Hyperbaric oxygen treatment increases intestinal stem cell proliferation through the mTORC1/S6K1 signaling pathway in Mus musculus

BACKGROUND

Hyperbaric oxygen treatment (HBOT) has been reported to modulate the proliferation of neural and mesenchymal stem cell populations, but the molecular mechanisms underlying these effects are not completely understood. In this study, we aimed to assess HBOT somatic stem cell modulation by evaluating the role of the mTOR complex 1 (mTORC1), a key regulator of cell metabolism whose activity is modified depending on oxygen levels, as a potential mediator of HBOT in murine intestinal stem cells (ISCs).

RESULTS

We discovered that acute HBOT synchronously increases the proliferation of ISCs without affecting the animal's oxidative metabolism through activation of the mTORC1/S6K1 axis. mTORC1 inhibition by rapamycin administration for 20 days also increases ISCs proliferation, generating a paradoxical response in mice intestines, and has been proposed to mimic a partial starvation state. Interestingly, the combination of HBOT and rapamycin does not have a synergic effect, possibly due to their differential impact on the mTORC1/S6K1 axis.

CONCLUSIONS

HBOT can induce an increase in ISCs proliferation along with other cell populations within the crypt through mTORC1/S6K1 modulation without altering the oxidative metabolism of the animal's small intestine. These results shed light on the molecular mechanisms underlying HBOT therapeutic action, laying the groundwork for future studies.

POS0796 TREATMENT, ADVERSE EVENTS AND FOLLOW UP IN PATIENTS WITH GIANT CELL ARTERITIS IN THE ARTESER MULTICENTER STUDY

Background

Glucocorticoids (GC) are the mainstay therapy in Giant Cell Arteritis (GCA), initially at high doses (40-60 mg/day) followed by gradual glucocorticoid tapering. This treatment, especially in older patients, is associated with numerous adverse effects (AE). In addition, there are frequent relapses. Therefore, conventional synthetic immunosuppressants such as methotrexate (MTX), leflunomide, azathioprine, cyclophosphamide or mycophenolate, have been used with controversial results. Studies with biological immunosuppressants, such as TNFi have been ineffective; in contrast, tocilizumab (TCZ) has obtained positive results and was approved for the treatment of GCA.

Objectives

In the ARTESER study we describe a) treatment with GC, synthetic or biological immunosuppressants; b) AE of CG; and c) evolution.

Methods

ARTESER is a retrospective observational study sponsored by the Spanish Society of Rheumatology. 26 Spanish centers participated and all new patients diagnosed with GCA from June 1, 2013 to March 29, 2019 were included. Data on GC and immunosuppressants were collected at the beginning and during the follow-up of GCA patients. For the calculation of the cumulative dose of GC, an application was developed that, by including the periods of time, dose and type of GC received during follow-up, performs the automatic calculation in mg of prednisone.

Results

Of the 1675 patients included, GC treatment was adequately recorded in 1650 patients (Table 1). All received oral treatment, being prednisone the most frequently drug used (N=1602, 97.09%). In addition, 426 (25.82%) patients received at least one iv pulse of methylprednisolone, being the 1000 mg regimen the most frequent (n=217; 50.9%). The total mean duration of GC treatment was 22.65 months. The mean cumulative dose per patient at the end of follow-up was 8514.98 mg of prednisone.

Table 1.

Corticosteroid treatment and immunosuppressive treatment

Patients taking oral corticosteroid1650 Prednisone, n (%)1602 (97.09) Methylprednisolone, n (%)164 (9.94) Deflazacort, n (%)64 (3.88)Patients receiving intravenous corticosteroid, n (%)426 (25.82)Mean duration of steroid treatment, mean (SD)22.65 (17.36)Mean cumulative dose at the end of follow-up per patient, mg of prednisone, mean (SD)8514.98 (6570.21)Methotrexate at diagnosis*, n (%)165 (9.9)Leflunomide at diagnosis*, n (%)2 (0.1)Azathioprine at diagnosis*, n (%)3 (0.2)Cyclophosphamide at diagnosis*, n (%)7 (0.4)Mycophenolate at diagnosis*, n (%)1 (0.1)Tocilizumab at diagnosis*, n (%)22 (1.3)Methotrexate during follow-up, n (%)532 (31.8)Leflunomide during follow-up, n (%)19 (1.2)Azathioprine during follow-up, n (%)26 (1.5)Cyclophosphamide during follow-up, n (%)10 (0.6)Mycophenolate during follow-up, n (%)10 (0.6)Tocilizumab during follow-up, n (%)153 (9.1)

The most widely used immunosuppressant was MTX both at diagnosis (n=165; 9.9%) and during follow-up (n=532; 31.8%), followed by TCZ, at diagnosis (22; 1.3%) and at follow-up (153; 9.1%).

