Influences of advanced age in rheumatoid arthritis: A multicentre ultrasonography cohort study.

OBJECTIVES: We aimed to evaluate the effects of age on clinical characteristics and outcomes in biologic or targeted synthetic disease-modifying antirheumatic drug (b/tsDMARD)-naïve patients with rheumatoid arthritis (RA). METHODS: We analysed the cases of 234 Japanese b/tsDMARD-naïve RA patients who underwent b/tsDMARD treatment in a multicentre ultrasound prospective observational cohort. We compared the clinical characteristics at baseline and outcomes at 12 months between those aged ≥60 years and those <60 years. RESULTS: Compared to the <60-year-old group (n = 78), the ≥60-year-old group (n = 156) had higher inflammatory marker values and ultrasound combined scores, especially wrist joints, at baseline. Age at baseline positively correlated significantly with the ultrasound scores at baseline; however, age was not a significant variable by the multiple regression analysis. The patients treated with different MOAs in the ≥60-year-old group had comparable outcomes and multiple regression analysis revealed that mechanism of action (MOA) was not a significant contributor to the Clinical Disease Activity Index at 12 months. CONCLUSIONS: RA patients with advanced age demonstrated distinctive clinical characteristics. The MOAs were not associated with clinical outcomes and ultrasound outcomes in RA patients with advanced age.

Exploring the role of insulin-like growth factor binding protein-1 in identifying idiopathic multicentric Castleman's disease types: Implications for the mTOR signaling pathway.

OBJECTIVE: To determine the molecular differences between iMCD-thrombocytopenia, anasarca, fevers, reticulin myelofibrosis, organomegaly (TAFRO), and iMCD-not otherwise specified (NOS). METHODS: CD4-positive T cells were isolated from two iMCD-TAFRO and two iMCD-NOS patients for RNA sequencing comparison. Serum proteins of two iMCD-TAFRO and four iMCD-NOS patients were comprehensively analyzed to identify pathogenesis-associated proteins. IGFBP-1 protein, extracted from serum analysis, was compared to healthy controls, iMCD, systemic lupus erythematosus, and rheumatoid arthritis patients. RESULTS: RNA sequencing of CD4-positive T cells revealed enhanced mTOR-related signaling in iMCD-TAFRO compared to iMCD-NOS. Comprehensive serum analysis found IGFBP-1 linked to iMCD pathogenesis, significantly higher in iMCD-TAFRO. This protein may be elevated in patients with iMCD caused by an enhanced mTOR pathway. CONCLUSION: The mTOR pathway is suggested to be activated in iMCD-TAFRO compared to iMCD-NOS, which may elevate the protein IGFBP-1. This protein may be a biomarker to distinguish iMCD-TAFRO from iMCD-NOS.

Comparison of risks of cancer, infection, and MACEs associated with JAK inhibitor and TNF inhibitor treatment: a multicentre cohort study.

OBJECTIVES: The objective of this study was to compare the incidence rates (IRs) of infectious diseases, major adverse cardiovascular events (MACEs), and malignancies in RA patients treated with tofacitinib, baricitinib or a TNF inhibitor. METHODS: We retrospectively analysed the cases of 499 RA patients treated with tofacitinib (n = 192), baricitinib (n = 104), or a TNF inhibitor (n = 203). We determined the IRs of infectious diseases and the standardized incidence ratio (SIR) of malignancies and investigated factors related to infectious diseases. After adjusting the clinical characteristic imbalance by propensity score weighting, we compared the incidence of adverse events between the Janus kinase (JAK)-inhibitor and TNF-inhibitor groups. RESULTS: The observational period was 959.7 patient-years (PY), and the median observational period was 1.3 years. The IRs within the JAK-inhibitor treatment group were: serious infectious diseases other than herpes zoster (HZ), 8.36/100 PY; HZ, 13.00/100 PY. Multivariable Cox regression analyses revealed independent risk factors: the glucocorticoid dose in serious infectious diseases other than HZ, and older age in HZ. Two MACEs and 11 malignancies were identified in JAK-inhibitor-treated patients. The overall malignancy SIR was (non-significantly) higher than that of the general population (1.61/100 PY, 95% CI: 0.80, 2.88). The IR of HZ in the JAK-inhibitor-treated group was significantly higher than the TNF-inhibitor-treated group, but there were no significant differences in the IRs of other adverse events between the JAK-inhibitor-treated group and the TNF-inhibitor-treated group, or between the treatment groups of the two JAK inhibitors. CONCLUSIONS: The infectious disease IR in RA was comparable between tofacitinib and baricitinib, but the IR for HZ in these treatment groups was high compared with that in the TNF inhibitor treatment group. The malignancy rate in the JAK-inhibitor-treated group was high but not significantly different from that of the general population or that of the TNF-inhibitor-treated group.

