EphB signaling directs peripheral nerve regeneration through Sox2-dependent Schwann cell sorting.

The peripheral nervous system has astonishing regenerative capabilities in that cut nerves are able to reconnect and re-establish their function. Schwann cells are important players in this process, during which they dedifferentiate to a progenitor/stem cell and promote axonal regrowth. Here, we report that fibroblasts also play a key role. Upon nerve cut, ephrin-B/EphB2 signaling between fibroblasts and Schwann cells results in cell sorting, followed by directional collective cell migration of Schwann cells out of the nerve stumps to guide regrowing axons across the wound. Mechanistically, we find that cell-sorting downstream of EphB2 is mediated by the stemness factor Sox2 through N-cadherin relocalization to Schwann cell-cell contacts. In vivo, loss of EphB2 signaling impaired organized migration of Schwann cells, resulting in misdirected axonal regrowth. Our results identify a link between Ephs and Sox proteins, providing a mechanism by which progenitor cells can translate environmental cues to orchestrate the formation of new tissue.

Reduced Immunogenicity of COVID-19 Vaccine in Obese Patients with Type 2 Diabetes: A Cross-Sectional Study.

The global pandemic of coronavirus infection 2019 (COVID-19) was an unprecedented public health emergency. Several clinical studies reported that heart disease, lung disease, diabetes, hypertension, dyslipidemia, and obesity are critical risk factors for increased severity of and hospitalization for COVID-19. This is largely because patients with these underlying medical conditions can show poor immune responses to the COVID-19 vaccinations. Diabetes is one of the underlying conditions most highly associated with COVID-19 susceptibility and is considered a predictor of poor prognosis of COVID-19. We therefore investigated factors that influence the anti-SARS-CoV-2 spike IgG antibody titer after three doses of vaccination in patients with type 2 diabetes. We found that obesity was associated with low anti-SARS-CoV-2 spike IgG antibody titers following three-dose vaccination in type 2 diabetics. Obese patients with type 2 diabetes may have attenuated vaccine efficacy and require additional vaccination; continuous infection control should be considered in such patients.

Examining the association between vaccine reactogenicity and antibody titer dynamics after the third dose of BNT162b2 vaccine using a mixed-effects model.

BACKGROUND: To mitigate the COVID-19 pandemic, many countries have recommended the use of booster vaccinations. The relationship between the degree of adverse vaccine reactions and elevated antibody titers is of interest; however, no studies have investigated the temporal changes in antibody titers based on repeated measurements after a third dose of the BNT162b2 vaccine. METHODS: This prospective longitudinal cohort study was conducted with 62 healthcare workers who received a third dose of the BNT162b2 at Okayama University Hospital, Japan. Venous blood draw and fingertip whole blood test sample collection were conducted at the early (3-13 days) and 1-month time points; only FWT sample collection was conducted at the 2-month time point. Information on adverse reactions within 1 week after vaccination was also obtained. The association between fever of 37.5 °C or higher and antibody titers after the third dose of BNT162b2 was examined using a mixed-effects model and Poisson regression with robust variance. RESULTS: A trend toward higher antibody titers in the early period after vaccination was observed in the febrile individuals, but the differences were not significant at 1 and 2 months post-vaccination (the partial regression coefficient for fever was 8094.3 [-1910.2, 18,098.8] at 1 month after vaccination, and 1764.1 [-4133.9, 7662.1] at 2 months after vaccination in the adjusted models). CONCLUSION: The findings suggest that the presence of fever after the third vaccine does not predict a sustained elevation in serum antibody titers.

Numerical evaluation reveals the effect of branching morphology on vessel transport properties during angiogenesis.