AE with GC were described in 393 patients (23.8%), highlighting serious infections (n=67; 10.03%) followed by diabetes mellitus (n=63; 9.43%), steroid myopathy (n=53; 7.9%), vertebral fractures (n=47; 7.04%), non-vertebral fractures (n=36; 5.39%), heart failure (n=36; 5.39%), arterial hypertension (n=34; 5.09%) and neuropsychiatric alterations (n=27; 4.04%).

During the follow-up, 334 (19.9%) patients had relapses, 532 (31.8%) were hospitalized on some occasion, and 142 patients (8.48%) died. The main cause of death were infections (n=44; 30.99%), neoplasms (n=23; 16.2%), cardiovascular (n=15; 10.56%), and cerebrovascular (n=10; 7.04%).

Conclusion

The main treatment for GCA was oral GC, which were required for almost two years on average, in a quarter of patients associated with IV pulses. The cumulative steroid dose was high as well as the side effects. MTX was the most widely used immunosuppressant and TCZ was prescribed in 10%. Relapses and admissions at the hospital were relatively frequent.

Acknowledgements

This study has been funded by ROCHE Farma. The funder has not participated in the design, analysis, or interpretation of the results

Disclosure of Interests

None declared

AB1171 PERSISTENT POST-DISCHARGE SYMPTOMS AFTER COVID-19 IN RHEUMATIC AND MUSCULOSKELETAL DISEASES

Background

The COVID-19 pandemic continues worldwide and has had a strong impact on public health. As the pandemic evolves, efforts have been intensified to identify persistent symptoms associated with the infection once resolved have intensified.

Objectives

We aimed to describe persistent symptoms and sequelae in patients with rheumatic and musculoskeletal diseases (RMD) after admission due to Covid-19. We also compared the role of autoimmune rheumatic diseases (ARD) with that of non–autoimmune rheumatic and musculoskeletal diseases (NARD) in persistent symptoms and sequelae.

Methods

We performed an observational study of patients with RMD who attended a rheumatology outpatient clinic in Madrid and required admission to hospital due to Covid-19 (1st March-30th May 2020) and survived. The study began at discharge and ran until 1st October 2020. The main outcomes were persistence of symptoms and sequelae related to Covid19. The independent variable was the RMD group (ARD and NARD). The covariates were sociodemographic data, clinical findings, and treatment. We ran a multivariate logistic regression model to assess the risk of the main outcomes by RMD group.

Results

We included 105 patients, of whom 51.5% had ARD and 68.57% reported at least 1 persistent symptom. The most frequent were dyspnea, fatigue, and chest pain. Sequelae were recorded in 31 patients. These included lung damage in 10.4% of patients, lymphopenia in 10%, central retinal vein occlusion (1 patient), and optic neuritis (1 patient). Two patients died. Eleven patients required readmission owing to Covid-19 problems (16.7% ARD vs 3.9% NARD; p=0.053). No statistically significant differences were found between RMD groups in the final models.

Conclusion

Many RMD patients have persistent symptoms, as in other populations. Lung damage is the most frequent sequela. Compared to NARD patients, ARD patients do not seem to differ in terms of persistent symptoms or sequelae, although ARD patients might generate more readmissions due to Covid-19.

References

[1]Zheng Z, Peng F, Xu B, Zhao J, Liu H, Peng J, et al. Risk factors of critical & mortal COVID-19 cases: A systematic literature review and meta-analysis. J Infect. 2020;81(2):e16–25

[2]Wang D, Hu B, Hu C, Zhu F, Liu X, Zhang J, et al. Clinical Characteristics of 138 Hospitalized Patients with 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA -J Am Med Assoc. 2020;323(11):1061–9

[3]Jiang F, Deng L, Zhang L, Cai Y, Cheung CW, Xia Z. Review of the Clinical Characteristics of Coronavirus Disease 2019 (COVID-19). J Gen Intern Med. 2020;35(5):1545–9.

