Conversion of T Follicular Helper Cells to T Follicular Regulatory Cells by Interleukin-2 Through Transcriptional Regulation in Systemic Lupus Erythematosus.

OBJECTIVE: This study was undertaken to identify characteristics of follicular regulatory T (Tfr) cells and elucidate the mechanisms by which follicular helper T (Tfh) cells convert to Tfr cells. We probed the phenotype of T helper cells in patients with systemic lupus erythematosus (SLE) and underlying transcriptional regulation using cytokine-induced STAT family factors. METHODS: Peripheral blood mononuclear cells from 41 patients with SLE and 26 healthy donors were used to sort out the memory Tfh cell subset, and Tfh cells were cultured under various conditions. The phenotype of T helper cells and underlying mechanisms of transcriptional regulation were probed using flow cytometry and quantitative polymerase chain reaction analyses. These analyses evaluated the expression of characteristic markers and phosphorylation of STATs. Chromatin immunoprecipitation was used to evaluate histone modifications. RESULTS: In patients with SLE, the proportion of CD4+CXCR5+FoxP3-PD-1high Tfh cells was increased (P < 0.01), whereas the proportion of CD4+CXCR5+CD45RA-FoxP3high activated Tfr cells was decreased (P < 0.05). Serum interleukin-2 (IL-2) levels were also reduced in patients with SLE. IL-2 induced conversion of memory Tfh cells to functional Tfr cells, which was characterized by CXCR5+Bcl-6+FoxP3high pSTAT3+pSTAT5+ cells. The loci of FOXP3 and BCL6 at STAT binding sites were marked by bivalent histone modifications. Following IL-2 stimulation, STAT3 and STAT5 selectively bound to FOXP3 and BCL6 gene loci accompanied by suppression of H3K27me3. Finally, IL-2 stimulation suppressed the generation of CD38+CD27high plasmablasts in Tfh and B cell coculture assays ex vivo. CONCLUSION: Impaired function of Tfr cells might be attributed to defective IL-2 production. Exogenous IL-2 restores the function of Tfr cells through the conversion of Tfh cells to Tfr cells in patients with SLE. Thus, restoring balance between Tfh and Tfr cells may provide new therapeutic approaches in SLE.

Correlation between serological biomarkers of extracellular matrix turnover and lung fibrosis and pulmonary artery hypertension in patients with systemic sclerosis.

OBJECTIVE: To determine the value of serological biomarkers of collagen degradation/turnover as serum markers of organ involvement in patients with systemic sclerosis (SSc). METHODS: Serum samples were obtained from 79 SSc patients and 19 healthy control subjects. Types I to VI collagen turnover, excluding type II collagen, were evaluated using nine serological biomarkers. Organ involvement, such as interstitial lung disease (ILD), pulmonary arterial hypertension (PAH), esophageal motility disorder, lower gastrointestinal lesions, joint contractures and digital ulceration, were evaluated and correlated with serum biomarkers. RESULTS: Among multiple serological biomarkers of collagen turnover, the mean level of C5M was higher in SSc (3.9 ng/mL) than healthy subjects (2.6 ng/mL). In addition, PRO-C6 (12.6 ng/mL vs 5.4 ng/mL) and C6M (26.0 ng/mL vs 16.7 ng/mL) were higher in SSc than the controls. The modified Rodnan skin score correlated with PRO-C3 and PRO-C6. Serum level of C6M was higher in patients with ILD. Furthermore, serum levels of PRO-C3, PRO-C6, and C6M were higher in patients with PAH. The use of high levels of these biomarkers as risk factors of PAH showed that all patients with PAH had high levels of risk factors. Of note, two-third of patients with serum PRO-C3, PRO-C6 and C6M values above the respective cut-off values had PAH. CONCLUSION: Our study indicated that collagen turnover abnormality, especially type VI collagen, is not only important pathologically in skin sclerosis but also in organ involvement. These biomarkers of collagen turnover are potentially clinically useful as biomarkers of organ involvement in SSc.

Distinctive association of peripheral immune cell phenotypes with capillaroscopic microvascular patterns in systemic sclerosis.

