Giuseppe Fenu

Overexpression of the Cytokine BAFF and Autoimmunity Risk

BACKGROUND Genomewide association studies of autoimmune diseases have mapped hundreds of susceptibility regions in the genome. However, only for a few association signals has the causal gene been identified, and for even fewer have the causal variant and underlying mechanism been defined. Coincident associations of DNA variants affecting both the risk of autoimmune disease and quantitative immune variables provide an informative route to explore disease mechanisms and drug‐targetable pathways. METHODS Using case–control samples from Sardinia, Italy, we performed a genomewide association study in multiple sclerosis followed by TNFSF13B locus–specific association testing in systemic lupus erythematosus (SLE). Extensive phenotyping of quantitative immune variables, sequence‐based fine mapping, cross‐population and cross‐phenotype analyses, and gene‐expression studies were used to identify the causal variant and elucidate its mechanism of action. Signatures of positive selection were also investigated. RESULTS A variant in TNFSF13B, encoding the cytokine and drug target B‐cell activating factor (BAFF), was associated with multiple sclerosis as well as SLE. The disease‐risk allele was also associated with up‐regulated humoral immunity through increased levels of soluble BAFF, B lymphocytes, and immunoglobulins. The causal variant was identified: an insertion–deletion variant, GCTGT→A (in which A is the risk allele), yielded a shorter transcript that escaped microRNA inhibition and increased production of soluble BAFF, which in turn up‐regulated humoral immunity. Population genetic signatures indicated that this autoimmunity variant has been evolutionarily advantageous, most likely by augmenting resistance to malaria. CONCLUSIONS A TNFSF13B variant was associated with multiple sclerosis and SLE, and its effects were clarified at the population, cellular, and molecular levels. (Funded by the Italian Foundation for Multiple Sclerosis and others.)

Environmental Factors Influencing Coastal Vegetation Pattern: New Insights from the Mediterranean Basin

Coastal dune ecosystems show strongly dynamic interactions between abiotic and biotic factors. The relationship between plant communities and environmental factors has been previously studied in oceanic dune systems, but few studies have been conducted along Mediterranean coasts. In this study we analyze the relative contribution of environmental factors associated with two of the main drivers of vegetation zonation: soil and wind. We chose two representative coastal dune systems in the western Mediterranean Basin subject to low levels of human disturbance. Within 54 plots we recorded floristic and environmental data. Vegetation zonation and relationships with environmental variables were investigated through unconstrained and constrained ordinations, correlation, and variance partitioning. Environmental factors shift along the gradient from coastal to inland dunes, concomitantly with the pattern of community types from annual beach communities to shrub-covered fixed dunes. This general gradient is similar both in the Mediterranean and in the oceanic coastal ecosystems, with the same factors that show similar trends along the dune profile. However, our results highlight some peculiarities of the Mediterranean dune systems in relation to the amount of variation explained by environmental factors. While most studies conducted in oceanic ecosystems find that wind-related parameters may control the vegetation zonation, in our study areas we observed a minor importance of the wind-related variables when compared to soil properties. In particular, organic matter and grain-size variability were found to be closely correlated with the distribution of plant communities along the gradient.

Epidemiology of multiple sclerosis in south-western Sardinia

Background: Sardinia is a known high-risk area for multiple sclerosis (MS), but no data for south-western Sardinia (SWS) are available. SWS has a genetically homogeneous population, apart from St Peter Island, and represents a peculiar environment related to the industrial, mineralogical and military economy. Objective: To estimate prevalence and incidence and to evaluate temporal trends and geographical distribution of MS in SWS. Methods: MS prevalence was evaluated on 31 December 2007 and crude mean annual incidence rate was defined between 2003 and 2007. Temporal trend in MS incidence was assessed using the Armitage test. To identify MS clusters, Standard Morbidity Ratio (SMR) was calculated for each village and geographical distribution prevalence by means of a Bayesian hierarchical model. Results: Total crude prevalence rate was 210.4 (95% CI 186.3–234.5): 280.3 (95% CI 241.4–319.3) for females, 138 (95% CI 110.1–165.8) for males. The crude mean annual incidence rate was 9.7/100,000 (95% CI 3.4–13.2): 4.7/100,000 (95% CI 2.4–17.0) and 14.6/100,000 (95% CI 11.8–34.8) for males and females respectively. MS incidence has increased over the last 50 years. Cluster analysis showed an SMR of 0.2 (95% CI 0.05–0.68, p = 0.002) on the island of San Pietro, and 2.0 (95% CI 1.35–2.95, p = 0.001) in Domusnovas. Spatial distribution of MS was confirmed by Bayesian geographical analysis. Conclusions: Our data confirm Sardinia as a high-risk area for MS and support the relevance of genetic factors in MS, as evidenced in St Peter Island. However, we found an unexpectedly high MS prevalence in one village, in particular in males, suggesting an environmental influence on MS occurrence.

