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Background & Aims The new curcumin derivative Theracurmin® has a 27–fold higher absorption rate than natural curcumin powder. Theracurmin® is an inhibitor of nuclear factor-κB, which mediates the expression of inflammatory cytokines. The effect of Theracurmin® on inflammatory bowel disease in humans has not been explored; therefore, we investigated the efficacy and safety of Theracurmin® in patients with Crohn’s disease. Methods In this randomized, double-blinded study performed at 5 independent medical centers in Japan, Theracurmin® (360 mg/day, n = 20) or placebo (n = 10) was administered to patients with active mild-to-moderate Crohn’s disease for 12 weeks. The agent’s efficacy was assessed by evaluating clinical and endoscopic remission, healing of anal lesions, and blood levels of inflammatory markers. Results In the Theracurmin® group, a significant reduction in clinical disease activity was observed in week 12 relative to that in week 0 (p = 0.005). On intention-to-treat analysis, clinical remission rates were 35%, 40%, and 40% at weeks 4, 8, and 12, respectively, which were significantly higher than those in the placebo group (all 0%; p = 0.033, p = 0.020, and p = 0.020, respectively). Furthermore, reduction in endoscopic Crohn’s disease severity (p = 0.032) was observed at week 12 in the Theracurmin® group. The endoscopic remission rates were 15% and 0% in the Theracurmin® and placebo groups, respectively. Significant healing of anal lesions (p = 0.017) was observed at week 8 in the Theracurmin® group. No serious adverse events were observed in either group throughout the study. Conclusions Theracurmin® shows significant clinical and endoscopic efficacy together with a favorable safety profile in patients with active mild-to-moderate Crohn’s disease. Clinical trial UMIN registration ID UMIN000015770.

Localized thyroid diffuse large B-cell lymphoma stage with stage IE according to the Ann Arbor clinical staging system was diagnosed in a 75-year-old woman. The patient was treated with three courses of chemotherapy followed by radiotherapy. Positron emission tomography/computed tomography (PET-CT) using 2-deoxy-2-[F-18] fluoro-D-glucose (FDG) PET-CT was performed two months after chemotherapy showed increased FDG uptakes in systemic lymph nodes and gluteal muscles. Standardized uptake value in the region of interest ranged from 7.1-26.1. Since it seemed too sudden to be a recurrence, a repeat biopsy was performed from inguinal lymph nodes. Histology revealed that there were no malignant lymphoma cells but noncaseous epithelioid granuloma with multinucleated giant cells. Taken together with the findings of bilateral hilar mediastinal lymphadenopathy and elevated serum angiotensin converting enzyme (ACE) levels (32.4 U/l), sarcoidosis secondary to lymphoma was diagnosed in this patient. Subsequently, both FDG uptake and serum ACE gradually improved without any therapy. The present case strongly suggests the importance of a re-biopsy when the clinical course of recurrence is unusual.

Adalimumab (ADA) trough level and anti-ADA antibody (AAA) positivity influence mucosal healing and loss of response in patients with inflammatory bowel disease (IBD). In this study, we clarified the correlation between ADA monitoring, including non-trough level, and real-world IBD clinical outcomes. This retrospective, observational, single-center study involved patients with ulcerative colitis (19) and Crohn’s disease (33) treated with ADA from January 2007 to August 2018. Serum ADA and AAA levels were measured 4‒14 days after ADA administration. The AAA positivity rate was 23.1% (12/52). ADA continuity was higher in AAA-negative patients than in AAA-positive patients (P = 0.223). Receiver operating characteristic (ROC) analysis revealed that a serum AAA cut-off of 9.2 μg/mL was associated with ADA continuity. The ADA level was significantly higher in the endoscopic remission group than in the non-remission group (P = 0.02). Based on the ROC curve analysis results of serum ADA level and endoscopic remission, the cut-off value of the serum ADA level was set to 11.1 μg/mL. Under the combined use of ADA with immunomodulators and AAA positivity, ADA continuity was significantly higher when the serum AAA level at 4–14 days after ADA administration was ≥9.2 μg/mL. Furthermore, endoscopic remission can be expected with a serum ADA level of ≥11.1 μg/mL. Overall, to predict clinical outcomes, it would be useful to measure the blood level of ADA regardless of the timing of the trough.