[4]Sung HK, Kim JY, Heo J, Seo H, Jang Y, Kim H, et al. Clinical Course and Outcomes of 3, 060 Patients with Coronavirus Disease 2019 in Korea, January – May 2020. 2020;35(30):1–11.

[5]Freites Nuñez DD, Leon L, Mucientes A, Rodriguez-Rodriguez L, Font Urgelles J, Madrid García A, et al. Risk factors for hospital admissions related to COVID-19 in patients with autoimmune inflammatory rheumatic diseases. Ann Rheum Dis. 2020;79(11):1393–9.

Disclosure of Interests

None declared

AB0906-HPR BENEFIT OF A NURSE-LED PROGRAM OF CARE FOR MANAGEMENT OF PATIENTS WITH ESTABLISHED RHEUMATOID ARTHRITIS: SYSTEMATIC LITERATURE REVIEW

Background:

Nowadays, many countries experience an urgent demand for rheumatologists and greater cost-effectiveness. Thus, different alternatives to conventional outpatient physician-led follow-up have been investigated. The alternative of community-based service delivery systems is intended to meet emerging needs, reducing the costs of hospital care and morbidity. In patients with long-term conditions, such as Rheumatoid Arthritis (RA), nurses are seen as essential in the delivery of promotion in self-care and decision-making, favoring the empowerment of patients.

Objectives:

To systematically investigate if the nurse led-care management (NLCM) education programs are beneficial in patients with RA.

Methods:

This is a systematic literature research publication on the following bibliographic databases: Medline, Embase and the Cochrane Central register of Controlled Trials from the beginning until 2019.

Results:

From a yield of 116 studies, 44 were included in the review. After quality assessment and exclusion of the lowest-ranked studies, 19 studies were analyzed. Outcomes were organized into six themes (1) disease activity; (2) adherence; (3)satisfaction; (4)treatment compliance, (5) depression and (6)quality of life. All studies had significant results in at least one of the outcomes.

Conclusion:

According to our results, we can conclude that, clinicians could benefit from support conducted by nurse in the management of these patients in tasks such as metrology clinic, participation in enforcement, self-administration, the correct dosage and side effects of treatments, and link the patient and other professionals or entities. It would therefore be advisable to conduct further studies to draw more accurate and reliable conclusions in this context.

References:

[1]Bech B, Primdahl J, Van Tubergen A, et al. 2018 update of the EULAR recommendations for the role of the nurse in the management of chronic inflammatory arthritis. Ann Rheum Dis 2020; 79: 61–68.

[2]Uthman I, Almoallim H, Buckley CD, et al. Nurse-led care for the management of rheumatoid arthritis: a review of the global literature and proposed strategies for implementation in Africa and the Middle East. Rheumatology International 2020; 1: 3.

[3]Garner S, Lopatina E, Rankin JA, et al. Nurse-led care for patients with rheumatoid arthritis: A systematic review of the effect on quality of care. J Rheumatol 2017; 44: 757–765.

Disclosure of Interests:

None declared

The Netrin-1-Neogenin-1 signaling axis controls neuroblastoma cell migration via integrin-β1 and focal adhesion kinase activation

Neuroblastoma is a highly metastatic tumor that emerges from neural crest cell progenitors. Focal Adhesion Kinase (FAK) is a regulator of cell migration that binds to the receptor Neogenin-1 and is upregulated in neuroblastoma. Here, we show that Netrin-1 ligand binding to Neogenin-1 leads to FAK autophosphorylation and integrin β1 activation in a FAK dependent manner, thus promoting neuroblastoma cell migration. Moreover, Neogenin-1, which was detected in all tumor stages and was required for neuroblastoma cell migration, was found in a complex with integrin β1, FAK, and Netrin-1. Importantly, Neogenin-1 promoted neuroblastoma metastases in an immunodeficient mouse model. Taken together, these data show that Neogenin-1 is a metastasis-promoting protein that associates with FAK, activates integrin β1 and promotes neuroblastoma cell migration.

