Masaya Harada

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.

IL-6 Amplifier, NF-κB–Triggered Positive Feedback for IL-6 Signaling, in Grafts Is Involved in Allogeneic Rejection Responses

The IL-6-amplifier first was discovered as a synergistic activation mechanism for NF-κB/STAT3 in type 1 collagen+ cells. This process is marked by the hyperinduction of chemokines and subsequent local inflammation that leads to autoimmune diseases. In this study, we show that IL-6 amplifier activation in grafts plays important roles in allogeneic graft rejection by using a tracheal heterotopic transplantation model that includes bronchiolitis obliterans, a pathological marker for chronic rejection. IL-6, epidermal growth factor, and IFN-γ all stimulate IL-6 amplifier activation, whereas CCL2, a chemotactic factor for Th1 cells, was one of the amplifier’s main targets. Interestingly, IFN-γ hyperinduced CCL2 in type 1 collagen+ cells via the IL-6 amplifier at least in vitro. In addition, we detected IL-6, CCL2, phospho-STAT3, and phospho-NF-κB in epithelial type 1 collagen+ cells of allogeneic tracheal grafts. These results show that IL-6 amplifier activation in grafts plays a critical role for graft rejection responses after allogeneic transplantation, including chronic rejection. From these results, we consider whether the IL-6 amplifier in grafts might be a valuable therapeutic target for the prevention of transplant rejection, including chronic rejection.

Disease-Association Analysis of an Inflammation-Related Feedback Loop

The IL-6-triggered positive feedback loop for NFκB signaling (or the IL-6 amplifier/Inflammation amplifier) was originally discovered as a synergistic-activation signal that follows IL-17/IL-6 stimulation in nonimmune cells. Subsequent results from animal models have shown that the amplifier is activated by stimulation of NFκB and STAT3 and induces chemokines and inflammation via an NFκB loop. However, its role in human diseases is unclear. Here, we combined two genome-wide mouse screens with SNP-based disease association studies, revealing 1,700 genes related to the IL-6 amplifier, 202 of which showed 492 indications of association with ailments beyond autoimmune diseases. We followed up on ErbB1 from our list. Blocking ErbB1 signaling suppressed the IL-6 amplifier, whereas the expression of epiregulin, an ErbB1 ligand, was higher in patients with inflammatory diseases. These results indicate that the IL-6 amplifier is indeed associated with human diseases and disorders and that the identified genes may make for potential therapeutic targets.

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.

IL-6 amplifier activation in epithelial regions of bronchi after allogeneic lung transplantation

The IL-6 amplifier, a positive feedback loop for NFκB signaling, which was originally found to be activated by IL-17A and IL-6 stimulation in non-immune cells, is molecularly a simultaneous activator of NFκB and signal transducer and activator of transcription 3 (STAT3), functionally a local chemokine inducer and pathologically a machinery for inflammation development. It has been shown that IL-6 amplifier activation in epithelial cells contributes to rejection responses in a mouse chronic rejection model that develops a bronchiolitis obliterans (BO)-like disease. We investigated whether the IL-6 amplifier is activated in BO regions of a human lung graft after allogeneic transplantation. NFκB and STAT3 molecules were phosphorylated in the epithelial regions of bronchi that localized in the BO regions. Additionally, chemokine ligand 2 (CCL2), and CD4(+) T cells and macrophages increased in these regions. Furthermore, human lung epithelial cells expressed CCL2 after stimulation by IFNγ in the presence of IL-6 and epidermal growth factor via enhanced STAT3 signaling, which parallels behavior seen in the mouse model. Thus, our results suggest that the IL-6 amplifier in the epithelial cells of grafts is involved in chronic rejection after lung transplantation, suggesting that the amplifier may be a valuable therapeutic target to prevent chronic rejection after lung transplantation.

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.

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.

Klotho-related Molecules Upregulated by Smoking Habit in Apparently Healthy Men: A Cross-sectional Study

While aging is unavoidable, the aging mechanism is still unclear because of its complexity. Smoking causes premature death and is considered as an environmental aging accelerator. In the present study, we focused on the influence of smoking to the serum concentration of anti-aging protein α-klotho (αKl) and the β-klotho-associated protein fibroblast growth factor (FGF)-21 in men. Subjects consisted of apparently healthy men over 40 years of age who underwent health examination. Physical and biochemical parameters, including the levels of several cytokines and growth factors, were obtained from the subjects. Among middle-aged men (46.1 ± 5.1 years), serum levels of FGF-21, soluble αKl (sαKl), and inflammation-related cytokine interleukin (IL)-6 were significantly higher in smokers than in never-smokers. Serum levels of FGF-21 increased and correlated with alanine transaminase, γ guanosine-5′-triphosphate, and total cholesterol only in smokers, suggesting FGF-21 as a metabolic disorder-related factor in smokers. In aged men (60.3 ± 1.7 years), although the serum levels of sαKl in never-smokers were low, smokers showed highly increased serum levels of sαKl. Serum levels of sαKl was correlated with IL-6 in middle-aged never-smokers, suggesting sαKl regulates IL-6. However, this correlation was disrupted in smokers and aged men.

Reverse Direction Method: A Possible Tool to Link Animal Models with Corresponding Human Diseases and Disorders

Animal models are integral to our understanding of the cellular and molecular pathogenesis of human diseases and disorders. Functional genome-wide methods such as DNA microarray and RNA interference-based highthroughput screening have recently emerged as powerful tools for such studies. However, genomic results from animal models may not necessarily correspond to the pathogenesis in humans. Thus, there is a need for new methods that better correlate the data from these models with human disease and disorders. Here we describe the reverse direction method, which combines the in vitro data of genome-wide screening of animal models with the data from genome-wide association studies (GWAS) of human diseases and disorders to effectively link the results of the two. This review introduces the concept of the reverse direction method when applied to the study of the inflammation amplifier, a chemokine inducer in non-immune cells for the development of chronic inflammatory diseases.