Role of apolipoprotein B100 and oxidized low-density lipoprotein in the monocyte tissue factor induction mediated by anti-β2 glycoprotein I antibodies

OBJECTIVE

The objective of this paper is to elucidate the not yet known plasma molecule candidates involved in the induction of tissue factor (TF) expression mediated by β2GPI-dependent anticardiolipin antibody (aCL/β2GPI) on monocytes.

METHODS

Human serum incubated with FLAG-β2GPI was applied for affinity chromatography with anti- FLAG antibody. Immunopurified proteins were analyzed by a liquid chromatography coupled with mass spectrometry (LC-MS). TF mRNA induced by the identified molecules on monocytes was also analyzed.

RESULTS

Apolipoprotein B100 (APOB) was the only identified serum molecule in the MS search. Oxidized LDL, containing APOB as well as ox-Lig1 (a known ligand of β2GPI), was revealed as a β2GPI-binding molecule in the immunoprecipitation assay. TF mRNA was markedly induced by oxidized LDL/β2GPI complexes with either WBCAL-1 (monoclonal aCL/β2GPI) or purified IgG from APS patients. The activities of lipoprotein-associated phospholipase A2, one of the component molecules of oxidized LDL, were significantly higher in serum from APS patients than in those from controls.

CONCLUSION

APOB (or oxidized LDL) was detected as a major β2GPI binding serum molecule by LC-MS search. Oxidized LDL/aCL/β2GPI complexes significantly induced TF expressions on monocytes. These data suggest that complexes of oxidized LDL and aCL/β2GPI may have a crucial role in the pathophysiology of APS.

Naïve T Cell Homeostasis Regulated by Stress Responses and TCR Signaling

The survival of naïve T cells is believed to require signals from TCR–pMHC interactions and cytokines such as IL-7. In contrast, signals that negatively impact naïve T cell survival are less understood. We conducted a forward genetic screening of mice and found a mutant mouse line with reduced number of naïve T cells (T-Red mice). T-Red mice have a point mutation in the Kdelr1 gene, and their naïve T cells show enhanced integrated stress response (ISR), which eventually induces their apoptosis. Therefore, naïve T cells require a KDEL receptor-mediated mechanism that efficiently relieves cellular stress for their survival in vivo. Interestingly, naïve T cells expressing TCR with higher affinity/avidity to self-antigens survive in T-Red mice, suggesting the possible link between TCR-mediated survival and ISR-induced apoptosis. In this article, we discuss the regulation of naïve T cell homeostasis, keeping special attention on the ISR and TCR signal.

Strong TCR-mediated signals suppress integrated stress responses induced by KDELR1 deficiency in naive T cells

KDEL receptor 1 (KDELR1) regulates integrated stress responses (ISR) to promote naive T-cell survival in vivo. In a mouse line having nonfunctional KDELR1, T-Red (naive T-cell reduced) mice, polyclonal naive T cells show excessive ISR and eventually undergo apoptosis. However, breeding T-Red mice with TCR-transgenic mice bearing relatively high TCR affinity rescued the T-Red phenotype, implying a link between ISR-induced apoptosis and TCR-mediated signaling. Here, we showed that strong TCR stimulation reduces ISR in naive T cells. In mice lacking functional KDELR1, surviving naive T cells expressed significantly higher levels of CD5, a surrogate marker of TCR self-reactivity. In addition, higher TCR affinity/avidity was confirmed using a tetramer dissociation assay on the surviving naive T cells, suggesting that among the naive T-cell repertoire, those that receive relatively stronger TCR-mediated signals via self-antigens survive enhanced ISR. Consistent with this observation, weak TCR stimulation with altered peptide ligands decreased the survival and proliferation of naive T cells, whereas stimulation with ligands having higher affinity had no such effect. These results suggest a novel role of TCR-mediated signals in the attenuation of ISR in vivo.

A pain-mediated neural signal induces relapse in murine autoimmune encephalomyelitis, a multiple sclerosis model

Although pain is a common symptom of various diseases and disorders, its contribution to disease pathogenesis is not well understood. Here we show using murine experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS), that pain induces EAE relapse. Mechanistic analysis showed that pain induction activates a sensory-sympathetic signal followed by a chemokine-mediated accumulation of MHC class II+CD11b+ cells that showed antigen-presentation activity at specific ventral vessels in the fifth lumbar cord of EAE-recovered mice. Following this accumulation, various immune cells including pathogenic CD4+ T cells recruited in the spinal cord in a manner dependent on a local chemokine inducer in endothelial cells, resulting in EAE relapse. Our results demonstrate that a pain-mediated neural signal can be transformed into an inflammation reaction at specific vessels to induce disease relapse, thus making this signal a potential therapeutic target.

