Study of Phospholipase A2 Levels and Its Comparison With Procalcitonin Levels in Patients With Sepsis Admitted in a Tertiary Care Hospital, Karnataka, India

INTRODUCTION

Sepsis is a complicated host response to infection involving organ failure which ultimately causes death of the host. Procalcitonin (PCT) is an effective marker used to diagnose sepsis but until now, there has been no ideal marker for sepsis. Phospholipase A2 (PLA2) also increases infections; however, only a few studies have assessed its capacity as a biomarker to diagnose sepsis. Thus, we aimed to examine PLA2 and compare its diagnostic capacity and accuracy with PCT as a biomarker of sepsis.

MATERIAL AND METHODS

Our study was a hospital-oriented cross-sectional study. Our study group included 80 patients of both sexes older than 18 years, meeting the quick sequential organ failure assessment (qSOFA) or systemic inflammatory response syndrome (SIRS) criteria of ≥2, hospitalized in a tertiary care hospital in Karnataka, India from January 2021 to December 2021. Out of them, 59 were found to have sepsis. Samples of all the patients were evaluated for relevant parameters, and data were statistically analyzed using SPSS v21 running on Windows 10. The statistical significance was set at p-value <0.05.

RESULTS

The mean PCT and PLA2 were significantly raised in sepsis patients compared to non-sepsis patients. Out of 59 septic patients, 45.76% had positive blood cultures, and 16.95% had positive urine culture reports. In blood cultures, the most common Gram-positive organism found was Staphylococcus, and the most common Gram-negative organism was Enterobacter. In urine cultures, Escherichia coli was the most common species. PLA2 was significantly higher in patients with bacterial etiology and Gram-positive cultures. The diagnostic capability, sensitivity, specificity, and accuracy of PLA2 were demonstrably higher than those of PCT.

CONCLUSION

Our study proves that PLA2 is a much better and more efficient biomarker in sepsis than PCT. The diagnostic capacity and accuracy of PLA2 clearly surpass PCT, so using PLA2 in sepsis as a biomarker can help clinicians in deciding on timely and appropriate management to speed the recovery of patients.

FFAR4 regulates cardiac oxylipin balance to promote inflammation resolution in HFpEF secondary to metabolic syndrome

Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome, but a predominant subset of HFpEF patients has metabolic syndrome (MetS). Mechanistically, systemic, nonresolving inflammation associated with MetS might drive HFpEF remodeling. Free fatty acid receptor 4 (Ffar4) is a GPCR for long-chain fatty acids that attenuates metabolic dysfunction and resolves inflammation. Therefore, we hypothesized that Ffar4 would attenuate remodeling in HFpEF secondary to MetS (HFpEF-MetS). To test this hypothesis, mice with systemic deletion of Ffar4 (Ffar4KO) were fed a high-fat/high-sucrose diet with L-NAME in their water to induce HFpEF-MetS. In male Ffar4KO mice, this HFpEF-MetS diet induced similar metabolic deficits but worsened diastolic function and microvascular rarefaction relative to WT mice. Conversely, in female Ffar4KO mice, the diet produced greater obesity but no worsened ventricular remodeling relative to WT mice. In Ffar4KO males, MetS altered the balance of inflammatory oxylipins systemically in HDL and in the heart, decreasing the eicosapentaenoic acid-derived, proresolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE), while increasing the arachidonic acid-derived, proinflammatory oxylipin 12-hydroxyeicosatetraenoic acid (12-HETE). This increased 12-HETE/18-HEPE ratio reflected a more proinflammatory state both systemically and in the heart in male Ffar4KO mice and was associated with increased macrophage numbers in the heart, which in turn correlated with worsened ventricular remodeling. In summary, our data suggest that Ffar4 controls the proinflammatory/proresolving oxylipin balance systemically and in the heart to resolve inflammation and attenuate HFpEF remodeling.

A beneficial role for immunoglobulin E in host defense against honeybee venom

Allergies are widely considered to be misdirected type 2 immune responses, in which immunoglobulin E (IgE) antibodies are produced against any of a broad range of seemingly harmless antigens. However, components of insect venoms also can sensitize individuals to develop severe IgE-associated allergic reactions, including fatal anaphylaxis, upon subsequent venom exposure. We found that mice injected with amounts of honeybee venom similar to that which could be delivered in one or two stings developed a specific type 2 immune response that increased their resistance to subsequent challenge with potentially lethal amounts of the venom. Our data indicate that IgE antibodies and the high affinity IgE receptor, FcεRI, were essential for such acquired resistance to honeybee venom. The evidence that IgE-dependent immune responses against venom can enhance survival in mice supports the hypothesis that IgE, which also contributes to allergic disorders, has an important function in protection of the host against noxious substances.

