Hypothalamus metabolomic profiling to elucidate the tissue-targeted biochemical basis of febrile response in yeast-induced pyrexia rats

Serum Metabolomics Analysis of the Anti-Inflammatory Effects of Gallic Acid on Rats With Acute Inflammation

Background: Gallic acid (GA) is a natural small-molecule polyphenol having a wide range of pharmacological activities. Until now, some works have studied the effect and the mechanisms of GA against inflammation. However, whether or how gallic acid regulates the downstream metabolic disorder against acute inflammation remains unclear. The present study explored the protective effect and the potential mechanism of GA on acute inflammation through the metabolomics approach.

Methods: An acute inflammation rat model was induced by local injection of carrageenin. Local swelling on paw and serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) were assessed in Control, Model and Gallic acid groups, respectively. Serum metabolomics based on high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) was also established to collect rats’ metabolic profiles and explore the metabolic changes related to GA pretreatment.

Results: Compared to the Modal group, local pain, redness, and swelling induced by carrageenin were significantly alleviated in GA groups in addition to the dose-dependent decreases of TNF-α and IL-6. Metabolomics analysis found significant alterations in metabolic signatures between the carrageenin-induced inflammation and control groups. Twelve potential biomarkers were further identified in acute inflammation by principal component analysis (PCA) and partial least squares discrimination analysis (PLS-DA). In addition, when rats were pretreated with gallic acid, serum levels of eleven biomarkers were observed to restore partially. Metabolic pathway and networks analysis revealed that GA might invert the pathological process of acute inflammation by regulating the key biomarkers involved in linoleic acid metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and arachidonic acid (AA) metabolism pathways.

Conclusion: The study elucidates the protective effect of gallic acid against acute inflammation and its possible regulating mechanism from a metabolomic perspective. These results could provide a theoretical basis for clarifying gallic acid’s mechanism and potential medicinal value in curing inflammation disorder in the clinic.

Mitochondrial pyruvate carrier as a key regulator of fever and neuroinflammation

The mitochondrial pyruvate carrier (MPC) is an inner-membrane transporter that facilitates pyruvate uptake from the cytoplasm into mitochondria. We previously reported that MPC1 protein levels increase in the hypothalamus of animals during fever induced by lipopolysaccharide (LPS), but how this increase contributes to the LPS responses remains to be studied. Therefore, we investigated the effect of UK 5099, a classical MPC inhibitor, in a rat model of fever, on hypothalamic mitochondrial function and neuroinflammation in LPS-stimulated preoptic area (POA) primary microcultures. Intracerebroventricular administration of UK 5099 reduced the LPS-induced fever. High-resolution respirometry revealed an increase in oxygen consumption and oxygen flux related to ATP synthesis in the hypothalamic homogenate from LPS-treated animals linked to mitochondrial complex I plus II. Preincubation with UK 5099 prevented the LPS-induced increase in oxygen consumption, ATP synthesis and spare capacity only in complex I-linked respiration and reduced mitochondrial H₂O₂ production. In addition, treatment of rat POA microcultures with UK 5099 reduced the secretion of the proinflammatory and pyrogenic cytokines TNFα and IL-6 as well as the immunoreactivity of inflammatory transcription factors NF-κB and NF-IL6 four hours after LPS stimulation. These results suggest that the regulation of mitochondrial pyruvate metabolism through MPC inhibition may be effective in reducing neuroinflammation and fever.

UPLC-HRMS-Based Plasma Metabolomic Profiling of Novel Biomarkers by Treatment with KDZI in Cerebral Ischemia Reperfusion Rats

Kudiezi injection (KDZI), also known as Diemailing injection, is a traditional Chinese medicine injection of the composite plant Ixeris sonchifolia Hance (also known as Kudiezi), and has been widely used to treat coronary heart disease, angina pectoris, and cerebral infarction, but its pharmacological mechanisms remain unclear. This study is designed to explore the effects of KDZI on middle cerebral artery occlusion and reperfusion (MCAO/R) rats, and to identify metabolic features of cerebral ischemia reperfusion by using a nontargeted metabolic profiling method based on ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). In this process, 32 potential biomarkers were found in plasma. KDZI significantly upregulated the levels of taurochenodesoxycholic acid, leucine, l-phenylalanine, l-tryptophan, arachidonic acid (ARA), and phosphatidyl ethanolamines (PE), phosphatidyl cholines (PC) and downregulated the levels of l-valine and 5-hydroxyindole-3-acetic acid (5-HIAA) in plasma. The results indicated that the mechanisms of KDZI on MCAO/R were related to the mechanisms of amino acid and lipid metabolism.

