Buprenorphine affects the initiation and severity of interleukin-induced acute pancreatitis in mice.

Acute pancreatitis (AP) is a common disease with no targeted therapy and has varied outcomes ranging from spontaneous resolution to being lethal. Although typically painful, AP can also be painless. Various agents, including opioids, are used for pain control in AP; the risks and benefits of which are often debated. As experimental AP in mice is used to study the efficacy of potential therapies, we studied the effect of a commonly used opioid, buprenorphine, on the initiation and progression of AP. For this, we administered extended-release buprenorphine subcutaneously before inducing the previously established severe AP model that uses interleukins 12 and 18 (IL12,18) in genetically obese (ob/ob) mice and compared this to mice with AP but without the drug. Mice were monitored over 3 days, and parameters of AP induction and progression were compared. Buprenorphine significantly reduced serum amylase, lipase, pancreatic necrosis, and AP-associated fat necrosis, which is ubiquitous in obese mice and humans. Buprenorphine delayed the AP-associated reduction of carotid artery pulse distention and the development of hypothermia, hastened renal injury, and muted the early increase in respiratory rate versus IL12,18 alone. The site of buprenorphine injection appeared erythematous, inflamed, and microscopically showed thinning, loss of epidermal layers that had increased apoptosis. In summary, subcutaneous extended-release buprenorphine interfered with the induction of AP by reducing serum amylase, lipase, pancreatic and fat necrosis, the worsening of AP by delaying hypotension, hypothermia, while hastening renal injury, respiratory depression, and causing cutaneous injury at the site of injection.NEW & NOTEWORTHY Extended-release buprenorphine interferes with the initiation and progression of acute pancreatitis at multiple levels.

Dissecting the Interaction Deficiency of a Cartilaginous Fish Digestive Lipase with Pancreatic Colipase: Biochemical and Structural Insights.

A full-length cDNA encoding digestive lipase (SmDL) was cloned from the pancreas of the smooth-hound (Mustelus mustelus). The obtained cDNA was 1350 bp long encoding 451 amino acids. The deduced amino acid sequence has high similarity with known pancreatic lipases. Catalytic triad and disulphide bond positions are also conserved. According to the established phylogeny, the SmDL was grouped with those of tuna and Sparidae lipases into one fish digestive lipase cluster. The recently purified enzyme shows no dependence for bile salts and colipase. For this, the residue-level interactions between lipase-colipase are yet to be clearly understood. The structural model of the SmDL was built, and several dissimilarities were noticed when analyzing the SmDL amino acids corresponding to those involved in HPL binding to colipase. Interestingly, the C-terminal domain of SmDL which holds the colipase shows a significant role for colipase interaction. This is apt to prevent the interaction between fish lipase and the pancreatic colipase which and can provide more explanation on the fact that the classical colipase is unable to activate the SmDL.

Intestinal phospholipase A2 from Sparidae species: Functional properties and cytotoxic potential evaluation.

Marine species have gained significant attention as potential source for a broad spectrum of bioactive proteins. Fish phospholipases A2 (PLA2) have attracted renewed interest due to their excellent properties in lipid digestion. Herein, we report for the first time the catalytic properties of two intestinal secreted PLA2 (sPLA2) identified from Diplodus sargus (IDsPLA2) and Sparus aurata (ISaPLA2). The highest sequence identity was obtained with recently isolated Sparidae digestive PLA2 (45%) and Human pancreatic PLA2 (42%). IDsPLA2 and ISaPLA2 were overexpressed in E. coli as inclusion bodies, refolded and purified. Both enzymes have improved thermostability compared to mammalian pancreatic sPLA2 since they are active and stable at 55 °C, with specific activities of 320 and 190 U mg-1 measured on phosphatidylcholine, respectively. Interestingly, IDsPLA2, but not ISaPLA2, revealed weak toxicity towards macrophages and suggests its involvement in cell membrane degradation. ISaPLA2 was found to be more active than IDsPLA2 when using the monolayer technique at 20 mN m-1. Structural models of both enzymes revealed their differences. In silico docking of phospholipids with both models allowed proposing key amino-acids in substrate binding and selectivity. Overall, these results provide insight into the enzymatic and structural properties of two novel sPLA2 with potential for future applications.

Purification and biochemical characterization of an organic solvent-tolerant and detergent-stable lipase from Staphylococcus capitis.