Translational studies on regulation of brain docosahexaenoic acid (DHA) metabolism in vivo

One goal in the field of brain polyunsaturated fatty acid (PUFA) metabolism is to translate the many studies that have been conducted in vitro and in animal models to the clinical setting. Doing so should elucidate the role of PUFAs in the human brain, and effects of diet, drugs, disease and genetics on this role. This review discusses new in vivo radiotracer kinetic and neuroimaging techniques that allow us to do this, with a focus on docosahexaenoic acid (DHA). We illustrate how brain PUFA metabolism is influenced by graded reductions in dietary n-3 PUFA content in unanesthetized rats. We also show how kinetic tracer techniques in rodents have helped to identify mechanisms of action of mood stabilizers used in bipolar disorder, how DHA participates in neurotransmission, and how brain DHA metabolism is regulated by calcium-independent iPLA₂β. In humans, regional rates of brain DHA metabolism can be quantitatively imaged with positron emission tomography following intravenous injection of [1-¹¹C]DHA.

Intestinal smooth muscle dysfunction develops postnatally in cystic fibrosis mice

OBJECTIVES

Intestinal dysmotility is one of the effects of cystic fibrosis (CF), but when and how this develops is not well understood. The goal of the present study was to use the Cftr knockout mouse to determine when in development circular smooth muscle of the small intestine becomes dysfunctional.

METHODS

Wild-type (WT) and CF mice were used at postnatal day 5 (P5) through adult. Pieces of small intestine were used to measure contractile activity of the circular muscle. Bacterial overgrowth was measured by quantitative polymerase chain reaction (PCR) of the bacterial 16S gene. Intestinal gene expression was determined by quantitative reverse transcription polymerase chain reaction (RT-PCR). Prostaglandin E2 (PGE2) and its metabolites were measured by enzyme immunoassay.

RESULTS

CF circular muscle response to cholinergic stimulation was similar to WT at P5, became somewhat impaired at P7, and was severely impaired by P14. In the CF intestine, bacterial overgrowth occurred by P4 and was maintained into adulthood. Eicosanoid metabolic gene expression in the CF intestine did not differ from WT shortly after birth. The phospholipase A2 genes, Pla2g4c and Pla2g5 exhibited increased expression in CF mice at P24. Prostaglandin degradative genes, Hpgd and Ptgr1, showed lower expression in CF as compared with WT at P16 and P24, respectively. PGE2 levels were significantly greater in CF mice at most ages from P7 through adulthood.

CONCLUSIONS

The results clearly demonstrate that lack of CFTR itself does not cause smooth muscle dysfunction, because the circular muscle from P5 CF mice had normal activity and dysfunction developed between P7 and P14.

Nutrition and gut immunity

The human intestine contains huge amounts of nonpathologic bacteria surviving in an environment that is beneficial to both the host and the bacterial populations. When short pauses in oral intake occur with minimal alterations in the mucosa-microbial interface, critical illness, with its attendant acidosis, prolonged gastrointestinal tract starvation, exogenous antibiotics, and breakdown in mucosal defenses, renders the host vulnerable to bacterial challenge and also threatens the survival of the bacteria. This review examines the altered innate and adaptive immunologic host defenses that occur as a result of altered oral or enteral intake and/or injury.

Lipid determinants of cell death

Lipids produced by the epidermis serve a number of protective functions, and also act as messengers which activate plant defense responses. The fatty acid elongases which catalyze the formation of very long-chain fatty acids, may be instrumental in the remodeling of the various classes of epidermal lipids, and they also provide a means with which to further investigate the defense mechanisms. In a recent publication, we reported that the epidermal mis-expression of FATTY ACID ELONGASE1 (FAE1) in the Arabidopsis plant both increased the levels of very long-chain fatty acids in various lipid classes, and unexpectedly induced a cell-type specific cell death program in trichome cells, giving the plants a glabrous appearance. Using these plants as a model system for a fatty acid-induced cell death (lipoapoptosis), and a platform for the chemical genetic screen, we identified trichome death inhibitors in the glycerophospholipid fatty acyl remodeling pathway: phospholipase A2 inhibitors, aristolochic acid and bromoenol lactone, as well as the putative lysophospholipid acyltransferase inhibitor, clofibrate. Herein, and due to space limitations, we will briefly discuss these results and the different ways in which the appearance of increasing chain-length fatty acids is likely to regulate the cellular life-or-death switch. The death receptor hypothesis implies the existence of a bioactive lipid ligand(s), the functionality of which is determined by phosphorylation, acyl chain length and saturation.

Phospholipase A2 modulates respiratory burst developed by neutrophils in patients with rheumatoid arthritis