An integrated strategy by using target tissue metabolomics biomarkers as pharmacodynamic surrogate indices to screen antipyretic components of Qingkaikling injection

Traditional Chinese medicine (TCM) treatment can be valuable therapeutic strategies. However, the active components and action mechanisms that account for its therapeutic effects remain elusive. Based on the hypothesis that the components of a formula which exert effect would be measurable in target tissue, a target tissue metabolomics-based strategy was proposed for screening of antipyretic components in Qingkaikling injection (QKLI). First, we detected the components of QKLI which could reach its target tissue (hypothalamus) by determining the hypothalamus microdialysate and discovered that only baicalin and geniposide could be detected. Then, by conducting hypothalamus metabolomics studies, 14 metabolites were screened as the potential biomarkers that related to the antipyretic mechanisms of QKLI and were used as its pharmacodynamic surrogate indices. Subsequently, the dynamic concentration of baicalin and geniposide in hypothalamus microdialysates and biomarkers in hypothalamus were measured and correlated with each other. The results indicated that only baicalin shown a good correlation with these biomarkers. Finally, a network pharmacology approach was established to validate the antipyretic activity of baicalin and the results elucidated its antipyretic mechanisms as well. The integrated strategy proposed here provided a powerful means for identifying active components and mechanisms contributing to pharmacological effects of TCM.

Plasma metabolomics combined with lipidomics profiling reveals the potential antipyretic mechanisms of Qingkailing injection in a rat model

Qingkailing injection (QKLI) has a notable antipyretic effect and is widely used in China as a clinical emergency medicine. To elucidate the pharmacological action thoroughly, following the investigation of the urine metabolome and hypothalamus metabolome, plasma metabolomics combined with lipidomics profiling of the QKLI antipyretic effect in a rat model is described in this paper. Compared with pure metabolomics profiling, this non-targeted plasma metabolomics combined with lipidomics profiling based on ultra-performance liquid chromatography-coupled with quadrupole time-of-flight mass spectrometry (UPLC Q-TOF/MS) could be used for a large-scale detection of features in plasma samples. The results showed that 15 metabolites at the 1 h time point and 19 metabolites at the 2 h time point after QKLI administration were associated with the antipyretic effect of QKLI, including amino acid, phosphatidylcholine and lysophosphatidylcholine. The metabolism pathway analysis revealed that the potential biomarkers, which were important for the antipyretic mechanism of QKLI, were closely responsible for correcting the perturbed pathways of amino acid metabolism and lipid metabolism. In conclusion, the use of complementary UPLC Q-TOF/MS based metabolomics and lipidomics allows for the discovery of new potential plasma biomarkers in the QKLI antipyretic process and the associated pathways, and aided in advancing the understanding of the holism and synergism of the Chinese drug.

Fever as an important resource for infectious diseases research

Fever or pyrexia is a process where normal body temperature is raised over homeostasis conditions. Although many effects of fever over the immune system have been known for a long time, it has not been until recent studies when these effects have been evaluated in several infection processes. Results have been promising, as they have reported new ways of regulation, especially in RNA molecules. In light of these new studies, it seems important to start to evaluate the effects of pyrexia in current research efforts in host-pathogen interactions. Viruses and bacteria are responsible for different types of infectious diseases, and while it is of paramount importance to understand the mechanisms of infection, potential effects of fever on this process may have been overlooked. This is especially relevant because during the course of many infectious diseases the organism develops fever. Due to the lack of specific treatments for many of those afflictions, experimental evaluation in fever-like conditions can potentially bring new insights into the infection process and can ultimately help to develop treatments. The aim of this review is to present evidence that the temperature increase during fever affects the way the infection takes place, for both the pathogen and the host.

LC-MS based metabolomics identification of novel biomarkers of tobacco smoke-induced chronic bronchitis

Tobacco smoke (TS) is a major causative agent to lead to chronic bronchitis (CB). However the mechanisms of CB induced by TS are unclear. In this report, rats were exposed to different concentrations of TS and the metabolic features of CB were characterized by using a nontargeted metabolic profiling method based on liquid chromatography-mass spectrometry (LC-MS) to detect the altered metabolic patterns in serum from CB rats and investigate the mechanisms of CB. 11 potential biomarkers were identified in serum of rats. Among them, the levels of lysophosphatidylethanolamine (18:1), lysophosphatidic acid (18:1), lysophosphatidylethanolamine (18:0), lysophosphatidylethanolamine (16:0), lysophosphatidylethanolamine (20:4), docosahexaenoic acid, 5-hydroxyindoleacetic acid and 5'-carboxy-γ-tocopherol were higher in TS group compared to control group. Conversely, the levels of 4-imidazolone-5-propionic acid, 12-hydroxyeicosatetraenoic acid and uridine were lower in TS group. The results indicated that the mechanism of CB was related to amino acid metabolism and lipid metabolism, particularly lipid metabolism. In addition, lysophosphatidylethanolamines were proved to be important mediators, which could be used as biomarkers to diagnose CB. These results also suggested that metabolomics was suitable for diagnosing CB and elucidating the possible metabolic pathways of TS-induced CB.