A mesophilic bacterial culture, producing an extracellular alkaline lipase, was isolated from the gas-washing wastewaters generated from the Sfax phosphate plant of the Tunisian Chemical Group and identified as Staphylococcus capitis strain. The lipase, named S. capitis lipase (SCL), has been purified to homogeneity from the culture medium. The purified enzyme molecular weight was around 45 kDa. Specific activities about 3,900 and 500 U/mg were measured using tributyrin and olive oil emulsion as substrates, respectively at 37°C and pH 8.5. Interestingly, the SCL maintained more than 60% of its initial activity over a wide pH values ranging from 5 to 11 with a high stability between pH 9 and 11 after 1 hr of incubation at room temperature. The lipase activity was enhanced in the presence of 2 mM of Mg2+ , Ca2+ , and K+ . SCL showed significant stability in the presence of detergents and organic solvents. Altogether, these features make the SCL useful for industrial applications. Besides, SCL was compatible with commercially available detergents, and its incorporation increases lipid degradation performances making it a potential candidate in detergent formulation.

Dissecting the membrane lipid binding properties and lipase activity of Mycobacterium tuberculosis LipY domains.

The Mycobacterium tuberculosis LipY protein, a prototype of the proline-glutamic acid (PE) family, exhibits a triacylglycerol (TAG) hydrolase activity that contributes to host cell lipid degradation and persistence of the bacilli. LipY is found either as a full-length intracytosolic form or as a mature extracellular form lacking the N-terminal PE domain. Even though the contribution of the extracellular form in TAG consumption has been partly elucidated, very little information is available regarding the potential interactions of either full-length LipY with the cytoplasmic membrane, or mature form LipY with the outer membrane. Herein, several LipY variants truncated in their N-terminal domain were produced and biochemically characterized in lipid-protein interaction assays, using the monomolecular film technique and FTIR. Comparison of the catalytic activities of these recombinant proteins showed that LipY∆149, corresponding to the extracellular form of LipY lacking the PE domain, is more active than the full-length protein. This confirms previous studies reporting that the PE domain negatively modulates the TAG hydrolase activity of LipY. Lipid-protein interaction studies indicate that the PE domain anchors LipY onto membrane lipids. Consistent with these findings, we show that LipY∆149 is loosely associated with the mycobacterial cell wall, and that this interaction is mediated by the sole lipase domain. Overall, our results bring new information regarding the molecular mechanisms by which LipY either binds and hydrolyses host cell lipids or degrades TAG, the major source of lipids within mycobacterial intracytosolic lipid inclusions.

Production, purification and biochemical characterization of a thermoactive, alkaline lipase from a newly isolated Serratia sp. W3 Tunisian strain.

A newly isolated Serratia sp. W3 strain was shown to secrete a non-induced lipase in the culture medium. Lipolytic activity was optimized using the response surface methodology (RSM) and the extracellular lipase from Serratia sp. W3 (SmL) was purified to homogeneity with a total yield of 10% and its molecular mass was estimated of about 67 kDa by SDS-PAGE. The amino acid sequence of the first 7 N-terminal residues of SmL revealed a high degree of homology with other Serratia lipase sequences. The purified SmL can be considered as thermoactive lipase, its maximal specific activity measured at pH 9 and 55 °C was shown to be 625 U/mg and 300 U/mg using tributyrin and olive oil emulsion as substrate, respectively. In contrast to other described Serratia lipases, SmL was found to be stable at a large scale of pH between pH 5 and pH 12. SmL was also able to hydrolyze its substrate in presence of various oxidizing agents as well as in presence of surfactants and some commercial detergents. Then, considering the overall biochemical properties of SmL, it can be considered as a potential candidate for industrial and biotechnological applications, such as synthesis of biodiesel and in the detergent industry.

Heterologous Expression and Functional Characterization of Sparidae Fish Digestive Phospholipase A2.

In this study, we have produced for the first time a fish phospholipase (PLA2) in heterologous system (E. coli). The Diplodus annularis PLA2 (DaPLA2) was then refolded from inclusion bodies and purified by Ni-affinity chromatography. We used the pH-stat method (with emulsified phosphatidylcholine as substrate) and the monomolecular film technique (using various glycerophospholipids substrates spread in the form of monomolecular films at the air-water interface) to access the biochemical and kinetic properties of the recombinant DaPLA2. The DaPLA2 was found to be active and stable at higher temperatures (37-50 °C) than expected. Interestingly, DaPLA2 hydrolyzes efficiently both purified phosphatidylglycerol and phosphatidylethanolamine at 20 mN/m. These analytical results corroborate with the fact that the catalytic activity of DaPLA2, measured with the pH-stat using egg yolk as substrate, is mainly due to the hydrolysis of the PE fraction present in egg yolk, whereas the phosphatidylglycerol is a hallmark substrate for the most secreted PLA2-IB.

