Phototrophic purple bacteria (PPB) are a ubiquitous group of anoxygenic phototrophs, that can use organic/inorganic electron donors for anaerobic growth under heterotrophic and autotrophic conditions. PPB can collect light via bacteriochlorophylls (BChls) and carotenoids (Crts), also in non-sterile environments, and can contain approximately 60% of crude protein. These factors make PPB an ideal microorganisms’ group for assimilation of nutrients from waste/wastewater, yielding a product with potential interest as aquaculture feed or fish-feed additive. In this work, wine lees (WL) was exploited as renewable carbon source for PPB production in three tubular pilot-scale photobioreactors (PBRs; 50 L each) under different operating conditions, which were set to investigate the impact of the light availability (24h/day and 12h/day) and hydraulic retention time (HRT; 3 – 6 days). The organic loading rate was set at 1.0 g COD/(L d) (as soluble COD); wine lees was previously fermented to produce a volatile fatty acids (VFA) rich stream mainly composed by acetic, butyric and propionic acid (65%, 29% and 8% respectively). Each PBR was maintained in a dark thermostatic (25°C) container, illuminated by 4 LED lamps (122W in total) in far-red and infrared spectrum. The continuous light availability supported the growth of PPB and the synthesis of pigments better than intermittent light, with a growth yield of 0.43 CODPPB/CODSOL (20% higher than PBR with 12 h light/day). However, intermittent light promoted the storage of intracellular polyhydroxyalkanoates (PHA; up to 6% of cells’ dry weight), presumably as response to the stress caused by discontinuous illumination. On the contrary, PHA was not detected in the PPB grown under continuous light. Regarding the effect of HRT, when it was set at 6 days a 100% VFA removal was observed, which decreased to 75% when the HRT was reduced to 3 days. This suggested the necessity to investigate intermediate HRT values. In terms of nutritional value, the crude protein content of the three biomasses (separately collected from the three PBRs) was in the range 44-56 wt%. The highest value was obtained in the PBR operated under continuous light and 3 days as HRT. Other analyses are ongoing and addressed to measure carbohydrates, lipids and aminoacidic profile highlighting the potential of PPB biomass as a high protein, pigment rich ingredient for aqua

Anaerobic digestion (AD) is a well-established technology for sludge stabilization and energy recovery; however, its application to PFAS-contaminated industrial sludge remains poorly understood. In this study, tannery sludge was treated under mesophilic (37 °C) and thermophilic (55 °C) conditions in continuous stirred tank reactors, to evaluate process performance and assess the fate of per- and polyfluoroalkyl substances (PFAS). Subsequently, adsorption was investigated as a post-treatment for PFAS removal from the clarified digestate (CD) using granular activated carbon (GAC) and a strong-base anion exchange resin (AER). Both reactors achieved stable operation, with thermophilic conditions resulting in higher specific gas production (0.62 vs 0.49 m3/kg VS) and volatile solids removal (54% vs 42%) compared with mesophilic digestion. However, PFAS concentrations in the CD remained above 10,000 ng/L; no significant differences were observed between mesophilic and thermophilic conditions, suggesting that AD thermal regime had a limited influence on PFAS occurrence in the liquid fraction. Adsorption experiments showed that AER exhibited a higher adsorption capacity than GAC for both total PFAS and individual congeners. The adsorbent dosages required to achieve target PFAS concentrations (500 and 100 ng/L) were estimated, and a preliminary full-scale assessment highlighted substantial differences in adsorbent inventory requirements and infrastructure footprint between the two technologies. Overall, the results demonstrate that, while AD is effective for energy recovery from tannery sludge, it does not mitigate PFAS contamination and therefore requires dedicated post-treatment. These findings provide new insights into the integrated management of PFAS-contaminated industrial sludge, supporting the development of scalable treatment strategies.