Blood flow governs transport of oxygen and nutrients into tissues. Hypoxic tissues secrete VEGFs to promote angiogenesis during development and in tissue homeostasis. In contrast, tumors enhance pathologic angiogenesis during growth and metastasis, suggesting suppression of tumor angiogenesis could limit tumor growth. In line with these observations, various factors have been identified to control vessel formation in the last decades. However, their impacts on the vascular transport properties of oxygen remain elusive. Here, we take a computational approach to examine the effects of vascular branching on blood flow in the growing vasculature. First of all, we reconstruct a 3D vascular model from the 2D confocal images of the growing vasculature at postnatal day 5 (P5) mouse retina, then simulate blood flow in the vasculatures, which are obtained from the gene targeting mouse models causing hypo- or hyper-branching vascular formation. Interestingly, hyper-branching morphology attenuates effective blood flow at the angiogenic front, likely promoting tissue hypoxia. In contrast, vascular hypo-branching enhances blood supply at the angiogenic front of the growing vasculature. Oxygen supply by newly formed blood vessels improves local hypoxia and decreases VEGF expression at the angiogenic front during angiogenesis. Consistent with the simulation results indicating improved blood flow in the hypo-branching vasculature, VEGF expression around the angiogenic front is reduced in those mouse retinas. Conversely, VEGF expression is enhanced in the angiogenic front of hyper-branching vasculature. Our results indicate the importance of detailed flow analysis in evaluating the vascular transport properties of branching morphology of the blood vessels.

Tubulin carboxypeptidase activity of vasohibin-1 inhibits angiogenesis by interfering with endocytosis and trafficking of pro-angiogenic factor receptors.

Receptor endocytosis is crucial for integrating extracellular stimuli of pro-angiogenic factors, including vascular endothelial growth factor (VEGF), into the cell via signal transduction. VEGF not only triggers various angiogenic events including endothelial cell (EC) migration, but also induces the expression of negative regulators of angiogenesis, including vasohibin-1 (VASH1). While we have previously reported that VASH1 inhibits angiogenesis in vitro and in vivo, its mode of action on EC behavior remains elusive. Recently VASH1 was shown to have tubulin carboxypeptidase (TCP) activity, mediating the post-translational modification of microtubules (MTs) by detyrosination of α-tubulin within cells. However, the role of VASH1 TCP activity in angiogenesis has not yet been clarified. Here, we showed that VASH1 detyrosinated α-tubulin in ECs and suppressed in vitro and in vivo angiogenesis. In cultured ECs, VASH1 impaired endocytosis and trafficking of VEGF receptor 2 (VEGFR2), which resulted in the decreased signal transduction and EC migration. These effects of VASH1 could be restored by tubulin tyrosine ligase (TTL) in ECs, suggesting that detyrosination of α-tubulin negatively regulates angiogenesis. Furthermore, we found that detyrosinated tubulin-rich MTs were not adequate as trafficking rails for VEGFR2 endocytosis. Consistent with these results, inhibition of TCP activity of VASH1 led to the inhibition of VASH1-mediated suppression of VEGF-induced signals, EC migration, and in vivo angiogenesis. Our results indicate a novel mechanism of VASH1-mediated inhibition of pro-angiogenic factor receptor trafficking via modification of MTs.

Ephrin-B2 controls PDGFRß internalization and signaling.

B-class ephrins, ligands for EphB receptor tyrosine kinases, are critical regulators of growth and patterning processes in many organs and species. In the endothelium of the developing vasculature, ephrin-B2 controls endothelial sprouting and proliferation, which has been linked to vascular endothelial growth factor (VEGF) receptor endocytosis and signaling. Ephrin-B2 also has essential roles in supporting mural cells (namely, pericytes and vascular smooth muscle cells [VSMCs]), but the underlying mechanism is not understood. Here, we show that ephrin-B2 controls platelet-derived growth factor receptor ß (PDGFRß) distribution in the VSMC plasma membrane, endocytosis, and signaling in a fashion that is highly distinct from its role in the endothelium. Absence of ephrin-B2 in cultured VSMCs led to the redistribution of PDGFRß from caveolin-positive to clathrin-associated membrane fractions, enhanced PDGF-B-induced PDGFRß internalization, and augmented downstream mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK) activation but impaired Tiam1-Rac1 signaling and proliferation. Accordingly, mutant mice lacking ephrin-B2 expression in vascular smooth muscle developed vessel wall defects and aortic aneurysms, which were associated with impaired Tiam1 expression and excessive activation of MAP kinase and JNK. Our results establish that ephrin-B2 is an important regulator of PDGFRß endocytosis and thereby acts as a molecular switch controlling the downstream signaling activity of this receptor in mural cells.

Regulation of cell polarity by cell adhesion receptors.

