Dopamine D2 receptor signalling controls inflammation in acute pancreatitis via a PP2A-dependent Akt/NF-κB signalling pathway

Chronic pharmacologic manipulation of dopamine transmission ameliorates metabolic disturbance in Trappc9-linked brain developmental syndrome

Loss-of-function mutations of the gene encoding the trafficking protein particle complex subunit 9 (Trappc9) cause autosomal recessive intellectual disability and obesity by unknown mechanisms. Genome-wide analysis links Trappc9 to nonalcoholic fatty liver disease (NAFLD). Trappc9-deficient mice have been shown to appear overweight shortly after weaning. Here, we analyzed serum biochemistry and histology of adipose and liver tissues to determine the incidence of obesity and NAFLD in Trappc9-deficient mice and combined transcriptomic and proteomic analyses, pharmacological studies, and biochemical and histological examinations of postmortem mouse brains to unveil mechanisms involved. We found that Trappc9-deficient mice presented with systemic glucose homeostatic disturbance, obesity, and NAFLD, which were relieved upon chronic treatment combining dopamine receptor D2 (DRD2) agonist quinpirole and DRD1 antagonist SCH23390. Blood glucose homeostasis in Trappc9-deficient mice was restored upon administering quinpirole alone. RNA-sequencing analysis of DRD2-containing neurons and proteomic study of brain synaptosomes revealed signs of impaired neurotransmitter secretion in Trappc9-deficient mice. Biochemical and histological studies of mouse brains showed that Trappc9-deficient mice synthesized dopamine normally, but their dopamine-secreting neurons had a lower abundance of structures for releasing dopamine in the striatum. Our study suggests that Trappc9 loss of function causes obesity and NAFLD by constraining dopamine synapse formation.

The Pivotal Role of Macrophages in the Pathogenesis of Pancreatic Diseases

The pancreas is an organ with both exocrine and endocrine functions, comprising a highly organized and complex tissue microenvironment composed of diverse cellular and non-cellular components. The impairment of microenvironmental homeostasis, mediated by the dysregulation of cell-to-cell crosstalk, can lead to pancreatic diseases such as pancreatitis, diabetes, and pancreatic cancer. Macrophages, key immune effector cells, can dynamically modulate their polarization status between pro-inflammatory (M1) and anti-inflammatory (M2) modes, critically influencing the homeostasis of the pancreatic microenvironment and thus playing a pivotal role in the pathogenesis of the pancreatic disease. This review aims to summarize current findings and provide detailed mechanistic insights into how alterations mediated by macrophage polarization contribute to the pathogenesis of pancreatic disorders. By analyzing current research comprehensively, this article endeavors to deepen our mechanistic understanding of regulatory molecules that affect macrophage polarity and the intricate crosstalk that regulates pancreatic function within the microenvironment, thereby facilitating the development of innovative therapeutic strategies that target perturbations in the pancreatic microenvironment.

Trace Amine-Associated Receptors and Monoamine-Mediated Regulation of Insulin Secretion in Pancreatic Islets

Currently, metabolic syndrome treatment includes predominantly pharmacological symptom relief and complex lifestyle changes. Trace amines and their receptor systems modulate signaling pathways of dopamine, norepinephrine, and serotonin, which are involved in the pathogenesis of this disorder. Trace amine-associated receptor 1 (TAAR1) is expressed in endocrine organs, and it was revealed that TAAR1 may regulate insulin secretion in pancreatic islet β-cells. For instance, accumulating data demonstrate the positive effect of TAAR1 agonists on the dynamics of metabolic syndrome progression and MetS-associated disease development. The role of other TAARs (TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9) in the islet's function is much less studied. In this review, we summarize the evidence of TAARs' contribution to the metabolic syndrome pathogenesis and regulation of insulin secretion in pancreatic islets. Additionally, by the analysis of public transcriptomic data, we demonstrate that TAAR1 and other TAAR receptors are expressed in the pancreatic islets. We also explore associations between the expression of TAARs mRNA and other genes in studied samples and demonstrate the deregulation of TAARs' functional associations in patients with metabolic diseases compared to healthy donors.

Profile of Pancreatic and Ileal Microbiota in Experimental Acute Pancreatitis

Acute pancreatitis (AP) is accompanied by gut microbiota dysbiosis. However, the composition of the pancreatic and ileal microbiota associated with AP is still unknown. This study aims to examine the alterations in the microbial composition of the pancreas and ileum in the context of experimental acute pancreatitis, as well as explore the potential interplay between these two regions. Methods: Caerulein (CAE), caerulein+lipopolysaccharide (CAE+LPS), and L-arginine (ARG) were used to induce AP in mice. The pancreas and ileum were collected for histological study and bacterial 16S rRNA gene sequencing. The results showed microbial structural segregation between the AP and control groups and between ARG and the two CAE groups (CAE, CAE+LPS) in the pancreas and ileum. Taxonomic analysis at the genus level and linear discriminant analysis effect size (LEfSe) at the operational taxonomic units (OTUs) level illustrated that AP mice exhibited a marked increase in the relative abundance of Muribaculaceae and a decrease in that of Dietzia both in the pancreas and ileum, and a reduction in Bifidobacterium only in the ileum; in addition, Roseburia was enriched in the two CAE groups in the pancreas and/or ileum, while Escherichia-Shigella expanded in the pancreas of the ARG group. Spearman correlation analysis between pancreatic and ileal microbiota revealed that the abundance of Muribaculaceae and Dietzia in the pancreas was related to that in the ileum. These findings demonstrated that caerulein and L-arginine differentially disturbed the pancreatic and ileal microbiota when inducing AP. Furthermore, these findings provide preliminary support for an association between the microbiota of the pancreas and ileum, which could be caused by AP-induced microbial translocation.

Galantamine ameliorates experimental pancreatitis

BACKGROUND

Acute pancreatitis is a common and serious inflammatory condition currently lacking disease modifying therapy. The cholinergic anti-inflammatory pathway (CAP) is a potent protective anti-inflammatory response activated by vagus nerve-dependent α7 nicotinic acetylcholine receptor (α7nAChR) signaling using splenic CD4+ T cells as an intermediate. Activating the CAP ameliorates experimental acute pancreatitis. Galantamine is an acetylcholinesterase inhibitor (AChEI) which amplifies the CAP via modulation of central muscarinic ACh receptors (mAChRs). However, as mAChRs also activate pancreatitis, it is currently unknown whether galantamine would be beneficial in acute pancreatitis.

METHODS

The effect of galantamine (1-6 mg/kg-body weight) on caerulein-induced acute pancreatitis was evaluated in mice. Two hours following 6 hourly doses of caerulein (50 µg/kg-body weight), organ and serum analyses were performed with accompanying pancreatic histology. Experiments utilizing vagotomy, gene knock out (KO) technology and the use of nAChR antagonists were also performed.

RESULTS

Galantamine attenuated pancreatic histologic injury which was mirrored by a reduction in serum amylase and pancreatic inflammatory cytokines and an increase the anti-inflammatory cytokine IL-10 in the serum. These beneficial effects were not altered by bilateral subdiaphragmatic vagotomy, KO of either choline acetyltransferase+ T cells or α7nAChR, or administration of the nAChR ganglionic blocker mecamylamine or the more selective α7nAChR antagonist methyllycaconitine.

CONCLUSION

Galantamine improves acute pancreatitis via a mechanism which does not involve previously established physiological and molecular components of the CAP. As galantamine is an approved drug in widespread clinical use with an excellent safety record, our findings are of interest for further evaluating the potential benefits of this drug in patients with acute pancreatitis.

Anti-Inflammatory Effects of Peripheral Dopamine

Dopamine is synthesized in the nervous system where it acts as a neurotransmitter. Dopamine is also synthesized in a number of peripheral organs as well as in several types of cells and has organ-specific functions and, as demonstrated more recently, is involved in the regulation of the immune response and inflammatory reaction. In particular, the renal dopaminergic system is very important in the regulation of sodium transport and blood pressure and is particularly sensitive to stimuli that cause oxidative stress and inflammation. This review is focused on how dopamine is synthesized in organs and tissues and the mechanisms by which dopamine and its receptors exert their effects on the inflammatory response.