Background: The new curcumin derivative, Theracurmin® has a 27-fold higher absorption rate than the natural curcumin powder. Its pharmacologic actions include inhibition of the nuclear factor NF-κB, known to mediate the expression of inflammatory cytokines. We were interested to evaluate efficacy of Theracurmin® in patients with Crohn's disease (CD). Methods: Theracurmin® (360mg/day, n=20) or placebo (n=10) was administered to patients with active mild to moderate CD for 12 weeks. Efficacy assessment included clinical and endoscopic remission, healing of anal lesions, and blood levels of inflammatory markers. Findings: In the Theracurmin® group, significant reduction of clinical disease activity was observed at 12 weeks relative to week 0 (P=0.005). The clinical remission rates were 35%, 40%, and 40% at weeks 4, 8, and 12, respectively, significantly higher than in the placebo group (P=0.033, P=0.020, and P=0.020). Further, in the Theracurmin® group, significant healing of anal lesions (P=0.017) and endoscopic CD severity (P=0.032) were observed at weeks 8 and 12, respectively, relative to week 0. However, the mucosal healing rate at week 12 in the Theracurmin® group was 15.0%. No serious adverse event was observed in either group throughout our observation time. Interpretation: In this study, Theracurmin® in patients with active mild to moderate CD produced significant clinical and endoscopic efficacy together with a favourable safety profile. Trial registration: UMIN000015770 Funding Statement: Theracurmin® was a gift from Theravalues Corporation, Tokyo, Japan. The authors received no external funding for this study. Declaration of Interests: All authors acknowledge having no conflict of interest in connection with the publication of this manuscript. Ethics Approval Statement: At each institution, the study protocol was reviewed and approved by the committee on the Ethics of Clinical Trials involving human subjects. Further, the trial was conducted by adherence to the principles of Good Clinical Practice (GCP) and the ethical standards laid down in the 1964 Helsinki Declaration and its subsequent amendments. Similarly, informed consent was obtained from all patients after explaining the purpose of the study and the nature of the procedures involved.

It has become evident that positron emission tomography/computed tomography (PET-CT) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) (FDG PET-CT) can detect anti-tumor immune response induced by various immunotherapies. To evaluate whether FDG PET-CT could detect anti-cancer immune response caused by cancer vaccine therapy, we performed a retrospective analysis of FDG PET-CT imaging of patients who were treated with Wilms Tumor 1 (WT1) vaccine therapy in Osaka University during July 2008 and June 2018. Increased FDG uptakes were detected in WT1-vaccinated skin and their draining lymph nodes during the repeated vaccination. While the FDG uptakes seemed to decrease with time after the cessation of WT1 peptide vaccinations, persistence of FDG uptakes for years in WT1-vaccinated skin were also observed in 2 cases who showed good clinical course. Moreover, the FDG uptakes of patients treated with the combination vaccine of WT1 specific cytotoxic T cell (CTL) and helper peptides were significantly stronger than of those treated with the WT1 CTL peptide alone. Since it is evident that the combination vaccine can induce a more robust anti-tumor immunity than can CTL peptide vaccine alone, the FDG uptakes in WT1-vaccinated skin might reflect the degree of immune response. These results suggest that PET-CT might be a good tool for prediction of anti-tumor immune response induced by WT1 vaccine therapy. Larger scale prospective studies therefore seem to be warranted.