The ability of cells to polarize is an intrinsic property of almost all cells and is required for the devlopment of most multicellular organisms. To develop cell polarity, cells integrate various signals derived from intrinsic as well as extrinsic sources. In the recent years, cell-cell adhesion receptors have turned out as important regulators of cellular polarization. By interacting with conserved cell polarity proteins, they regulate the recruitment of polarity complexes to specific sites of cell-cell adhesion. By initiating intracellular signaling cascades at those sites, they trigger their specific subcellular activation. Not surprisingly, cell-cell adhesion receptors regulate diverse aspects of cell polarity, including apico-basal polarity in epithelial and endothelial cells, front-to-rear polarity in collectively migrating cells, and planar cell polarity during organ development. Here, we review the recent developments highlighting the central roles of cell-cell adhesion molecules in the development of cell polarity.

PAR-3 controls endothelial planar polarity and vascular inflammation under laminar flow.

Impaired cell polarity is a hallmark of diseased tissue. In the cardiovascular system, laminar blood flow induces endothelial planar cell polarity, represented by elongated cell shape and asymmetric distribution of intracellular organelles along the axis of blood flow. Disrupted endothelial planar polarity is considered to be pro-inflammatory, suggesting that the establishment of endothelial polarity elicits an anti-inflammatory response. However, a causative relationship between polarity and inflammatory responses has not been firmly established. Here, we find that a cell polarity protein, PAR-3, is an essential gatekeeper of GSK3ß activity in response to laminar blood flow. We show that flow-induced spatial distribution of PAR-3/aPKCλ and aPKCλ/GSK3ß complexes controls local GSK3ß activity and thereby regulates endothelial planar polarity. The spatial information for GSK3ß activation is essential for flow-dependent polarity to the flow axis, but is not necessary for flow-induced anti-inflammatory response. Our results shed light on a novel relationship between endothelial polarity and vascular homeostasis highlighting avenues for novel therapeutic strategies.

Regulation of programmed cell death ligand 1 expression by atypical protein kinase C lambda/iota in cutaneous angiosarcoma.

The expression of immune checkpoint proteins such as programmed cell death protein 1 (PD-1) and its ligand (PD-L1) has been shown to correlate with patient prognosis in many malignant cancers. The expression of PD-L1 is controlled by c-Myc; however, further upstream regulation of PD-L1 expression is largely unknown. We have previously shown that atypical protein kinase C lambda/iota (aPKCλ) phosphorylates the Forkhead box protein O1 (FoxO1) transcription factor at Ser218 to suppress its DNA-binding ability, thereby regulating c-Myc expression and controlling physiologic and pathologic endothelial proliferation. The presence of phosphorylation of FoxO1 at Ser218 (pSer218 FoxO1) in cutaneous angiosarcoma (CAS) strongly correlates with poor patient prognosis. Here, we reported that patients with PD-L1+ cells in CAS lesions showed significantly worse prognosis compared to those that were PD-L1- . Expression of PD-L1 correlated with that of aPKCλ or the presence of pSer218FoxO1. Moreover, suppression of aPKCλ expression or inhibition of its activity in HUVECs or AS-M, an established human angiosarcoma cell line, resulted in decreased PD-L1 expression. Our results suggest that combined treatment with immune checkpoint inhibitors and aPKCλ inhibitors could be a novel treatment strategy for CAS patients.

Factors associated with decreasing serum 25(OH)D among Japanese patients with rheumatoid arthritis: Results from the IORRA cohort study.

OBJECTIVE: The aim of this study was to investigate factors that predict a decrease in serum 25(OH)D among Japanese patients with rheumatoid arthritis (RA). METHODS: In 2011 and 2013, serum 25(OH)D was evaluated in the same 2534 Japanese patients with RA (2179 women and 355 men) who participated in the Institute of Rheumatology Rheumatoid Arthritis (IORRA) cohort study. A vitamin D deficiency was defined as serum 25(OH)D levels <20 ng/mL. Predictive factors resulting in decreased serum 25(OH)D over a 2-year period were evaluated using multivariate logistic regression. RESULTS: The prevalence of vitamin D deficiency was 73.3% in 2011 and 68.2% in 2013. Serum 25(OH)D levels decreased by >5 ng/mL from 2011 to 2013 in 224 (8.8%) patients. A serum 25(OH)D decrease of >5 ng/mL was significantly associated with female gender, younger age, and disuse of bisphosphonates among all patients, and younger age, higher Japanese health assessment questionnaire disability index (JHAQ-DI), increased tender joint counts, and disuse of bisphosphonates and/or active vitamin D3 among women with RA. CONCLUSION: Female gender, younger age, JHAQ-DI, tender joint counts, and disuse of bisphosphonates and/or active vitamin D3 appear to be associated with a decrease in serum 25(OH)D in Japanese patients with RA.