DOI:http://dx.doi.org/10.7554/eLife.08733.001

Multiple sclerosis (or MS for short) is a disease in which the insulating covers of nerve cells in the brain and spinal cord become inflamed and damaged. Depending on which nerves are affected, this disease can cause a wide range of symptoms, ranging from numbness and muscle spasms to visual disturbances and chronic pain. Many other diseases and disorders also have pain as a symptom, but it is not well understood if pain itself can directly contribute to the development of disease.

Most people with MS will, initially, experience periods when their symptoms get worse (called ‘relapses’), which are then followed by periods of improvement. Arima, Kamimura et al. investigated whether the sensation of pain itself could trigger a relapse in a mouse model of MS. The experiments showed that a painful sensation could trigger a relapse in the mice via the so-called ‘gateway reflex’. This reflex describes the phenomenon whereby nerve impulses lead to the release of signaling molecules that cause the walls of nearby blood vessels to open and allow immune cells to move from the bloodstream to the central nervous system. This in turn stimulates the development of inflammation, which causes an imbalance in the affected sites of the central nervous system.

These findings demonstrate that pain itself triggers a signal—sent via nerve impulses followed by the release of signaling molecules—that can lead to a relapse; and suggest that interfering with this signal could potentially help to treat to protect against relapses in MS. Following on from this work, it will be important to confirm if the gateway reflex exists in humans, and whether it is linked to other diseases that don't involve the central nervous system.

DOI:http://dx.doi.org/10.7554/eLife.08733.002

KDEL receptor 1 regulates T-cell homeostasis via PP1 that is a key phosphatase for ISR

KDEL receptors are responsible for retrotransporting endoplasmic reticulum (ER) chaperones from the Golgi complex to the ER. Here we describe a role for KDEL receptor 1 (KDELR1) that involves the regulation of integrated stress responses (ISR) in T cells. Designing and using an N-ethyl-N-nitrosourea (ENU)-mutant mouse line, T-Red (naïve T-cell reduced), we show that a point mutation in KDELR1 is responsible for the reduction in the number of naïve T cells in this model owing to an increase in ISR. Mechanistic analysis shows that KDELR1 directly regulates protein phosphatase 1 (PP1), a key phosphatase for ISR in naïve T cells. T-Red KDELR1 does not associate with PP1, resulting in reduced phosphatase activity against eIF2α and subsequent expression of stress responsive genes including the proapoptotic factor Bim. These results demonstrate that KDELR1 regulates naïve T-cell homeostasis by controlling ISR.

KDEL receptors are known to be involved in retrotransporting chaperones to the endoplasmic reticulum from the Golgi complex. Here the authors unravel a role of KDEL receptor 1 in regulating integrated stress responses in naïve T cells through its association with protein phosphatase 1.

[Gateway Reflex, a regulator of the inflammation feedback loop by regional neural activation]

Inflammation is observed in many diseases and disorders. We discovered a key machinery of inflammation, the inflammation amplifier, which is induced by the simultaneous activation of NFκB and STAT3 followed by the hyper-activation of NFκB in non-immune cells, including endothelial cells and fibroblasts. Since that discovery, we found the Gateway Reflex, which describes regional neural activations that enhance the inflammation amplifier to create a gateway for immune cells to bypass the blood-brain barrier. In addition, we have identified over 1,000 positive regulators and over 500 targets of the inflammation amplifier, which include a significant numbers of human disease-associated genes. In parallel, we performed a comprehensive analysis of human disease samples and found that the inflammation amplifier was activated during the development of chronic inflammation. Thus, we concluded that the inflammation amplifier is associated with various human diseases and disorders, including autoimmune diseases, metabolic syndromes, neurodegenerative diseases, and other inflammatory diseases. We are now attempting drug discovery for inflammatory diseases and disorders based on the inflammation amplifier and Gateway Reflex. In this review, we discuss the Gateway Reflex as an example for the neuro-immune interaction in vivo.

