Manae S. Kurokawa

Nicotine inhibits the production of proinflammatory mediators in human monocytes by suppression of I-κB phosphorylation and nuclear factor-κB transcriptional activity through nicotinic acetylcholine receptor α7

Macrophages/monocytes and the proinflammatory mediators, such as tumour necrosis factor (TNF)‐α, prostaglandin E2 (PGE2), macrophage inflammatory protein (MIP)‐1α and MIP‐1α, play a critical role in the progression of immunological disorders including rheumatoid arthritis, Behçet’s disease and Crohn’s disease. In addition, the nicotinic acetylcholine receptor‐α7 (α7nAChR) subunit is an essential regulator of inflammation. In this study, we evaluated the expression of the α7nAChR subunit on human peripheral monocytes and the effect of nicotine on the production of these proinflammatory mediators by activated monocytes. Fluorescein isothiocyanate (FITC)‐labelled α‐bungarotoxin demonstrated the cell surface expression of the α7nAchR subunit. Pretreatment with low‐dose nicotine caused inhibition of TNF‐α, PGE2, MIP‐1α and MIP‐1α production, and mRNA expression of TNF‐α, MIP‐1α and MIP‐1α and COX‐2 in lipopolysaccharide (LPS)‐activated monocytes. These suppressive effects of nicotine were caused at the transcriptional level and were mediated through α7nAChR. Nicotine suppressed the phosphorylation of I‐κB, and then inhibited the transcriptional activity of nuclear factor‐κB. These immunosuppressive effects of nicotine may contribute to the regulation of some immune diseases.

Involvement of Th1 cells and heat shock protein 60 in the pathogenesis of intestinal Behcet's disease.

Involvement of excessive Th1 cell functions and heat shock protein expression in the pathogenesis of Behçets disease (BD) has been reported. In this study we have characterized immune responses in intestinal lesions of BD. Peripheral blood lymphocytes (PBL) of BD and healthy controls (HC) and tissue specimens of intestinal Behçets disease (intestinal BD), Crohns disease (CD) and ulcerative colitis (UC) were analysed for mRNA and protein expression by reverse transcriptase‐polymerase chain reaction (PCR) and immunohistochemistry, respectively. PBL of BD patients expressed the Th1‐related chemokine receptor, CCR5 and CXCR3 preferentially compared with those of healthy controls. Intestinal lesions of BD expressed interferon (IFN)‐γ, tumour necrosis factor (TNF)‐α and interleukin (IL)‐12 mRNA, indicating Th1 skewed responses in vivo. mRNA of Txk, a Tec family tyrosine kinase specific to Th1 cells, was expressed in the lesions, suggesting its contribution to the Th1‐dominant responses. In the intestinal samples, CCR5 was detected in all the cases with BD, whereas Th2‐related CCR3 and CCR4 were detected randomly, mainly in the cases with inactive BD and those receiving large amounts of prednisolone, indicating the Th1‐dominant immune responses in the intestinal lesions. As the ligands of CCR5, MIP1α and MIP1β were detected, whereas RANTES was not. Heat shock protein (HSP) 60 was expressed in PBL and intestinal tissues of BD. Th1‐dominant immune responses and HSP60 expression may induce the inflammatory responses and thus be associated with the pathogenesis of intestinal BD.

Implication of granulocyte-macrophage colony-stimulating factor induced neutrophil gelatinase-associated lipocalin in pathogenesis of rheumatoid arthritis revealed by proteome analysis