Efficient heterologous expression, functional characterization and molecular modeling of annular seabream digestive phospholipase A2.

Here we report the cDNA cloning of a phospholipase A2 (PLA2) from five Sparidae species. The deduced amino acid sequences show high similarity with pancreatic PLA2. In addition, a phylogenetic tree derived from alignment of various available sequences revealed that Sparidae PLA2 are closer to avian PLA2 group IB than to mammals' ones. In order to understand the structure-function relationships of these enzymes, we report here the recombinant expression in E.coli, the refolding and characterization of His-tagged annular seabream PLA2 (AsPLA2). A single Ni-affinity chromatography step was used to obtain a highly purified recombinant AsPLA2 with a molecular mass of 15kDa as attested by gel electrophoresis and MALDI-TOF mass spectrometry data. The enzyme has a specific activity of 400U.mg-1 measured on phosphatidylcholine at pH 8.5 and 50°C. The enzyme high thermo-activity and thermo-stability make it a potential candidate in various biological applications. The 3D structure models of these enzymes were compared with structures of phylogenetically related pancreatic PLA2. By following these models and utilizing molecular dynamics simulations, the resistance of the AsPLA2 at high temperatures was explained. Using the monomolecular film technique, AsPLA2 was found to be active on various phospholipids spread at the air/water interface at a surface pressure between 12 and 25dyncm-1. Interestingly, this enzyme was shown to be mostly active on dilauroyl-phosphatidylglycerol monolayers and this behavior was confirmed by molecular docking and dynamics simulations analysis. The discovery of a thermo-active new member of Sparidae PLA2, provides new insights on structure-activity relationships of fish PLA2.

The smooth-hound lipolytic system: Biochemical characterization of a purified digestive lipase, lipid profile and in vitro oil digestibility.

In order to identify fish enzymes displaying novel biochemical properties, we choose the common smooth-hound (Mustelus mustelus) as a starting biological material to characterize the digestive lipid hydrolyzing enzyme. A smooth-hound digestive lipase (SmDL) was purified from a delipidated pancreatic powder. The SmDL molecular weight was around 50kDa. Specific activities of 2200 and 500U/mg were measured at pH 9 and 40°C using tributyrin and olive oil emulsion as substrates, respectively. Unlike known mammal pancreatic lipases, the SmDL was stable at 50°C and it retained 90% of its initial activity after 15min of incubation at 60°C. Interestingly, bile salts act as an activator of the SmDL. It's worth to notice that the SmDL was also salt-tolerant since it was active in the presence of high salt concentrations reaching 0.8M. Fatty acid (FA) analysis of oil from the smooth-hound viscera showed a dominance of unsaturated ones (UFAs). Interestingly, the major n-3 fatty acids were DHA and EPA with contents of 18.07% and 6.14%, respectively. In vitro digestibility model showed that the smooth hound oil was efficiently hydrolyzed by pancreatic lipases, which suggests the higher assimilation of fish oils by consumers.

Functional and Structural Characterization of a Thermostable Phospholipase A2 from a Sparidae Fish (Diplodus annularis).

Novel phospholipase (PLA2) genes from the Sparidae family were cloned. The sequenced PLA2 revealed an identity with pancreatic PLA2 group IB. To better understand the structure/function relationships of these enzymes and their evolution, the Diplodus annularis PLA2 (DaPLA2) was overexpressed in E. coli. The refolded enzyme was purified by Ni-affinity chromatography and has a molecular mass of 15 kDa as determined by MALDI-TOF spectrometry. Interestingly, unlike the pancreatic type, the DaPLA2 was active and stable at higher temperatures, which suggests its great potential in biotechnological applications. The 3D structure of DaPLA2 was constructed to gain insights into the functional properties of sparidae PLA2. Molecular docking and dynamic simulations were performed to explain the higher thermal stability and the substrate specificity of DaPLA2. Using the monolayer technique, the purified DaPLA2 was found to be active on various phospholipids ranging from 10 to 20 mN·m-1, which explained the absence of the hemolytic activity for DaPLA2.

A newly thermoactive and detergent-stable lipase from annular sea bream (Diplodus annularis): Biochemical properties.

