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1.
Ocul Surf ; 31: 1-8, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38049032

RESUMO

PURPOSE: This double-blinded randomized clinical trial aimed to evaluate the efficacy of injecting allogeneic adipose-derived mesenchymal stem cells (ASCs) into the lacrimal gland (LG) for the treatment of dry eye disease (DED) secondary to Sjögren's syndrome (SS). METHODS: Fifty-four participants with severe DED secondary to SS were included and allocated to either ASCs (n = 20), vehicle (n = 20), or a non-randomized observation group (n = 14). The intervention groups received a single injection of either ASCs or an active comparator (vehicle, Cryostor® CS10) into the LG in one eye, while the observation group received lubricating eye drops only. The primary outcome measure was changes in Ocular Surface Disease Index (OSDI) score and secondary outcome measures were non-invasive tear break-up time, tear meniscus height, Schirmer's test, and Oxford score within a 12-month follow-up. RESULTS: A significant reduction in OSDI score was observed in the ASCs and vehicle groups compared to the observation group. In addition, the ASCs group demonstrated a significant increase in non-invasive tear break-up time compared to the vehicle group at the 4-week follow-up and to the observation group at the 12-month follow-up. A significant improvement in ocular surface staining, tear osmolarity, and Schirmer test score from baseline was also observed in the ASCs group; however, these changes were not significant compared to the other groups. CONCLUSION: Improvement of subjective and objective signs and symptoms of DED was observed in both intervention groups following injection into the LG compared to the observation group. Future studies should investigate the mode-of-action of both injection treatments.


Assuntos
Síndromes do Olho Seco , Transplante de Células-Tronco Hematopoéticas , Transplante de Células-Tronco Mesenquimais , Síndrome de Sjogren , Humanos , Síndrome de Sjogren/complicações , Síndrome de Sjogren/terapia , Síndrome de Sjogren/diagnóstico , Síndromes do Olho Seco/etiologia , Síndromes do Olho Seco/terapia , Síndromes do Olho Seco/diagnóstico , Lágrimas/metabolismo
2.
Acta Ophthalmol ; 101 Suppl 277: 3-27, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37840443