OBJECTIVE: The pathological changes in SSc include immune system dysregulation and microvascular damage. However, the association of immune cell phenotype heterogeneity and microvascular abnormalities is unclear. The aim of this study is to elucidate this association in SSc. METHODS: Peripheral blood mononuclear cells obtained from 150 SSc patients were used for comprehensive flow cytometric analysis based on the Human Immunology Project. Hierarchical cluster analysis was used to classify SSc patients into subgroups and their association with microvascular abnormalities, as assessed by nailfold videocapillaroscopy (i.e. 'early', 'active' and 'late' patterns), was analysed. RESULTS: The proportions of activated CD4+ T cells, T cells re-expressing CD45RA, activated Th1 and Th17 cells and IgD-CD27- B cells were higher in SSc patients than in healthy individuals. Hierarchical cluster analysis stratified SSc patients into three groups: patients with few immune abnormalities (fewer abnormalities group), patients with high proportions of activated T and Treg cells (Treg-dominant group) and patients with high proportions of Tfh and plasmablasts (Tfh-dominant group). Age and disease duration were comparable among the groups. On the other hand, microvascular abnormalities, especially the 'late' nailfold videocapillaroscopy pattern, correlated with internal organ involvement. Among the groups stratified according to immune cell phenotype, the progression to the 'late' nailfold videocapillaroscopy pattern was more frequent in the Tfh-dominant group. CONCLUSION: Our study confirmed the presence of immunophenotypic abnormalities in SSc. Immunological abnormalities were not uniform but rather limited to subpopulations, particularly the Tfh-dominant group, where they were highly associated with microvascular abnormalities and organ involvement.

Significance of nailfold videocapillaroscopy in patients with idiopathic inflammatory myopathies.

Objective: The aim of this study was to investigate the clinical and immunological significance of nailfold videocapillaroscopy (NVC) abnormalities in patients with idiopathic inflammatory myopathies (IIMs). Methods: Seventy consecutive Japanese patients with untreated IIMs, enrolled between April 2014 and August 2017, were prospectively studied. Clinical features, NVC findings, autoantibody profile by immunoprecipitation and ELISA, and histopathological findings of skin biopsies of DM rash were assessed at baseline and after 1-year of immunosuppressive therapy. Results: NVC abnormalities were found in 55.7% (39/70) of IIM patients, with significantly higher prevalence in DM (65.4%) compared with PM (27.8%) (P = 0.01). In subsets of patients classified by autoantibody specificities, the prevalence of NVC abnormalities was significantly higher in patients with anti-MDA5 (87.5%) and anti-transcriptional intermediary factor 1γ (88.9%) vs anti-aminoacyl-tRNA synthetase (26.9%, P < 0.001). Perivascular lymphocytic infiltration in the upper dermis of skin rash biopsy of DM was more severe in patients with NVC abnormalities (P < 0.05). Unexpectedly, NVC abnormalities disappeared in 75% of IIM patients after 1-year of immunosuppressive therapy in contrast to stable NVC changes seen in scleroderma patients. Conclusion: Nailfold microvascular abnormalities were common in DM patients, associated with anti-MDA5 and transcriptional intermediary factor 1γ antibodies, and perivascular inflammation in skin histology. NVC abnormalities in IIMs may become clinically useful markers for defining subsets of DM and understanding the pathogenesis of the clinical features seen in these patients.

Small Cell Lung Cancer Patient with Anti-transcriptional Intermediary Factor 1γ Antibody Who Developed Dermatomyositis after Successful Chemoradiotherapy.

We herein report a 63-year-old woman with small-cell lung cancer (SCLC) who developed dermatomyositis (DM) after initial chemoradiotherapy despite tumor reduction. Serum anti-transcriptional in termediary factor (TIF) 1γ antibody was detected before the development of DM, and its levels increased over time. She died five months after the diagnosis of SCLC. Anti-TIF1γ antibody is known to be a marker for cancer-associated DM (CAM); however, the present case indicates that the antibody can be found in cancer patients without DM. This case is also unusual, as DM developed later despite successful chemoradiotherapy.

Comparative analysis of binding energy of chymostatin with human cathepsin A and its homologous proteins by molecular orbital calculation.

