Association between 25 Hydroxyvitamin D Concentrations and Lipid Profiles in Japanese with Type 2 Diabetes Mellitus.

Low 25 hydroxyvitamin D (25(OH)D) levels are closely associated with the risk of cardiovascular disease. Vitamin D deficiency is more common in patients with type 2 diabetes mellitus than in the general population. In addition, vitamin D status is lower in patients with the metabolic syndrome than in those without the syndrome. Therefore, we examined the association between lipid profiles and 25(OH)D levels. In this case control study, 285 type 2 diabetic patients who attended the Manda Memorial Hospital from March to October 2017 were selected and 25(OH)D, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride (TG) levels, were obtained. Multiple regression analysis revealed that the association between 25(OH)D concentrations and TG levels was statistically significant (p<0.01) after adjusting for age, sex, body mass index, estimated glomerular flow rate (eGFR), insulin use, duration of diabetes mellitus, glycosylated hemoglobin (HbA1c), alcohol consumption, current smoking, and sampling timing. The serum 25(OH)D level was inversely associated with the TG level after the adjustment for the characteristics of Japanese patients with type 2 diabetes mellitus.

Efficacy and Safety of Low-Dose Pemafibrate Therapy for Hypertriglyceridemia in Patients with Type 2 Diabetes.

INTRODUCTION: Pemafibrate is a potent selective peroxisome proliferator-activated receptor α (PPARα) modulator that may be safer than conventional PPARα agonists in the treatment of dyslipidemia. This study was designed to investigate the efficacy of low-dose pemafibrate (0.1 mg/day) therapy for hypertriglyceridemia in 31 patients with type 2 diabetes and high triglyceride (TG) levels at the Manda Memorial Hospital. METHODS: TG, remnant lipoprotein cholesterol (RLP-C), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) AI, Apo AII, Apo B, Apo CII, Apo CIII, and Apo E levels were evaluated. Liver, kidney, and muscle toxicity tests were also performed. Pemafibrate (0.1 mg) was administered once daily. RESULTS: This treatment significantly decreased TG, RLP-C, Apo CII, Apo CIII, and Apo E levels while significantly increasing HDL-C, Apo AI, and Apo AII levels. No significant changes were observed in LDL-C and Apo B levels. There were no significant liver-, kidney-, or muscle-related adverse events. CONCLUSIONS: The results of this study show that low-dose pemafibrate administration improves the lipid profile in Japanese patients with hypertriglyceridemia and type 2 diabetes.

Breakpoint Cluster Region-Mediated Inflammation Is Dependent on Casein Kinase II.

The breakpoint cluster region (BCR) is known as a kinase and cause of leukemia upon fusing to Abl kinase. In this study, we demonstrate that BCR associated with the α subunit of casein kinase II (CK2α), rather than BCR itself, is required for inflammation development. We found that BCR knockdown inhibited NF-κB activation in vitro and in vivo. Computer simulation, however, suggested that the putative BCR kinase domain has an unstable structure with minimal enzymatic activity. Liquid chromatography-tandem mass spectrometry analysis showed that CK2α associated with BCR. We found the BCR functions are mediated by CK2α. Indeed, CK2α associated with adaptor molecules of TNF-αR and phosphorylated BCR at Y177 to establish a p65 binding site after TNF-α stimulation. Notably, p65 S529 phosphorylation by CK2α creates a p300 binding site and increased p65-mediated transcription followed by inflammation development in vivo. These results suggest that BCR-mediated inflammation is dependent on CK2α, and the BCR-CK2α complex could be a novel therapeutic target for various inflammatory diseases.

Strong TCR-mediated signals suppress integrated stress responses induced by KDELR1 deficiency in naive T cells.

KDEL receptor 1 (KDELR1) regulates integrated stress responses (ISR) to promote naive T-cell survival in vivo. In a mouse line having nonfunctional KDELR1, T-Red (naive T-cell reduced) mice, polyclonal naive T cells show excessive ISR and eventually undergo apoptosis. However, breeding T-Red mice with TCR-transgenic mice bearing relatively high TCR affinity rescued the T-Red phenotype, implying a link between ISR-induced apoptosis and TCR-mediated signaling. Here, we showed that strong TCR stimulation reduces ISR in naive T cells. In mice lacking functional KDELR1, surviving naive T cells expressed significantly higher levels of CD5, a surrogate marker of TCR self-reactivity. In addition, higher TCR affinity/avidity was confirmed using a tetramer dissociation assay on the surviving naive T cells, suggesting that among the naive T-cell repertoire, those that receive relatively stronger TCR-mediated signals via self-antigens survive enhanced ISR. Consistent with this observation, weak TCR stimulation with altered peptide ligands decreased the survival and proliferation of naive T cells, whereas stimulation with ligands having higher affinity had no such effect. These results suggest a novel role of TCR-mediated signals in the attenuation of ISR in vivo.