Primary prophylaxis to prevent obstetric complications in asymptomatic women with antiphospholipid antibodies: a systematic review

OBJECTIVE

Obstetric complications are common in patients with antiphospholipid syndrome. However, the impact of antiphosholipid antibodies (aPL) in the pregnancy outcomes of asymptomatic aPL carriers is uncertain. The aim of this systematic review is to assess whether primary prophylaxis is beneficial to prevent obstetric complications during pregnancy in asymptomatic women positive for aPL who have no history of recurrent pregnancy loss or intrauterine fetal death.

METHODS

Studies evaluating the effect of prophylactic treatment versus no treatment in asymptomatic pregnant aPL carriers were identified in an electronic database search. Design, population and outcome homogeneity of studies was assessed and meta-analysis was performed. The pooled Mantel-Haenszel relative risk of specific pregnancy outcomes was obtained using random effects models. Heterogeneity was measured with the I(2) statistic. All analyses were conducted using Review Manager 5.3.

RESULTS

Data from five studies involving 154 pregnancies were included and three studies were meta-analysed. The risk ratio and 95% confidence interval (CI) of live birth rates, preterm birth, low birth weight and overall pregnancy complications in treated and untreated pregnancies were 1.14 (0.18-7.31); 1.71 (0.32-8.98); 0.98 (0.07-13.54) and 2.15 (0.63-7.33),respectively. Results from the meta-analysis revealed that prophylactic treatment with aspirin is not superior to placebo to prevent pregnancy complications in asymptomatic aPL carriers.

CONCLUSION

This systematic review did not find evidence of the superiority of prophylactic treatment with aspirin compared to placebo or usual care to prevent unfavourable obstetric outcomes in otherwise healthy women with aPL during the first pregnancy.

The efficacy of calcineurin inhibitors for the treatment of interstitial lung disease associated with polymyositis/dermatomyositis

Interstitial lung disease (ILD) in patients with polymyositis (PM) and dermatomyositis (DM) is often resistant to treatment and life threatening, being recognized as one of the severest complication in these autoimmune disorders. Patients with clinically amyopathic dermatomyositis (CADM) or those with anti-CADM140/MDA5 antibody are especially prone to develop rapidly progressive interstitial pneumonia. We retrospectively analyzed 46 patients with PM/DM admitted to our hospital and identified DM, rapidly progressive disease, honeycomb lung, CADM and extensive ILD as risk factors for recurrence or death. In the presence of two or more risk factors, the sensitivity and specificity for the prediction of death or relapse were 81.3% and 76.7%, respectively. Calcineurin inhibitors have been widely used as induction and maintenance therapy for PM/DM-associated ILD. Recently we reported the benefit of tacrolimus on the disease-free survival and event-free survival of the patients with PM/DM-associated ILD. Among those patients treated with tacrolimus, poor prognostic factors for death, recurrence or severe adverse event were identified as acute progression of the disease, honeycomb lung, forced vital capacity (FVC) less than 80% and having DM. The potential effectiveness of an intensive therapy protocol with triple therapy that comprises high-dose corticosteroids, calcineurin inhibitors and cyclophosphamide has been reported.

The Gateway Reflex, which is mediated by the inflammation amplifier, directs pathogenic immune cells into the CNS

The brain-blood barrier (BBB) tightly limits immune cell migration into the central nervous system (CNS), avoiding unwanted inflammation under the normal state. However, immune cells can traverse the BBB when inflammation occurs within the CNS, suggesting a certain signal that creates a gateway that bypasses the BBB might exist. We revealed the inflammation amplifier as a mechanism of this signal, and identified dorsal vessels of the fifth lumber (L5) spinal cord as the gateway. The inflammation amplifier is driven by a simultaneous activation of NF-κB and STATs in non-immune cells, causing the production of a large amount of inflammatory chemokines to open the gateway at L5 vessels. It was found that the activation of the amplifier can be modulated by neural activation and artificially operated by electric pulses followed by establishment of new gateways, Gateway Reflex, at least in mice. Furthermore, genes required for the inflammation amplifier have been identified and are highly associated with various inflammatory diseases and disorders in the CNS. Thus, physical and/or pharmacological manipulation of the inflammation amplifier holds therapeutic value to control neuro-inflammation.