Cathepsin A is a mammalian lysosomal enzyme that catalyzes the hydrolysis of the carboxy-terminal amino acids of polypeptides and also regulates beta-galactosidase and neuraminidase-1 activities through the formation of a multienzymic complex in lysosomes. Human cathepsin A (hCathA), yeast carboxypeptidase (CPY), and wheat carboxypeptidase II (CPW) belong to the alpha/beta-hydrolase fold family. They have structurally similar active-site clefts, but there are small differences in the amino acid residues comprising their active sites that might determine the substrate specificity and sensitivity to microbial inhibitors including chymostatin. To examine the selectivity and binding mechanism of chymostatin as to hCathA, CPY, and CPW at the atomic level, we analyzed the interaction energy between chymostatin and each protein quantitatively by semiempirical molecular orbital calculation AM1 with the continuum solvent model. We predicted the electrostatic repulsion between the P3 cyclic arginine residue of the inhibitor and the Arg344 in the S3 active subsite of hCathA. Genetic conversion of Arg344 of the wild-type hCathA to Ile also caused an increase in its sensitivity to chymostatin, which was correlated with the decrease in the interaction energy calculated with the molecular orbital method. The present results suggest that such molecular calculation should be useful for evaluating the interactions between ligands, including inhibitors and homologous enzymes, in their docking models.

Prediction of the mechanism of action of omuralide (clasto-lactacystin beta-lactone) on human cathepsin A based on a structural model of the yeast proteasome beta5/PRE2-subunit/omuralide complex.

Cathepsin A (CathA) is a lysosomal serine carboxypeptidase that exhibits homology and structural similarity to the yeast and wheat serine carboxypeptidases (CPY and CPW) belonging to the alpha/beta-hydrolase fold family. Human CathA (hCathA) and CPW have been demonstrated to be inhibited by a proteasome (threonine protease) inhibitor, lactacystin, and its active derivative, omuralide (clasto-lactacystin beta-lactone), as well as chymostatin. A hCathA/omuralide complex model constructed on the basis of the X-ray crystal structures of the CPW/chymostatin complex and the yeast proteasome beta-subunit (beta5/PRE2)/omuralide one predicted that the conformation of omuralide in the active-site cleft of proteasome beta5/PRE2 should be very similar to that of chymostatin at the S1 catalytic subsites in the hCathA- and CPW-complexes. The relative positions of the glycine residues, i.e., Gly57 in hCathA, Gly53 in CPW, and Gly47 in beta5/PRE2, present in the oxyanion hole of each enzyme were also highly conserved. These results suggest that omuralide might inhibit hCathA and CPW at the S1 subsite in their active-site clefts through direct binding to the active serine residue.

Anti-obese action of raspberry ketone.

Raspberry ketone (4-(4-hydroxyphenyl) butan-2-one; RK) is a major aromatic compound of red raspberry (Rubus idaeus). The structure of RK is similar to the structures of capsaicin and synephrine, compounds known to exert anti-obese actions and alter the lipid metabolism. The present study was performed to clarify whether RK helps prevent obesity and activate lipid metabolism in rodents. To test the effect on obesity, our group designed the following in vivo experiments: 1) mice were fed a high-fat diet including 0.5, 1, or 2% of RK for 10 weeks; 2) mice were given a high-fat diet for 6 weeks and subsequently fed the same high-fat diet containing 1% RK for the next 5 weeks. RK prevented the high-fat-diet-induced elevations in body weight and the weights of the liver and visceral adipose tissues (epididymal, retroperitoneal, and mesenteric). RK also decreased these weights and hepatic triacylglycerol content after they had been increased by a high-fat diet. RK significantly increased norepinephrine-induced lipolysis associated with the translocation of hormone-sensitive lipase from the cytosol to lipid droplets in rat epididymal fat cells. In conclusion, RK prevents and improves obesity and fatty liver. These effects appear to stem from the action of RK in altering the lipid metabolism, or more specifically, in increasing norepinephrine-induced lipolysis in white adipocytes.

Microbial serine carboxypeptidase inhibitors--comparative analysis of actions on homologous enzymes derived from man, yeast and wheat.