The risk of Bipolar Disorders in Multiple Sclerosis

BACKGROUND The aim was to determine the risk of Mood Disorders (MD), particularly Bipolar Disorders (BD), in Multiple Sclerosis (MS) using standardized psychiatric diagnostic tools. METHODS Case-control study. CASES 201 consecutive-patients with MS. CONTROLS 804 sex- and age-matched subjects without MS, randomly selected from a database concurrently used for an epidemiological study on the MD prevalence in the community. Psychiatric diagnoses according to DSM-IV were determined by physicians using structured interview tools (ANTAS-SCID). RESULTS Compared to controls, MS patients had a higher lifetime prevalence of DSM-IV Major Depressive Disorders (MDD; P<0.0001), BD I (P=0.05), BD II (P<0.0001) and Cyclothymia (P=0.0001). As people with MS had a higher risk of depressive and bipolar spectrum disorders, ratio MDD/bipolar spectrum disorders was lower among cases (P<0.005) indicating a higher association with Bipolar Spectrum Disorders and MS. LIMITATIONS MS diagnosis was differently collected in cases and controls. Even if this might have produced false negatives in controls, it would have reinforced the null hypothesis of no increased risk for MD in MS; therefore, it does not invalidate the results of the study. CONCLUSIONS This study was the first to show an association between BD and MS using standardized diagnostic tools and a case-control design. The results suggest a risk of under-diagnosis of BD (particularly type II) in MS and caution in prescribing ADs to people with depressive episodes in MS without prior excluding BD. The association between auto-immune degenerative diseases (like MS) and BD may be an interesting field for the study of the pathogenic hypothesis.

The brief international cognitive assessment for multiple sclerosis (BICAMS): normative values with gender, age and education corrections in the Italian population

BackgroundBICAMS (Brief International Cognitive Assessment for Multiple Sclerosis) has been recently developed as brief, practical and universal assessment tool for cognitive impairment in MS subjects. It includes the Symbol Digit Modalities Test (SDMT), the California Verbal Learning Test-2 (CVLT2) and the Brief Visuospatial Memory Test-Revised (BVMT-R) . In this study we aimed at gathering regression based normative data for the BICAMS battery in the Italian population.MethodsHealthy subjects were consecutively recruited among patient friends and relatives. Corrections for demographics were calculated using multivariable linear regression models. Test-retest reliability was assessed using the Pearson correlation coefficient.ResultsThe BICAMS battery was administered to 273 healthy subjects (180 women, mean age 38.9 ± 13.0 years, mean education 14.9 ± 3.0 years). Test-retest reliability was good for all the tests.ConclusionsThe study provided normative data of the BICAMS for the Italian population confirming good test-retest reliability which can facilitate the use of the battery in clinical practice, also for longitudinal patient assessments.

Relationships between coastal sand dune properties and plant community distribution: The case of Is Arenas (Sardinia)

Abstract Coastal dune environments are selective ecosystems characterized by a close interaction between abiotic and biotic factors in a dynamic balance. The present study focused on the psammophilous geosigmetum, the most affected by the interactions between physical processes and biological and anthropic processes. The main purpose was to study the relationships between the abiotic properties of the dune and the presence of the various plant communities, combining morpho-sedimentological, geopedological, and geobotanical data. The study was carried out on the well-preserved dune system of Is Arenas (CW Sardinia) which is one of the most important in the Mediterranean area. The analyses revealed differences at the morphodynamic, sedimentological, and geopedological levels. The micro-topography of the dunes affects the values of the main abiotic variables, and determines the presence of various microhabitats of great heterogeneity. This work shows that thedata on the geomorphological dynamics and the chemical–physical processes, correlated with the geobotanical analyses, might make it possible to identify the ecosystemic processes, and thereby plan adequate management and conservation strategies for this coastal dune system.

Spatial genetic structure of Aquilegia taxa endemic to the island of Sardinia

BACKGROUND AND AIMS The Mediterranean Basin is one of the most important regions for the Earths plant biodiversity; however, the scarcity of studies on fine scale patterns of genetic variation in this region is striking. Here, an assessment is made of the spatial genetic structure of all known locations of the three Sardinian endemic species of Aquilegia in order to determine the relative roles of gene flow and genetic drift as underlying evolutionary forces canalizing the divergence of Sardinian Aquilegia taxa, and to see if the spatial genetic structure found fits the current taxonomic differentiation of these taxa. METHODS DNA from 89 individuals from all known locations of Aquilegia across Sardinia was analysed by means of amplified fragment length polymorphism (AFLP) markers. Both principal co-ordinates analysis (PCoA) and Bayesian clustering analyses were used to determine the spatial genetic structure irrespective of any taxonomic affiliation. Historical effects of gene flow and genetic drift were assessed by checking for the existence of isolation-by-distance patterns. KEY RESULTS STRUCTURE and PCoA analyses revealed a pattern of genetic variation geographically structured into four spatial genetic groups. No migration-drift equilibrium was detected for Aquilegia in Sardinia, when analysed either as a whole or in individual groups. The scenario approached a Case III pattern sensu Hutchinson and Templeton, which is associated with extreme isolation conditions where genetic drift has historically played a dominant role over gene flow. CONCLUSIONS The pattern of genetic variation of Sardinian taxa of Aquilegia indicates that genetic drift has been historically more influential than gene flow on population structure of Sardinian species of Aquilegia. Limited seed dispersal and divergent selection imposed by habitat conditions have been probably the main causes reinforcing post-Pleistocene geographical isolation of Aquilegia populations. The spatial genetic structure found here is not fully compatible with current taxonomic affiliations of Sardinian Aquilegia taxa. This is probably a consequence of the uncoupling between morphological and genetic patterns of differentiation frequently found in recently radiated taxa.