Antiphospholipid scoring: significance in diagnosis and prognosis

Recently our group introduced the “antiphospholipid score” (aPL-S), a quantitative marker that represents aPL profile. We have validated its efficacy for the diagnosis of antiphospholipid syndrome (APS) and predictive value for thrombosis. The study comprised two independent sets of patients with autoimmune diseases. In the first set of patients ( n = 233), the aPL-S was established by analyzing aPL profiles. In the second set of patients ( n = 411), the predictive value of the aPL-S for thrombosis was evaluated. To define aPL-S, we calculated the relative risks (approximated by odds ratios (ORs)) of having APS manifestations (thrombosis and/or pregnancy morbidity) for each of the aPL tests and devised an original formula in which aPL-S was determined by OR: aPL-S = 5 × exp ([OR] −5)/4. The receiver operating characteristic (ROC) curve showed a hyperbolic pattern and the area under the ROC curve value was 0.752 (0.686 for revised Sapporo criteria), implying that aPL-S is a potential quantitative marker for APS diagnosis. The OR for thrombosis in patients with a high aPL-S (≥30) was 5.27 (95% confidence interval (95% CI) 2.32–11.95, p < 0.0001). By multivariate analysis, an aPL-S of ≥30 appeared to be an independent risk factor for thrombosis (hazard ratio 3.144 (95% CI 1.383–7.150), p = 0.006). The aPL-S is a useful quantitative index for diagnosing APS and may be a predictive marker for thrombosis in autoimmune diseases.

Long-term outcome in Japanese patients with lupus nephritis

The objective of this study was to clarify the long-term outcome in patients with lupus nephritis (LN) according to the International Society of Nephrology and Renal Pathology Society classification. This retrospective analysis comprised 186 Japanese patients given a diagnosis of LN by renal specimen with a mean observation period of 12 years. Primary end point was defined as death or end-stage renal disease, and standardized mortality ratios were calculated. Five patients presented with histopathological class I, 62 with II, 21 with III or III+V, 73 with IV or IV+V and 25 with V. Fourteen deaths occurred, corresponding to an overall standardized mortality ratio of 3.59 (95% confidence interval 2.02-5.81, p < 0.0001). Kaplan-Meier analysis revealed a 10-year overall survival of 95.7%. Nephrotic proteinuria (≥3.5 g/day) at baseline was identified as an independent poor prognostic factor for overall survival in Cox regression analysis. Kaplan-Meier analysis revealed a 10-year renal survival as 94.3%. Male gender and nephrotic proteinuria at baseline were identified as independent poor prognostic factors for renal survival in Cox regression analysis. In conclusion, LN was associated with a 3.59-fold increase in mortality compared with the general population. Male gender and nephrotic proteinuria were predictive for poor renal outcome.

The inhibition of protein C anticoagulant activity by anti-β2-glycoprotein I (β2GPI) antibodies isolated from patients with antiphospholipid syndrome by chromatography methods

Abstract Antiphospholipid antibodies (aPL) are associated with an increased risk of thrombosis; however, the mechanism remains unknown. Recent studies have focused on the impediment of protein C anticoagulant activity by anti-β2-glycoprotein I (β2GPI) antibodies (aβ2GPI Ab). We purified IgG fractions containing a high concentration of aβ2GPI Ab from patients with antiphospholipid syndrome (APS) and then investigated the effect of purified aβ2GPI Ab on the activity of activated protein C (APC). Using a three-step chromatography method (DEAE-sepharose column, phosphatidylserine polyacrylamide gel column dependent on the presence of β2GPI, and protein G column chromatography), we successfully isolated anti-β2GPI IgG from nine patients with APS. Seven of nine samples inhibited APC activity in a concentration-dependent manner only in the presence of β2GPI, as observed by a chromogenic assay that was able to determine thrombin activity even in the presence of APC. The extent of APC inhibition by these fractions appeared to be related to aβ2GPI Ab titers of the purified IgG. However, the inhibitory effect of IgG from patients was not detected in the absence of β2GPI. IgG purified from three normal subjects did not affect APC activity. Herein, we show a useful method for the isolation of IgG containing a high concentration of aβ2GPI Ab. Moreover, the present findings indicate that inhibition by aβ2GPI Ab on APC anticoagulant activity could explain one of the mechanisms for the thrombotic state in APS.