Waste-based sustainable solutions proposed by scientific and industrial communities for energy production are an approach that can respond to the growing concerns regarding climate change and fossil resources depletion. This study investigates a two-phase bioprocess combining dark fermentation (DF) and photo-fermentation (PF) to enhance hydrogen yield while anaerobically treating urban organic food waste and sewage sludge. A key objective was to assess the effect of waste composition and temperature on hydrogen accumulation, with particular attention to the fermentation product and the role of zeolite in improving process efficiency. In the DF stage, the addition of zeolite significantly enhanced hydrogen production by increasing microbial activity and improving substrate bioavailability. As a result, hydrogen production increased up to 27.3 mmol H2/(L d) under thermophilic conditions. After the suspended solids were removed from the dark fermentation broth, a photo-fermentation step driven by a pure strain of Rhodopseudomonas palustris was performed under permanent IR light and different substrate-to-inoculum [S/I] ratios. The maximum hydrogen production rate was 9.33 mmol H2/(L d), when R. palustris was inoculated at the lowest [S/I] ratio (<20 COD/COD) and with 0.5 g VSS/L as the initial concentration. This condition in the photo-fermentation process led to an increase in the hydrogen yield up to 35% compared to values obtained from dark fermentation alone.

This study evaluated single-cell protein production from PHA-rich mixed microbial cultures obtained from fermentation and subsequent PHA storage, using urban (namely food waste and municipal sewage sludge; FW-MSS) and agricultural waste (namely wine lees; WL) streams as substrates. FW-MSS fermentation achieved stable short-chain fatty acid (SCFA) production and a high CODSCFA/CODSOL ratio of 0.77 ± 0.01, which allowed to select a mixed microbial culture (MMC) with intracellular PHA content of 15.1 wt%, which aligns with fish dietary standards and yielded a MMC biomass with a protein level of 55.1 wt% and a balanced essential amino acid (EAA) profile. In contrast, WL fermentation showed lower SCFA content and stability, yielding a MMC with 45.8 wt% of protein along with a high non-conformance rate (53.65 %), and 7.2 wt% PHA, making the resulting MMC more suited as a supplemental protein source. Distinct microbial communities developed in the two SBRs due to different feedstocks, influencing the abundance of PHA-storing bacteria, with no known fish pathogens detected in either sample. Statistical analysis confirmed FW-MSS's superior product consistency, supporting its potential as a good quality SCP for aquafeed, especially for rainbow trout, as confirmed by its high essential amino acid index (EAAI).

Food waste (FW) was subjected to thermal-alkaline hydrolysis before to be used as source for organic acids (OAs) production under different temperatures and hydraulic regime in long-term acidification process. Mesophilic environment led to the highest acidification yield (0.87 g CODOAs/g VS) with chain-elongation process to caproic acid production (>9.0 g CODcap/L) occurring at lower HRT (2 days). The product's quality, in terms of OAs production and composition, was evaluated through a multivariate approach, which indicated that the mesophilic condition was also appropriate to steadily maintain the requested product's features.The specific gas production (SGP) from the solid-rich acidified residue was 0.47 Nm(3)/kg VS and, in a full-scale scenario of 150,000 kg FW/d, it can be potentially converted into 24.9 MWh/d as electrical energy. Also, according to the acidification performances, an overall OAs production of 7.2 ton/y has been estimated, generating a yearly economic outcome higher than 4,800,000 .

This study explores the potential of utilizing tannery sludge for short-chain fatty acids (SCFAs) production through fermentation, incorporating zeolites in the process. The study involved a mild thermal pretreatment of the sludge as well, aimed at enhancing the subsequent fermentation process by increasing the solubilization of the organic matter. Six thermophilic continuously stirred tank reactor runs with varying hydraulic retention times (HRT) and zeolite addition are conducted. Zeolites, known for their low cost and absorption properties, significantly impacted chromium concentrations. SCFA production levels remain relatively consistent across tests. However, the acidification efficiency, as reflected in the SCFAs/sCOD ratios, shows improvement in the presence of Chabazite. Specifically, the acidification efficiency is highest in test RB8 (0.92 COD/COD). This suggests that the addition of Chabazite enhances acidification efficiency in tannery sludge applications. The findings highlight zeolites' potential to absorb heavy metals and improve acidification efficiency, indicating promising practical applications for tannery sludge treatment.