RESUMO

ENGLISH SUMMARY: Dry eye disease (DED) is characterized by ocular dryness, irritation and blurred vision and has a significant impact on the patient's quality of life. This condition can be particularly severe in patients with aqueous deficient dry eye disease (ADDE) due to Sjögren's syndrome (SS), an autoimmune disease that affects the lacrimal and salivary glands. Current treatments for ADDE are often limited to symptomatic relief. A literature review was conducted to explore the current surgical interventions used or tested in humans with ADDE (I). These interventions include procedures involving the eyelids and tear ducts, transplantation of amniotic membrane or salivary glands, injections around the tear ducts and cell-based injections into the lacrimal gland (LG). Each treatment has its advantages and disadvantages; however, treating dry eyes in patients with SS presents a particular challenge due to the systemic nature of the disease. Moreover, there is a need for new therapeutic options. Mesenchymal stem cells (MSCs) are a type of stem cell that have shown promise in regenerating damaged tissue and reducing inflammation in various diseases. Previous studies in animal models have suggested that MSCs could be effective in treating ADDE. Thus, this thesis aims to investigate the safety and efficacy of injecting MSCs into the LG as a treatment option for patients with ADDE secondary to SS. The study also aims to see this treatment in light of existing and novel investigational treatment options. The clinical studies conducted for this thesis are the first of their kind in humans. MSCs derived from healthy donors' adipose tissue (ASCs) were cultured in a laboratory, frozen and thawed ready for use. In the safety study, we performed the first human trial involving the administration of a single injection of ASCs into the LG of one eye in seven patients suffering from severe ADDE (II). The primary objective was to test the safety of this treatment, while the secondary objective was to assess improvements in subjective and objective signs of dry eye. The results of the trial showed no serious side effects within 4 months of follow-up after treatment. On average, there was a 40% reduction in dry eye symptoms assessed with the Ocular Surface Disease Index (OSDI) questionnaire. Additionally, in the treated eye, there was a significant decrease in tear osmolarity, an increase in tear film stability and an increase in tear production. To further investigate the efficacy of this treatment, our research group performed a clinical, randomized study aiming to compare the ASC injection into the LG with the injection of a vehicle (the excipient in which the ASCs are dissolved) and observation (no intervention) (III). The study involved 20 subjects receiving ASC injection, 20 subjects receiving vehicle injection and 14 patients being observed without intervention. The subjects were examined to assess the outcomes with a 12-month follow-up after treatment. Both intervention groups showed a significant reduction in subjective dry eye symptoms of approximately 40%. This improvement was evident at the 1-week follow-up and persisted until the 12-month follow-up. The observation group did not experience any change in OSDI score. The ASCs group exhibited a significant mean increase in non-invasive tear break-up time (NIKBUT) of 6.48 s (149%) at the four-week follow-up, which was significantly higher than that in the vehicle group (p = 0.04). Moreover, the ASCs group showed a significant increase in NIKBUT compared to that in the observation group at the 12-month follow-up (p = 0.004). In both the ASCs and vehicle group, a significant increase in Schirmer test scores at the 4-month follow-up and the 12-month follow-up was observed. In conclusion, this thesis contributes valuable findings with a new treatment option for patients with dry eye disease. Injection of ASCs into the LG was shown to be safe and to improve subjective dry eye symptoms and specifically the tear film stability in patients with ADDE due to SS. Compared to other treatment modalities of ADDE, this treatment has greater potential, as ASCs could potentially be used as an anti-inflammatory therapeutic option for managing DED of other causes as well. RESUMÉ (DANISH SUMMARY): Tørre øjne, karakteriseret ved tørhedsfornemmelse og irritation af øjnene samt sløret syn, har en betydelig indvirkning på patientens livskvalitet. Denne tilstand kan vaere saerligt alvorlig hos patienter med nedsat tåreproduktion (ADDE) som følge af Sjögrens syndrom (SS), en autoimmun sygdom, der påvirker tårekirtlerne og spytkirtlerne. Nuvaerende behandlinger for ADDE er ofte begraenset til symptomlindring. Vi gennemførte en litteraturgennemgang for at undersøge, hvilke nuvaerende kirurgiske behandlingsmetoder, der anvendes eller testes hos patienter med ADDE (I). Disse interventioner inkluderer procedurer, der involverer øjenlåg og tårekanaler, transplantation af amnionhinde eller spytkirtler, injektioner omkring tårekanalerne samt cellebaserede injektioner i tårekirtlen. Hver behandling har sine fordele og ulemper, men behandling af tørre øjne hos patienter med SS udgør en saerlig udfordring på grund af sygdommens systemiske udbredning, og der er behov for nye behandlingsmuligheder. Mesenkymale stamceller (MSCs) er en type stamcelle, der har vist lovende resultater med hensyn til at regenerere beskadiget vaev og reducere inflammation i forskellige sygdomme. Tidligere undersøgelser i dyremodeller har indikeret, at MSCs kan vaere en effektiv behandling af ADDE. Denne afhandling har til formål at undersøge sikkerheden og effekten af injektion af MSCs i tårekirtlen som en mulig behandling til patienter med ADDE som følge af SS. Afhandlingen sigter også mod at sammenligne denne behandling med andre eksisterende, kirurgiske behandlingsmuligheder af ADDE. Som led i dette projekt udførte vi de første kliniske forsøg af sin art i mennesker. MSCs fra raske donorers fedtvaev (ASCs) blev dyrket i et laboratorium, frosset ned og er optøet klar til brug. Det første mål var at teste sikkerheden ved denne behandling og sekundaert at undersøge behandlingens effekt. For at undersøge dette modtog syv forsøgspersoner med svaer ADDE én injektion med ASCs i tårekirtlen på det ene øje (II). Resultaterne af forsøget viste ingen alvorlige bivirkninger inden for fire måneders opfølgning efter behandlingen. I gennemsnit fandt vi yderligere en 40% reduktion i symptomer på tørre øjne vurderet med et spørgeskema, og en markant stigning i tåreproduktionen og af tårefilmens stabilitet i det behandlede øje. For yderligere at undersøge effekten af denne behandling udførte vi et klinisk, randomiseret forsøg med det formål at sammenligne injektion af ASCs i tårekirtlen med injektion af en kontrolopløsning (vaesken, hvor stamcellerne var opløst) og observation (ingen intervention) (III). Studiet omfattede 20 forsøgspersoner, der modtog ASC-injektion, 20 forsøgspersoner, der modtog injektion af kontrolopløsningen, og 14 forsøgspersoner i observationsgruppen. Forsøgspersonerne blev undersøgt med en opfølgningstid på 12 måneder efter behandling. Begge interventionsgrupper viste en betydelig reduktion på ca. 40% i subjektive symptomer på tørre øjne. Denne forbedring var betydelig allerede ved opfølgning efter en uge og varede ved 12 måneder efter behandling. Observationsgruppen oplevede ingen betydelig aendring i symptomer. ASCs gruppen viste desuden en signifikant stigning i tårefilmsstabiliteten (NIKBUT) på 6,48 sekunder (149%) ved opfølgning efter fire uger, hvilket var markant højere end efter injektion af kontrolopløsning (p = 0,04). Desuden viste ASCs gruppen en betydelig stigning i NIKBUT sammenlignet med observationsgruppen ved opfølgning efter 12 måneder (p = 0,004). Både injektion af ASCs og kontrolopløsning medførte en betydelig stigning i tåreproduktionen ved opfølgning fire måneder og 12 måneder efter behandling. Denne afhandling bidrager med vigtige resultater inden for en ny behandlingsmulighed af tørre øjne. Injektion af ASCs i tårekirtlen viste sig at vaere sikker, forbedrede subjektive symptomer på tørre øjne og øgede saerligt tårfilmens stabilitet hos patienter med ADDE på grund af SS. Sammenlignet med andre behandlingsmuligheder for ADDE har denne behandling vist et stort potentiale. ASCs kan muligvis også bruges som en anti-inflammatorisk behandling af tørre øjne af andre årsager i fremtiden.