AB0077 CONTRIBUTION OF NOTUM TO THE DEVELOPMENT OF OSTEOARTHRITIS

Background:

Osteoarthritis (OA) is a degenerative disease characterized by altered homeostasis of joint cartilage and bone, the functionality of which relies on chondrocytes and osteoblasts, that leads to the formation of a defective extracellular matrix (ECM). The ECM plays an essential role in bone biology as it provides the structure of cartilage which serves as a template for bone formation. Collagen X, main component of the ECM, has been described by our group as down-regulated in OA [1]. Our data also points to an important role of the Wnt pathway in OA [1,2]. Furthermore, Wnt proteins have been reported to inhibit chondrogenesis [3], and the Wnt pathway and its modulators have gained attention [4]. Glypicans (GPC1 to GPC6) and NOTUM, among others, have been identified as modulators of this pathway [5,6]. Notably, due to its highly specific inhibition of the Wnt pathway, NOTUM has been proposed as a therapeutic target in conditions with a high activity of the Wnt pathway is involved, such as OA [7].

Objectives:

We hypothesize that modulators of the Wnt pathway are involved in the development of OA. The aim of this study is to evaluate the presence of Glypicans and NOTUM in the serum of OA patients and healthy individuals in order to determine whether significant differences exist and could clarify their likely involvement in OA.

Methods:

Peripheral blood samples were obtained from OA patients during routine rheumatologist hospital visits. OA diagnosis was established according to the ACR criteria. Samples from healthy individuals were obtained from the local Blood Bank. In both cases, blood samples were centrifugated (2000g, 15 minutes, 10°C) and serum was obtained.

Quantitative ELISA assays for GPC1-6 and NOTUM were carried out using commercial kits (Human GPC1 ELISA Kit, #E-EL-H1710, Elabscience; Human GPC2 ELISA Kit, #E-EL-H1711, Elabscience; Human GPC3 ELISA Kit, #E-EL-H1712, Elabscience; Human GPC4 ELISA Kit, #E-EL-H1713, Elabscience; Human GPC5 ELISA Kit, #ELH-GPC5, RayBiotech; Human GPC6 ELISA Kit, #CSB-EL009708HU, Cusabio; Human Protein NOTUM homolog ELISA Kit, #EK3787, Sab Biotech) and measured in a plate reader (Heales MB-580,Shenzhen Heales Technology Development Co. Ltd.). Protein concentration in serum was calculated using GraphPad Prism 7 software. Differences between samples were analysed with Mann-Withney U test. Significance level set wasp<0.05.

Results:

Serum from 40 OA patients and 40 healthy donors were included in the study. There were no differences between groups (Table 1).

Table 1.

Cohort description

Control group (n=40)OA group (n=40)Age66,82±5,7569,59±11,24Women (%)32 (80%)30 (75%)

Out of 7 proteins analyzed, only NOTUM showed a significant difference between healthy and OA groups (MedianOA=0.4451ng/mL, MedianCONTROL=0.8263ng/mL,p=0.0013). Besides, GPC4 showed an approaching formal significance (MedianOA=0.1254ng/mL, MedianCONTROL=0.1596ng/mL,p=0.0767). The rest of Glypicans analyzed showed no significance differences between groups (GPC1, MedianOA=0.1346ng/mL, MedianCONTROL=0.1190ng/mL,p=0.2379; GPC2, MedianOA=2.593ng/mL, MedianCONTROL=2.955ng/mL,p=0.7489; GPC3, MedianOA=2.024ng/mL, MedianCONTROL=1.422ng/mL,p=0.3574; GPC5, MedianOA=3.663ng/mL, MedianCONTROL=5.529ng/mL,p=0.8829; GPC6, MedianOA=0.3922ng/mL, MedianCONTROL=0.3558ng/mL,p=0.3212).

Conclusion:

Our results suggest that low levels of NOTUM may contribute to the development of OA. The lack of this inhibitor promotes the activation of the Wnt pathway, high activity of which has been related with OA.

References:

[1]Lamas JRet al.Ann Rheum Dis, 2010. 69(10):1880-5.