The present study describes the microbial production of polyhydroxyalkanoates (PHA) from thermally pre-treated sewage sludge at pilot scale level, investigating for the first time the effect of the organic loading rate (OLR) under oxygen limitation on biomass storage properties and kinetics. Polymer characteristics have been also evaluated. The selection/enrichment of PHA-storing biomass was successfully achieved in a Sequencing Batch Reactor (SBR) under short hydraulic retention time (HRT; 2 days). Low OLR (2.05 g COD/L d) was ideal for the selection of an efficient PHA-producing consortium cultivated under limited oxygen availability. In the fed-batch accumulation conducted under high DO regime, such biomass was characterized by 51% of PHA content on cell dry weight, with a related storage yield (YP/Sbatch) of 0.61 CODPHA/CODS. On the contrary, medium OLR (4.56 g COD/L d) was not technically feasible to sustain the required consortium's selection under low DO regime. The PHA produced by biomass cultivated under low DO regime was characterized higher thermal stability and crystalline domain compared to PHA traditionally produced under high DO regime. The mass balance assessment highlighted a global yield of 51 g PHA/kg VS (volatile solids of thickened sludge), which was 9% lower than yield obtained under high DO regime, in the face of a realistic reduction of the energy cost of the process.

A pilot-scale system of three parallel plug flow reactors was utilized for the treatment of tannery wastewaters with powdered activated carbon (PAC) at different dosage in activated sludge process. The SRT and the carbon replacement (XCI) were set at 35 d and 0 mg PAC/L (R1), 25 d and 100 mg PAC/L (R2), 20 d and 300 mg PAC/L (R3), at fixed HRT (4 days) and temperature (20-22 degrees C). The removal of per- and polyfluoroalkyls substances (PFASs), organics, chromium and color were assessed. Due to competition phenomena for adsorption between the organics and the PFASs, the highest PAC dosage (R3) was the only one able to decrease the concentration of total PFASs below the limit of 500 ng/L. Soluble COD and chromium removal efficiency up to 92.8 % and 68 % was respectively achieved; in terms of color abatement, the treated wastewaters showed a reduced absorbance up to 56 % compared to condition R1. The mass balance assessment revealed a maximum cost's increase of 0.923 euro/m3 of treated water associated to the use of the PAC (R3), highlighting the necessity to adopt sustainable strategies to valorize the generated tannery sludge instead of landfilling, which is still the only disposal practice of this waste.

Within the urban scenario, the application of a biorefinery technology value chain can foster the conversion of different organic substrates into marketable and added-value products. In this work, a pilot-scale dark fermen-tation (DF) process has been carried out as a key step for volatile fatty acids (VFA) and hydrogen production from the liquid fraction of sewage sludge and food waste mixture. Six operating conditions have been monitored in terms of yield and process stability, by changing the hydraulic retention time (HRT) from 4 to 6 days and applying a short-term hyper-thermophilic hydrolysis (70 degrees C, 8 h) on the same feedstock mixture. A tubular centrifugation was utilized to remove part of the biosolids (driven to biogas production) before the DF step, which was applied on the soluble and/or colloidal organic matter only. The hydrolysis step favored the following acidification process, in which a fermentation yield up to 0.42 g CODVFA/g VS0 was achieved at 5 days as HRT. Hydrogen production (up to 34.4% v/v and 0.046 m3 H2/kg VS0) was positively affected by the hydrolysis application and by the decrease of the HRT, highlighting the possibility to produce biohythane in the modeled two-phases anaerobic bioprocess. On the other hand, without the application of the hydrolysis, a selective production of butyric acid (up to 75% COD basin) was achieved, furnishing a different valorization route for the chosen urban organic feedstock. Changes in operating conditions and performances were also reflected by the adaptation of the microbial community, whose characterization highlighted the occurrence of several fermen-tative microorganisms (e.g., Clostridiaceae, Ruminococcaceae).