A lipolytic activity was located in the annular seabream pyloric caeca, from which a digestive lipase (AsDL) was purified. Pure AsDL has an apparent molecular mass of 50 kDa. The purified lipase is thermoactive as it displays its maximal activity on short- and long-chain triacylglycerols at a temperature of 50 °C. The enzyme is alkaline resistant as it retains 90% of its maximal activity when incubated during 1 H at pH 10. No colipase was detected in the annular seabream pyloric caeca. Similar results were reported for the sardine and the gray mullet digestive systems. This is in line with the idea that colipase might have evolved in mammal animals simultaneously with the appearance of an exocrine pancreas. AsDL is a serine enzyme, like all known lipases from different origins. Interestingly, the pure lipase was found to be insensitive to Triton X-100, a synthetic detergent, addition even at a concentration as high as 12 mM. The purified enzyme has potential applications in detergent and food industry because of its thermal activity and alkaline nature.

Biochemical characterization, cloning and molecular modeling of a digestive lipase from red seabream (Pagrus major): Structural explanation of the interaction deficiency with colipase and lipidic interface.

Red seabream digestive lipase (RsDL) was purified from fresh pyloric caeca. Pure RsDL has an apparent molecular mass of 50 kDa. The RsDL is more active on short-chain triacylglycerols (TC4), and enzymatic activity decreases when medium (TC8) or long-chain (olive oil) triacylglycerols were used as substrates. The specific activities of RsDL are very weak as compared to those obtained with classical pancreatic lipases. No colipase was detected in the red seabream pyloric caeca. Furthermore, the RsDL was not activated by a mammal colipase. Similar results were reported for annular seabream lipase. In order to explain structurally the discrepancies between sparidae and mammal lipases, genes encoding mature RsDL and five other lipases from sparidae fish species were cloned and sequenced. Phylogenetic studies indicated the closest homology of sparidae lipases to bird pancreatic ones. Structural models were built for annular seabream and RsDL under their closed and open forms using mammal pancreatic lipases as templates. Several differences were noticed when analyzing the amino acids corresponding to those involved in HPL binding to colipase. This is likely to prevent interaction between the fish lipase and the mammalian colipase and may explain the fact that mammalian colipase is not effective in activating sparidae lipases. In addition, several hydrophobic residues, playing a key role in anchoring pancreatic lipase onto the lipid interface, are replaced by polar residues in fish lipases. This might explain the reason why the latter enzymes display weak activity levels when compared to mammalian pancreatic lipases.

Experimental Models of Foamy Macrophages and Approaches for Dissecting the Mechanisms of Lipid Accumulation and Consumption during Dormancy and Reactivation of Tuberculosis.

Despite a slight decline since 2014, tuberculosis (TB) remains the major deadly infectious disease worldwide with about 1.5 million deaths each year and with about one-third of the population being latently infected with Mycobacterium tuberculosis, the etiologic agent of TB. During primo-infection, the recruitment of immune cells leads to the formation of highly organized granulomas. Among the different cells, one outstanding subpopulation is the foamy macrophage (FM), characterized by the abundance of triacylglycerol-rich lipid bodies (LB). M. tuberculosis can reside in FM, where it acquires, from host LB, the neutral lipids which are subsequently processed and stored by the bacilli in the form of intracytosolic lipid inclusions (ILI). Although host LB can be viewed as a reservoir of nutrients for the pathogen during latency, the molecular mechanisms whereby intraphagosomal mycobacteria interact with LB and assimilate the LB-derived lipids are only beginning to be understood. Past studies have emphasized that these physiological processes are critical to the M. tuberculosis infectious-life cycle, for propagation of the infection, establishment of the dormancy state and reactivation of the disease. In recent years, several animal and cellular models have been developed with the aim of dissecting these complex processes and of determining the nature and contribution of their key players. Herein, we review some of the in vitro and in vivo models which allowed to gain significant insight into lipid accumulation and consumption in M. tuberculosis, two important events that are directly linked to pathogenicity, granuloma formation/maintenance and survival of the tubercle bacillus under non-replicative conditions. We also discuss the advantages and limitations of each model, hoping that this will serve as a guide for future investigations dedicated to persistence and innovative therapeutic approaches against TB.

A grey mullet enzyme displaying both lipase and phospholipase activities: purification and characterization.

A lipase from the golden grey mullet viscera was purified to homogeneity by ammonium sulphate precipitation, gel filtration, anionic and cation exchange chromatographies. The pure enzyme tentatively named grey mullet digestive lipase (GmDL) is a monomer having a molecular mass of about 35 kDa, as determined by SDS-PAGE analysis. No similarity was found between the NH2-terminal amino acid residues of GmDL and those of other known digestive lipases. GmDL is a serine enzyme, like all known lipases from different origins. Interestingly, GmDL has not only lipase activity but also a phospholipase activity which requires the presence of Ca(2+) and bile salts. Specific activities of 64 U/mg, 55 U/mg and 63 U/mg were measured using tributyrin, olive oil emulsion or phosphatidylcholine as substrate, respectively at pH 8 and at 50°C. GmDL is therefore a thermo-active enzyme as compared to other fish lipases studied so far. It is worth to notice that grey mullet lipase was active in the presence of salt concentrations as high as 0.8M.