Correlation between the dopaminergic system and inflammation disease: a review

The dopaminergic system is inextricably linked with neurological diseases and addiction. In recent years, many studies have found that the dopaminergic system involves in inflammatory diseases, particularly neuroinflammatory diseases development; This review summarizes the studies of dopaminergic system in inflammatory diseases, and specifically highlights the mechanisms of how dopaminergic system regulates inflammation; In addition, we speculate that there are some cavities in current research, including mixed usage of inhibitors, agonists and lack of systematic controls; We expect this review would provide directions to future research of dopaminergic system and inflammatory diseases.

Bromocriptine monotherapy overcomes prostate cancer chemoresistance in preclinical models

Chemoresistance is a major obstacle in the clinical management of metastatic, castration-resistant prostate cancer (PCa). It is imperative to develop novel strategies to overcome chemoresistance and improve clinical outcomes in patients who have failed chemotherapy. Using a two-tier phenotypic screening platform, we identified bromocriptine mesylate as a potent and selective inhibitor of chemoresistant PCa cells. Bromocriptine effectively induced cell cycle arrest and activated apoptosis in chemoresistant PCa cells but not in chemoresponsive PCa cells. RNA-seq analyses revealed that bromocriptine affected a subset of genes implicated in the regulation of the cell cycle, DNA repair, and cell death. Interestingly, approximately one-third (50/157) of the differentially expressed genes affected by bromocriptine overlapped with known p53-p21- retinoblastoma protein (RB) target genes. At the protein level, bromocriptine increased the expression of dopamine D2 receptor (DRD2) and affected several classical and non-classical dopamine receptor signal pathways in chemoresistant PCa cells, including adenosine monophosphate-activated protein kinase (AMPK), p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor kappa B  (NF-κB), enhancer of zeste homolog 2 (EZH2), and survivin. As a monotherapy, bromocriptine treatment at 15 mg/kg, three times per week, via the intraperitoneal route significantly inhibited the skeletal growth of chemoresistant C4-2B-TaxR xenografts in athymic nude mice. In summary, these results provided the first preclinical evidence that bromocriptine is a selective and effective inhibitor of chemoresistant PCa. Due to its favorable clinical safety profiles, bromocriptine could be rapidly tested in PCa patients and repurposed as a novel subtype-specific treatment to overcome chemoresistance.

Salidroside ameliorates severe acute pancreatitis-induced cell injury and pyroptosis by inactivating Akt/NF-κB and caspase-3/GSDME pathways

Our previous studies showed that Salidroside (Sal), a glucoside of the phenylpropanoid tyrosol isolated from Rhodiola rosea L, alleviated severe acute pancreatitis (SAP) by inhibiting inflammation. However, the detailed mechanism remains unclear. Recent evidence has indicated a critical role of Sal in ameliorating inflammatory disorders by regulating pyroptosis. The present study aimed to explore the involvement of Sal and pyroptosis in the pathogenesis of SAP and investigate the potential mechanism. The effects of Sal on pyroptosis were first evaluated using SAP rat and cell model. Our results revealed that Sal treatment significantly decreased SAP-induced pancreatic cell damage and pyroptosis in vivo and in vitro, as well as reduced the release of lactate dehydrogenase (LDH), IL-1β and IL-18. Search Tool for Interacting Chemicals (STITCH) online tool identified 4 genes (CASP3, AKT1, HIF1A and IL10) as candidate targets of Sal in both rattus norvegicus and homo sapiens. Western blot and immunohistochemistry staining validated that Sal treatment decreased the phosphorylation levels of Akt and NF-κB p65, as well as cleaved caspase-3 and N-terminal fragments of GSDME (GSDME-N), suggesting that Sal might suppress pyroptosis through inactivating Akt/NF-κB and Caspase-3/GSDME pathways. Furthermore, overexpression of AKT1 or CASP3 could partially reverse the inhibitory effects of Sal on cell injury and pyroptosis, while downregulation of AKT1 or CASP3 promoted the inhibitory effects of Sal. Taken together, our data indicate that Sal suppresses SAP-induced pyroptosis through inactivating Akt/NF-κB and Caspase-3/GSDME pathways.

Pramipexole inhibits formalin-induce acute and long-lasting mechanical hypersensitivity via NF-kB pathway in rats

Pain is one of the most frequent causes for patients to seek medical care. It interferes with daily functioning and affects the quality of life of the patient. There is a clear need to investigate nonopioid or non-nonsteroidal anti-inflammatory drug alternatives for the treatment of pain. In this study, we determined the effect of acute pre- and posttreatment with pramipexole (PPX), a dopamine D2/D3 selective agonist, on formalin 1%-induced acute and long-lasting nociceptive behavior sensitivity in rats. Moreover, we sought to investigate whether the antiallodynic and antihyperalgesic effect induced by PPX was mediated through the nuclear factor-κB (NF-kB) signaling pathway. Moreover, acute systemic pretreatment with PPX (1 and 3 mg/kg, ip) suppressed the formalin-induced nociceptive behavior during both phases of the formalin test and the development of formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. Acute systemic posttreatment with PPX (3 mg/kg, ip) reverted the formalin-induced long-lasting secondary mechanical allodynia and hyperalgesia. Furthermore, PPX inhibits the protein expression of NF-κB-p65 and the levels of tumor necrosis factor-α and interleukin-1β in the spinal cord of animals with secondary mechanical allodynia and hyperalgesia induced by formalin. These data suggest that PPX has a potential role in producing anti-inflammatory activity. Moreover, the antiallodynic and antihyperalgesic effects induced by PPX can be mediated through the NF-kB signaling pathway.

Roles of Pancreatic Islet Catecholamine Neurotransmitters in Glycemic Control and in Antipsychotic Drug-Induced Dysglycemia

Catecholamine neurotransmitters dopamine (DA) and norepinephrine (NE) are essential for a myriad of functions throughout the central nervous system, including metabolic regulation. These molecules are also present in the pancreas, and their study may shed light on the effects of peripheral neurotransmission on glycemic control. Though sympathetic innervation to islets provides NE that signals at local α-cell and β-cell adrenergic receptors to modify hormone secretion, α-cells and β-cells also synthesize catecholamines locally. We propose a model where α-cells and β-cells take up catecholamine precursors in response to postprandial availability, preferentially synthesizing DA. The newly synthesized DA signals in an autocrine/paracrine manner to regulate insulin and glucagon secretion and maintain glycemic control. This enables islets to couple local catecholamine signaling to changes in nutritional state. We also contend that the DA receptors expressed by α-cells and β-cells are targeted by antipsychotic drugs (APDs)-some of the most widely prescribed medications today. Blockade of local DA signaling contributes significantly to APD-induced dysglycemia, a major contributor to treatment discontinuation and development of diabetes. Thus, elucidating the peripheral actions of catecholamines will provide new insights into the regulation of metabolic pathways and may lead to novel, more effective strategies to tune metabolism and treat diabetes.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Dopamine D2 receptor agonist Bromocriptine ameliorates Aβ1-42-induced memory deficits and neuroinflammation in mice

Alzheimer's Disease (AD) is the most common neurodegenerative disease, which lacks disease-modifying therapeutics so far. Studies have shown that the dysfunction of the dopaminergic system is related to a variety of pathophysiology of AD, and the expression of Dopamine D2 receptor (DRD2) in the brains of AD patients and animal models is significantly downregulated, suggesting that DRD2 may represent a therapeutic target for AD. However, the strategy of targeting DRD2 for AD treatment still lacks some key experimental evidences. Here we show that DRD2 agonist Bromocriptine improved Aβ_1-42 induced neuroinflammation, neuronal apoptosis, and memory deficits in mice. For animal study, the mice have injected intracerebroventricularly (i.c.v.) with Aβ_1-42(410 pmol/5 μl) to induced AD cognitive deficit model (Mazzola et al., 2003; van der Stelt et al., 2006). After 7 days, Bromocriptine (2.5 mg/kg, 5 mg/kg and 10 mg/kg) or normal saline was administered intragastrically once a day for 30 days. Behavioral tests about the Y maze and Morris water maze in mice were initiated on the twenty-fourth day of drug administration for 7 days. In vivo and in vitro mechanism research revealed that Bromocriptine, via activating DRD2, promoted the recruitment of PP2A and JNK by scaffold protein β-arrestin 2, that repressed JNK-mediated transcription of proinflammatory cytokines and activation of NLRP3 inflammasome in microglia. Collectively, our findings suggest that Bromocriptine can ameliorate Aβ_1-42 induced neuroinflammation and memory deficits in mice through DRD2/β-arrestin 2/PP2A/JNK signaling axis, which provides an experimental basis for the development of Bromocriptine as a drug for AD.