Assuntos
Síndromes do Olho Seco , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Masculino , Humanos , Qualidade de Vida , Síndromes do Olho Seco/terapia , Inflamação , Ensaios Clínicos Controlados Aleatórios como Assunto
3.
J Ocul Pharmacol Ther ; 39(10): 692-698, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37566528

RESUMO

Dry eye disease (DED) is a multifactorial disease affecting 5% to 50% in different populations. The most severe cases of DED are often caused by aqueous deficient dry eye disease (ADDE) due to lacrimal gland (LG) hypofunction. Many patients with severe ADDE do not experience adequate symptom relief from topical treatment, severely reducing their quality of life. The focus of this review is to describe the surgical interventions presently being used or investigated when topical treatment with eye drops is insufficient. The conventional surgical approach is to proceed to punctal occlusion or partial or total tarsorrhaphy. However, novel surgical procedures have been reported to have higher efficacy and patient satisfaction than conventional treatments. These procedures include amniotic membrane transplantation, transposition or transplantation of the salivary glands, and cell-based injections into the LG, each with strengths and weaknesses. Further development of these treatment modalities might prove pivotal in treating dry eye patients in the future.


Assuntos
Síndromes do Olho Seco , Aparelho Lacrimal , Humanos , Qualidade de Vida , Síndromes do Olho Seco/tratamento farmacológico , Síndromes do Olho Seco/cirurgia , Síndromes do Olho Seco/diagnóstico , Aparelho Lacrimal/cirurgia , Lágrimas
4.
J Ocul Pharmacol Ther ; 39(4): 275-278, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36944128

RESUMO

Purpose: To develop a method of injecting a volume up to 50% of the lacrimal gland (LG) volume while minimizing patient discomfort and maximizing accurate drug delivery. Herein we describe a series of ultrasound (US)-guided transcutaneous injections in the LG and discuss the safety and feasibility of this technique. Methods: Ultrasonography was performed in 40 patients with aqueous deficient dry eye disease using a GE Logic E10 (Milwaukee, Wisconsin, USA) US machine with a 6-24 MHz transducer. US was performed by 2 medical experts in ultrasonography. We recorded the injection and observed an enlargement of the LG ensuring delivery within the LG before the needle was removed. Assessment of injection-related adverse event was performed immediately after the injection. Results: The position of the injection needle within the LG was documented in all 40 patients. Injection of the stem cells and vehicle (N = 20) or solely vehicle (N = 20) led to an enlargement of the glandular structures in all cases. No serious adverse reactions related to the injections were observed. Conclusion: US-guided injection into the LG enables injection on a closed eye causing minimum patient discomfort and maximum certainty of accurate drug delivery. US can provide real-time images and may be used to safely guide the needle ensuring correct placement and injection within the gland capsule. This reduces the risk of injury to the eye and adjacent structures and makes a precise transcutaneous injection possible. Clinical Trial Registration number: NCT04615455.