[2]Tornero-Esteban Pet al. PLoS One, 2015. 10(9): p. e0137170.

[3]Dayet al. Dev Cell. 2005. 8(5):739-50.

[4]Monteagudo S and Lories RJ. Nat Rev Rheumatol, 2017. 13(11): p. 670-681.

[6]Li Net al. Trends Cancer. 2018 Nov;4(11):741-754.

[7]De Robertis Met al. Oncotarget, 2015. 6(38): p. 41237-57.

[8]Nusse R. Nature, 2015. 519(7542): p. 163-4.

Disclosure of Interests:

Arkaitz Mucientes: None declared, Eva Herranz: None declared, Pia Lois: None declared, Francisco J. Blanco Grant/research support from: Sanofi-Aventis, Lilly, Bristol MS, Amgen, Pfizer, Abbvie, TRB Chemedica International, Glaxo SmithKline, Archigen Biotech Limited, Novartis, Nichi-iko pharmaceutical Co, Genentech, Jannsen Research & Development, UCB Biopharma, Centrexion Theurapeutics, Celgene, Roche, Regeneron Pharmaceuticals Inc, Biohope, Corbus Pharmaceutical, Tedec Meiji Pharma, Kiniksa Pharmaceuticals, Ltd, Gilead Sciences Inc, Consultant of: Lilly, Bristol MS, Pfizer, Lydia Abasolo: None declared, Luis Rodriguez Rodriguez: None declared, José Ramón Lamas: None declared, Benjamin Fernandez: None declared

AB0290 HERPES ZOSTER INFECTIONS IN RHEUMATOID ARTHRITIS PATIENTS EXPOSED TO BIOLOGICAL AGENTS AND JAK INHIBITORS. REAL-WORLD EVIDENCE

Background:

The overall occurrence of Herpes zoster (HZ) infections in patients with rheumatoid arthritis (RA) is greater than in the general population although is controversial whether the use of the different disease-modifying antirheumatic drugs (DMARDs) increases this risk.

Objectives:

To investigate the incidence and factors associate to HZ infections in patients with RA exposed to biologic agents (BA) and small molecule JAK inhibitors (JAKi), and to describe RA disease features at the moment of HZ infection.

Methods:

Retrospective longitudinal study was conducted. We included RA patients seen at the rheumatology outpatient clinic of tertiary hospital, commencing BA (anti-TNF therapy and no anti-TNF therapy) or JAKi from Jan 2007 until Dec 2017, and followed up until end of study (Dec 2019). The outcome of interest was the occurrence of HZ infection, the diagnosis of HZ events was based on the rheumatologist’s report. Covariables: sociodemographic, clinical, and concomitant treatments including glucocorticoids, conventional synthetic DMARDs (csDMARDs). Survival techniques were used to estimate the incidence of HZ (IR), per 1000 patient-year (PYs) with the respective Confidence Interval [95%CI]. Cox multivariate regression model to compare the risk of HZ was performed. Results were expressed in Hazard ratio (HR).

Results:

474 RA patients were included, starting 881 different courses of treatment (1954.86 patients-years of follow-up). 382 (80.6%) were women with a mean (SD) age of 56.9 (15.0) years at first BA. Across all groups of treatments, a total 18 HZ were recorded, events were non-serious and involved 1 or 2 dermatomes. The mean age (SD) at moment of the infection was 62 (11) years and 10 cases were on prednisone > 7.5 mg/day. 13 HZ cases (72.2%) occurred on treatment with anti-TNF treatment (6 with adalimumab, 4 with certolizumab and 1 with infliximab), 4 (22.2%) cases were on treatment with rituximab one occurred during tocilizumab prescription. The overall incidence of HZ was 9.20 cases per 1000PYs [5.80-14.61]. The crude IR was similar between gender, increased with age (Patients < 46 years: 2.17 [0.3-15.4]; >70 years 14.1 [5.8-33.8]), was higher with concomitant use of two csDMARDs (IR: 15.68 [7.8-31.7], and was similar between anti-TNF and non anti-TNF therapy. None HZ event was recorded in patients exposed to JAKi. In the multivariate analysis, age (HR: 1.05, p: 0.006), prednisone dose > 7.5 mg/day (HR: 2.83, p: 0.02) and the concomitant use of two csDMARDs (HR: 2.34 p: 0.039) increase the risk for HZ. Lymphopenia (HR: 2.6; p=0.06) achieved a trend and BA therapy dropped from the model.