Inverse Salt Sensitivity of Blood Pressure Is Associated with an Increased Renin-Angiotensin System Activity

High and low sodium diets are associated with increased blood pressure and cardiovascular morbidity and mortality. The paradoxical response of elevated BP in low salt diets, aka inverse salt sensitivity (ISS), is an understudied vulnerable 11% of the adult population with yet undiscovered etiology. A linear relationship between the number of single nucleotide polymorphisms (SNPs) in the dopamine D₂ receptor (DRD2, rs6276 and 6277), and the sodium myo-inositol cotransporter 2 (SLC5A11, rs11074656), as well as decreased expression of these two genes in urine-derived renal proximal tubule cells (uRPTCs) isolated from clinical study participants suggest involvement of these cells in ISS. Insight into this newly discovered paradoxical response to sodium is found by incubating cells in low sodium (LS) conditions that unveil cell physiologic differences that are then reversed by mir-485-5p miRNA blocker transfection and bypassing the genetic defect by DRD2 re-expression. The renin-angiotensin system (RAS) is an important counter-regulatory mechanism to prevent hyponatremia under LS conditions. Oversensitive RAS under LS conditions could partially explain the increased mortality in ISS. Angiotensin-II (AngII, 10 nmol/L) increased sodium transport in uRPTCs to a greater extent in individuals with ISS than SR. Downstream signaling of AngII is verified by identifying lowered expression of nuclear factor erythroid 2-related factor 2 (NRF2), CCCTC-binding factor (CTCF), and manganese-dependent mitochondrial superoxide dismutase (SOD2) only in ISS-derived uRPTCs and not SR-derived uRPTCs when incubated in LS conditions. We conclude that DRD2 and SLC5A11 variants in ISS may cause an increased low sodium sensitivity to AngII and renal sodium reabsorption which can contribute to inverse salt-sensitive hypertension.

The role of PP2A /NLRP3 signaling pathway in ambient particulate matter 2.5 induced lung injury

Ambient particulate matter 2.5 (PM_2.5) exposure has been linked to pulmonary fibrosis. However, the key signaling pathways remained unclear. In the present study, we applied a mouse model with myeloid-specific deletion of Ppp2r1a gene (encoding protein phosphatase 2 A (PP2A) A subunit) to identify the key signaling pathways involved in PM_2.5-induced pulmonary fibrosis. PP2A Aα^-/- homozygote mice and matched wild-type (WT) littermates were exposed to filtered air (FA), unfiltered air (UA), and concentrated PM_2.5 (CA) in a real-ambient PM exposure system for 8 weeks and 16 weeks, respectively. The mice exposed to PM_2.5 displayed a progressive inflammation and pulmonary fibrosis. Moreover, the expressions of NLRP3, pro-caspase-1, caspase-1, ASC and IL-1β were increased in mice lung following PM_2.5 exposure, indicating PM_2.5 exposure caused pulmonary inflammation by the NLRP3 pathways activation. Furthermore, the effects of PM exposure on pulmonary inflammation, pulmonary fibrosis, oxidative stress, and pulmonary function damage were significantly enhanced in PP2A^-/- mice compared to WT mice, indicating the role of PP2A in the regulation of pulmonary injury induced by PM exposure. In vitro study confirmed that PP2A was involved in the PM_2.5-induced inflammation response and NLRP3 inflammasome activation. Importantly, we identified PP2A regulated the activation of NLRP3 pathways by direct dephosphorylating IRE1α in response to PM_2.5 exposure. Taken together, our results demonstrated that PP2A-IRE1α-NLRP3 signaling pathway played a crucial role in regulating the inflammation response, triggering the lung fibrogenesis upon PM_2.5 exposure. Our findings provide new insights into regulatory role of PP2A in human diseases upon the PM exposure.

Identification of ceRNA regulatory network in acute pancreatitis and acute recurrent pancreatitis

OBJECTIVE

The aim of this study was to find differentially expressed long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs and related signaling pathways, contributing to understanding the molecular mechanism of acute recurrent pancreatitis (ARP).

METHODS

First, peripheral whole blood samples from five acute pancreatitis (AP) patients, five ARP patients and five healthy individuals ( N ) were collected for RNA sequencing. Second, differentially/specifically expressed lncRNAs, miRNAs and mRNAs were identified in AP vs. N , ARP vs. N and ARP. Third, the ceRNA (lncRNA-miRNA-mRNA) networks of common/specifical lncRNAs, miRNAs and mRNAs were constructed in AP vs. N , ARP vs. N and ARP. Finally, functional analysis of common mRNAs in AP vs. N and ARP vs. N was performed.

RESULTS

A total of 315 common lncRNAs, 12 common miRNAs and 909 common mRNAs were identified between AP and ARP. Ninety-four specifically expressed lncRNAs, one specifically expressed miRNAs and 286 specifically expressed mRNAs were found in ARP. Some interaction pairs were identified in AP and ARP, such as LUCAT1/NEAT1-hsa-miR-16-2-3p-HK2, CHRM3-AS2-hsa-miR-122-5p/hsa-miR-145-3p-DBH/CACNA1C, CHRM3-AS2-hsa-miR-200a-3p-PDGFD, RBM26-AS1-hsa-miR-200b-3p-FHIT and LINC00891/KTN1-AS1-hsa-miR-143-3p-tyrosine kinase (TXK). ASAP1-IT2/DGCR9-hsa-miR-342-5p-ABCC5/MAP2K6 was the only one specific interaction pair identified in ARP. Four significantly enriched signaling pathways were identified in AP vs. N and ARP vs. N , including amino sugar and nucleotide sugar metabolism (involved NPL and HK2), MAPK signaling pathway (involved CACNA1C and PDGFD), metabolic pathways (involved DBH and FHIT) and leukocyte transendothelial migration (involved TXK).

CONCLUSION

The identified altered lncRNAs, miRNAs, mRNAs and related signaling pathways may be involved in the AP development and recurrence.