Background: Although evidence for the short- to medium-term efficacy of adalimumab in ulcerative colitis (UC) patients is emerging, there are a limited number of reports on the long-term efficacy of adalimumab. This study was to understand baseline demographic features, which potentially could be risk factors for relapse or colectomy following induction of remission by adalimumab in UC patients. Additionally, factors affecting long-term outcomes were to be identified. Methods: Twenty-one patients with UC who had been treated with adalimumab were reviewed retrospectively. Comparative analyses were undertaken by factoring steroid withdrawal versus non-withdrawal, long-term remission versus relapse following remission, and requiring surgical intervention for UC versus surgery-free. Results: Adalimumab treatment was associated with steroid tapering in steroid-dependent cases in the long term. Of the 14 patients in whom clinical remission was achieved, the cumulative nonrelapse survival rate at 350 weeks was 43.8% and the cumulative nonoperative survival rate was 85.7%. Risk factors for surgery included intolerance to salicylates (p = 0.005) and past treatment with tacrolimus (p = 0.023). Conclusions: Adalimumab treatment was associated with long-term efficacy in patients with mild UC – patients achieved a high cumulative nonoperative survival rate over a long period of time, beyond 6 years.

Adsorptive granulomonocytapheresis (GMA) with the Adacolumn has been introduced as a non-pharmacologic treatment for ulcerative colitis (UC). However, a subset of patients who might respond well to GMA needs to be targeted. This study was conducted at three IBD centers to determine factors affecting the efficacy of GMA in patients with moderately-to-severely active UC.From January 2008 to December 2017, a total of 894 active episodes (first attack or relapse) in 593 patients were treated with GMA. Clinical remission was defined as normal stool frequency and no rectal bleeding. Multiple clinical and laboratory parameters at entry were considered for efficacy assessment.Clinical remission was achieved during 422 (47%) of the 894 treatment cases. In the multivariate analysis, predictors for favorable response to GMA were age ≤60 years, UC duration1 year, Mayo endoscopic subscore 2 (vs. 3), steroid naïve UC, and biologic naïve UC. Clinical remission rate was 70% in patients with four of the five factors, 52% in patients with three factors, 46% in patients with two factors, 39% in patients with one factor, and 18% in patients with none of these factors. Overall, the clinical remission rate was significantly higher in patients with a greater number of the five predictors (P 0.0001).GMA appeared to be effective in steroid naïve and biologic naïve patients with short duration of UC. Elderly patients (60 years) and those with severe endoscopic activity did not respond well to GMA. Additional, well designed, prospective, controlled trials should strengthen our findings.

A multicenter retrospective study aiming to identify patients who respond well to adsorptive granulomonocytapheresis in moderately to severely active ulcerative colitis.

Activation of c-jun N-terminal kinase (JNK) through c-kit-mediated phosphatidylinositol 3 (PI3) and Src kinase pathways plays an important role in cell proliferation and survival in mast cells. Gain-of-function mutations in c-kit are found in several human neoplasms. Constitutive activation of c-kit has been observed in human mastocytosis and gastrointestinal stromal tumor. In the present study, we demonstrate that an anthrapyrazole SP600125, a reversible ATP-competitive inhibitor of JNK inhibits proliferation of human HMC-1 mast cells expressing constitutively activated c-kit catalytic domain mutations. HMC-1 showed constitutive activation of JNK/c-Jun, and the inhibitory effect of SP600125 on cell proliferation was associated with cell cycle arrest at the G 1 phase and apoptosis accompanied by cleavage of caspase-3 and PARP. Caspase-3 inhibitor Z-DEVD-FMK almost completely inhibited SP600125-induced apoptosis of HMC-1 cells. In contrast, caspase-9 inhibitor Z-LEHD-FMK failed to block SP600125-induced apoptosis. Following SP600125 treatment, down-regulation of cyclin D3 protein expression, but not p53 was also observed. Thus, JNK/c-Jun is essential for proliferation and survival of HMC-1 cells. The results obtained from the present study suggest the possibility that JNK/c-Jun may be a therapeutic target in diseases associated with mutations in the catalytic domain of c-kit.