Exploiting tannery sludge as potential source of short-chain fatty acids (SCFAs) and biogas offers a promising solution for a new management of this waste, which is currently landfilled due to chromium presence. This study assessed the optimal hydrogen peroxide (H2O2) dosage, temperature (T) and hydraulic retention time (HRT) through hydrolysis and acidification tests to maximize SCFAs production and to recover biogas from the solidrich fermentation residue. A dosage of 0.4 g H2O2/g TS and mesophilic T (40 degrees C) were the most suitable conditions to promote sludge biodegradability and SCFAs production in batch tests. Afterwards, among the two investigated HRT (4 and 8 days) in the semi-continuous processes, longer HRT increased SCFAs concentration and acidification yield up to 16.0 g CODSCFAs/L and 0.32 g CODSCFA/g VS0, respectively. Chromium was initially released in the liquid phase, but completely removed in less than 5 HRTs, allowing the utilization of fermentation liquid without environmental-safety issues. Finally, the solid-rich residue showed its potential as biogas source, having a specific gas production (SGP) of 0.48 m3/kg VS. According to the mass balance assessment, more than 50% of sludge can be saved from landfill, with potential economic benefit close to 2,700,000 euro/y compared to the current management practice.

Tannery sludge, a challenging waste, was utilized as a substrate for the production of Short-Chain Fatty Acids (SCFAs) through a series of six thermophilic Continuous Stirred-Tank Reactor runs. The sludge was subjected to a mild thermal pre-treatment and incorporated zeolites (chabazite in run II, and clinoptilolite in run III) in the acidification process. Results highlighted zeolites' impact on chromium concentration and the SCFAs/CODSOL ratio. Ammonia release remained consistent at around 47 % and 51 % for run I and II, respectively, but surpassed 60% in run III, suggesting limited zeolite effectiveness in NH4 absorption. Chromium release in the liquid fraction, due to thermal pretreatment, reached 335 mg/L. While in tests without zeolite, complete removal proved challenging, in zeolite-amended runs, complete removal was achieved, showcasing the materials' heavy metal absorption capacity. SCFA concentrations reached 20260 mgCOD/L, with acidification efficiency varying; runs I and III had ratios around 0.70 COD/COD, while run II showed substantial improvement (0.92) with chabazite. Anaerobic fermentation-digestion mass balance indicated a 41% reduction in landfill sludge mass, reducing its environmental footprint while yielding valuable byproducts like biogas and SCFAs. These findings underscore zeolites' potential in heavy metal absorption and acidification process enhancement, paving the way for applications with tannery sludge.

Dairy products, extra virgin olive oil, red and white wines are excellent food products, appreciated all around the world. Their productions generate large amounts of by-products which urge for recycling and valorization. Moreover, another abundant waste stream produced in urban context is the Organic Fraction of Municipal Solid Wastes (OFMSW), whose global annual capita production is estimated at 85 kg. The recent environmental policies encourage their exploitation in a biorefinery loop to produce Volatile Fatty Acids (VFAs) and polyhydroxyalkanoates (PHAs). Typically, VFAs yields are high from cheese whey and OFMSW (0.55-0.90 gCOD_VFAs/ gCOD), lower for Olive Mill and Winery Wastewaters. The VFAs conversion into PHAs can achieve values in the range 0.4-0.5 gPHA/gVSS for cheese whey and OFMSW, 0.6-0.7 gPHA/gVSS for winery wastewater, and 0.2-0.3 gPHA/gVSS for olive mill wastewaters. These conversion yields allowed to estimate a huge potential annual PHAs production of about 260 M tons.