Intestinal TLR4 deletion exacerbates acute pancreatitis through gut microbiota dysbiosis and Paneth cells deficiency

Toll-like receptor 4 (TLR4) has been identified as a potentially promising therapeutic target in acute pancreatitis (AP). However, the role of intestinal TLR4 in AP and AP-associated gut injury remains unclear. This study aimed to explore the relationship between intestinal TLR4 and gut microbiota during AP. A mouse AP model was establish by intraperitoneal injection of L-arginine. Pancreatic injury and intestinal barrier function were evaluated in wild-type and intestinal epithelial TLR4 knockout (TLR4ΔIEC) mice. Gut microbiota was analyzed by 16S rRNA sequencing. Quadruple antibiotics were applied to induce microbiota-depleted mice. Differentially expressed genes in gut were detected by RNA sequencing. L. reuteri treatment was carried out in vivo and vitro study. Compared with wild-type mice, AP and AP-associated gut injury were exacerbated in TLR4ΔIEC mice in a gut microbiota-dependent manner. The relative abundance of Lactobacillus and number of Paneth cells remarkably decreased in TLR4ΔIEC mice. The KEGG pathway analysis derived from RNA sequencing suggested that genes affected by intestinal TLR4 deletion were related to the activation of nod-like receptor pathway. Furthermore, L. reuteri treatment could significantly improve the pancreatic and intestinal injury in TLR4ΔIEC mice through promoting Paneth cells in a NOD2-dependent manner. Loss of intestinal epithelial TLR4 exacerbated pancreatic and intestinal damage during AP, which might be attributed to the gut microbiota dysbiosis especially the exhausted Lactobacillus. L. reuteri might maintain intestinal homeostasis and alleviate AP via Paneth cells modulation.Abbreviations: AP Acute pancreatitis, TLR4 Toll-like receptor 4, IL-1β Interleukin-1β, IL-6 Interleukin-6, TNF-α Tumor necrosis factor-α, SIRS Systematic inflammatory response syndrome, LPS Lipopolysaccharides, SPF Specific pathogen-free, ZO-1 Zonula occludens-1, CON Control, H&E Hematoxylin and eosin, FISH Fluorescence in situ hybridization, DAPI 4',6-diamidino-2-phenylindole, PCoA Principal co-ordinates analysis, SCFA Short chain fatty acid, LEfSe Linear discriminant analysis Effect Size, ANOVA Analysis of variance, F/B Firmicutes/Bacteroidetes, PCA Principal component analysis, NOD2 Nod-like receptor 2, ABX antibiotics, PCNA proliferating cell nuclear antigen.

Endoplasmic reticulum stress promoted acinar cell necroptosis in acute pancreatitis through cathepsinB-mediated AP-1 activation

Acinar cell death and inflammatory response are two important events which determine the severity of acute pancreatitis (AP). Endoplasmic reticulum (ER) stress and necroptosis are involved in this process, but the relationships between them remain unknown. Here, we analyzed the interaction between ER stress and necroptosis and the underlying mechanisms during AP. Experimental pancreatitis was induced in Balb/C mice by caerulein (Cae) and lipopolysaccharide (LPS) or L-arginine (L-Arg) in vivo, and pancreatic acinar cells were also used to follow cellular mechanisms during cholecystokinin (CCK) stimulation in vitro. AP severity was assessed by serum amylase, lipase levels and histological examination. Changes in ER stress, trypsinogen activation and necroptosis levels were analyzed by western blotting, enzyme-linked immunosorbent assay (ELISA), adenosine triphosphate (ATP) analysis or lactate dehydrogenase (LDH) assay. The protein kinase C (PKC)α -mitogen-activated protein kinase (MAPK) -cJun pathway and cathepsin B (CTSB) activation were evaluated by western blotting. Activating protein 1 (AP-1) binding activity was detected by electrophoretic mobility shift assay (EMSA). We found that ER stress is initiated before necroptosis in CCK-stimulated acinar cells in vitro. Inhibition of ER stress by 4-phenylbutyrate (4-PBA) can significantly alleviate AP severity both in two AP models in vivo. 4-PBA markedly inhibited ER stress and necroptosis of pancreatic acinar cells both in vitro and in vivo. Mechanistically, we found that 4-PBA significantly reduced CTSB maturation and PKCα-JNK-cJun pathway -mediated AP-1 activation during AP. Besides, CTSB inhibitor CA074Me markedly blocked PKCα-JNK-cJun pathway -mediated AP-1 activation and necroptosis in AP. However, pharmacologic inhibition of trypsin activity with benzamidine hydrochloride had no effect on PKCα-JNK-cJun pathway and necroptosis in CCK-stimulated pancreatic acinar cells. Furthermore, SR11302, the inhibitor of AP-1, significantly lowered tumor necrosis factor (TNF) α levels, and its subsequent receptor interacting protein kinases (RIP)3 and phosphorylated mixed lineagekinase domain-like (pMLKL) levels, ATP depletion and LDH release rate in CCK-stimulated pancreatic acinar cells. To sum up, all the results indicated that during AP, ER stress promoted pancreatic acinar cell necroptosis through CTSB maturation, thus induced AP-1 activation and TNFα secretion via PKCα-JNK-cJun pathway, not related with trypsin activity. These findings provided potential therapeutic target and treatment strategies for AP or other cell death-related diseases.

Bromocriptine-QR Therapy Reduces Sympathetic Tone and Ameliorates a Pro-Oxidative/Pro-Inflammatory Phenotype in Peripheral Blood Mononuclear Cells and Plasma of Type 2 Diabetes Subjects

Bromocriptine-QR is a sympatholytic dopamine D2 agonist for the treatment of type 2 diabetes that has demonstrated rapid (within 1 year) substantial reductions in adverse cardiovascular events in this population by as yet incompletely delineated mechanisms. However, a chronic state of elevated sympathetic nervous system activity and central hypodopaminergic function has been demonstrated to potentiate an immune system pro-oxidative/pro-inflammatory condition and this immune phenotype is known to contribute significantly to the advancement of cardiovascular disease (CVD). Therefore, the possibility exists that bromocriptine-QR therapy may reduce adverse cardiovascular events in type 2 diabetes subjects via attenuation of this underlying chronic pro-oxidative/pro-inflammatory state. The present study was undertaken to assess the impact of bromocriptine-QR on a wide range of immune pro-oxidative/pro-inflammatory biochemical pathways and genes known to be operative in the genesis and progression of CVD. Inflammatory peripheral blood mononuclear cell biology is both a significant contributor to cardiovascular disease and also a marker of the body’s systemic pro-inflammatory status. Therefore, this study investigated the effects of 4-month circadian-timed (within 2 h of waking in the morning) bromocriptine-QR therapy (3.2 mg/day) in type 2 diabetes subjects whose glycemia was not optimally controlled on the glucagon-like peptide 1 receptor agonist on (i) gene expression status (via qPCR) of a wide array of mononuclear cell pro-oxidative/pro-inflammatory genes known to participate in the genesis and progression of CVD (OXR1, NRF2, NQO1, SOD1, SOD2, CAT, GSR, GPX1, GPX4, GCH1, HMOX1, BiP, EIF2α, ATF4, PERK, XBP1, ATF6, CHOP, GSK3β, NFkB, TXNIP, PIN1, BECN1, TLR2, TLR4, TLR10, MAPK8, NLRP3, CCR2, GCR, L-selectin, VCAM1, ICAM1) and (ii) humoral measures of sympathetic tone (norepinephrine and normetanephrine), whole-body oxidative stress (nitrotyrosine, TBARS), and pro-inflammatory factors (IL-1β, IL-6, IL-18, MCP-1, prolactin, C-reactive protein [CRP]). Relative to pre-treatment status, 4 months of bromocriptine-QR therapy resulted in significant reductions of mRNA levels in PBMC endoplasmic reticulum stress-unfolded protein response effectors [GRP78/BiP (34%), EIF2α (32%), ATF4 (29%), XBP1 (25%), PIN1 (14%), BECN1 (23%)], oxidative stress response proteins [OXR1 (31%), NRF2 (32%), NQO1 (39%), SOD1 (52%), CAT (26%), GPX1 (33%), GPX4 (31%), GCH1 (30%), HMOX1 (40%)], mRNA levels of TLR pro-inflammatory pathway proteins [TLR2 (46%), TLR4 (20%), GSK3β (19%), NFkB (33%), TXNIP (18%), NLRP3 (32%), CCR2 (24%), GCR (28%)], mRNA levels of pro-inflammatory cellular receptor proteins CCR2 and GCR by 24% and 28%, and adhesion molecule proteins L-selectin (35%) and VCAM1 (24%). Relative to baseline, bromocriptine-QR therapy also significantly reduced plasma levels of norepinephrine and normetanephrine by 33% and 22%, respectively, plasma pro-oxidative markers nitrotyrosine and TBARS by 13% and 10%, respectively, and pro-inflammatory factors IL-18, MCP1, IL-1β, prolactin, and CRP by 21%,13%, 12%, 42%, and 45%, respectively. These findings suggest a unique role for circadian-timed bromocriptine-QR sympatholytic dopamine agonist therapy in reducing systemic low-grade sterile inflammation to thereby reduce cardiovascular disease risk.