Assuntos
Síndromes do Olho Seco , Aparelho Lacrimal , Humanos , Ultrassonografia , Síndromes do Olho Seco/tratamento farmacológico , Células-Tronco , Ultrassonografia de Intervenção/métodos
5.
Commun Med (Lond) ; 2(1): 160, 2022 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-36496530

RESUMO

BACKGROUND: Hyposalivation and xerostomia (dry mouth), are the leading site-effects to treatment of head and neck cancer. Currently, there are no effective therapies to alleviate radiation-induced hyposalivation. Adipose tissue-derived mesenchymal stem/stromal cells (AT-MSCs) have shown potential for restoring salivary gland function. However, the mode of action is unknown. The purpose of the present study was therefore to characterize the effect of AT-MSC therapy on the salivary proteome in previously irradiated head and neck cancer patients. METHODS: Whole saliva was collected from patients with radiation-induced salivary gland hypofunction (n = 8) at baseline, and 120 days after AT-MSC treatment, and from healthy controls (n = 10). The salivary proteome was characterized with mass spectrometry based proteomics, and data was compared within the AT-MSC group (baseline versus day 120) and between AT-MSC group and healthy controls. Significance levels between groups were determined by using double-sided t-test, and visualized by means of principal component analysis, volcano plots and cluster analysis. RESULTS: Here we show that 140 human proteins are significantly differentially expressed in saliva from patients with radiation-induced hypofunction versus healthy controls. AT-MSC treatment induce a significant impact on the salivary proteome, as 99 proteins are differentially expressed at baseline vs. 120 days after treatment. However, AT-MSC treatment does not restore healthy conditions, as 212 proteins are significantly differentially expressed in saliva 120 days after AT-MSCs treatment, as compared to healthy controls. CONCLUSION: The results indicate an increase in proteins related to tissue regeneration in AT-MSCs treated patients. Our study demonstrates the impact of AT-MSCs on the salivary proteome, thereby providing insight into the potential mode of action of this novel treatment approach.


Currently, there are no effective treatments to ease dry mouth, which is a leading long-term side effect of radiation treatment for head and neck cancer. However, treatment with stem cells has shown potential for restoring function of the salivary glands, which are damaged due to radiation. We compared proteins in saliva of previously radiation-treated patients with healthy non-irradiated persons and found differences in the levels of 140 proteins. After stem cell treatment of irradiated patients, we found changes in the salivary content of proteins related to tissue regeneration. Our study demonstrates the impact of stem cell treatment on proteins in saliva, thereby providing insight into the potential mode of action of this treatment approach for patients with radiation-induced dry mouth. Consequently, this could potentially help to improve treatment of dry mouth in the future.

6.
Stem Cells Transl Med ; 11(5): 478-489, 2022 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-35435231

RESUMO

No effective therapy exists for the most common long-term side effect of radiation therapy for head and neck cancer (HNC)-xerostomia. The objective was to evaluate safety and provide proof of concept for efficacy of allogeneic adipose tissue-derived mesenchymal stem/stromal cells (AT-MSCs) injected into the major salivary glands of irradiated patients. This open-label, first-in-human, phase 1b, and single-center trial was conducted with repeated measurements days 0, 1, 5, and 30 and 4 months. Eligible patients with objective and subjective signs of radiation-induced salivary gland damage after treatment of oropharyngeal squamous cell carcinoma stages I-II (UICC 8) were enrolled. Twenty-five million cryopreserved AT-MSCs were injected into each submandibular and 50 million AT-MSCs into each parotid gland. Data were collected on adverse events, unstimulated and stimulated whole saliva (UWS and SWS) flow rates and saliva composition, patient-reported outcomes (EORTC QLQ-H&N35 and Xerostomia Questionnaire [XQ]), blood samples and salivary gland scintigraphy. Data were analyzed using repeated measures linear mixed models. Ten patients (7 men, 3 women, 59.5 years [range: 45-70]) were treated in 4 glands. No treatment-related serious adverse events occurred. During 4 months, UWS flow rate increased from 0.13 mL/minute at baseline to 0.18 mL/minute with a change of 0.06 (P = .0009) mL/minute. SWS flow rate increased from 0.66 mL/minute at baseline to 0.75 mL/minute with a change of 0.09 (P = .017) mL/minute. XQ summary score decreased by 22.6 units (P = .0004), EORTC QLQ-H&N35 dry mouth domains decreased by 26.7 (P = .0013), sticky saliva 23.3 (P = .0015), and swallowing 10.0 (P = .0016). Our trial suggests treatment of the major salivary glands with allogenic AT-MSCs is safe, warranting confirmation in larger trials.