The actions of peptidase inhibitors derived from Streptomycete on human cathepsin A (hCath A), yeast carboxypeptidase Y (CPY), and wheat carboxypeptidase II (CPW) were analyzed comparatively. Lactacystin and omuralide (clasto-lactacystin beta-lactone), well-known cytoplasmic proteasome inhibitors, both had a potent and non-competitive inhibitory effect on these homologous serine carboxypeptidases, although they inhibited CPW and hCath A more effectively than CPY in vitro. Ebelactone B exhibited a mixed non-competitive inhibitory effect and selectivity for CPY. Piperastatin A showed competitive inhibition of CPY and hCath A but had little effect on CPW. In contrast, chymostatin inhibited CPW efficiently, while it had less effect on hCath A and CPY. In cell culture system, lactacystin was the most potent as to inactivation of the intralysosomal recombinant hCath A activity expressed in a genetically engineered fibroblastic cell line with galactosialidosis (hCath A deficiency). These results suggest that the specific inhibitory effects of lactacystin and its derivatives on hCath A might be applicable to elucidate the pathophysiological roles in the human deficinecy.

Expression of lysosomal protective protein/cathepsin A in a stably transformed human neuroblastoma cell line during bi-directional differentiation into neuronal and Schwannian cells.

Human neuroblastoma GOTO cell lines were established that stably express recombinant human lysosomal protective protein/cathepsin A (PPCA) cDNA by transfection. Intracellular cathepsin A (acid serine carboxypeptidase) activity increased four-fold compared with in those of the parent and mock-transfected cell lines. The immunoreactive 54 kDa precursor/zymogen and mature 32/20 kDa two-chain forms were produced in the cells. The amount of the latter form expressed in the GOTO cells was significantly larger than those in the PPCA-overexpressing CHO cell lines previously established. The intracellular proteins showed a typical lysosomal granular distribution and the glycosylated 54 kDa precursor was secreted into the culture medium without the addition of an alkalizing agent. The PPCA-overexpressing cell lines also retained the ability to differentiate bi-directionally as well as the parent cells; into neuronal cells on induction by dibutyryl cAMP in serum-free medium and into Schwannian cells on induction by bromodeoxyuridine. During the course of differentiation into neuronal and Schwannian cells, the intracellular cathepsin A activity further increased two and five times, respectively, which was associated with an increase in the expression of the 32/20 kDa two-chain form. The glycosylated precursor proteins were taken up via the mannose 6-phosphate receptors, and the cathepsin A, alpha-neuraminidase and beta-galactosidase (beta-Gal) activities deficient in the fibroblasts derived from a patient with PPCA deficiency (galactosialidosis) were restored. These results suggest that the bi-directional differentiation of GOTO cell lines stably expressing the recombinant human PPCA gene could be a model system for analyzing the functions of PPCA in peripheral neuronal cells and Schwannian cells as well as the recombinant PPCA could be a useful source for enzyme replacement therapy (ERT) for galactosialidosis patients.

Functional and physical interaction between Sgs1 and Top3 and Sgs1-independent function of Top3 in DNA recombination repair.

A mutant allele of SGS1 of Saccharomyces cerevisiae was identified as a suppressor of the slow-growth phenotype of top3 mutants. We previously reported the involvement of Top3 via the interaction with the N-terminal region of Sgs1 in the complementation of methylmethanesulfonate (MMS) sensitivity and the suppression of hyper recombination of a sgs1 mutant. In this study, we found that several amino acids residues in the N-terminal region of Sgs1 between residues 4 and 33 were responsible for binding to Top3 and essential for complementing the sensitivity to MMS of sgsl cells. Two-hybrid assays suggested that the region of Top3 responsible for the binding to Sgs1 was bipartite, with portion in the N- and C-terminal domains. Although disruption of the SGS1 gene suppressed the semi-lethality of the top3 mutant of strain MR, the sgsl-top3 double mutant grew more slowly and was more sensitive to MMS than the sgsl single mutant, indicating that Top3 plays some role independently of Sgs1. The DNA topoisomerase activity of Top3 was required for the Top3 function to repair DNA damages induced by MMS, as shown by the fact that the TOP3 gene carrying a mutation (Phe for Tyr) at the amino acid residue essential for its activity (residue 356) failed to restore the MMS sensitivity of sgs1-top3 to the level of that of the sgs1 single mutant. Epistatic analysis using the sgs1-top3 double mutant, rad52 mutant and sgs1-top3-rad52 triple mutant indicated that TOP3 belongs to the RAD52 recombinational repair pathway.