Dopamine D2 Receptor Signaling Attenuates Acinar Cell Necroptosis in Acute Pancreatitis through the Cathepsin B/TFAM/ROS Pathway

Acute pancreatitis (AP) is an inflammatory disease that is associated with trypsinogen activation, mitochondrial dysfunction, cell death, and inflammation. Dopamine D2 receptor (DRD2) plays an essential role in alleviating AP, while it is unclear whether it is involved in regulating acinar cell necroptosis. Here, we found that DRD2 agonist quinpirole alleviated acinar cell necroptosis via inhibiting cathepsin B (CTSB). Moreover, CTSB inhibition by CA-074Me ameliorated AP severity by reducing necroptosis. Notably, knockdown of TFAM reversed the therapeutic effect of either quinpirole or CA-074Me. We identified a new mechanism that DRD2 signaling inhibited CTSB and promoted the expression of mitochondrial transcription factor A(TFAM), leading to reduction of ROS production in AP, which attenuated acinar cell necroptosis ultimately. Collectively, our findings provide new evidence that DRD2 agonist could be a new potential therapeutic strategy for AP treatment.

Inverse Salt Sensitivity of Blood Pressure: Mechanisms and Potential Relevance for Prevention of Cardiovascular Disease

PURPOSE OF REVIEW

To review the etiology of inverse salt sensitivity of blood pressure (BP).

RECENT FINDINGS

Both high and low sodium (Na⁺) intake can be associated with increased BP and cardiovascular morbidity and mortality. However, little is known regarding the mechanisms involved in the increase in BP in response to low Na⁺ intake, a condition termed inverse salt sensitivity of BP, which affects approximately 15% of the adult population. The renal proximal tubule is important in regulating up to 70% of renal Na⁺ transport. The renin-angiotensin and renal dopaminergic systems play both synergistic and opposing roles in the regulation of Na⁺ transport in this nephron segment. Clinical studies have demonstrated that individuals express a "personal salt index" (PSI) that marks whether they are salt-resistant, salt-sensitive, or inverse salt-sensitive. Inverse salt sensitivity results in part from genetic polymorphisms in various Na⁺ regulatory genes leading to a decrease in natriuretic activity and an increase in renal tubular Na⁺ reabsorption leading to an increase in BP. This article reviews the potential mechanisms of a new pathophysiologic entity, inverse salt sensitivity of BP, which affects approximately 15% of the general adult population.

A novel resveratrol analog upregulates sirtuin 1 and inhibits inflammatory cell infiltration in acute pancreatitis

Acute pancreatitis (AP), an inflammatory disorder of the pancreas, is a complicated disease without specific drug therapy. (R)-4,6-dimethoxy-3-(4-methoxy phenyl)-2,3-dihydro-1H-indanone [(R)-TML104] is a synthesized analog of the natural product resveratrol sesquiterpenes (±) -isopaucifloral F. This study aimed to investigate the effect and underlying mechanism of (R)-TML104 on AP. The experimental AP model was induced by caerulein hyperstimulation in BALB/c mice. (R)-TML104 markedly attenuated caerulein-induced AP, as evidenced by decreased pancreatic edema, serum amylase levels, serum lipase levels, and pancreatic myeloperoxidase activity. In addition, (R)-TML104 significantly inhibited the expression of pancreatic chemokines C-C motif chemokine ligand 2 and macrophage inflammatory protein-2 and the infiltration of neutrophils and macrophages. Mechanistically, (R)-TML104 activated AMP-activated protein kinase and induced sirtuin 1 (SIRT1) expression. (R)-TML104 treatment markedly induced the SIRT1-signal transducer and activator of transcription 3 (STAT3) interaction and reduced acetylation of STAT3, thus inhibiting the inflammatory response mediated by the interleukin 6-STAT3 pathway. The effect of (R)-TML104 on SIRT1-STAT3 interaction was reversed by treatment with a SIRT1 inhibitor selisistat (EX527). Together, our findings indicate that (R)-TML104 alleviates experimental pancreatitis by reducing the infiltration of inflammatory cells through modulating SIRT1.

Reorienting of pramipexole as a promising therapy for acute pancreatitis in a rat model by suppressing TLR-4\NF-κB p65\NLRP3 inflammasome signaling

OBJECTIVE

Acute pancreatitis (AP), a disorder of global importance, has a growing incidence and prevalence, particularly in the western world. Its complications include pseudo-cysts and chronic pancreatitis. Pramipexole (PMX), a D2/3 receptor selecting agonist used in Parkinsonism, has reported anti-inflammatory effects lately.

PURPOSE

Exploring the potential curative role of PMX in an l-arginine-induced acute pancreatitis rat model besides a possible mechanistic pathway.

METHODS

Rats were divided randomly into three groups: control, l-arginine, and "l-arginine + PMX". 7 days after AP induction, rats decapitated and estimated for serum amylase, lipase, glucose, pancreatic inflammatory mediators "toll-like receptor-4, nuclear factor- kappa B p65 ,serum tumor necrosis factor-α, NLRP3 inflammasome, caspase-1, interleukin-1 beta, oxidative biomarkers "malondialdehyde, myeloperoxidase, nitrite/nitrate, reduced glutathione, and the apoptotic marker "caspase-3", with pancreatic histopathological changes.

RESULTS

L-arginine mediated AP proved by elevated serum lipase and amylase, pancreatic inflammatory, oxidative and apoptotic markers with infiltration of inflammatory cells using hematoxylin and eosin stain. PMX improved all these adverse signs of AP greatly.

CONCLUSION

PMX might be considered as an innovative therapy for AP due to its remarkable antioxidant, anti-apoptotic, and anti-inflammatory effects, which are attributed to the suppression of the NLRP3 inflammasome and its downstream inflammatory cytokines.

Continuous Activation of Dopamine Receptors Alleviates LPS-Induced Liver Injury in Mice via β-arrestin2 Dependent Akt/NF-κB Pathway

Many studies showed that dopamine receptors (DRs) agonists have anti-inflammatory effects. Rotigotine, a non-ergot dopamine receptor agonist, mainly actives DRD2/DRD3/DRD1. Rotigotine extended-release microspheres (RoMS) are a sustained-release formulation that can release sustainably rotigotine for more than 7 days after a single dose of RoMS. This study aimed to investigate whether RoMS can attenuate the lipopolysaccharide (LPS)-induced liver injury of mice. The liver injury was evaluated by assaying serum transaminase and observing histopathological changes. The levels of pro-inflammatory cytokines in serum were also detected. Western blot was employed to assay the expression of proteins in the Akt/NF-κB pathway. The results showed that pre-administration with a single dose of RoMS could inhibit the increase of serum transaminase induced by LPS, alleviate the pathological damage of liver tissue, and decrease the levels of tumor necrosis factor-α and interleukin-6. In addition, RoMS decreased Toll-like receptor 4 protein expression in liver tissue. RoMS mitigated liver injury by activating DRs and negatively regulating the β-arrestin2-dependent Akt/NF-κB signaling pathway. The effects of RoMS could be weakened or abolished by the specific DRD2 antagonist, R121. In conclusion, activation of DRs inhibited the releases of pro-inflammatory cytokines and alleviated the immune-mediated liver injury induced by LPS in mice. The anti-inflammatory mechanism of RoMS may be related to the regulation of the β-arrestin2-dependent Akt/NF-κB signaling pathway.

Activation of the aryl hydrocarbon receptor by clozapine induces preadipocyte differentiation and contributes to endothelial dysfunction

BACKGROUND

The superior therapeutic benefit of clozapine is often associated with metabolic disruptions as obesity, insulin resistance, tachycardia, higher blood pressure, and even hypertension.

AIMS

These adverse vascular/ metabolic events under clozapine are similar to those caused by polycyclic aromatic hydrocarbons (PAHs), and clozapine shows structural similarity to well-known ligands of the aryl hydrocarbon receptor (AhR). Therefore, we speculated that the side effects caused by clozapine might rely on AhR signaling.