Conclusion:

HZ incidence rate was 9.20 cases per 1000PYs, HZ occurrence in RA patients cannot be attributed solely to the current BA or JAKi treatment and other factors involved must be taking in count as age, concomitant DMARDs prescriptions, and use of glucocorticoids. Our data suggest that preventive strategies for HZ should be developed for patients with RA.

Disclosure of Interests:

None declared

Adaptive Physiological and Morphological Adjustments Mediated by Intestinal Stem Cells in Response to Food Availability in Mice

Several studies have evaluated plastic changes in the morphology of the digestive tract in rodents subjected to caloric restriction or restricted availability. Nevertheless, studies that link these morphological responses to physiological consequences are scarce. In order to investigate short-term plastic responses in the intestine, we acclimated adult Mus musculus (BALB/c) males for 20 days to four distinctive treatments: two caloric regimens (ad libitum and 60% of calorie ingestion) and two levels of periodicity of the regimens (continuous and stochastic treatment). At the end of the treatment we analyzed the cell proliferation and cell death dynamics of small intestinal crypts in these animals. In addition, we measured organ masses and lengths, hydrolytic digestive enzyme activities, and energy output from feces. Finally, in order to explore the metabolic changes generated by these dietary conditions we assessed the catabolic activity (i.e., enzymes) of the liver. Our results show that individuals acclimated to a continuous and 60% regimen presented longer intestines in comparison to the other treatments. Indeed, their intestines grew with a rate of 0.22 cm/day, generating a significant caloric reduction in the content of their feces. Besides, both mass and intestinal lengths were predicted strongly by the stabilization coefficient of BrdU+ proliferating cells per crypt, the latter correlating positively with the activity of n-aminopeptidases. Interestingly, by using pharmacological inhibition of the kinase mammalian target of rapamycin complex 1 (mTORC1) by Rapamycin, we were able to recapitulate similar changes in the proliferation dynamics of intestinal stem cells. Based on our results, we propose that the impact of caloric restriction on macroscopic variation in morphology and functional changes in digestive n-aminopeptidases occurs through synchronization in the proliferation rate of stem and/or progenitor cells located in the small intestinal crypts and requires mTORC1 as a key mediator. Hence, we suggest that an excessive stem and progenitor activity could result in increased crypts branching and might therefore underlie the reported intestinal tissue expansion in response to short-term caloric restriction. Summarizing, we demonstrate for the first time that short-term caloric restriction induces changes in the level of cell proliferation dynamics explaining in part digestive tract plasticity in adaptive performance.

The Netrin-4/Laminin γ1/Neogenin-1 complex mediates migration in SK-N-SH neuroblastoma cells

Neuroblastoma (NB) is the most common pediatric extracranial solid tumor. It arises during development of the sympathetic nervous system. Netrin-4 (NTN4), a laminin-related protein, has been proposed as a key factor to target NB metastasis, although there is controversy about its function. Here, we show that NTN4 is broadly expressed in tumor, stroma and blood vessels of NB patient samples. Furthermore, NTN4 was shown to act as a cell adhesion molecule required for the migration induced by Neogenin-1 (NEO1) in SK-N-SH neuroblastoma cells. Therefore, we propose that NTN4, by forming a ternary complex with Laminin γ1 (LMγ1) and NEO1, acts as an essential extracellular matrix component, which induces the migration of SK-N-SH cells.

Hyperbaric Oxygen Increases Stem Cell Proliferation, Angiogenesis and Wound-Healing Ability of WJ-MSCs in Diabetic Mice