Inflammation amplifier, a new paradigm in cancer biology

Tumor-associated inflammation can induce various molecules expressed from the tumors themselves or surrounding cells to create a microenvironment that potentially promotes cancer development. Inflammation, particularly chronic inflammation, is often linked to cancer development, even though its evolutionary role should impair nonself objects including tumors. The inflammation amplifier, a hyperinducer of chemokines in nonimmune cells, is the principal machinery for inflammation and is activated by the simultaneous stimulation of NF-κB and STAT3. We have redefined inflammation as local activation of the inflammation amplifier, which causes an accumulation of various immune cells followed by dysregulation of local homeostasis. Genes related to the inflammation amplifier have been genetically associated with various human inflammatory diseases. Here, we describe how cancer-associated genes, including interleukin (IL)-6, Ptgs2, ErbB1, Gas1, Serpine1, cMyc, and Vegf-α, are strongly enriched in genes related to the amplifier. The inflammation amplifier is activated by the stimulation of cytokines, such as TNF-α, IL-17, and IL-6, resulting in the subsequent expression of various target genes for chemokines and tumor-related genes like BCL2L11, CPNE7, FAS, HIF1-α, IL-1RAP, and SOD2. Thus, we conclude that inflammation does indeed associate with the development of cancer. The identified genes associated with the inflammation amplifier may thus make potential therapeutic targets of cancers.

The gateway theory: bridging neural and immune interactions in the CNS

The central nervous system (CNS) is considered an immune-privileged tissue protected by a specific vessel structure, the blood-brain barrier (BBB). Upon infection or traumatic injury in the CNS, the BBB is breached, and various immune cells are recruited to the affected area. In the case of autoimmune diseases in the CNS like multiple sclerosis (MS), autoreactive T cells against some CNS-specific antigens can theoretically attack neurons throughout the CNS. The affected CNS regions in MS patients can be detected as multiple focal plaques in the cerebrum, thoracic cord, and other regions. Vision problems are often associated with the initial phase of MS, suggesting a disturbance in the optic nerves. These observations raise the possibility that there exist specific signals that direct autoreactive T cells past the BBB and into particular sites of the CNS. Using a mouse model of MS, experimental autoimmune encephalomyelitis (EAE), we recently defined the mechanism of the pathogenesis in which regional neural stimulations modulate the status of the blood vessel endothelium to allow the invasion of autoreactive T cells into specific sites of the CNS via the fifth lumbar cord. This gate for autoreactive T cells can be artificially manipulated by removing gravity forces on the hind legs or by electric pulses to the soleus muscles, quadriceps, and triceps of mice, resulting in an accumulation of autoreactive T cells in the intended regions via the activation of regional neurons. Gating blood vessels by regional neural stimulations, a phenomenon we call the gateway theory, has potential therapeutic value not only in preventing autoimmunity, but also in augmenting the effects of cancer immunotherapies.

Metformin prevents liver tumorigenesis induced by high-fat diet in C57Bl/6 mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is increasing with the growing epidemics of obesity and diabetes. NAFLD encompasses a clinicopathologic spectrum of disease ranging from isolated hepatic steatosis to NASH, which is a more aggressive form of fatty liver disease, to cirrhosis and, finally, hepatocellular carcinoma (HCC). The exact mechanism behind the development of HCC in NASH remains unclear; however, it has been established that hepatic steatosis is the important risk factor in the development of HCC. Metformin has recently drawn attention because of its potential antitumor effect. Here, we investigated the effects of metformin on high-fat diet (HFD)-induced liver tumorigenesis, using a mouse model of NASH and liver tumor. Metformin prevented long-term HFD-induced liver tumorigenesis in C57Bl/6 mice. Of note, metformin failed to protect against liver tumorigenesis in mice that had already begun to develop NAFLD. Metformin improved short-term HFD-induced fat accumulation in the liver, associated with the suppression of adipose tissue inflammation. Collectively, these results suggest that metformin may prevent liver tumorigenesis via suppression of liver fat accumulation in the early stage, before the onset of NAFLD, which seems to be associated with a delay in the development of inflammation of the adipose tissue.

The involvement of CD36 in monocyte activation by antiphospholipid antibodies

Background

CD36, known as a scavenger receptor, is a transmembrane glycoprotein expressed on monocytes, platelets and endothelial cells, recognizes multiple ligands, including phosphatidylserine, and regulates atherogenesis and thrombosis. The objective of this study is to investigate the possible involvement of CD36 in the pathophysiology of thrombosis in patients with antiphospholipid syndrome (APS).