METHODS

We examined clozapine-induced AhR activation by luciferase reporter assays in hepatoma HepG2 cells and we proved upregulation of the prototypical AhR target gene Cyp1A1 by realtime-PCR (RT-PCR) analysis and enzyme activity. Next we studied the physiological role of AhR in clozapine's effects on human preadipocyte differentiation and on vasodilatation by myography in wild-type and AhR-/- mice.

RESULTS

In contrast to other antipsychotic drugs (APDs), clozapine triggered AhR activation and Cyp1A1 expression in HepG2 cells and adipocytes. Clozapine induced adipogenesis via AhR signaling. After PGF2α-induced constriction of mouse aortic rings, clozapine strongly reduced the maximal vasorelaxation under acetylcholine in rings from wild-type mice, but only slightly in rings from AhR-/- mice. The reduction was also prevented by pretreatment with the AhR antagonist CH-223191.

CONCLUSION

Identification of clozapine as a ligand for the AhR opens new perspectives to explain common clozapine therapy-associated adverse effects at the molecular level.

Striatal Chloride Dysregulation and Impaired GABAergic Signaling Due to Cation-Chloride Cotransporter Dysfunction in Huntington’s Disease

Intracellular chloride (Cl–) levels in mature neurons must be tightly regulated for the maintenance of fast synaptic inhibition. In the mature central nervous system (CNS), synaptic inhibition is primarily mediated by gamma-amino butyric acid (GABA), which binds to Cl– permeable GABAA receptors (GABAARs). The intracellular Cl– concentration is primarily maintained by the antagonistic actions of two cation-chloride cotransporters (CCCs): Cl–-importing Na+-K+-Cl– co-transporter-1 (NKCC1) and Cl– -exporting K+-Cl– co-transporter-2 (KCC2). In mature neurons in the healthy brain, KCC2 expression is higher than NKCC1, leading to lower levels of intracellular Cl–, and Cl– influx upon GABAAR activation. However, in neurons of the immature brain or in neurological disorders such as epilepsy and traumatic brain injury, impaired KCC2 function and/or enhanced NKCC1 expression lead to intracellular Cl– accumulation and GABA-mediated excitation. In Huntington’s disease (HD), KCC2- and NKCC1-mediated Cl–-regulation are also altered, which leads to GABA-mediated excitation and contributes to the development of cognitive and motor impairments. This review summarizes the role of Cl– (dys)regulation in the healthy and HD brain, with a focus on the basal ganglia (BG) circuitry and CCCs as potential therapeutic targets in the treatment of HD.

The Effects of NLRP3 Inflammasome Inhibition in Experimental Acute Pancreatitis: A Systematic Review and Meta-Analysis

ABSTRACT

Acute pancreatitis (AP) is an inflammatory disease, and NLRP3 inflammasome activation is involved in the pathogenesis of AP. Previous research showed that inhibition of NLRP3 inflammasome may exert protective effects on animal models of AP and reduces disease severity. The aim of this systematic review and meta-analysis is to evaluate the effects of drug treatment of NLRP3 inflammasome on the outcomes of experimental AP. PubMed, Embase, Medline, and Web of Science databases were searched for relevant articles without language restrictions. The main outcomes for this study included local pancreatic injury, the incidence of systemic inflammatory responses, and the incidence of organ failure. Twenty-eight animal studies including 556 animals with AP were included in the meta-analysis. Compared with controls, inhibition of NLRP3 inflammasome significantly reduced the pancreatic histopathological scores, serum amylase, and lipase levels. In addition, inhibition of NLRP3 inflammasome reduced the levels of circulating inflammatory cytokines, as well as mitigating severity of AP-associated acute lung injury and acute intestinal injury. To conclude, inhibition of NLRP3 inflammasome has protective effects on AP by mitigating organ injury and systemic inflammation in animal studies, indicating that NLRP3 inflammasome holds promise as a target for specific AP therapy.

Dopamine, a co-regulatory component, bridges the central nervous system and the immune system

Dopamine (DA) is a crucial neurotransmitter that plays an important role in maintaining physiological function in human body. In the past, most studies focused on the relationship between the dopaminergic system and neurological-related diseases. However, it has been found recently that DA is an immunomodulatory mediator and many immune cells express dopamine receptors (DRs). Some immune cells can synthesize and secrete DA and then participate in regulating immune function. DRs agonists or antagonists can improve the dysfunction of immune system through classical G protein signaling pathways or other non-receptor-dependent pathways. This article will discuss the relationship between the dopaminergic system and the immune system. It will also review the use of DRs agonists or antagonists to treat chronic and acute inflammatory diseases and corresponding immunomodulatory mechanisms.

MicroRNA-361-5p Aggravates Acute Pancreatitis by Promoting Interleukin-17A Secretion via Impairment of Nuclear Factor IA-Dependent Hes1 Downregulation

This study set out to explore the potential role of microRNA-361-5p (miR-361-5p) in acute pancreatitis through regulation of interleukin-17A (IL-17A). We first identified the expression of miR-361-5p, IL-17A, nuclear factor IA (NFIA), and hes family bHLH transcription factor 1 (Hes1) in serum samples collected from patients with acute pancreatitis, caerulein-induced mice, and a Th17 cell model. The predicted binding of miR-361-5p to NFIA was confirmed in vitro. Gain- and loss-of-function assays of miR-361-5p and NFIA were employed to elucidate their effects on acute pancreatitis. miR-361-5p promoted Th17 cells to secrete IL-17A and then aggravated acute pancreatitis. miR-361-5p directly targeted NFIA by binding to its promoter region, leading to its downregulation. Overexpression of NFIA reduced Hes1 expression and rescued the promoting effect of miR-361-5p on IL-17A secretion. In summary, miR-361-5p enhances IL-17A secretion from Th17 cells and thus aggravates acute pancreatitis by targeting NFIA and upregulating Hes1.

Pancreatic acinar cells utilize tyrosine to synthesize L-dihydroxyphenylalanine

The pancreatic β cells can synthesize dopamine by taking L-dihydroxyphenylalanine, but whether pancreatic acinar cells synthesize dopamine has not been confirmed. By means of immunofluorescence, the tyrosine hydroxylase -immunoreactivity and aromatic amino acid decarboxylase (AADC)- immunoreactivity were respectively observed in pancreatic acinar cells and islet β cells. Treatment with L-dihydroxyphenylalanine, not tyrosine, caused the production of dopamine in the incubation of INS-1 cells (rat islet β cell line) and primary isolated islets, which was blocked by AADC inhibitor NSD-1015. However, only L-dihydroxyphenylalanine, but not dopamine, was detected when AR42J cells (rat pancreatic acinar cell line) were treated with tyrosine, which was blocked by tyrosine hydroxylase inhibitor AMPT. Dopamine was detected in the coculture of INS-1 cells with AR42J cells after treatment with tyrosine. In an in vivo study, pancreatic juice contained high levels of L-dihydroxyphenylalanine and dopamine. Both L-dihydroxyphenylalanine and dopamine accompanied with pancreatic enzymes and insulin in the pancreatic juice were all significantly increased after intraperitoneal injection of bethanechol chloride and their increases were all blocked by atropine. Inhibiting TH with AMPT blocked bethanechol chloride-induced increases in L-dihydroxyphenylalanine and dopamine, while inhibiting AADC with NSD-1015 only blocked the dopamine increase. Bilateral subdiaphragmatic vagotomy of rats leads to significant decreases of L-dihydroxyphenylalanine and dopamine in pancreatic juice. These results suggested that pancreatic acinar cells could utilize tyrosine to synthesize L-dihydroxyphenylalanine, not dopamine. Islet β cells only used L-dihydroxyphenylalanine, not tyrosine, to synthesize dopamine. Both L-dihydroxyphenylalanine and dopamine were respectively released into the pancreatic duct, which was regulated by the vagal cholinergic pathway. The present study provides important evidences for the source of L-dihydroxyphenylalanine and dopamine in the pancreas.