Inhibition of calcium/calmodulin-dependent protein kinase IV in arthritis: dual effect on Th17 cell activation and osteoclastogenesis.

OBJECTIVE: To investigate the role of calcium/calmodulin-dependent protein kinase IV (CaMK4) in the development of joint injury in a mouse model of arthritis and patients with RA. METHODS: Camk4-deficient, Camk4flox/floxLck-Cre, and mice treated with CaMK4 inhibitor KN-93 or KN-93 encapsulated in nanoparticles tagged with CD4 or CD8 antibodies were subjected to collagen-induced arthritis (CIA). Inflammatory cytokine levels, humoral immune response, synovitis, and T-cell activation were recorded. CAMK4 gene expression was measured in CD4+ T cells from healthy participants and patients with active RA. Micro-CT and histology were used to assess joint pathology. CD4+ and CD14+ cells in patients with RA were subjected to Th17 or osteoclast differentiation, respectively. RESULTS: CaMK4-deficient mice subjected to CIA displayed improved clinical scores and decreased numbers of Th17 cells. KN-93 treatment significantly reduced joint destruction by decreasing the production of inflammatory cytokines. Furthermore, Camk4flox/floxLck-Cre mice and mice treated with KN93-loaded CD4 antibody-tagged nanoparticles developed fewer Th17 cells and less severe arthritis. CaMK4 inhibition mitigated IL-17 production by CD4+ cells in patients with RA. The number of in vitro differentiated osteoclasts from CD14+ cells in patients with RA was significantly decreased with CaMK4 inhibitors. CONCLUSION: Using global and CD4-cell-targeted pharmacologic approaches and conditionally deficient mice, we demonstrate that CaMK4 is important in the development of arthritis. Using ex vivo cell cultures from patients with RA, CaMK4 is important for both Th17 generation and osteoclastogenesis. We propose that CaMK4 inhibition represents a new approach to control the development of arthritis.

Prediction of radiographic progression during a treat-to-target strategy by the sequential application of MRI-proven bone marrow oedema and power-Doppler grade ≥2 articular synovitis in rheumatoid arthritis: Retrospective observational study.

OBJECTIVES: To investigate the appropriate timing, useful findings and combination of magnetic resonance imaging (MRI) and ultrasound (US) for predicting the radiographic progression in early rheumatoid arthritis (RA). METHODS: Forty-four active RA patients, who examined by both of MRI and US in the symptomatic wrist and finger joints, were recruited in Nagasaki University Hospital from 2010 to 2017 and treated by the treat-to-target therapeutic strategy for 1 year. MRI was evaluated by RA MRI scoring and US by Outcomes Measures in Rheumatology Clinical Trial, respectively. Plain radiographs were assessed by the Genant-modified Sharp score for the symptomatic side in the same manner as MRI and US. Radiographic progression was defined as an annual increase ≥0.75 at 1 year. Factors associated with radiographic progression were analysed. Also, the optimal combination of MRI and US at each timepoint was considered. RESULTS: Logistic regression model revealed that MRI-proven bone marrow oedema at baseline and 6 months and joint counts of power-Doppler grade ≥2 articular synovitis at 3 or 6 months were significantly associated with radiographic progression at 1 year. CONCLUSION: This study may suggest the favourable timing and combination of MRI and US at each point to predict radiographic progression in patients with early-stage RA.