Natural rubber (NR) contains linked fatty acids, composed of mainly saturated fatty acids, in conjunction with a mixture of free saturated and unsaturated fatty acids. The crystallization of synthetic cis-1,4-polyisoprene (IR) is accelerated by the addition of 1 wt % mixture of saturated fatty acid as a nucleating agent and unsaturated fatty acid as a plasticizer. As an NR model, IR was esterified with stearic acid selectively at the 3,4-isoprene units after introduction of hydroxyl group by hydroboration. The linked stearoyl group stimulated the crystallization of IR at −25 °C, while linked fatty acids other than stearoyl group showed no stimulating effect on the crystallization. The addition of methyl linoleate to the stearoyl-esterified IR gave the highest rate of crystallization at −25°C. A rapid crystallization of NR is presumed to originate from the mixed saturated and unsaturated fatty acids composition present and the presence of saturated fatty acids linked to NR.

Machiko Tsukaguchi, Masaru Shibano, Ai Matsuura, Satoru MukaiDepartment of Hematology,Sakai City Hospital, Osaka, JapanAbstract: Peripheral neuropathy (PN) caused by bortezomib is an important complication of multiple myeloma. Subcutaneous injection of bortezomib reduced PN, but 24% of cases were grade 2 PN and 6% of cases were grade 3 PN. PN higher than grade 2 was not resolved by subcutaneous injection. PN higher than grade 3 has serious dose limiting toxicity and is the cause of discontinuing bortezomib treatment. Lafutidine is an H2-blocker with gastroprotective activity and is thought to function by increasing mucosal blood flow via capsaicin sensitive neurons. The same activity of lafutidine is considered to improve glossodynia and taxane induced PN. We hypothesized that lafutidine prevents or improves PN that is caused by bortezomib. In the current study, bortezomib was administered in the usual manner (intravenous administration of bortezomib 1.3 mg/m2, twice a week for 2 weeks, followed by 1 week without treatment) for up to four cycles to compare our data with other studies. Lafutidine was administered orally at a dose of 10 mg twice daily. In our eight evaluated cases, the total occurrence of PN was four out of eight patients (50%). There were only grade 1 PN (4 out of 8) cases, and no cases higher than grade 2. We conclude that (1) the total occurrence of PN was not improved, (2) there was no PN after the first course, (3) there were only grade 1 cases and there were no cases higher than grade 2, and (4) no cases discontinued bortezomib treatment because of PN. This is the first report showing that lafutidine is useful for the amelioration of bortezomib induced PN.Keywords: bortezomib induced peripheral neuropathy, lafutidine, capsaicin sensitive neurons, calcitonin gene-related peptide, transient receptor potential 1, multiple myeloma

Objective Constitutive activation of nuclear factor (NF)-κB is a common feature of human T-cell leukemia virus type I (HTLV-I)–transformed T cells. Inhibition of NF-κB activity reduces cell growth and induces apoptosis of HTLV-I–transformed T cells, suggesting a central role of NF-κB in their proliferation and survival. In this study, we investigated whether MyD88, an adaptor protein of Toll-like receptor (TLR) signaling, contributes to constitutive NF-κB activation in HTLV-I–transformed T cells. Materials and Methods Activation status of MyD88 and interleukin (IL)-1R–associated kinase 1 (IRAK1) in HTLV-I–transformed human T cells, MT2, MT4, and HUT102 was examined by using Western blot and immunoprecipitation. TLR expression was evaluated with reverse transcription polymerase chain reaction. An expression vector encoding a dominant negative MyD88 with a deletion of its death domain (MyD88dn) was transfected into MT2 cells to evaluate roles of MyD88 in spontaneous activation of cytokine gene promoters and transcription factors, proliferation, and apoptosis in HTLV-I–transformed T cells. Results Constitutive association of MyD88 with IRAK1 was observed in all three of HTLV-I–transformed T cells, but not in HTLV-I–negative T cells, such as Jurkat, HUT78, and MOLT4. MT2 cells showed expression of TLR-1, -6, and -10 mRNAs. Constitutive activation of NF-κB and NF–IL-6 and cytokine gene promoters, such as IL-1α, interferon-γ, and tumor necrosis factor-α in MT2 cells was inhibited by MyD88dn expression. MyD88dn reduced proliferation and induced apoptosis of MT2 cells. HTLV-I Tax enhanced TLR expression and synergistically activated NF-κB with wild-type MyD88. Conclusion Our results show a novel pathway in NF-κB activation in HTLV-I–transformed T cells and further demonstrate a critical role of MyD88 in their dysregulated gene activation, survival, and proliferation.