KDEL receptor 1 regulates T-cell homeostasis via PP1 that is a key phosphatase for ISR.

KDEL receptors are responsible for retrotransporting endoplasmic reticulum (ER) chaperones from the Golgi complex to the ER. Here we describe a role for KDEL receptor 1 (KDELR1) that involves the regulation of integrated stress responses (ISR) in T cells. Designing and using an N-ethyl-N-nitrosourea (ENU)-mutant mouse line, T-Red (naïve T-cell reduced), we show that a point mutation in KDELR1 is responsible for the reduction in the number of naïve T cells in this model owing to an increase in ISR. Mechanistic analysis shows that KDELR1 directly regulates protein phosphatase 1 (PP1), a key phosphatase for ISR in naïve T cells. T-Red KDELR1 does not associate with PP1, resulting in reduced phosphatase activity against eIF2α and subsequent expression of stress responsive genes including the proapoptotic factor Bim. These results demonstrate that KDELR1 regulates naïve T-cell homeostasis by controlling ISR.

Temporal expression of growth factors triggered by epiregulin regulates inflammation development.

In this study, we investigated the relationship between several growth factors and inflammation development. Serum concentrations of epiregulin, amphiregulin, betacellulin, TGF-α, fibroblast growth factor 2, placental growth factor (PLGF), and tenascin C were increased in rheumatoid arthritis patients. Furthermore, local blockades of these growth factors suppressed the development of cytokine-induced arthritis in mice by inhibiting chemokine and IL-6 expressions. We found that epiregulin expression was early and followed by the induction of other growth factors at different sites of the joints. The same growth factors then regulated the expression of epiregulin at later time points of the arthritis. These growth factors were increased in patients suffering from multiple sclerosis (MS) and also played a role in the development of an MS model, experimental autoimmune encephalomyelitis. The results suggest that the temporal expression of growth factors is involved in the inflammation development seen in several diseases, including rheumatoid arthritis and MS. Therefore, various growth factor pathways might be good therapeutic targets for various inflammatory diseases.

Naïve T Cell Homeostasis Regulated by Stress Responses and TCR Signaling.

The survival of naïve T cells is believed to require signals from TCR-pMHC interactions and cytokines such as IL-7. In contrast, signals that negatively impact naïve T cell survival are less understood. We conducted a forward genetic screening of mice and found a mutant mouse line with reduced number of naïve T cells (T-Red mice). T-Red mice have a point mutation in the Kdelr1 gene, and their naïve T cells show enhanced integrated stress response (ISR), which eventually induces their apoptosis. Therefore, naïve T cells require a KDEL receptor-mediated mechanism that efficiently relieves cellular stress for their survival in vivo. Interestingly, naïve T cells expressing TCR with higher affinity/avidity to self-antigens survive in T-Red mice, suggesting the possible link between TCR-mediated survival and ISR-induced apoptosis. In this article, we discuss the regulation of naïve T cell homeostasis, keeping special attention on the ISR and TCR signal.

The Gateway Reflex, which is mediated by the inflammation amplifier, directs pathogenic immune cells into the CNS.

The brain-blood barrier (BBB) tightly limits immune cell migration into the central nervous system (CNS), avoiding unwanted inflammation under the normal state. However, immune cells can traverse the BBB when inflammation occurs within the CNS, suggesting a certain signal that creates a gateway that bypasses the BBB might exist. We revealed the inflammation amplifier as a mechanism of this signal, and identified dorsal vessels of the fifth lumber (L5) spinal cord as the gateway. The inflammation amplifier is driven by a simultaneous activation of NF-κB and STATs in non-immune cells, causing the production of a large amount of inflammatory chemokines to open the gateway at L5 vessels. It was found that the activation of the amplifier can be modulated by neural activation and artificially operated by electric pulses followed by establishment of new gateways, Gateway Reflex, at least in mice. Furthermore, genes required for the inflammation amplifier have been identified and are highly associated with various inflammatory diseases and disorders in the CNS. Thus, physical and/or pharmacological manipulation of the inflammation amplifier holds therapeutic value to control neuro-inflammation.