Tannery sludge is disposed of in landfills as it is considered a special residue by the Italian legislation, creating pollution and waste. This paper aims at evaluating the performance of the anaerobic fermentation process to obtain short-chain fatty acids (SCFAs) from this waste. The assessment of the most appropriate conditions, in terms of pH, temperature, initial total solids (TSs) content, and application of oxidizing-thermal pretreatment has been developed. The batch test trials revealed that the combined microwave and hydrogen peroxide (MW-H2O2) pretreatment followed by thermophilic conditions gave the best results, in terms of the acidification yield (0.31 gCODSCFA/gVS0) and maximal SCFA concentration (above 26 g CODSCFA/L). In the tests conducted without pretreatment, the mesophilic temperature should be preferred since the acidification performances were comparable to or even better than their thermophilic counterparts. The SCFA composition analysis showed that in mesophilic fermentation, tannery sludge can generate up to 50% acetic acid (CODAc/CODSCFA), if previously pretreated (MW-H2O2). This research acts as a forerunner for the appropriate handling of this resource, to employ it for the development of a new tannery industry focused on a circular approach, rather than to simply dispose of it in landfills.

The disposal of sewage sludge potentially reaches the 50-60% of WWTP’s total operation cost. Such stream can be considered a renewable carbon source to produce added-value products. Different pre-treatment methods have been applied on thickened sewage sludge (SS) coming from the domestic wastewater treatment plant (WWTP) of Treviso (northeast Italy) to favour its acidogenic fermentability. Alkaline (pH 9-11) and thermal (50-70°C) hydrolysis were applied separately and in combination The following fermentation process was addressed to the recovery of volatile fatty acids (VFA) as valuable building blocks substances. Batch fermentation tests were conducted at lab-scale under controlled temperature (T): 20, 37, 55 and 70°C by using an available mixed fermentative consortium as inoculum. Thermophilic T (55°C) was chosen in the following semi-continuous fermentation process (fill and draw), carried out with three different hydraulic retention time (HRT; 4-5-6 days). In terms of organic matter solubilisation, the thermal hydrolysis (70°C) allowed to obtain a soluble chemical oxygen demand (CODSOL) concentration around 10.0 g/L, with no additional benefits from the combined alkaline treatment. The batch acidogenic fermentation tests highlighted the T effect on acidification performances; thermophilic trials (55°C) showed the highest CODVFA/CODSOL ratio (0.81). The three semi-continuous tests (HRT 4-5-6 days) were followed for 45 days (roughly), under the chosen thermophilic condition (55°C). The highest fermentation rate was obtained at 4.0 d as HRT (22 mgCODVFA/gVS d); on the contrary, the highest fermentation yield (0.30 gCODVFA/gVS) and CODVFA/CODSOL ratio (0.73) were obtained at 6.0 d as HRT. In practice, low HRT selected for a mixed consortium with high fermentation rate, but less efficient in the conversion of the organic matter into VFA. No HRT’s effect was instead observed in the VFA composition, always rich in acetic (29-31% COD basis) and butyric acid (31-32%), and poorer in propionic (14-15%), valeric (12-13%) and caproic acid (11-12%).