The impact of hindfoot deformities for the recurrence of hallux valgus after joint-preserving surgeries for rheumatoid forefoot deformities.

BACKGROUND: Recurrence of hallux valgus (HV) is a common complication after forefoot surgery for rheumatoid forefoot deformities. The aim of this study is to evaluate the impact of hindfoot malalignment on recurrence. METHODS: This was a retrospective observational study designed to analyze the radiographic outcomes of 87 feet in 64 patients with rheumatoid arthritis treated with a joint-preserving surgery for HV deformity. Differences in hindfoot alignment preoperatively between the recurrence and nonrecurrence groups was compared. RESULTS: There were no significant differences in hindfoot alignment preoperatively between groups. To estimate the impact of technical problems, the HV and intermetatarsal angles measured from radiographs 3 months postoperatively were compared between groups. The HV angles in the recurrence group were significantly larger than those in the nonrecurrence group (p=0.02). CONCLUSIONS: There were no significant differences between preoperative hindfoot malalignment and postoperative recurrence of HV in rheumatoid forefoot surgeries.

Tocilizumab treatment in patients with rheumatoid arthritis is associated with reduced fibrinogen levels and increased blood loss after total knee arthroplasty.

OBJECTIVE: Since IL-6 has been associated with activation of the coagulation cascade and upregulation of fibrinogen transcription, we retrospectively tested the hypothesis that patients with rheumatoid arthritis (RA) treated with tocilizumab (TCZ) may lose more blood when undergoing total knee arthroplasty (TKA). METHODS: This study included 115 RA patients who underwent primary TKA and were preoperatively tested for fibrinogen levels. The blood volume of each patient was calculated using the Nadler formula, and estimated blood loss after TKA was calculated as the change between pre-operative and post-operative hematocrits. If salvaged blood was reinfused, the volume was measured and added to the volume of the estimated blood loss. RESULTS: We observed that patients treated with TCZ had significantly lower pre-operative fibrinogen levels than those not treated with TCZ (190.0 mg/dL versus 347.0 mg/dL, respectively; p = .00018). We also observed a statistically significant increase in mean total volume of estimated blood loss after TKA in RA patients who had been treated with TCZ compared with those not treated with TCZ (797.1 mL versus 511.4 mL, respectively; p = .0039). CONCLUSION: TCZ treatment in patients with RA may increase the risk of blood loss after TKA because of decreased fibrinogen levels.

Regulation of vascular endothelial growth factor receptor function in angiogenesis by numb and numb-like.

OBJECTIVE: Vascular endothelial growth factor (VEGF) signaling is a major regulator of physiological and pathological angiogenesis. VEGF receptor activity is strongly controlled by endocytosis, which can terminate or enhance signal transduction in the angiogenic endothelium, but the exact molecular regulation of these processes remains incompletely understood. We have therefore examined the function of Numb family clathrin-associated sorting proteins in angiogenesis. APPROACH AND RESULTS: We show that Numb proteins are expressed by endothelial cells during retinal angiogenesis in mice. Inducible inactivation of the Numb/Numbl genes in the postnatal endothelium led to impaired vessel growth, reduced endothelial proliferation and sprouting, and decreased VEGF receptor activation. Biochemistry and cell biology experiments established that Numb can interact with VEGFR2 and VEGFR3 and controls VEGF receptor activation in response to ligand stimulation. Experiments in cultured endothelial cells showed that Numb proteins counteract VEGF receptor degradation and promote VEGFR2 recycling back to the plasma membrane. CONCLUSIONS: Numb proteins control VEGF receptor endocytosis, signaling, and recycling in endothelial cells, which promotes the angiogenic growth of blood vessels.