Activated by bacterial peptides, phorbol esters, calcium ionophores and other agonists, neutrophils (PMNs) release the proinflammatory mediator, arachidonic acid (AA) via the intervention of phospholipase A(2) (PLA(2)). AA may play an essential role in activation of NADPH-oxidase, which is involved in the generation of superoxide anion by neutrophils. The present study is focused on the involvement of PLA(2) in the respiratory burst developed by PMNs isolated from patients with rheumatoid arthritis (RA). PLA(2) exists in very high levels in diseases such as rheumatoid arthritis and may cause acute inflammatory and proliferative changes in synovial structures. The respiratory burst was evaluated as superoxide anion release, using an amplified chemiluminescence method. The assays were performed using PMNs untreated or treated with different doses of stimulatory reagents (phorbol 12-myristate-13-acetate (PMA), calcium ionophore (A23187)). Our data suggested that PMA stimulated the production of superoxide anion in a dose-response manner, as compared with A23187, which did not induce a significant release of superoxide anion in PMNs-RA. The exogenous addition of AA significantly amplified the superoxide anion release by PMNs-RA stimulated with PMA and to a lesser extent, by PMNs stimulated with A23187. AA has also reversed the inhibitory effect of arachidonyl-trifluorometylketone and E-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)2H-pyran-2-one (BEL) on the superoxide anion release by PMNs-RA. In conclusion, the differential responses to these two agents suggested that different isoforms of PLA(2) were activated by A23187 or PMA, and support the idea that activation of these different PLA(2) served distinct functions of PMNs. Therefore, the inhibition of PLA(2) enzymes might be of great importance in the immunotherapy of rheumatoid arthritis.

Association studies of cytosolic phospholipase A2 polymorphisms and schizophrenia among two independent family-based samples

An association between the cytosolic phospholipase A2 locus (cPLA2) and schizophrenia has been reported using two polymorphic DNA markers. In an attempt to replicate these results, two independent family-based samples were ascertained from the United States and India (86 and 159 families, respectively). No significant associations were detected in either sample.

Serum phospholipase A2 in canine acute pancreatitis

During 3 years 28 cases of acute pancreatitis were diagnosed in dogs. In 26 of these dogs, the disease was fatal. The most frequent symptoms were vomiting, anorexia and lethargy. Two thirds showed tenderness upon abdominal palpation. Ascites was found in 3 cases. Of the blood, parameters, serum amylase level was elevated in 86 % and lipase in 89 % of the cases. Sixteen dogs were uremic and half of the dogs were hyperglycemic. Two thirds of the dogs had leukocytosis. Using stepwise multiple regression the best blood parameters explaining acute pancreatitis were leukocytes together with lipase and glucose.

In an attempt to find a more specific serum test for dogs to diagnose acute pancreatitis serum phospholipase A2 (PLA₂) activity was measured. In sixteen out of the 28 dogs with acute pancreatitis, serum PLA₂ activity was increased. The ascites fluids were rich in PLA2. Serum PLA₂ is more often increased in the severe necrotizing pancreatitis (80 %) than in the milder forms of acute pancreatitis (44 %). All dogs with increased serum PLA₂ had also increased serum amylase and lipase activities. The dogs with an increased serum PLA₂ and dogs with ascites had fat necrosis in the vicinity of the pancreas. Experimental pancreatitis was induced in 4 dogs by injecting Na-taurocholate and trypsin into the pancreas. In these cases, very high PLA₂ activities in the serum and ascites fluids were detected, but none seemed to be present in the urine samples.

Search for relationships among the hemolytic, phospholipolytic, and neurotoxic activities of snake venoms

Several snake venom neurotoxins are larger and more complex than the well-studied group of postsynaptic toxins exemplified by alpha-bungarotoxin. Several of these, exemplified by beta-bungarotoxin, show phospholipase A2 activity (phosphatide 2-acylhydrolase, EC 3.1.1.4) when tested in the presence of detergents. The high hemolytic activity of crotoxin, the neurotoxin of Crotalus durissus terrificus, in the presence of lecithin has been attributed to this activity. The phospholipase A2 activity of several snake venom proteins has now been compared under the physiological conditions of the hemolysis tests. It appears that only the basic component of crotoxin, B, is enzymatically active, and that its activity is not inhibited by component A under these conditions, or in the presence of deoxycholate. Phosphatidylserine is found to be digested more readily than egg white phosphatidylcholine; and also causes hemolysis in conjunction with much lower levels of crotoxin. In neither case is calcium required or stimulating. Phospholipase from Crotalus adamanteus, which is not neurotoxic, digests phosphatidylcholine more rapidly than does crotoxin, but phosphatidylserine more slowly; yet it is slightly less active than crotoxin in the hemolysis test with phosphatidylcholine, and much less with phosphatidylserine. The digestion of several phospholipids by either enzyme fails to release the expected protons in the absence of detergents at 37 degrees .beta-Bungarotoxin, highly neurotoxic, has negligible phospholipase A2 activity in the absence of detergents, and is almost nonhemolytic in conjunction with all phospholipids tested.Binding studies with (125)I-labeled compounds show that rabbit erythrocytes and ghosts have much greater affinity for crotoxin than for beta-bungarotoxin and do not bind Crotalus adamanteus phospholipase. The crotoxin complex is split in the course of binding, with only component B, the hemolytic component, becoming bound. It appears that the role of component A may be to diminish the nonspecific binding tendency of component B. Our data appear to be consistent with the concepts that affinity to membranes, particularly to specific sites on synaptic membranes, is the critical requirement for beta type neurotoxicity, and that this property, at least in some instances, has evolved from phospholipase A2 enzymes, but does not necessarily require retention and expression of enzymatic activity.