A 57-year-old woman with chronic myeloid leukemia showing severe basophilia (WBC 17.1 X 10(9)/L, basophils 23%) was treated with 400mg imatinib in June 2003. A high basophil count (WBC 10.6 X 10(9)/L, basophils 31%) was still observed after 1 week of therapy. After 9 days of therapy, she developed generalized pruritic skin erythema, chills and high fever. After terminating imatinib treatment, prednisolone therapy was initiated. The rash quickly disappeared. Four days after withdrawal of imatinib, leukocyte count was 13.0 X 10(9)/L with 3% of basophils, suggesting the possibility that rapid decrease in basophils following imatinib therapy may induce severe cutaneous reactions.

Galectins are a family member of animal lectins that function both extracellularly (by interacting with cell surface and extracellular matrix glycoproteins and glycolipids) and intracellularly (by interacting with cytoplasmic and nuclear proteins) to modulate signaling pathways. To date, 15 galectins have been cloned in mammals. The members can be classified into 3 subtypes according to their structure. The proto type and chimera type galectins have a single CRD. The tandem-repeat type galectins have two CRDs. In this regard, galectin-9 is a tandem repeat type galectin, which has been identified as a tumor antigen of unknown functions in patients with Hodgkin lymphoma. Galectin-9 has recently demonstrated to induce chemotaxis of eosinophils and apoptosis in a variety of cells, resulting in immunomodulation, inflammation and anti-metastatic potential of tumor cells. However, the role of galectin-9 in the inflammatory responses still remains unclear. In the present study, we investigated whether intracellular galectin-9 contributes to activation of the inflammatory cytokine genes such as IL-1α, IL-1β and IFNγin human monocytes. Protein expression of galectin-9 in human THP-1 monocytic cells was examined in western blot with anti-galectin-9 Ab and immunostaining studies using a confocal microscopy. A galectin-9 expression vector pBKCMV3-Galectin-9 was transiently cotransfected into THP-1 cells along with luciferase reporter plasmids for IL-1α, IL-1β and IFNγgene promoters. Galectin-9 was detected in the cytoplasm of untreated THP-1 cells, and the expression levels of galectin-9 protein was significantly enhanced in THP-1 cells treated with lipopolysaccharide (LPS). In transient transfection studies, overexpression of galectin-9 dose-dependently activated IL-1α, IL-1β and IFNγgene promoters in THP-1 cells, showing that intracellular galectin-9 has capacity to induce the inflammatory cytokine genes in monocytes. This argument was further supported by our reverse transcription-polymerase chain reaction (RT-PCR) data that galectin-9 overexpression enhanced mRNA levels of IL-1α and β in THP-1 cells. When luciferase reporter plasmids for transcription factors including NF-IL6, NF-κB and AP-1 were transiently cotransfected into THP-1 cells along with pBKCMV3-Galectin-9, NF-IL6 and AP-1 activities were induced by galectin-9 overexpression. Our coimmunoprecipitation study, using anti-galectin-9 Ab and anti-NF-IL6 Ab revealed that intracellular galectin-9 was physically associated with NF-IL6. On the other hand, galectin-9 failed to induce NF-κB activity. Additionally, in contrast to the data obtained from transient transfection studies using pBKCMV3-Galectin-9, no significant induction of IL-1α promoter activity was observed by adding galectin-9 protein to THP-1 cell culture medium, indicating that extracellular galectin-9 dose not affect the inflammatory cytokine gene regulation. Our results strongly suggested that intracellular galectin-9 has the capability to transactivate the inflammatory cytokine genes through the physical interaction with leucin zipper transcription factors such as NF-IL6 in monocytes.