Comparison of the quantitative measurement of 18F-FDG PET/CT and histopathological findings in IgG4-related disease.

OBJECTIVES: To investigate the utility of 18F-FDG PET/CT in the diagnostic procedure of IgG4-related disease (IgG4-RD), we analysed the association between quantitative method of 18F-FDG PET/CT and histological findings. METHODS: Twenty-one patients with IgG4-RD in whom 18F-FDG PET/CT was performed at the time of diagnosis were enrolled. Tissue biopsy was performed at 24 sites in 21 patients. To perform quantitative analysis of 18F-FDG PET/CT imaging, the highest standardised uptake value (SUV) of the pixels (SUVmax) and the average SUV (SUVmean) within the biopsied lesion were measured. The SUVmean of the liver was also measured as a reference. RESULTS: The mean age at diagnosis was 64.6±11.9 years, and the median serum IgG4 level was 650 mg/dl. Histological findings were consistent with IgG4-RD (histopathology-positive) at 19 out of 24 sites. Although there was no significant difference in the values of SUVmax between histopathology-positive and histopathology-negative tissues, the values of SUVmean were significantly higher in the histopathology-positive tissue (4.98 and 3.54, respectively p<0.05). The values of SUVmean/liver were also higher in the histopathology-positive tissue (2.17 and 1.52, respectively p<0.05). To establish a cut-off value of SUVmean to determine which of multiple lesions should be biopsied, a ROC curve was constructed. ROC curve analysis indicated SUVmean=4.07 or SUVmean/liver=1.66 as a cut-off value. CONCLUSIONS: Our present study suggested that quantitative analysis of 18F-FDG-PET/CT imaging might be useful for selecting the biopsy site in IgG4-RD. The calculation of SUVmean, not of SUVmax, is important for evaluating IgG4-RD-related lesions in 18F-FDG PET/CT imaging.

Effectiveness and safety of non-tumor necrosis factor inhibitor therapy for anti-human T-cell leukemia virus type 1 antibody-positive rheumatoid arthritis.

OBJECTIVES: Our previous study showed that the effectiveness of tumor necrosis factor (TNF) inhibitors was attenuated in anti-human T-cell leukemia virus type 1 (HTLV-1) antibody-positive patients with rheumatoid arthritis (RA). We aimed to evaluate the effectiveness and safety of non-TNF inhibitors in anti-HTLV-1 antibody-positive patients with RA. METHODS: We reviewed patients with RA who received abatacept or tocilizumab as the first biologic agent. We used the data of patients treated with TNF inhibitors from our previous study to compare the effectiveness between the anti-HTLV-1 antibody-positive patients treated with TNF inhibitors and non-TNF inhibitors using the inverse probability of treatment weights (IPTW) method. RESULTS: A total of 359 patients were divided into anti-HTLV-1 antibody-negative and -positive patients of 332 and 27, respectively. No statistically significant difference was observed in the change in the clinical disease activity index between the anti-HTLV-1 antibody-positive and -negative patients. The results using the IPTW method showed a significant association between the non-TNF inhibitors treatment and a better response. None of the patients developed adult T-cell leukemia/lymphoma or HTLV-1-associated myelopathy/tropical spastic paraparesis during the 24 weeks. CONCLUSION: Our results indicate that non-TNF inhibitors treatment is safety, and the effectiveness is not attenuated also in anti-HTLV-1 antibody-positive patients.

Next-generation sequencing of the whole MEFV gene in Japanese patients with familial Mediterranean fever: a case-control association study.