Methods

First, rs3765187, a missense mutation linked to CD36 deficiency, was investigated by TaqMan polymerase chain reaction (PCR) genotyping method in 819 Japanese, including 132 patients with APS, 265 with systemic lupus erythematosus (SLE) in the absence of APS, and 422 healthy subjects. Then, the involvement of CD36 in antiphospholipid antibody (aPL)-induced tissue factor (TF) expression was examined using CD36-null mice or anti-CD36. Purified IgG from patients with APS and a monoclonal phosphatidylserine-dependent antiprothrombin antibody were used in these experiments. TF expression was tested by real-time PCR and flow cytometry.

Results

Minor allele carrier of rs3765187 was less frequent in patients with APS (3.8% p = 0.032), but not in patients with SLE in the absence of APS (7.9% p = 0.32), compared with healthy subjects (10.2%). The aPL-induced TF expression was significantly suppressed on peritoneal macrophages from CD36-null mice compared to wild type and significantly inhibited by anti-CD36 on human monocytes.

Conclusions

The gene mutation linked to CD36 deficiency was less frequent in patients with APS. The deficient or suppressed CD36 function significantly reduced aPL-induced TF expression in vitro. Taken together, in a susceptible background CD36 scavenger receptor function may be involved in the thrombotic pathophysiology in patients with APS.

Epalrestat improves diabetic wound healing via increased expression of nerve growth factor

AIMS/INTRODUCTION

Aldose reductase inhibitors (ARIs) are a useful therapy for diabetic neuropathy. Nerve damage is associated with delayed wound healing of skin ulcers in diabetic patients. Therefore, we hypothesized that ARI supplementation would improve diabetic wound healing.

MATERIALS AND METHODS

Control and streptozotocin-induced diabetic mice were fed either control diet or diet containing the ARI Epalrestat (40 mg/kg). After 12 weeks, we created skin wounds on the backs of the mice. Wound healing was determined by measuring the reduction in wound area.

RESULTS

The wound gap of the diabetic group was significantly larger 9 days after creating the wounds when compared to the other groups (p<0.01). Interestingly, wound healing in the diabetic mice fed Epalrestat was comparable to the non-diabetic mice. To clarify the mechanism(s) behind this improved wound healing, mRNA expression of growth factors reported to be involved in wound healing were examined. Among the growth factors investigated, only the expression of nerve growth factor (NGF) was -significantly decreased (54.0%) in the healing lesions of diabetic mice. Similarly, NGF protein expression was decreased in diabetic mice and recovered in Epalrestat treated diabetic mice. Inhibition of NGF via 2 separate inhibitors (K252a and BSO) reduced the ability of Epalrestat to improve wound healing in diabetic mice.

CONCLUSIONS

These findings suggest that Epalrestat is a potential therapy for improving diabetic wound healing and the mechanism involves upregulation of NGF.

Predominant prevalence of arterial thrombosis in Japanese patients with antiphospholipid syndrome

Objective: To study the clinical and immunological manifestations of antiphospholipid syndrome (APS) in the Japanese population by a single-centre registration. Methods: In this retrospective cohort study, 141 consecutive patients with APS, fulfilling the Sydney revised Sapporo criteria for definite APS, who visited our autoimmune clinic from 1988 to 2010, were recruited and followed up. All the patients were interviewed and underwent a general physical examination by qualified rheumatologists on the day of blood sampling. Results: The population comprised 119 woman and 22 men with a mean age at diagnosis of 44 years (range 9–79 years). Seventy patients (49.6%) had primary APS, and 71 (50.4%) had systemic lupus erythematosus. The prevalence of thrombosis was 85.8 per cent, arterial thrombosis was found in 93 patients (66.0%) and venous thrombosis was found in 46 patients (32.6%). The most common thrombosis was cerebral infarction [86/141 (61.0%)] followed by deep vein thrombosis [33/141 (23.4%)]. Among 70 pregnant women, 45 (64.3%) had obstetric complications. Lupus anticoagulant was detected in 116 patients (82.3%), anticardiolipin antibodies in 83 (58.9%), anti-β2 glycoprotein I antibodies in 73 (51.8%) and phosphatidylserine-dependent antiprothrombin antibodies in 98 (69.5%). Conclusion: High prevalence of arterial thrombosis was noted in Japanese patients with APS. The profile of heterogeneous and complex clinical manifestations was substantiated in Japanese patients with APS.