Assuntos
Neoplasias de Cabeça e Pescoço , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Mesenquimais , Lesões por Radiação , Xerostomia , Feminino , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Masculino , Lesões por Radiação/etiologia , Lesões por Radiação/terapia , Xerostomia/etiologia , Xerostomia/terapia
7.
Ocul Surf ; 19: 43-52, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33253910

RESUMO

PURPOSE: To evaluate the safety and feasibility of injecting allogeneic adipose-derived mesenchymal stem cells (ASCs) into the lacrimal gland (LG) as a treatment of aqueous deficient dry eye disease (ADDE). METHODS: In this open-label, 5-visit clinical trial (baseline, treatment and weeks 1, 4 and 16) seven subjects with ADDE received one transconjunctival injection of allogeneic ASCs into the LG in one eye. The ASC product contained 22 million ASCs/ml and the injected volume was maximally 50% of the LG volume as determined on magnetic resonance imaging (MRI). Treatment related adverse events (AEs) were assessed at each visit (primary endpoint). Ocular Surface Disease Index (OSDI), tear osmolarity, tear film breakup time (TBUT), corneal staining (Oxford grade) and Schirmer's I test were assessed at each timepoint. RESULTS: No AEs related to the study treatment were observed. Mean follow-up time was 126 days after treatment. The mean OSDI score decreased from 58.9 ± 20.6 at baseline to 34.1 ± 21.6 (p < 0.002). In the study eye mean tear osmolarity decreased from 312.9 ± 10.4 to 291.6 ± 10.9 mosm/l (p < 0.002), mean TBUT increased from 3.7 ± 1.5 to 7.1 ± 1.9 s (p < 0.002), mean Schirmer's I test increased from 4.6 ± 0.7 to 8.1 ± 3.1 mm/5 min (p < 0.03), while mean Oxford grade showed a trend towards a decrease from 2.4 ± 0.7 to 1.3 ± 1 (p < 0.10). CONCLUSION: Our trial suggests that injection of allogeneic ASCs into the LG is a safe and feasible treatment of severe ADDE. A randomized placebo-controlled trial aimed at elucidating the therapeutic effect of allogeneic ASCs in a larger patient cohort from our research group is currently underway.


Assuntos
Síndromes do Olho Seco , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Síndromes do Olho Seco/terapia , Estudos de Viabilidade , Humanos , Lágrimas
8.
Acta Ophthalmol ; 99(5): 478-488, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33191633

RESUMO

PURPOSE: We aimed to study the prevalence of human papillomavirus (HPV) in conjunctival intraepithelial neoplasia and carcinoma. Furthermore, we aimed to explore whether geographical differences or different detection modalities are associated with the conflicting information regarding HPV and the development of the disease. METHODS: We searched the MEDLINE, EMBASE and Scopus databases for studies reporting on HPV and conjunctival intraepithelial neoplasia or carcinoma. The pooled prevalence proportions, odds ratio (OR) and corresponding 95% confidence intervals were calculated assuming a random-effects model. Subgroup analyses and meta-regression explored possible sources of heterogeneity. RESULTS: A total of 39 studies were included in the systematic review. The pooled prevalence of HPV in conjunctival intraepithelial neoplasia and carcinoma was 26%, with HPV16, 18, and 33 being the most frequently reported genotypes. Human papillomavirus (HPV) infection was associated with an increased risk of conjunctival intraepithelial neoplasia and carcinoma (OR 8.4, 95% confidence interval (CI) 3.7-19.1); lower in studies from African countries (OR 1.7, 95% CI 0.9-3.5) than other countries (OR 16.1, 95% CI 5.8-44.3), p = 0.013. CONCLUSION: Human papillomavirus infection increases the odds of conjunctival intraepithelial neoplasia and carcinoma by 8.4 compared to healthy conjunctival mucosa or other ocular surface diseases. There seem to be geographical differences regarding HPV in conjunctival intraepithelial neoplasia and carcinoma. HPV16 was the most prevalent genotype, followed by HPV18 and HPV33, meaning that most of the HPV-related conjunctival intraepithelial neoplasia and carcinoma may be prevented by the HPV vaccines that are currently available.