OBJECTIVES: We aimed to identify the whole nucleotide sequence of the Mediterranean fever (MEFV) gene in familial Mediterranean fever (FMF) and reveal novel single nucleotide variants (SNVs) associated with the susceptibility of FMF. METHODS: SeqCap capturing technique followed by Illumina next-generation sequencing have been used to assess two hundred SNVs in the whole region of MEFV in 266 Japanese patients with FMF and 288 ethnically matched controls. We performed an association analysis using these SNVs to identify genetic variants that predispose to FMF. RESULTS: We identified the two most significant SNVs [rs28940578; M694I in exon 10, odds ratio (OR) = 153, p=2.47×10-21 and rs3743930; E148Q in exon 2, OR = 1.65, p<0.0005]. Stratified analysis identified rs28940578 as a risk allele in typical FMF. Haplotype AG, defined by rs401298 and rs28940578, was the most significant and prevalent among patients with typical FMF compared with controls (22.4% vs. 0%, respectively; OR = 137, p=1.44×10-31). Haplotype GTC, defined by rs11466018, rs224231, and rs401877, was the most significant among patients with typical FMF without the rs28940578 mutation compared with controls (15.9% vs. 6%, respectively; OR = 12.4, p=0.004). CONCLUSIONS: rs28940578 is associated with the highest risk in typical FMF cases. This is consistent with results from previous studies in Japan. We found a novel MEFV gene haplotype that confers susceptibility of FMF among typical FMF without the rs28940578 mutation. There were no relevant SNVs identified in MEFV among the atypical FMF group.

Insulin-Like Growth Factor-1 (IGF-1) and Reduced Tongue Pressure in Relation to Atherosclerosis Among Community-Dwelling Elderly Japanese Men: A Cross-Sectional Study.

Even though higher serum insulin-like growth factor-1 (IGF-1) levels have a positive effect on preventing reduction in muscle strength, a U-shaped association between IGF-1 and mortality has been reported. Since a recent experimental study revealed that IGF-1 is associated with atherosclerotic lesion formation, the inflammatory status of atherosclerosis could act as a confounding factor on the association between IGF-1 levels and reduced muscle strength. This study aimed to clarify the atherosclerosis-specific association between IGF-1 levels and reduced muscle strength. We conducted a cross-sectional study of 410 elderly men aged 60-89 years. Since a reduction in maximum voluntary tongue pressure against the palate (MTP) is reportedly associated with sarcopenia, we evaluated muscle strength by using MTP and defined reduced MTP as the lowest tertiles of the study population. Among study population, 295 showed no atherosclerosis (carotid intima-media thickness < 1.1 mm). Even though a significant inverse association between IGF-1 and reduced MTP was observed for subjects without atherosclerosis, no such association was detected for subjects with atherosclerosis. The known cardiovascular risk-factor adjusted odds ratio (OR) of a one-standard deviation (SD) increment (28.1 ng/mL) of IGF-1 for reduced MTP was 0.69 (0.51, 0.95) for subjects without atherosclerosis and 1.93 (1.05, 3.52) for subjects with atherosclerosis. IGF-1 was found to be inversely associated with a reduced MTP among elderly men without atherosclerosis but not among those with atherosclerosis. Atherosclerosis can thus act as a powerful confounding factor on the association between IGF-1 levels and a reduced MTP.

Denosumab is effective toward glucocorticoid-induced osteoporosis patients complicated with rheumatic diseases regardless of prior anti-osteoporotic drugs.

