoimmune disorders including multiple sclerosis (MS).