IntroductionIn rheumatoid arthritis (RA), synovial fluid (SF) contains a large number of neutrophils that contribute to the inflammation and destruction of the joints. The SF also contains granulocyte-macrophage colony-stimulating factor (GM-CSF), which sustains viability of neutrophils and activates their functions. Using proteomic surveillance, we here tried to elucidate the effects of GM-CSF on neutrophils.MethodsNeutrophils stimulated by GM-CSF were divided into four subcellular fractions: cytosol, membrane/organelle, nuclei, and cytoskeleton. Then, proteins were extracted from each fraction and digested by trypsin. The produced peptides were detected using matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS).ResultsWe detected 33 peptide peaks whose expression was upregulated by more than 2.5-fold in GM-CSF stimulated neutrophils and identified 11 proteins out of the 33 peptides using MALDI-TOF/TOF MS analysis and protein database searches. One of the identified proteins was neutrophil gelatinase-associated lipocalin (NGAL). We confirmed that the level of NGAL in SF was significantly higher in patients with RA than in those with osteoarthritis. We next addressed possible roles of the increased NGAL in RA. We analysed proteome alteration of synoviocytes from patients with RA by treatment with NGAL in vitro. We found that, out of the detected protein spots (approximately 3,600 protein spots), the intensity of 21 protein spots increased by more than 1.5-fold and the intensity of 10 protein spots decreased by less than 1 to 1.5-fold as a result of the NGAL treatment. Among the 21 increased protein spots, we identified 9 proteins including transitional endoplasmic reticulum ATPase (TERA), cathepsin D, and transglutaminase 2 (TG2), which increased to 4.8-fold, 1.5-fold and 1.6-fold, respectively. Two-dimensional electrophoresis followed by western blot analysis confirmed the upregulation of TERA by the NGAL treatment and, moreover, the western blot analysis showed that the NGAL treatment changed the protein spots caused by post-translational modification of TERA. Furthermore, NGAL cancelled out the proliferative effects of fibroblast growth factor (FGF)-2 and epidermal growth factor (EGF) on chondrocytes from a patient with RA and proliferative effect of FGF-2 on chondrosarcoma cells.ConclusionsOur results indicate that GM-CSF contributes to the pathogenesis of RA through upregulation of NGAL in neutrophils, followed by induction of TERA, cathepsin D and TG2 in synoviocytes. NGAL and the upregulated enzymes may therefore play an important role in RA.

Involvement of innate immunity in the pathogenesis of intestinal Behçet's disease.

The involvement of excessive T helper 1 (Th1) cell functions in the pathogenesis of Behçets disease (BD) has been reported. We therefore studied Toll‐like receptor (TLR)‐expressing cells, which play important roles in innate immunity in patients with BD. Peripheral blood mononuclear cells (PBMC) of BD and healthy controls, and tissue specimens of intestinal BD and Crohns disease (CD) were analysed for messenger RNA (mRNA) and protein expressions by reverse transcription–polymerase chain reaction and immunostaining respectively. PBMC of BD expressed TLR‐2 and TLR‐4 mRNA almost comparable with healthy controls. Intestinal lesions of BD expressed TLR‐2 and TLR‐4 mRNA consistently. In contrast, TLR‐4 mRNA was expressed preferentially and TLR‐2 mRNA was expressed less frequently in CD lesions. In intestinal samples of BD, TLR‐2 and TLR‐4 mRNA were detected in ileocaecal ulcer lesions, but not in unaffected sites of the same sample, indicating the association of the TLR expression with the disease manifestation of intestinal BD. TLR‐2‐expressing cells which were simultaneously cluster of distribution (CD)68‐positive produced interleukin (IL)‐12 in the lesions, indicating the participation of TLR‐2‐expressing cells in the Th1 skewed responses in vivo. As a possible ligand of TLR‐2, in BD self‐heat shock protein 60 was expressed in peripheral blood lymphocytes and intestinal tissues. Collectively, TLR‐2‐expressing cells as well as TLR‐4‐expressing cells accumulated in the intestinal lesions of BD. IL‐12 produced by TLR‐2‐expressing cells may contribute to the induction of Th1‐dominant immune responses in intestinal BD.

Anatomical and functional recovery by embryonic stem cell-derived neural tissue of a mouse model of brain damage

We have treated undifferentiated mouse embryonic stem (ES) cells with all-trans retinoic acid (RA) to induce differentiation in vitro into neuron-like cells with good cell viability for use as a graft. Furthermore, we asked whether the RA-induced neuron-like cells restored neurological dysfunction. To this end, the cells were transplanted into right hemiplegia model of mice, developed by a cryogenic injury of motor cortex. Motor function of the recipients was gradually improved, whereas little improvement was observed in control mice. The lesion showed clustering of mature and almost mature neuron-like cells in mice transplanted with the RA-treated cells. The grafted cells had synaptic vesicles. This finding may suggest their maturation and synaptic connection in the recipient brain. Even though further study is necessary to elucidate molecular and cellular mechanisms responsible for the functional recovery, we consider that the ES cells may have advantage for use as a donor source in various neurological disorders including motor dysfunction.