Activation of c-jun N-terminal kinase (JNK) through c-kit-mediated phosphatidylinositol 3 (PI3) and Src kinase pathways plays an important role in cell proliferation and survival in mast cells. Gain-of-function mutations in c-kit are found in several human neoplasms. Constitutive activation of c-kit has been observed in human mastocytosis, acute myeloid leukemia, lymphoma, germ tumor and gastrointestinal stromal tumor. In the present study, we demonstrate that an anthrapyrazole SP600125, a reversible ATP-competitive inhibitor of JNK inhibits proliferation of human HMC-1 mast cells expressing constitutively activated c-kit mutant. We found that JNK/c-Jun was constitutively activated in HMC-1 cells without stimulation. When spontaneous activation of JNK/c-Jun was inhibited by treatment with SP600125, cell proliferation was suppressed. The concentration which effectively inhibited JNK/c-Jun activity in our experiment had no effect on SCF-induced phosphorylation of Akt or Erk, suggesting that SP600125 specifically inhibited JNK/c-Jun activity in HMC-1 cells. Moreover, we demonstrated that SP600125 induced HMC-1 cell apoptosis in dose- and time-dependent manner. Caspase-3 and PARP were cleaved as early as 12 h after treatment with SP600125, but caspase-9 was not. Also, cell cycle arrest in G1 phase was observed in SP600125 treated cells. Thus, the inhibitory effect of SP600125 on cell proliferation was associated with cell cycle arrest at the G1 phase and apoptosis accompanied by cleavage of caspase-3 and PARP. Caspase-3 inhibitor Z-DEVD-FMK almost completely inhibited SP600125-induced apoptosis of HMC-1 cells. In contrast, caspase-9 inhibitor Z-LEHD-FMK failed to block SP600125-induced apoptosis, suggesting that apoptosis induced by SP600125 was caspase-3 dependent. Following SP600125 treatment, down-regulation of cyclin D3 protein expression, but not p53 was also observed. Take together, JNK/c-Jun is essential for proliferation and survival of HMC-1 cells. The results obtained from the present study suggest the possibility that JNK/c-Jun may be a therapeutic target in diseases associated with c-kit mutant.