The reverse-direction method links mass experimental data to human diseases.

Genome-wide analyses such as DNA microarray, RNA sequencing and RNA interference-based high-throughput screening are prevalent to decipher a biological process of interest, and provide a large quantity of data to be processed. An ultimate goal for researchers must be extrapolation of their data to human diseases. We have conducted functional genome-wide screenings to elucidate molecular mechanisms of the inflammation amplifier, a NFκB/STAT3-dependent machinery that potently drives recruitment of immune cells to promote inflammation. Using a public database of genome-wide association studies (GWAS), we recently reported the reverse-direction method by which our mass screening data were successfully linked to many human diseases. As an example, the epiregulin-epidermal growth factor receptor pathway was identified as a regulator of the inflammation amplifier, and associated with human diseases by GWAS. In fact, serum epiregulin levels were higher in patients with chronic inflammatory disorders. The reverse-direction method can be a useful tool to narrow mass data down to focus on human disease-related genes.

Inflammation amplifier, a new paradigm in cancer biology.

Tumor-associated inflammation can induce various molecules expressed from the tumors themselves or surrounding cells to create a microenvironment that potentially promotes cancer development. Inflammation, particularly chronic inflammation, is often linked to cancer development, even though its evolutionary role should impair nonself objects including tumors. The inflammation amplifier, a hyperinducer of chemokines in nonimmune cells, is the principal machinery for inflammation and is activated by the simultaneous stimulation of NF-κB and STAT3. We have redefined inflammation as local activation of the inflammation amplifier, which causes an accumulation of various immune cells followed by dysregulation of local homeostasis. Genes related to the inflammation amplifier have been genetically associated with various human inflammatory diseases. Here, we describe how cancer-associated genes, including interleukin (IL)-6, Ptgs2, ErbB1, Gas1, Serpine1, cMyc, and Vegf-α, are strongly enriched in genes related to the amplifier. The inflammation amplifier is activated by the stimulation of cytokines, such as TNF-α, IL-17, and IL-6, resulting in the subsequent expression of various target genes for chemokines and tumor-related genes like BCL2L11, CPNE7, FAS, HIF1-α, IL-1RAP, and SOD2. Thus, we conclude that inflammation does indeed associate with the development of cancer. The identified genes associated with the inflammation amplifier may thus make potential therapeutic targets of cancers.

The gateway theory: bridging neural and immune interactions in the CNS.

The central nervous system (CNS) is considered an immune-privileged tissue protected by a specific vessel structure, the blood-brain barrier (BBB). Upon infection or traumatic injury in the CNS, the BBB is breached, and various immune cells are recruited to the affected area. In the case of autoimmune diseases in the CNS like multiple sclerosis (MS), autoreactive T cells against some CNS-specific antigens can theoretically attack neurons throughout the CNS. The affected CNS regions in MS patients can be detected as multiple focal plaques in the cerebrum, thoracic cord, and other regions. Vision problems are often associated with the initial phase of MS, suggesting a disturbance in the optic nerves. These observations raise the possibility that there exist specific signals that direct autoreactive T cells past the BBB and into particular sites of the CNS. Using a mouse model of MS, experimental autoimmune encephalomyelitis (EAE), we recently defined the mechanism of the pathogenesis in which regional neural stimulations modulate the status of the blood vessel endothelium to allow the invasion of autoreactive T cells into specific sites of the CNS via the fifth lumbar cord. This gate for autoreactive T cells can be artificially manipulated by removing gravity forces on the hind legs or by electric pulses to the soleus muscles, quadriceps, and triceps of mice, resulting in an accumulation of autoreactive T cells in the intended regions via the activation of regional neurons. Gating blood vessels by regional neural stimulations, a phenomenon we call the gateway theory, has potential therapeutic value not only in preventing autoimmunity, but also in augmenting the effects of cancer immunotherapies.

Regulation of immune cell infiltration into the CNS by regional neural inputs explained by the gate theory.