Lipopolysaccharide/D-galactosamine-induced acute liver injury could be attenuated by dopamine receptor agonist rotigotine via regulating NF-κB signaling pathway

The pathological of lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced acute liver injury is similar to what is seen clinically, and be mediated by the release of pro-inflammatory mediators. A growing body of studies have shown that dopamine (DA) and DA receptor agonist are associated with inflammation and immune response. Rotigotine, a non-ergoline dopamine receptor agonist, is a drug for the treatment of Parkinson's disease. Rotigotine-loaded microspheres (RoMS) is an intramuscular extended-release agent, which can steadily release rotigotine for more than 7 days after a single administration. The present study aimed to investigate the effects of rotigotine and RoMS on inflammation and acute liver injury induced by LPS/D-Gal in mice. The LPS/D-Gal-induced liver injury was evidenced by increases of serum aminotransferases activities and liver histological lesions. Pretreatment with rotigotine or RoMS not only ameliorated the liver histologic lesions, but also reduced the activities of serum aminotransferases and the production of TNF-α. It also showed that rotigotine and RoMS increased DA receptor 2 (DRD2) expression in LPS/D-Gal-exposed mice. Rotigotine and RoMS activated β-arrestin 2, inhibited the phosphorylation of Akt, IκB and the transposition of NF-κB. In line with the above findings, the protective effects of rotigotine and RoMS were abrogated by haloperidol, a DA receptor antagonist. In conclusion, dopamine receptor agonist can regulate NF-κB inflammatory signaling pathway and exert protective effects in LPS/D-Gal-induced liver injury.

Pathophysiologic Role of Neurotransmitters in Digestive Diseases

Neurotransmitters are special molecules that serve as messengers in chemical synapses between neurons, cells, or receptors, including catecholamines, serotonin, dopamine, and other neurotransmitters, which play an important role in both human physiology and pathology. Compelling evidence has indicated that neurotransmitters have an important physiological role in various digestive diseases. They act as ligands in combination with central or peripheral receptors, and transmits signals through chemical synapses, which are involved in regulating the physiological and pathological processes of the digestive tract organs. For instance, neurotransmitters regulate blood circulation and affect intestinal movement, nutrient absorption, the gastrointestinal innate immune system, and the microbiome. In this review, we will focus on the role of neurotransmitters in the pathogenesis of digestive tract diseases to provide novel therapeutic targets for new drug development in digestive diseases.

Pretreatment with chitosan oligosaccharides attenuate experimental severe acute pancreatitis via inhibiting oxidative stress and modulating intestinal homeostasis

Severe acute pancreatitis (SAP) is a severe acute abdominal disease. Recent evidence shows that intestinal homeostasis is essential for the management of acute pancreatitis. Chitosan oligosaccharides (COS) possess antioxidant activity that are effective in treating various inflammatory diseases. In this study we explored the potential therapeutic effects of COS on SAP and underlying mechanisms. Mice were treated with COS (200 mg·kg-1·d-1, po) for 4 weeks, then SAP was induced in the mice by intraperitoneal injection of caerulein. We found that COS administration significantly alleviated the severity of SAP: the serum amylase and lipase levels as well as pancreatic myeloperoxidase activity were significantly reduced. COS administration suppressed the production of proinflammatory cytokines (TNF-α, IL-1β, CXCL2 and MCP1) in the pancreas and ileums. Moreover, COS administration decreased pancreatic inflammatory infiltration and oxidative stress in SAP mice, accompanied by activated Nrf2/HO-1 and inhibited TLR4/NF-κB and MAPK pathways. We further demonstrated that COS administration restored SAP-associated ileal damage and barrier dysfunction. In addition, gut microbiome analyses revealed that the beneficial effect of COS administration was associated with its ability to improve the pancreatitis-associated gut microbiota dysbiosis; in particular, probiotics Akkermansia were markedly increased, while pathogenic bacteria Escherichia-Shigella and Enterococcus were almost eliminated. The study demonstrates that COS administration remarkably attenuates SAP by reducing oxidative stress and restoring intestinal homeostasis, suggesting that COS might be a promising prebiotic agent for the treatment of SAP.

The Role of Chinese Herbal Therapy in Methamphetamine Abuse and its Induced Psychiatric Symptoms

Repeated intake of methamphetamine (METH) leads to drug addiction, the inability to control intake, and strong drug cravings. It is also likely to cause psychiatric impairments, such as cognitive impairment, depression, and anxiety. Because the specific neurobiological mechanisms involved are complex and have not been fully and systematically elucidated, there is no established pharmacotherapy for METH abuse. Studies have found that a variety of Chinese herbal medicines have significant therapeutic effects on neuropsychiatric symptoms and have the advantage of multitarget comprehensive treatment. We conducted a systematic review, from neurobiological mechanisms to candidate Chinese herbal medicines, hoping to provide new perspectives and ideas for the prevention and treatment of METH abuse.

Dopamine receptor agonists ameliorate bleomycin-induced pulmonary fibrosis by repressing fibroblast differentiation and proliferation

Idiopathic pulmonary fibrosis (IPF) is the most common fatal interstitial lung disease, with limited therapeutic options. The abnormal and uncontrolled differentiation and proliferation of fibroblasts have been confirmed to play a crucial role in driving the pathogenesis of IPF. Therefore, effective and well-tolerated antifibrotic agents that interfere with fibroblasts would be an ideal treatment, but no such treatments are available. Remarkably, we found that dopamine (DA) receptor D1 (D1R) and DA receptor D2 (D2R) were both upregulated in myofibroblasts in lungs of IPF patients and a bleomycin (BLM)-induced mouse model. Then, we explored the safety and efficacy of DA, fenoldopam (FNP, a selective D1R agonist) and sumanirole (SMR, a selective D2R agonist) in reversing BLM-induced pulmonary fibrosis. Further data showed that DA receptor agonists exerted potent antifibrotic effects in BLM-induced pulmonary fibrosis by attenuating the differentiation and proliferation of fibroblasts. Detailed pathway analysis revealed that DA receptor agonists decreased the phosphorylation of Smad2 induced by TGF-β1 in primary human lung fibroblasts (PHLFs) and IMR-90 cells. Overall, DA receptor agonists protected mice from BLM-induced pulmonary fibrosis and may be therapeutically beneficial for IPF patients in a clinical setting.

Tumor suppressor DRD2 facilitates M1 macrophages and restricts NF-κB signaling to trigger pyroptosis in breast cancer

Rationale: Breast cancer (BrCa) is the most common cancer worldwide, and the 5-year relative survival rate has declined in patients diagnosed at stage IV. Advanced BrCa is considered as incurable, which still lack effective treatment strategies. Identifying and characterizing new tumor suppression genes is important to establish effective prognostic biomarkers or therapeutic targets for late-stage BrCa.

Methods: RNA-seq was applied in BrCa tissues and normal breast tissues. Through analyzing differentially expressed genes, DRD2 was selected for further analysis. And expression and promoter methylation status of DRD2 were also determined. DRD2 functions were analyzed by various cell biology assays in vitro. Subcutaneous tumor model was used to explore DRD2 effects in vivo. A co-cultivated system was constructed to investigate interactions of DRD2 and macrophages in vitro. WB, IHC, IF, TUNEL, qRT-PCR, Co-IP, Antibody Array, and Mass Spectrum analysis were further applied to determine the detailed mechanism.

Results: In BrCa, DRD2 was found to be downregulated due to promoter methylation. Higher expression of DRD2 positively correlated with longer survival times especially in HER2-positive patients. DRD2 also promoted BrCa cells sensitivity to Paclitaxel. Ectopic expression of DRD2 significantly inhibited BrCa tumorigenesis. DRD2 also induced apoptosis as well as necroptosis in vitro and in vivo. DRD2 restricted NF-κB signaling pathway activation through interacting with β-arrestin2, DDX5 and eEF1A2. Interestingly, DRD2 also regulated microenvironment as it facilitated M1 polarization of macrophages, and triggered GSDME-executed pyroptosis.