A thermoactive uropygial esterase from chicken: purification, characterisation and synthesis of flavour esters.

A lipolytic activity was located in the chicken uropygial glands, from which a carboxylesterase (CUE) was purified. Pure CUE has an apparent molecular mass of 50 kDa. The purified esterase displayed its maximal activity (200 U/mg) on short-chain triacylglycerols (tributyrin) at a temperature of 50°C. No significant lipolytic activity was found when medium chain (trioctanoin) or long chain (olive oil) triacylglycerols were used as substrates. The enzyme retained 75% of its maximal activity when incubated during 2h at 50°C. The NH(2)-terminal amino acid sequence showed similarities with the esterase purified recently from turkey pharyngeal tissue. Esterase activity remains stable after its incubation during 30 min in presence of organic solvents such as hexane or butanol. CUE is a serine enzyme since it was inactivated by phenylmethanesulphonyl fluoride (PMSF), a serine-specific inhibitor. The purified enzyme, which tolerates the presence of some organic solvent and a high temperature, can be used in non-aqueous synthesis reactions. Hence, the uropygial esterase immobilised onto CaCO(3) was tested to produce the isoamyl and the butyl acetate (flavour esters). Reactions were performed at 50°C in presence of hexane. High synthesis yields of 91 and 67.8% were obtained for isoamyl and butyl acetate, respectively.

Lipolytic activity levels and colipase presence in digestive glands of some marine animals.

Studies on the digestive secretions in aquatic animals can elucidate certain aspects of their nutritive physiology. The aim of the present study was to compare the digestive lipase and phospholipase activities in ten marine species belonging to four classes following the taxonomic classification of marine organisms. All aquatic digestive tissues tested are equipped with lipase and phospholipase activities, assuming the hydrolysis of fat-rich food. The lipolytic activities determined in the pancreases of cartilaginous fishes were greater than those in bony fishes, molluscs and crustaceans. This finding might be explained by the strong digestive utilization of fat-rich macronutrients by these carnivorous fishes. A trend of activities and stabilities at different pH and temperatures for crude lipases and phospholipases from these aquatic animals suggests that the optimum pH and temperature for marine lipases are species dependent. Interestingly, the sardine caecal lipase and phospholipase were found to be mostly stable in a broad range of acidic pH values. The maximum activities of lipolytic enzymes from the hepatopancreases of Hexaplex trunculus (molluscs) and Carcinus mediterranus (crustaceans) were found to be 50 and 60 °C, respectively, whereas the optimal temperature of lipolytic enzymes for the other species was classically around 40 °C. Thermoactivity of molluscs' lipolytic preparations makes them potential candidates in industrial applications. Among digestive glands studied, only pancreas (cartilaginous fish) contained the classically known colipase. Regarded as the most primitive living jawed vertebrates, cartilaginous fishes represented by sharks and rays could be considered as the oldest vertebrates possessing a complex digestive system like that of mammals.

Purification and biochemical characterization of an acid-stable lipase from the pyloric caeca of sardine (Sardinella aurita).

A lipolytic activity was located in the sardine digestive glands (pyloric caeca), from which a sardine digestive lipase (SaDL) was purified. Pure SaDL has a molecular mass of 43 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. The enzyme was found to be more active on short-chain triacylglycerols than on long-chain ones. SaDL does not present the interfacial activation phenomenon. Control experiments were performed under the same experimental conditions, with dromedary and turkey pancreatic lipases and showed a positive interfacial activation phenomenon. Sodium deoxycholate (NaDC) has an inhibitory effect on the lipase activity. The pure enzyme lost 40% of its activity in presence of 8 mM NaDC. SaDL was found to be mostly stable at low pH values. Interestingly, no colipase was detected in the sardine pyloric caeca. Analogous results were reported for the scorpion and the crab digestive systems. This is in line with the idea that colipase might has evolved in mammal animals simultaneously with the appearance of an exocrine pancreas. No similarity was found between the NH(2)-terminal amino acid residues of SaDL and those of lipases from the digestive tract of other species. Altogether, these results suggest that SaDL is a member of a new group of lipases belonging to aquatic species.