We examined the efficacy and safety of denosumab as treatment for glucocorticoid-induced osteoporosis (GIOP) patients complicated with rheumatic diseases, by measuring patients' lumber bone mineral density (BMD) and bone turnover markers. A total of 66 consecutive patients for whom denosumab was initiated between July 2013 and August 2016 were enrolled and evaluated for 12 months. All of the patients were treated with glucocorticoids for underlying rheumatic diseases. The clinical assessment included measurements of the BMD of the lumbar spine (L2-L4) by a dual-energy X-ray absorptiometry technique and the bone turnover markers N-terminal telopeptide of type 1 collagen (NTX) in urine, serum intact procollagen type 1 N-terminal propeptide (P1NP), and bone-specific alkaline phosphatase (BAP) at baseline, 6 months and 12 months after the start of denosumab treatment. Adverse events (AEs) until 12 months were also analyzed. The mean percentage changes in BMD from baseline to 6 and 12 months were significant (2.85% increase, p < 0.0001 and 4.40% increase, p < 0.0001, respectively) regardless of the prior anti-osteoporotic drugs treatment (16 no transition from anti-osteoporotic drugs, 27 transition from bisphosphonate, 23 transition from teriparatide). The decreases in NTX, P1NP and BAP at 6 and 12 months were also significant. No serious AEs were noted. A multivariable logistic analysis showed that the prednisolone dose at baseline was associated with the clinical response to denosumab. In a real-world setting, denosumab was effective and safe for treating GIOP patients complicated with rheumatic diseases regardless of prior anti-osteoporotic drug treatment.

Short stature-related single-nucleotide polymorphism (SNP) activates endothelial repair activity in elderly Japanese.

BACKGROUND: Hypertension and atherosclerosis are bidirectionally related, while platelet count could serve as an indicator of endothelial repair. Therefore, high platelet counts could be associated with hypertension by indicating more intense endothelial repair activity. Furthermore, short stature has been shown to constitute a risk of atherosclerosis. Since inflammation-related single-nucleotide polymorphism (SNP (rs3782886)) is reportedly associated with myocardial infarction and short stature, rs3782886 could be associated with a high platelet count and thus more intense endothelial repair activity. METHODS: We conducted a cross-sectional study of 988 elderly Japanese who participated in a general health check-up. Short stature was defined as a height of at or under the 25th percentile of the study population, and high platelet count as the highest tertiles of the platelet levels. RESULTS: High platelet counts were found to be independently and positively associated with hypertension while rs3782886 was independently associated with high platelet levels and short stature. The classical cardiovascular risk factor-adjusted odds ratio (OR) and 95% confidence interval (CI) of high platelet count for hypertension was 1.34 (1.02, 1.77). With non-minor homo of the rs3782886 as the reference group, the adjusted OR and 95% CI for high platelet count and short stature of minor home were 2.40 (1.30, 4.42) and 2.21 (1.16, 4.21), respectively. CONCLUSION: SNP (rs3782886) was shown to be associated with high platelet count and short stature. This result partly explains how a genetic factor can influence the impact of height on endothelial repair.

Human T-Cell Leukemia Virus-1 Infection Is Associated With Atherosclerosis as Measured by Carotid Intima-Media Thickness in Japanese Community-Dwelling Older People.

The association between human T-cell leukemia virus-1 (HTLV-1) and atherosclerosis remains to be determined. This case-control study aimed to investigate this association as measured by carotid intima-media thickness (CIMT). HTLV-1 infection was positively associated with CIMT, independent of atherosclerotic risks.

Podocyte foot process width is a prediction marker for complete renal response at 6 and 12 months after induction therapy in lupus nephritis.

Morphological change that includes diffuse effacement of podocyte foot processes is correlated with proteinuria in patients with lupus nephritis (LN). We collected the data of clinico-pathological parameters and assessed foot process width (FPW) as an index of podocyte effacement in 73 patients with LN who had undergone renal biopsy. The multivariate analysis revealed that female gender (OR: 5.288; 95%CI: 1.197-37.29; p = .0267) and FPW (OR = 0.999, 95%CI = 0.997-0.999, p = .0150) were significantly predictive of a complete renal response (CR) at 6 months, while lymphocyte counts (OR = 1.002; 95%CI = 1.001-1.003, p = .0028) and FPW (OR = 0.998, 95%CI = 0.996-0.999, p = .0027) were significantly predictive of CR at 12 months. The cut-off point determined by the Classification and Regression Trees algorithm showed that FPW <908.3 nm provides the best performance for predicting patients who achieve CR at 12 months. A smaller FPW appears to be a predictive factor for CR at 6 and 12 months after induction therapy.