Excessive expression of Txk, a member of the Tec family of tyrosine kinases, contributes to excessive Th1 cytokine production by T lymphocytes in patients with Behcet's disease

Excessive Th1 cell function is importantly involved in the pathogenesis of Behcets disease (BD). We previously found that Txk, a member of the Tec family of tyrosine kinases, acts as a Th1 cell specific transcription factor. To investigate immune aberration in the pathogenesis of BD, we studied the expression of Txk and Th1 cytokines in peripheral blood lymphocytes (PBL) and skin lesions in patients with BD. Cytokine production by the lymphocytes was assessed using ELISA. PBL produced excessive Th1 associated cytokines including IFN‐γ and IL‐12 spontaneously and in response to exogenous HSP60‐derived peptide stimulation, which was shown to induce proliferation of PBL, in patients with BD. Circulating CD4+ T cells expressed excessive Txk protein. A majority of cells infiltrating into skin lesions expressed IFN‐γ in the BD specimens. IL‐12 and IL‐18 were also expressed in the mononuclear cell aggregates. Lymphocytes accumulating in the skin lesion expressed higher levels of Txk as compared with atopic dermatitis lesions, a typical Th2 disease. IFN‐γ, IL‐18 and Il‐12 were detected in the BD skin lesions, which may induce preferential development of Th1 cells in patients with BD. The mononuclear cell aggregates contained Txk expressing cells in such skin lesions. Collectively, Txk expressing Th1 cells and the Th1 associated cytokines may play a critical role in the development of skin lesions in BD.

Analysis of accumulated T cell clonotypes in patients with systemic lupus erythematosus.

OBJECTIVE To compare the accumulated T cell clonotypes in peripheral blood (PB) samples obtained at various times, and the accumulated T cell clonotypes in a PB sample and in an affected kidney, from patients with systemic lupus erythematosus (SLE). METHODS Peripheral blood mononuclear cells (PBMC) were obtained at 2-4 different times from each of 5 SLE patients, with or without flare-up of the disease; in addition, a biopsied kidney tissue sample was obtained from 1 of the patients. RNA was extracted from each sample and complementary DNA was prepared. Genes that encode the variable region of T cell receptor (TCR) B chains (BV) of 3 BV families, 5S1, 8, and 14, were amplified by reverse transcription-polymerase chain reaction (PCR), and the PCR products were cloned for sequencing. RESULTS A total of 877 cloned TCR genes was detected in the PBMC samples and the kidney sample. Oligoclonal T cell expansion was detected in 34 of the 36 PCR-amplified BV samples from PBMC (amplification of 3 BV families in 2-4 samples from 5 patients). The composition of clonally expanded T cell clonotypes was relatively stable in the patients with inactive SLE. In contrast, the composition of clonotypes in the PB changed drastically after the patient experienced the active phase of the disease. T cell clonotypes that had accumulated in the kidney appeared to be restricted and distinct from those that had accumulated in the PB of the same patient. CONCLUSION Different T cell clonotypes expand at different times and at different sites in patients with active SLE. The sensitizing antigens may change over the course of the disease and may be different at each site.

Establishment and application of a novel T cell clonality analysis using single-strand conformation polymorphism of T cell receptor messenger signals

To identify the existence of antigen specific T cell responses and to follow the changes of these reactions, it is considered useful to evaluate whether certain T cells clonally accumulate in the lymphocyte population. For this purpose, we have established a novel method to analyze T cell clonality using a combination of reverse transcriptase-polymerase chain reaction of T cell receptor beta chain transcripts and single-strand conformation polymorphism (SSCP). Using this method, we obtained a smear-like pattern of electrophoresed DNA from the heterogeneous T cell population. On the other hand, a single T cell clone exhibits a band in the appropriate VP amplification and an accumulated T cell clone in a heterogeneous lymphocyte population is identified as a band in the background smear pattern. If a lymphocyte population was stimulated by an antigen either in vitro or in vivo, several distinct bands were found to be generated in the background smear. Thus, the dynamic changes of T cell clonal responses could be monitored with this method. Analyses of several immunological disorders, including autoimmune diseases, malignant disorders, and transplantations, revealed the involvement of antigen-specific T cell immune responses in these disorders. Furthermore, taking advantage of the reproducible mobility of a band of SSCP gel, we are now able to compare identities of the accumulated T cell clones in different samples without the need for nucleotide sequencing of each clone. Such information can thus elucidate the occurrence of uniform or stable immunological reactions in the host and also suggests that these reactions play an important role in vivo. Therefore, taken together, the above described novel T cell clonality analysis is considered to be useful in studying the T cell immune responses in various fields of immunology.