In the present study, polyhydroxyalkanoates (PHA) production by mixed microbial cultures (MMC) has been carried out using thermally pre-treated excess thickened waste activated sludge (WAS), applying the feast-famine approach at pilot scale. The preliminary results of WAS fermentation conducted both in mesophilic and thermophilic conditions, in combination with a thermal pre-treatment at 70 degrees C for 48 h, highlighted how the thermal hydrolysis has a crucial role for the solubilization of the chemical oxygen demand (COD), which allows a significant increase of the final volatile fatty acid (VFA) concentration (roughly 8.5 g CODVFA/L). Since thermophilic fermentation after thermal pre-treatment was the best performing condition, it has been applied at pilot scale in order to routinely produce VFA as precursors for the following PHA synthesis. The selection and enrichment of PHA-producing biomass was successfully established and maintained in a Sequencing Batch Reactor (SBR) during the whole experimentation period, under short hydraulic retention time (HRT; 2 days) and medium-low organic loading rate (OLR; 2.0-2.2 g COD/L d). At the end of the production process an average PHA content of 53 +/- 3 %w/w was achieved. The polymer was finally extracted and recovered from the biomass using traditional chloroform and sodium hypochlorite extraction and then characterized for the quantification of thermal properties (Tm = 156.8-160.9 degrees C) and molecular weight (Mv = 396-405 kDa). A final overall mass balance, usually poorly reported in the literature, has been also assessed, resulting in an overall yield of 56 g PHA per kg of volatile solids (VS).

50.3 M tons of wastes are annually produced at urban level in the EU-27. Sewage sludge, Organic Fraction of Municipal Solid Wastes (OFMSW) and food industrial wastewaters, are the major typologies of wastes produced at urban level. OFMSW and sewage sludge account for the 28 % and 23 % of the EU-27 wastes streams, respectively. Their abundance and the high content of nutrients (nitrogen and phosphorous) make them very interesting as substrates in a biorefinery loop to produce biofuels and bio-based products. This review provides an overview on the conversion of urban wastes into Volatile Fatty Acids (VFAs) at different operational condi-tions, from small laboratory scales to full industrial plants. Mono-fermentation of no pretreated substrates OFMSW and Thickened Primary Sludge (TPS) led to low VFAs yields of 0.25-0.30 and 0.50 gVFA-COD/gCOD, respectively. The co-fermentation of OFMSW and sewage sludge achieved higher VFAs yields (0.38 gVFA-COD/ gCOD). Co-fermentation yields was further improved (0.85gVFA-COD/gCOD) by the adoption of thermophilic temperature (55 degrees C). Regarding VFAs profile, it was observed that substrates with lower VFAs yields presented a higher concentration of acetic acid, while the improvement of the acidogenic fermentation's yield had as consequence the increasing of propionic and butyric acids' concentrations. Finally, innovative electro-driven approaches, electro-fermentation and electrodialysis, employing polarized electrodes have been investigated to favor the production of desired VFAs or to enhance acids separation from the fermentation broth.

The bio-based production of added-value products and energy from waste streams while minimizing environmental impacts is a crucial aspect within the circular economy's principles. A two-phases anaerobic digestion process to produce volatile fatty acids (VFA) and biogas production in an energetically feasible manner from the organic fraction of municipal solid waste (OFMSW) has been investigated. Mesophilic temperature (T) coupled to 5.0 days as hydraulic retention time (HRT) gave a VFA-rich stream with an overall concentration of 24.4 +/- 0.2 g CODVFA/L, dominated by propionic and valeric acids, and high acidification yield, being VFA close to 90% of the soluble COD. The pH was maintained around 7.0 by the digestate recirculation from the second methanation reactor (HRT of 20 days) where biogas production was quantified under mesophilic and thermophilic T. The assessment of energy balance showed the benefits to carry out the second methanation stage under thermophilic condition, having more income from electricity generation without losing the thermal sustainability of the two-phases process as a whole.