Ephrin-B2 controls VEGF-induced angiogenesis and lymphangiogenesis.

In development, tissue regeneration or certain diseases, angiogenic growth leads to the expansion of blood vessels and the lymphatic vasculature. This involves endothelial cell proliferation as well as angiogenic sprouting, in which a subset of cells, termed tip cells, acquires motile, invasive behaviour and extends filopodial protrusions. Although it is already appreciated that angiogenesis is triggered by tissue-derived signals, such as vascular endothelial growth factor (VEGF) family growth factors, the resulting signalling processes in endothelial cells are only partly understood. Here we show with genetic experiments in mouse and zebrafish that ephrin-B2, a transmembrane ligand for Eph receptor tyrosine kinases, promotes sprouting behaviour and motility in the angiogenic endothelium. We link this pro-angiogenic function to a crucial role of ephrin-B2 in the VEGF signalling pathway, which we have studied in detail for VEGFR3, the receptor for VEGF-C. In the absence of ephrin-B2, the internalization of VEGFR3 in cultured cells and mutant mice is defective, which compromises downstream signal transduction by the small GTPase Rac1, Akt and the mitogen-activated protein kinase Erk. Our results show that full VEGFR3 signalling is coupled to receptor internalization. Ephrin-B2 is a key regulator of this process and thereby controls angiogenic and lymphangiogenic growth.

Coordination of VEGF receptor trafficking and signaling by coreceptors.

During development, regeneration and in certain pathological settings, the vasculature is expanded and remodeled substantially. Proper morphogenesis and function of blood vessels are essential in multicellular organisms. Upon stimulation with growth factors including vascular endothelial growth factors (VEGFs), the activation, internalization and sorting of receptor tyrosine kinases (RTKs) orchestrate developmental processes and the homeostatic maintenance of all organs including the vasculature. Previously, RTK signaling was thought to occur exclusively at the plasma membrane, a process that was subsequently terminated by endocytosis and receptor degradation. However, this model turned out to be an oversimplification and there is now a substantial amount of reports indicating that receptor internalization and trafficking to intracellular compartments depends on coreceptors leading to the activation of specific signaling pathways. Here we review the latest findings concerning endocytosis and intracellular trafficking of VEGFRs. The body of evidence is compelling that VEGF receptor trafficking is coordinated with other proteins such as Neuropilin-1, ephrin-B2, VE-cadherin and protein phosphatases.

Factors associated with sarcopenia in Japanese patients with rheumatoid arthritis: results from the IORRA cohort study.

To investigate the prevalence of and factors associated with sarcopenia in Japanese patients with rheumatoid arthritis (RA). We analyzed a cross-section of patients with RA participating in the Institute of Rheumatology Rheumatoid Arthritis cohort survey in 2021. Participants completed self-administered questionnaires, including a 5-item sarcopenia screening index (SARC-F). Patients with a SARC-F score of 4 or higher were categorized as having sarcopenia. Among 2416 Japanese patients with RA (2113 women and 303 men; mean age 63.9 years), 341 (14.1%) patients were categorized as having sarcopenia. In a multivariable analysis of patients of all ages, age, body mass index (BMI), disease duration, history of fracture, patient pain on a visual analog scale (VAS), patient or physician global assessments based on VAS, and use of nonsteroidal anti-inflammatory drugs (NSAIDs), biologic disease-modifying antirheumatic drugs (bDMARDs), and corticosteroids were significantly (P < 0.05) associated with sarcopenia. Disease duration, patient global assessments based on VAS, and use of NSAIDs and bDMARDs were significantly associated with sarcopenia among the patients aged < 65 years, whereas age, female sex, BMI, disease duration, history of fracture, patient pain VAS and global assessments based on VAS, and use of bDMARDs and corticosteroids were significantly associated with sarcopenia in patients aged ≥ 65 years. In Japanese patients with RA, age, BMI, disease duration, history of fracture, patient pain VAS and global assessments based on VAS, and use of NSAIDs, bDMARDs, and corticosteroids were associated with sarcopenia. Among older patients with RA, female sex was additionally associated with sarcopenia. Key Points • To our knowledge, this is the first report showing factors associated with sarcopenia in Japanese patients with rheumatoid arthritis using a large cohort database. • Age, BMI, disease duration, history of fracture, patient pain on a visual analog scale, and use of nonsteroidal anti-inflammatory drugs, biologic disease-modifying antirheumatic drugs, and corticosteroids were associated with sarcopenia in Japanese patients with rheumatoid arthritis. Limited to elderly patients, female sex was also associated with sarcopenia.