Novel anti-suprabasin antibodies may contribute to the pathogenesis of neuropsychiatric systemic lupus erythematosus.

Neuropsychiatric systemic lupus erythematosus (NPSLE) is often difficult to diagnose and distinguish from other diseases, because no NPSLE-specific antibodies have been identified. We developed a novel proteomic strategy for identifying and profiling antigens in immune complexes in the cerebrospinal fluid (CSF), and applied this strategy to 26 NPSLE patients. As controls, we also included 25 SLE patients without neuropsychiatric manifestations (SLE), 15 with relapsing remitting multiple sclerosis (MS) and 10 with normal pressure hydrocephalus (NPH). We identified immune complexes of suprabasin (SBSN) in the CSF of the NPSLE group. The titer of anti-SBSN antibodies was significantly higher in the CSF of the NPSLE group compared to those of the SLE, MS and NPH groups. Microarray data showed that the senescence and autophagy pathways were significantly changed in astrocytes exposed to anti-SBSN antibodies. Our findings indicate that SBSN could be a novel autoantibody for the evaluation of suspected NPSLE.

CD4+ CD52lo T-cell expression contributes to the development of systemic lupus erythematosus.

The cell-surface glycoprotein CD52 is widely expressed in lymphocytes. CD4+CD52hi T cells are functioning suppressor CD4+T cells. We investigated the role of the immune regulation of CD4+CD52 T cells in systemic lupus erythematosus (SLE). CD4+CD52lo T cells were increased in SLE patients, in positive correlation with SLEDAI, anti-ds-DNA antibody, and IgG concentration. Circulating follicular helper-like T cells (Tfh-like cells) were also increased in SLE, in positive correlation with CD4+CD52lo T cells. Chemokine receptor 8 (CCR8) expression in CD4+CD52lo T cells was increased. In vitro experiments using CD4 T cells of SLE patients showed that thymus and activation-regulated chemokine (TARC), a ligand of CCR8, contributed to the development of CD4+CD52hi T cells into CD4+CD52lo T cells. Our findings suggest that CD4+CD52lo T-cell upregulation is involved in the production of pathogens by autoantibodies, and TARC may contribute to the development of SLE through an aberrant induction of CD4+CD52lo T cells.

MicroRNA-204-3p inhibits lipopolysaccharide-induced cytokines in familial Mediterranean fever via the phosphoinositide 3-kinase γ pathway.

Objective: We sought to identify the microRNA (miRNA) profile and potential biomarkers in FMF and to clarify their gene targets to elucidate the pathogenesis of FMF. Methods: We performed an miRNA microarray using serum from FMF patients in attack and in remission. We then examined the expression of miRNAs in macrophages derived from THP-1 cells stimulated with toll-like receptor (TLR) ligands. Macrophages derived from THP-1 cells transfected with pre-miRNA were stimulated with lipopolysaccharides (LPSs) for the quantification of inflammatory cytokine production. To identify the target genes, we overexpressed their miRNA and performed a complementary DNA microarray. Transfection with reporter construct and the precursor miRNA was performed to confirm the suppression of target mRNA. Results: We found that miR-204-3p was greatly decreased in the serum from FMF patients in attack. The expression of miR-204-3p was suppressed by LPS stimulation in the macrophages derived from THP-1 cells and the inhibition of miR-204-3p significantly induced the production of TLR4-related cytokines. The bioinformatic analysis showed that miR-204-3p is predicted to target genes implicated in the TLR pathway through the regulation of PI3Kγ signalling. The reporter assay revealed that miR-204-3p directly suppressed the luciferase activity of 3'-UTR of PIK3CG reporter construct. The inhibition of PI3Kγ resulted in decreased amounts of IL-6 and IL-12p40 in monocytes from FMF patients. Conclusion: These data suggest that serum miR-204-3p has potential as a useful biomarker in FMF patients and that miR-204-3p serves as a suppressor of inflammatory cytokine production in FMF by targeting the PI3Kγ pathway.