This study focuses on the application of the circular economy approach, with generation of energy and production of added-value products from organic waste, while minimizing environmental impacts. Within this purpose, an urban biorefinery technology chain has been designed at pilot scale for the production of biogas and biopolymers (polyhydroxyalkanoates, PHA). The pilot system (100-400 L) comprised different units: a) biowaste acidogenic fermentation; b) solid/liquid separation unit (a coaxial centrifuge and a tubular ultrafiltration membrane); c) a Sequencing Batch Reactor (SBR) for the production of aerobic PHA-storing biomass; d) aerobic fed-batch PHA accumulation reactor and e) anaerobic co-digestion (ACoD). The thermal pre-treatment of the biowaste before mesophilic fermentation increased the carbon conversion into volatile fatty acids (VFA), being the final VFA/CODSOL (soluble COD) higher than 0.80. The VFA-rich stream was utilized in a high-rate SBR for the enrichment of PHA-accumulating biomass, at short solid retention time (SRT of 1 d), 12 h of cycle length and 4.0 gCOD/L d as organic loading rate (OLR). The aerobic biomass was characterized by a high accumulating capacity (with PHA content around 60% on cell dry weight). The global PHA yield of 0.1 kg PHA/kg VS (volatile solids) was estimated as the best scenario. The excess sludge and the solid-rich biorefinery overflows were utilized for biogas production in a dedicated anaerobic digestion section to sustain a closed loop approach and to prevent secondary wastes production.

Abstract Background Peripheral artery disease (PAD) is highly prevalent in people with type 2 diabetes and associates with chronic limb ischemia and poor prognosis. Understanding the mechanisms of impaired blood vessel growth in diabetic patients is of paramount importance to develop new angiogenic therapies in this setting. Dysregulation of epigenetic mechanisms of gene transcription in vascular cells contributes to cardiovascular disease development but is currently not targeted by therapies. Apabetalone (RVX-208) – an FDA approved small molecule inhibitor of the epigenetic readers bromodomain and extra-terminal (BET) proteins – has recently shown to modulate transcriptional programs implicated in vascular inflammation and atherosclerosis. Purpose To investigate RVX-208 effects in modulating angiogenic response and post-ischemic vascularization in diabetes. Methods Primary human aortic endothelial cells (HAECs) were exposed to normal glucose (NG, 5 mM) or high glucose (HG, 20 mM) for 48 hours in presence of RVX-208 (20μM) or vehicle (DMSO). Scratch and tube formation assays were performed to investigate the impact of RVX-208 on angiogenic properties of HAECs. T1D mice (streptozotocin-induced diabetes) and T2D mice (Lepdb/db) were orally treated with apabetalone or vehicle for 5 days. Hindlimb ischemia was induced in T1D mice & blood flow recovery analysed at 30 minutes, 7 and 14 days by laser Doppler imaging. Sprouting and matrigel plug assays were performed in Lepdb/db mice. Gastrocnemius muscle samples from patients with and without T2D were employed to translate our experimental findings. Results HG impaired HAECs migration and tube formation as compared to NG, whereas treatment with RVX-208 rescued HG-induced impairment of angiogenic properties. Real time PCR arrays in HG-treated HAECs showed that RVX-208 treatment prevents the dysregulation of genes implicated in endothelial migration, sprouting and inflammation, namely the anti-angiogenic molecule thrombospondin (THBS1), VEGF-A, IL-1β, IL-6, VCAM-1, and CXCL1. Of interest, both gene silencing of BET protein (BRD4) or its pharmacological inhibition by RVX-208 reduced THBS1 expression while restoring VEGFA levels in HG-treated HAECs. ChIP assays showed the enrichment of both BRD4 and the active chromatin mark H3K27Ac on THBS1 promoter. Mechanistic experiments uncovered the inhibitory role of THBS1 on VEGFA signalling, as also confirmed by STRING analysis. Treatment of T1D mice with RVX-208 improved blood flow reperfusion and vascular density at 14 days as compared to vehicle-treated animals. Moreover, RVX-208 restored endothelial sprouting in T2D-Lepdb/db mice. Of clinical relevance, THBS1 was upregulated while VEGFA expression was reduced in gastrocnemius muscle specimens from T2D patients with PAD as compared to non-diabetic controls. Conclusion In vivo targeting of BET-proteins by RVX-208 may represents a novel therapeutic approach to boost post-ischemic neovascularization in diabetes. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): University of Zurich

EDITORIAL article Front. Bioeng. Biotechnol., 02 June 2021 | https://doi.org/10.3389/fbioe.2021.694484