Therapeutic Intervention for Osteoporosis of Surgical Cases With Non-Vertebral Fractures for Three Years in a Newly Established Rural Hospital in Japan.

Objectives Our hospital was newly opened in the spring of 2020 in a rural area of Japan, with a remarkably developing aging society and population decline. This study aimed to clarify and evaluate the practice of osteoporosis care in our hospital for three years since its establishment. We report a retrospective review of therapeutic interventions for osteoporosis for patients who underwent surgical treatment for non-vertebral fragility fractures in our hospital. Methods We evaluated the practice of osteoporosis intervention in patients who underwent surgery for proximal humerus fractures (PHFs), distal radius fractures (DRFs), or proximal femoral fractures (PFFs) from April 2020 to the end of March 2023. Results There were 115 surgical cases with non-vertebral fractures (10 patients with PHF, 41 patients with DRF, and 64 with PFF). Among the patients who had received osteoporosis treatment at other hospitals before the injury, only 15 (13.0%) patients had been administered therapeutic intervention for osteoporosis by other clinics or hospitals. Also, 82 (71.3%) patients were newly diagnosed with osteoporosis in our hospital after surgery according to the Japanese osteoporosis guideline. New postoperative osteoporosis interventions were administered to 39 (47.0%) patients, of which the rate was higher than the previous reports in Japan. While there was no significant difference between upper limb fracture and PFF in the percentage per young adult mean of spine areal bone marrow density (aBMD), the femoral neck aBMDs in the upper limb fracture group were significantly higher than in the PFF group. The serum total P1NP levels were significantly lower and the 25(OH)D levels were also greater in the upper limb fracture group than in the PFF group, whereas the serum TRACP-5b levels were not significantly different between the two groups. Two (1.7%) patients were affected with secondary fractures during the study period. Conclusions The rates of therapeutic intervention for osteoporosis of patients with non-vertebral fractures, especially in those with upper limb fractures, in our hospital were considered to be greater than those in the previous reports. However, the intervention rate for patients with PFFs was not much, and there was still room for improvement in our hospital concerning osteoporosis diagnosis and treatment.

Augmented humoral response to third and fourth dose of SARS-CoV-2 mRNA vaccines in lung transplant recipients.

BACKGROUND: Since lung transplant recipients (LTRs) exhibit low immunogenicity after two doses of SARS-CoV-2 mRNA vaccines, optimal vaccine strategies for SARS-CoV-2 are required in LTRs. This study aimed to investigate the efficacy and safety of the third and fourth doses of the SARS-CoV-2 mRNA vaccines in LTRs. METHODS: We conducted a single-center study of 73 LTRs and 23 healthy controls (HCs). Participants received two-to-four doses of SARS-CoV-2 mRNA vaccines. The LTRs were divided into three groups based on the number of vaccine dose. IgG titers against SARS-CoV-2 spike protein were measured, and adverse events were assessed. Factors associated with humoral response were analyzed using univariate and multivariate analyses. RESULTS: The Dose 4 group (n = 27) had a higher humoral response rate (P = 0.018) and higher levels of anti-SARS-CoV-2 IgG antibody (P = 0.04) than the Dose 2 group (n = 14). The Dose 3 group (n = 32) had lower humoral response rates (P = 0.005) and levels of anti-SARS-CoV-2 IgG antibody (P = 0.0005) than the HCs (n = 23) even after the same dose. Systemic adverse events were milder in the LTRs than in the HCs (P < 0.05). Increased number of vaccine dose was identified as a predictor of positive humoral response (P = 0.021). CONCLUSION: Booster doses of SARS-CoV-2 mRNA vaccines may enhance humoral response with mild adverse events in LTRs. Repeated vaccination might be warranted for LTRs to prevent SARS-CoV-2 infection.