Protein profiles of peripheral blood mononuclear cells are useful for differential diagnosis of ulcerative colitis and Crohn’s disease

BackgroundEffective biomarkers for discrimination between ulcerative colitis (UC) and Crohn’s disease (CD) have not been established yet. In this study, we analyzed protein profiles of peripheral blood mononuclear cells (PBMCs) of the patients to find such a biomarker.MethodsPeripheral blood mononuclear cell proteins from 17 UC patients, 13 CD patients, and 17 healthy controls were separated by two-dimensional gel electrophoresis. The intensities of individual protein spots were subjected to discriminant analysis of UC and CD using the SIMCA-P+program.ResultsWe found that 547 protein spots were commonly detected among the UC, CD, and healthy groups. Orthogonal partial least squares-discriminant analysis using 276 protein spots clearly discriminated the UC patients from the CD patients (R2 0.994; Q2 0.462). A similar analysis using a further selected 58 protein spots showed higher performance for discrimination of the diseases (R2 0.948; Q2 0.566). Eleven out of the 58 protein spots were successfully identified; these were functionally related to inflammation, oxidation/reduction, the cytoskeleton, endocytotic trafficking, and transcription. In addition, the PBMC protein profiles were useful for the prediction of disease activity in the UC and the CD patients, and they were also useful for predicting disease severity and responses to treatments in the UC patients.ConclusionsPBMC protein profiles are useful for the discrimination of UC from CD. The profiles could be a potent biomarker for the differential diagnosis of these diseases. Further investigation of the proteins which contributed to the discrimination could promote elucidation of the pathophysiology of UC and CD.

Peroxiredoxin 2 is a novel autoantigen for anti‐endothelial cell antibodies in systemic vasculitis

Anti‐endothelial cell antibodies (AECA) have been frequently detected in systemic vasculitis, which affects blood vessels of various sizes. To understand the pathogenic roles of AECA in systemic vasculitis, we attempted to identify target antigens for AECA comprehensively by a proteomic approach. Proteins extracted from human umbilical vein endothelial cells (HUVEC) were separated by two‐dimensional electrophoresis, and Western blotting was subsequently conducted using sera from patients with systemic vasculitis. As a result, 53 autoantigenic protein spots for AECA were detected, nine of which were identified by mass spectrometry. One of the identified proteins was peroxiredoxin 2 (Prx2), an anti‐oxidant enzyme. Frequency of anti‐Prx2 autoantibodies, measured by enzyme‐linked immunosorbent assay (ELISA), was significantly higher in systemic vasculitis (60%) compared to those in collagen diseases without clinical vasculitis (7%, P < 0·01) and healthy individuals (0%, P < 0·01). Further, the titres changed in parallel with the disease activity during time–courses. The presence of anti‐Prx2 autoantibodies correlated significantly with elevation of serum d‐dimers and thrombin–antithrombin complex (P < 0·05). Immunocytochemical analysis revealed that live endothelial cells expressed Prx2 on their surface. Interestingly, stimulation of HUVEC with rabbit anti‐Prx2 antibodies increased secretion of interleukin (IL)‐6, IL‐1β, IL‐1ra, growth regulated oncogene (GRO)‐α, granulocyte colony‐stimulating factor (G‐CSF), granulocyte macrophage colony‐stimulating factor (GM–CSF), IL‐8 and monocyte chemoattractant protein (MCP)‐1 more than twofold compared to that of with rabbit immunoglobulin (Ig)G. Taken together, our data suggest that anti‐Prx2 autoantibodies would be a useful marker for systemic vasculitis and would be involved in the inflammatory processes of systemic vasculitis.