Prediction of organ involvement in systemic sclerosis by serum biomarkers and peripheral endothelial function.

OBJECTIVES: To identify prognostic factors among serum biomarkers and endothelial vasodilator function findings in patients with systemic sclerosis (SSc). METHODS: This is a clinical observational study. We assessed 60 consecutive SSc patients (44 limited cutaneous-type, 16 diffuse cutaneous-type). Circulating growth differentiation factor-15 (GDF-15), placenta growth factor (PlGF), endostatin, vascular endothelial growth factor (VEGF), and pentraxin 3 (PTX3) were measured by ELISA. Peripheral endothelial function was measured by forearm blood dilatation response to brachial artery occlusion using noninvasive plethysmography (EndoPAT2000), which is associated with nitric-oxide-dependent vasodilatation and yields a reactive hyperemia index (RHI). We evaluated whether abnormalities in these values were associated with type of SSc - namely, diffuse cutaneous SSc (dcSSc) or limited cutaneous SSc (lcSSc) - or organ involvement including interstitial lung disease (ILD), digital ulcer (DU) and estimated right ventricular systolic pressure (RVSP) by echocardiography >30 mmHg. RESULTS: SSc patients showed significantly elevated serum GDF-15, PlGF, endostatin and VEGF but not PTX3 compared with controls. GDF-15 and PlGF were high in dcSSc patients. EndoPAT-RHI was low, and incidence of RVSP >30 mmHg was high in dcSSc. Multivariate analysis revealed that elevated GDF-15 was highly predictive of dcSSc, ILD or RVSP >30 mmHg. PlGF for DU was also found. Conversely, a low EndoPAT-RHI value was predictive of the presence of dcSSc, ILD or DU. CONCLUSIONS: This is the first study to inclusively investigate the relationships among biomarkers, EndoPAT-RHI and organ involvement in patients with SSc. Our data suggest a complex pathological progression of SSc through fibrotic impairment and microvascular damage.

Association of hemoglobin concentration with handgrip strength in relation to hepatocyte growth factor levels among elderly Japanese men aged 60-69 years: a cross-sectional study.

BACKGROUND: Hemoglobin concentration reportedly is positively associated with muscle strength, for example, handgrip strength. However, hemoglobin cannot repair muscle directly, but is beneficial only in a supportive role. Since hepatocyte growth factor (HGF) regulates muscle satellite cell production and differentiation, which is stimulated by organ injury, the supportive effect of hemoglobin should thus be stronger for participants with high HGF than for those with low HGF. However, the association between hemoglobin concentration and handgrip strength in relation to HGF levels remains unknown. METHODS: We conducted a cross-sectional study of 255 Japanese elderly men aged 60-69 years who participated in annual health check-ups in 2014-2015. The study population was categorized on the basis of a median value of HGF of 300.6 pg/mL. RESULTS: Among present study population, 128 participants showed low HGF. For participants with low HGF, hemoglobin concentration showed no significant association with handgrip strength (standardized parameter estimate (ß) = 0.03, p = 0.767), but for those with high HGF, hemoglobin concentration was significantly positively associated with handgrip strength (ß = 0.23, p = 0.014). CONCLUSIONS: A significant positive association between hemoglobin level and handgrip strength was established for elderly Japanese men aged 60-69 years with high HGF but not for participants with low HGF. Our finding indicates that HGF levels could determine the relationship of hemoglobin concentration with handgrip strength in elderly Japanese men aged 60-69 years. This result can be expected to serve as an effective tool for the clarification of the roles played by HGF and hemoglobin concentration in maintenance of muscle strength.