The central nervous system (CNS) is an immune-privileged environment protected by the blood-brain barrier (BBB), which consists of specific endothelial cells that are brought together by tight junctions and tight liner sheets formed by pericytes and astrocytic end-feet. Despite the BBB, various immune and tumor cells can infiltrate the CNS parenchyma, as seen in several autoimmune diseases like multiple sclerosis (MS), cancer metastasis, and virus infections. Aside from a mechanical disruption of the BBB like trauma, how and where these cells enter and accumulate in the CNS from the blood is a matter of debate. Recently, using experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we found a "gateway" at the fifth lumber cord where pathogenic autoreactive CD4+ T cells can cross the BBB. Interestingly, this gateway is regulated by regional neural stimulations that can be mechanistically explained by the gate theory. In this review, we also discuss this theory and its potential for treating human diseases.

Expression of inducible 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase/PFKFB3 isoforms in adipocytes and their potential role in glycolytic regulation.

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase) catalyzes the synthesis and degradation of fructose 2,6-bisphosphate (F2,6BP), which is a powerful activator of 6-phosphofructo-1-kinase, the rate-limiting enzyme of glycolysis. Four genes encode PFK-2/FBPase (PFKFB1-4), and an inducible isoform (iPFK-2/PFKFB3) has been found to mediate F2,6BP production in proliferating cells. We have investigated the role of iPFK-2/PFKFB3 and related isoforms in the regulation of glycolysis in adipocytes. Human visceral fat cells express PFKFB3 mRNA, and three alternatively spliced isoforms of iPFK-2/PFKFB3 are expressed in the epididymal fat pad of the mouse. Forced expression of the iPFK-2/PFKFB3 in COS-7 cells resulted in increased glucose uptake and cellular F2,6BP content. Prolonged insulin treatment of 3T3-L1 adipocytes led to reduced PFKFB3 mRNA expression, and epididymal fat pads from db/db mice also showed decreased expression of PFKFB3 mRNA. Finally, anti-phospho-iPFK-2(Ser461) Western blotting revealed strong reactivity in insulin-treated 3T3-L1 adipocyte, suggesting that insulin induces the phosphorylation of PFKFB3 protein. These data expand the role of these structurally unique iPFK-2/PFKFB3 isoforms in the metabolic regulation of adipocytes.

Phosphorylation of the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase/PFKFB3 family of glycolytic regulators in human cancer.

PURPOSE: Fructose 2,6-bisphosphate (F2,6BP) is a potent activator of phosphofructokinase, which is a rate-limiting enzyme of glycolysis. The concentration of F2,6BP depends on the activity of the bifunctional enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase). Four genes encoding PFK-2/FBPase have been identified and termed PFKFB1 to PFKFB4. PFKFB3 protein is expressed in high levels in human tumors in situ. The purpose of this study was to determine the role of functional interactions between the phosphorylation of PFKFB3 and activated glycolysis in human cancer cells. EXPERIMENTAL DESIGN: cDNA from several human tumor cell lines and human colon carcinoma were analyzed by reverse transcription-PCR to identify different splicing variants of PFKFB3. The effect of phosphorylation of Ser461 was studied by recombinantly replacing this residue with glutamate (PFKFB3S461E). The phosphorylation of PFKFB3 protein in human cancer was determined by immunostaining using an anti-phospho-PFK-2(PFKFB3) antibody. RESULTS: Two splicing variants of PFKFB3 are expressed in human cancer cell lines: PFKFB3-ACG and PFKFB3-AG. Quantitative, real-time PCR analysis confirmed the overexpression of PFKFB3 mRNA in colon carcinoma, with the dominant variant being the PFKFB3-ACG isoform that contains a phosphorylation site at Ser461. Forced expression of PFKFB3-ACG in COS-7 cells resulted in enhanced glycolysis. Introduction of PFKFB3-ACGS461E into COS-7 cells led to increased the lactate production and cell proliferation. Highly phosphorylated PFKFB3 protein was found in human tumor cells, vascular endothelial cells, and smooth muscle cells, as determined by immunostaining with an anti-phospho-PFK-2(PFKFB3) antibody. CONCLUSIONS: These findings support a potential role for the phosphorylation of PFKFB3 protein in the progression of cancer and angiogenesis.