Distribution, status and conservation of a Critically Endangered, extremely narrow endemic: Lamyropsis microcephala (Asteraceae) in Sardinia

The aims of this work were to verify the distribution and population size of Lamyropsis microcephala (Asteraceae), characterize its habitat, assess its conservation status and initiate conservation measures for this Critically Endangered species. Distribution was determined by field surveys and mapping. To estimate population size and density 81 permanent monitoring plots were randomly established. Ex situ conservation measures were activated by harvesting and appropriate storage of seed. We confirmed the presence of L. microcephala at two previously known sites and found it in two previously unknown localities. The areas in which the species occur vary from 200 to 240,000 m 2 , at altitudes of 1,450–1,820 m, on slopes of 15–45° with aspects from north to west. The estimated number of ramets per population varied from c. 2,000 to c. 2,000,000, with a mean density of 8.29 ± SD 14.3 to 10.33 ± SD 10.05 ramets m -2 . Our findings confirmed the Critically Endangered status of this species, although with different criteria. This study is an example of an integrated approach for the conservation of an extremely narrow endemic plant species and may be useful for other little-known threatened species for which urgent conservation measures are needed.

Adaptation to habitat in Aquilegia species endemic to Sardinia (Italy): Seed dispersal, germination and persistence in the soil

Abstract The autecology of the Sardinian endemics Aquilegia barbaricina Arrigoni et Nardi and A. nugorensis Arrigoni et Nardi were investigated. Peaks of anthesis and seed dispersal were recorded for five populations occurring in two distinct habitats, one riparian and one rupicolous. Germination tests were carried out on seed lots belonging to each population by sowing seeds at 10, 15, 20, 25 and 25/15°C. In addition, seeds were incubated for 2 months at either 25°C (summer), 5°C (winter) or 25°C for 2 months plus 2 months at 5°C (summer followed by winter–SW), and then moved to the germination temperatures. Embryo measurements were taken during pre-treatments and germination. Experimental seed burials were carried out for two populations of each species. Both species dispersed in summer. The population of A. nugorensis occurring on rocky outcrops differed in phenology from both the other A. nugorensis population from riparian vegetation and from A. barbaricina. Both species showed morphophysiological seed dormancy, with <50% germination under laboratory conditions. All riparian populations germinated only after the SW pre-treatment, while the rupicolous population germinated at 25°C, without any pre-treatment. Low germination percentages were observed in the experimental seed burials, suggesting the ability for both species to form a persistent soil seed bank.

The Endemic Vascular Flora of Supramontes (Sardinia), a Priority Plant Conservation Area

Abstract FENU, G., E. MATTANA, A. CONGIU & G. BACCHETTA (2010). The endemic vascular flora of Supramontes (Sardinia), a priority plant conservation area. Candollea 65: 347–358. In English, English and French abstracts. The main aim of this work is to present a checklist of the endemic vascular flora of the Supramontes region (Central Eastern Sardinia) in order to classify this area in the Sardinian biogeographic subprovince and to better assess its conservation priorities. It is one of the most interesting regions of the Island and spreads for 335 km2 from the inland limestone massif to the Orosei gulf. This work was based on bibliographic and herbarium studies, integrated by several field surveys carried out from 2004 to 2009. In this study 138 endemic taxa, belonging to 98 genera and 42 families, have been found, with 92 of which being species, 40 subspecies, 5 varieties and 1 hybrid. The analysis of biologic and chorologic data highlighted the peculiarities of this territory. Due to the relatively high number of Supramontes exclusive endemics and to the geologic and geomorphologic peculiarities, it is here proposed a biogeographic classification for these territories and the identification of an autonomous biogeographic sector divided in two distinct subsectors. According to the recent conservation policies at local level, we propose the definition of micro hotspots for this sector, which hold ca. the 40% of the endemic flora of Sardinia, and the concept of nano hotspots for three narrows areas with an exceptional concentration of endemic species, which represent less than 1% of the whole sector surface and whose in situ protection may allow conserving of more than 80% of the vascular endemic flora of this sector.