Hyperbaric oxygen therapy (HBOT) is effective for the medical treatment of diverse diseases, infections, and tissue injury. In fact, in recent years there is growing evidence on the beneficial effect of HBOT on non-healing ischemic wounds. However, there is still yet discussion on how this treatment could benefit from combination with regenerative medicine strategies. Here we analyzed the effects of HBOT on three specific aspects of tissue growth, maintenance, and regeneration: (i) modulation of adult rodent (Mus musculus) intestinal stem cell turnover rates; (ii) angiogenesis dynamics during the development of the chorio-allantoic membrane (CAM) in Gallus gallus embryos; (iii) and wound-healing in a spontaneous type II diabetic mouse model with a low capacity to regenerate skin. To analyze these aspects of tissue growth, maintenance, and regeneration, we used HBOT alone or in combination with cellular therapy. Specifically, Wharton Jelly Mesenchymal Stem cells (WJ-MSC) were embedded in a commercial collagen-scaffold. HBOT did not affect the metabolic rate of adult mice nor of chicken embryos. Notwithstanding, HBOT modified the proliferation rate of stem cells in the mice small intestinal crypts, increased angiogenesis in the CAM, and improved wound-healing and tissue repair in diabetic mice. Moreover, our study demonstrates that combining stem cell therapy and HBOT has a collaborative effect on wound-healing. In summary, our data underscore the importance of oxygen tension as a regulator of stem cell biology and support the potential use of oxygenation in clinical treatments.

The salivary peptide histatin-1 promotes endothelial cell adhesion, migration, and angiogenesis

Saliva is a key factor that contributes to the high efficiency of wound healing in the oral mucosa. This is not only attributed to physical cues but also to the presence of specific peptides in the saliva, such as histatins. Histatin-1 is a 38 aa antimicrobial peptide, highly enriched in human saliva, which has been previously reported to promote the migration of oral keratinocytes and fibroblasts in vitro However, the participation of histatin-1 in other crucial events required for wound healing, such as angiogenesis, is unknown. Here we demonstrate that histatin-1 promotes angiogenesis, as shown in vivo, using the chick chorioallantoic membrane model, and by an in vitro tube formation assay, using both human primary cultured endothelial cells (HUVECs) and the EA.hy926 cell line. Specifically, histatin-1 promoted endothelial cell adhesion and spreading onto fibronectin, as well as endothelial cell migration in the wound closure and Boyden chamber assays. These actions required the activation of the Ras and Rab interactor 2 (RIN2)/Rab5/Rac1 signaling axis, as histatin-1 increased the recruitment of RIN2, a Rab5-guanine nucleotide exchange factor (GEF) to early endosomes, leading to sequential Rab5/Rac1 activation. Accordingly, interfering with either Rab5 or Rac1 activities prevented histatin-1-dependent endothelial cell migration. Finally, by immunodepletion assays, we showed that salivary histatin-1 is required for the promigratory effects of saliva on endothelial cells. In conclusion, we report that salivary histatin-1 is a novel proangiogenic factor that may contribute to oral wound healing.-Torres, P., Díaz, J., Arce, M., Silva, P., Mendoza, P., Lois, P., Molina-Berríos, A., Owen, G. I., Palma, V., Torres, V. A. The salivary peptide histatin-1 promotes endothelial cell adhesion, migration, and angiogenesis.

Netrin-1 acts as a non-canonical angiogenic factor produced by human Wharton's jelly mesenchymal stem cells (WJ-MSC)

BACKGROUND

Angiogenesis, the process in which new blood vessels are formed from preexisting ones, is highly dependent on the presence of classical angiogenic factors. Recent evidence suggests that axonal guidance proteins and their receptors can also act as angiogenic regulators. Netrin, a family of laminin-like proteins, specifically Netrin-1 and 4, act via DCC/Neogenin-1 and UNC5 class of receptors to promote or inhibit angiogenesis, depending on the physiological context.

METHODS

Mesenchymal stem cells secrete a broad set of classical angiogenic factors. However, little is known about the expression of non-canonical angiogenic factors such as Netrin-1. The aim was to characterize the possible secretion of Netrin ligands by Wharton's jelly-derived mesenchymal stem cells (WJ-MSC). We evaluated if Netrin-1 presence in the conditioned media from these cells was capable of inducing angiogenesis both in vitro and in vivo, using human umbilical vein endothelial cells (HUVEC) and chicken chorioallantoic membrane (CAM), respectively. In addition, we investigated if the RhoA/ROCK pathway is responsible for the integration of Netrin signaling to control vessel formation.