Assuntos
Carcinoma de Células Escamosas/epidemiologia , Neoplasias da Túnica Conjuntiva/epidemiologia , DNA Viral/análise , Estudos Observacionais como Assunto , Papillomaviridae/genética , Infecções por Papillomavirus/epidemiologia , Carcinoma de Células Escamosas/etiologia , Carcinoma de Células Escamosas/virologia , Neoplasias da Túnica Conjuntiva/etiologia , Neoplasias da Túnica Conjuntiva/virologia , Saúde Global , Humanos , Incidência , Infecções por Papillomavirus/complicações
9.
Scand Cardiovasc J ; 50(1): 52-7, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26485501

RESUMO

OBJECTIVE: Cardiovascular implantable electronic device (CIED) infections are increasing in numbers. The objective was to review the clinical presentation and outcome in patients affected with CIED infections with either local pocket or systemic presentation. DESIGN: All device removals due to CIED infection during the period from 2005 to 2012 were retrospectively reviewed. CIED infections were categorized as systemic or pocket infections. Treatment included complete removal of the device, followed by antibiotic treatment of six weeks. RESULTS: Seventy-one device removals due to infection (32 systemic and 39 pocket infections) were recorded during the study period. Median follow-up time was 26 (IQR 9-41) months, 30 day and 12 month mortality were 4% and 14%, respectively. There was no long-term difference in mortality between patients with pocket vs. systemic infection (p = 0.48). During follow-up no relapses and two cases of new infections were noted (2.8%). CONCLUSIONS: CIED infection with systemic or pocket infection was difficult to distinguish in clinical presentation and outcome. Complete device removal and antibiotic treatment of long duration was safe and without relapses.


Assuntos
Antibacterianos/administração & dosagem , Estimulação Cardíaca Artificial/efeitos adversos , Desfibriladores Implantáveis/efeitos adversos , Remoção de Dispositivo , Cardioversão Elétrica/efeitos adversos , Marca-Passo Artificial/efeitos adversos , Infecções Relacionadas à Prótese/terapia , Esquema de Medicação , Cardioversão Elétrica/instrumentação , Humanos , Estimativa de Kaplan-Meier , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/microbiologia , Infecções Relacionadas à Prótese/mortalidade , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento
10.
Genetics ; 190(2): 725-36, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22135355

RESUMO

Our understanding of the genetic basis of local adaptation has recently benefited from the increased power to identify functional variants associated with environmental variables at the genome scale. However, it often remains challenging to determine whether locally adaptive alleles are actively maintained at intermediate frequencies by spatially varying selection. Here, we evaluate the extent to which this particular type of balancing selection explains the retention of adaptive genetic variation in the extreme situation of perfect panmixia, using the American eel (Anguilla rostrata) as a model. We first conducted a genome scan between two samples from opposite ends of a latitudinal environmental gradient using 454 sequencing of individually tagged cDNA libraries. Candidate SNPs were then genotyped in 992 individuals from 16 sampling sites at different life stages of the same cohort (including larvae from the Sargasso Sea, glass eels, and 1-year-old individuals) as well as in glass eels of the following cohort. Evidence for spatially varying selection was found at 13 loci showing correlations between allele frequencies and environmental variables across the entire species range. Simulations under a multiple-niche Levene's model using estimated relative fitness values among genotypes rarely predicted a stable polymorphic equilibrium at these loci. Our results suggest that some genetic-by-environment interactions detected in our study arise during the progress toward fixation of a globally advantageous allele with spatially variable effects on fitness.


Assuntos
Anguilla/genética , Variação Genética , Seleção Genética , Adaptação Fisiológica/genética , Alelos , Animais , Evolução Molecular , Frequência do Gene , Interação Gene-Ambiente , Loci Gênicos , Genótipo , Modelos Genéticos , Oceanos e Mares , Polimorfismo Genético , Polimorfismo de Nucleotídeo Único , Temperatura
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