Signal transducer and activator of transcription (STAT) proteins are activated in response to cytokine stimulation. STAT3 is activated in response to interleukin (IL)-6 family of cytokines, following activation of Janus family of tyrosine kinases JAK1 and JAK2, which in turn phosphorylate STAT3 on tyrosine 705 (tyr-705). On the other hand, STAT4 is activated in response to IL-12 following activation of Janus family of tyrosine kinases JAK2 and Tyk2, which in turn phosphorylate STAT4 on tyrosine 693 (tyr-693). p38/MKK6 signaling pathway activated by IL-12 further phosphorylates STAT4 on serine 721 (ser-721). STAT4 plays a crucial role in the development of type-1 helper T (Th1) cells and production of interferon (IFN)-γ in response to IL-12. STAT4 is activated by IFN-α as well as IL-12. Several STAT heterodimer complexes have been demonstrated. Selective interactions of individual STATs upon complex formation might contribute to the transcriptional target specificity of cytokine and growth factor signaling. In the present study, we demonstrated that STAT4 forms a heterodimer with STAT3 to synergistically transactivate the high-affinity sis-inducible element (hSIE). A wild-type STAT3 expression vector Rc/CMV-STAT3WT and/or a wild-type STAT4 expression vector Rc/CMV-STAT4WT were cotransfected along with a hSIE reporter pGLmfoshSIE into Hep3B cells, and cells were treated with IL-6 and/or IFN-α. In the absence of overexpression of STAT3 and STAT4, little increase in hSIE activities was observed following treatment with the cytokines, However, when Rc/CMV-STAT3WT and -STAT4WT were cotransfected, transcriptional activities were synergistically enhanced following simultaneous stimulation with IL-6 and IFN-α. γ-interferon activated site (GAS) activity was not enhanced by the two STATs. No synergistic activation of hSIE was detected between STAT1 and STAT4, when a wild-type STAT1 expression vector was used instead of Rc/CMV-STAT3WT. Our mutational analyses further revealed that the synergy between STAT3 and STAT4 was almost completely abrogated by either mutation of STAT4 at tyr-693 or STAT3 at tyr-705, suggesting direct interaction of STAT3 with STAT4 as well as the importance of STAT tyrosine phosphorylation. However, mutation of STAT4 at ser-721 caused only a little suppression of the synergy. Similar results were obtained from mutation of STAT3 at ser-727. Our immunoprecipitation (IP)/western blot (WB) analyses exhibited that STAT4 forms a heterodimer with STAT3 in response to stimulation with IL-6 and IFN-α. Moreover, in electrophoretic mobility shift assay (EMSA), hSIE preferentially bound STAT3/STAT4 heterodimer. Based upon our results, STAT3 and STAT4 can form a heterodimer, which exhibits significantly different transcripitional activities and sequence preferences to bind its target DNA. Thus, the specificity in STAT signaling is at least partly dependent on selective interactions between individual STATs upon complex formation. STAT3/STAT4 heterodimer may play an important role in immune and inflammatory reactions in NK and T-cells in response to IL-12 and IFN-α.

Human T-cell leukemia virus type I (HTLV-I) is etiologically associated with the development of an aggressive and fatal malignancy of CD4+ T lymphocytes called adult T-cell leukemia (ATL). Constitutive activation of nuclear factor-κB (NF-κB) is a common feature of ATL. Although the mechanism by which NF-κB is spontaneously activated in ATL cells still remains unclear, inhibition of NF-κB activity induces apoptosis, suggesting a central role of NF-κB in their proliferation. Toll like receptors (TLRs) are involved in innate cell activation by conserved structures expressed by microorganisms. Engagement of IL-1R or TLR with their cognate ligands causes an adaptor protein MyD88 to be recruited to the receptor complex, which in turn promotes its association with the IL-1R-associated kinase (IRAK) via an interaction between the respective death domains of each molecule. Several recent reports have indicated unique expression profiles of TLRs on different subsets of human T cells, and that some TLR ligands modulate the function of human T cells. We examined expression of the TLR mRNAs in primary ATL cells and ATL cell lines, MT2, MT4 and HUT102 by RT-PCR. Expression of TLR mRNAs, except of TLR7 and TLR8, was detected in all cell samples examined. We further demonstrated constitutive association of MyD88, an adaptor protein for the TLR signaling, with the IL-1R-associated kinase 1 (IRAK1) in ATL cell lines, MT2, MT4 and HUT102. In MT2 cells, constitutive activation of NF-κB and NF-IL6, but not Stat3 was significantly inhibited by expression of a dominant negative form of MyD88 protein (MyD88dn). Spontaneous transcriptional activation of IL-1α, IFN-γ and TNF-α gene promoters in MT2 cells was also suppressed by MyD88dn expression. MyD88dn inhibited cell proliferation and induced apoptosis of MT2 cells. In addition, overexpression of wild-type MyD88 and HTLV-I Tax induces synergistically transcriptional activity of NF-κB in 293T cells, showing interaction of Tax with MyD88. Thus, our results show a critical role of MyD88 in dysregulated gene activation and cell proliferation in HTLV-I-transformed T-cells, and further suggest the involvement of MyD88 in Tax-mediated intracellular signal transduction in HTLV-I-infected cells. Considering the fact that blocking NF-κB is a potential strategy to treat ATL, our argument raises a possibility that we may be able to find new treatment targets against ATL.