RESULTS

The paracrine angiogenic effect of the WJ-MSC-conditioned media is mediated at least in part by Netrin-1 given that pharmacological blockage of Netrin-1 in WJ-MSC resulted in diminished angiogenesis on HUVEC. When HUVEC were stimulated with exogenous Netrin-1 assayed at physiological concentrations (10-200 ng/mL), endothelial vascular migration occurred in a concentration-dependent manner. In line with our determination of Netrin-1 present in WJ-MSC-conditioned media we were able to obtain endothelial tubule formation even in the pg/mL range. Through CAM assays we validated that WJ-MSC-secreted Netrin-1 promotes an increased angiogenesis in vivo. Netrin-1, secreted by WJ-MSC, might mediate its angiogenic effect through specific cell surface receptors on the endothelium, such as UNC5b and/or integrin α6β1, expressed in HUVEC. However, the angiogenic response of Netrin-1 seems not to be mediated through the RhoA/ROCK pathway.

CONCLUSIONS

Thus, here we show that stromal production of Netrin-1 is a critical component of the vascular regulatory machinery. This signaling event may have deep implications in the modulation of several processes related to a number of diseases where angiogenesis plays a key role in vascular homeostasis.

Shh Signaling through the Primary Cilium Modulates Rat Oligodendrocyte Differentiation

Primary Cilia (PC) are a very likely place for signal integration where multiple signaling pathways converge. Two major signaling pathways clearly shown to signal through the PC, Sonic Hedgehog (Shh) and PDGF-Rα, are particularly important for the proliferation and differentiation of oligodendrocytes, suggesting that their interaction occurs in or around this organelle. We identified PC in rat oligodendrocyte precursor cells (OPCs) and found that, while easily detectable in early OPCs, PC are lost as these cells progress to terminal differentiation. We confirmed the interaction between these pathways, as cyclopamine inhibition of Hedgehog function impairs both PDGF-mediated OPC proliferation and Shh-dependent cell branching. However, we failed to detect PDGF-Rα localization into the PC. Remarkably, ciliobrevin-mediated disruption of PC and reduction of OPC process extension was counteracted by recombinant Shh treatment, while PDGF had no effect. Therefore, while PDGF-Rα-dependent OPC proliferation and survival most probably does not initiate at the PC, still the integrity of this organelle and cilium-centered pathway is necessary for OPC survival and differentiation.

Sonic Hedgehog modulates EGFR dependent proliferation of neural stem cells during late mouse embryogenesis through EGFR transactivation

Sonic Hedgehog (Shh/GLI) and EGFR signaling pathways modulate Neural Stem Cell (NSC) proliferation. How these signals cooperate is therefore critical for understanding normal brain development and function. Here we report a novel acute effect of Shh signaling on EGFR function. We show that during late neocortex development, Shh mediates the activation of the ERK1/2 signaling pathway in Radial Glial cells (RGC) through EGFR transactivation. This process is dependent on metalloprotease activity and accounts for almost 50% of the EGFR-dependent mitogenic response of late NSCs. Furthermore, in HeLa cancer cells, a well-known model for studying the EGFR receptor function, Shh also induces cell proliferation involving EGFR activation, as reflected by EGFR internalization and ERK1/2 phosphorylation. These findings may have important implications for understanding the mechanisms that regulate NSC proliferation during neurogenesis and may lead to novel approaches to the treatment of tumors.

Comparison of dose distribution by means of bolus versus water bath phantom techniques in treatment of cutaneous sarcoma of an extremity

Cutaneous involvement by Kaposi's sarcoma (KS) is frequently diffuse, requiring large field irradiation. Selective tissue compensation techniques, accomplished with either a 1.5 cm bolus cast or water bath phantom, are compared. Dosimetric determinations were performed using 6 MVX with bone heterogeneity corrections. Application of 1.5 cm bolus effectively eliminated dose buildup and provided tissue compensation equivalent to water bath phantom technique. Treatment of other cutaneous malignancies, such as angiosarcoma, requiring higher total doses, should be accompanied by dosimetric evaluation, because cutaneous and midline dose inhomogeneity may result in a significant total dose differential over the target volume. Application of 1.5 cm bolus improved accuracy in treatment positioning, eliminated concerns regarding infection control in AIDS-related KS, and provided dose homogeneity comparable to the more standard water bath phantom technique.