Conclusion: Collectively, this study novelly manifests the role of DRD2 in suppressing BrCa tumorigenesis, predicting prognosis and treatment response. And this study further reveals the critical role of DRD2 in educating M1 macrophages, restricting NF-κB signaling pathway and triggering different processes of programmed cell death in BrCa. Taking together, those findings represent a predictive and therapeutic target for BrCa.

Cyclin G2 promotes the formation of smooth muscle cells derived foam cells in atherosclerosis via PP2A/NF-κB/LOX-1 pathway

Background

To investigate the role and underlying mechanism of cyclin G2 (G2-type cyclin) in the formation of vascular smooth muscle cells (VSMCs) derived foam cells.

Methods

The levels of α-SMA (alpha-SM-actin), p-NF-κB (phosphorylation nuclear transcription factors kappa B), and LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) were measured by immunohistochemistry and western blotting. The mouse aortic root smooth muscle cell line MOVAS was transfected to over-express cyclin G2, which were then stimulated with 80 µg/mL ox-LDL (oxidized low-density lipoprotein) to induce foam cell formation. DT-061 an activator of PP2A (protein phosphatase 2A) agonist was used to verify the role of PP2A in the process.

Results

Knocking out the Ccng2 gene in Apoe^-/- mice alleviated aortic lipid plaque, foam cell formulation, ameliorative body weight, and LDL-cholesterol. We observed that the number of α-SMA positive cells was significantly decreased in Apoe^-/-Ccng^2-/- mice compared to Apoe^-/- mice. Also, the protein levels of p-NF-κB and LOX-1 were markedly reduced in the aortic root of Apoe^-/-Ccng2^-/- mice. Upon stimulation with ox-LDL, upregulated cyclin G2 increased the intracellular lipid accumulation in MOVAS cells. Also, it suppressed the activity of PP2A but up-regulated LOX-1. Additionally, the cell nuclear translocation of p-NF-κB was increased. Interestingly, DT-061 intervention, re-activating the activity of PP2A, reduced the levels of nuclear p-NF-κB and LOX-1. This led to decreased lipid endocytosis reducing the formation of VSMCs- derived foam cells.

Conclusions

Cyclin G2 increases the nuclear translocation of p-NF-κB by reducing the enzymatic activity of PP2A and upregulating LOX-1, thereby promotes the formation of VSMCs -derived foam cells in atherosclerosis.

Quinpirole-Mediated Regulation of Dopamine D2 Receptors Inhibits Glial Cell-Induced Neuroinflammation in Cortex and Striatum after Brain Injury

Brain injury is a significant risk factor for chronic gliosis and neurodegenerative diseases. Currently, no treatment is available for neuroinflammation caused by the action of glial cells following brain injury. In this study, we investigated the quinpirole-mediated activation of dopamine D2 receptors (D2R) in a mouse model of traumatic brain injury (TBI). We also investigated the neuroprotective effects of quinpirole (a D2R agonist) against glial cell-induced neuroinflammation secondary to TBI in adult mice. After the brain injury, we injected quinpirole into the TBI mice at a dose of 1 mg/kg daily intraperitoneally for 7 days. Our results showed suppression of D2R expression and deregulation of downstream signaling molecules in ipsilateral cortex and striatum after TBI on day 7. Quinpirole administration regulated D2R expression and significantly reduced glial cell-induced neuroinflammation via the D2R/Akt/glycogen synthase kinase 3 beta (GSK3-β) signaling pathway after TBI. Quinpirole treatment concomitantly attenuated increase in glial cells, neuronal apoptosis, synaptic dysfunction, and regulated proteins associated with the blood–brain barrier, together with the recovery of lesion volume in the TBI mouse model. Additionally, our in vitro results confirmed that quinpirole reversed the microglial condition media complex-mediated deleterious effects and regulated D2R levels in HT22 cells. This study showed that quinpirole administration after TBI reduced secondary brain injury-induced glial cell activation and neuroinflammation via regulation of the D2R/Akt/GSK3-β signaling pathways. Our study suggests that quinpirole may be a safe therapeutic agent against TBI-induced neurodegeneration.

Intravenous Administration of Triptonide Attenuates CFA-Induced Pain Hypersensitivity by Inhibiting DRG AKT Signaling Pathway in Mice

Background

Currently, medical treatment of inflammatory pain is limited by a lack of safe and effective therapies. Triptonide (TPN), a major component of Tripterygium wilfordii Hook.f. with low toxicity, has been shown to have good anti-inflammatory and neuroprotective effects. The present study aims to investigate the effects of TPN on chronic inflammatory pain.

Materials and Methods

Inflammatory pain was induced by intraplantar injection of complete Freund’s adjuvant (CFA). TPN’s three different doses were intravenously administered to compare the analgesic efficacy: 0.1 mg/kg, 0.5 mg/kg, and 2.0 mg/kg. The foot swelling was quantitated by measuring paw volume. Mechanical allodynia and thermal hyperalgesia were assessed with von Frey filament testing and Hargreaves’ test, respectively. Western blots, qRT–PCR and immunofluorescence tests were used to analyze the expression of pAKT, tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6). Two AKT inhibitors, AKT inhibitor Ⅳ and MK-2206, were used to examine AKT’s effects on pain behavior and cytokines expression.

Results

Intravenous treatment with TPN attenuated CFA-induced paw edema, mechanical allodynia, and thermal hyperalgesia. Western blotting and immunofluorescence results showed that CFA induced AKT activation in the dorsal root ganglion (DRG) neurons. However, these effects were suppressed by treatment with TPN. Furthermore, TPN treatment inhibited CFA-induced increase of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. Consistent with the in vivo data, TPN inhibited LPS-induced Akt phosphorylation and inflammatory mediator production in ND7/23 cells. Finally, intrathecal treatment with AKT inhibitor Ⅳ or MK-2206, attenuated CFA-induced mechanical allodynia and thermal hyperalgesia, and simultaneously decreased the mRNA expression of TNF-α, IL-1β, and IL-6 in DRG.

Conclusion

These data indicate that TPN attenuates CFA-induced pain potentially via inhibiting AKT-mediated pro-inflammatory cytokines production in DRG. TPN may be used for the treatment of chronic inflammatory pain.

Drd2 biased agonist prevents neurodegeneration against NLRP3 inflammasome in Parkinson's disease model via a β-arrestin2-biased mechanism

Activated astrocytes secrete inflammatory cytokines such as interleukin-1β (IL-1β) into the extracellular milieu, damaging surrounding neurons and involving in the pathogenesis of neurodegenerative diseases, such as Parkinson's disease (PD). Dopamine receptor D2 (Drd2) expresses both in neurons and astrocytes, and neuronal Drd2 is a significant target in therapy of PD. Our previous study reveals that astrocytic Drd2 exerts anti-inflammatory effect via non-classical β-arrestin2 signaling in PD model. Therefore, seeking new biased ligands of Drd2 with better efficacy and fewer side effects to treat PD is desirable and meaningful. In the present study, we evaluated the effects of UNC9995, a novel biased Drd2 agonist on astrocyte-derived neuroinflammation and dopaminergic (DA) neuron degenerationin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We showed that UNC9995 rescued the TH⁺ neurons loss and inhibited glial cells activation in mouse substantia nigra in a Drd2 dependent manner. Focusing on astrocytes, we found UNC9995 shows a relatively safe concentration range and significantly suppresses astrocytic NLRP3 inflammasome activation induced by lipopolysaccharide plus ATP. Further study revealed that the anti-inflammatory effect of UNC9995 is independent of Drd2 / Gα_i protein pathway. It activates β-arrestin2 by recruiting it to cell membrane. Critically, UNC9995 enhances β-arrestin2 interacting with NLRP3 to interfere inflammasome assembly, which consequently reduces IL-1β production. On the other hand, UNC9995 inhibits IL-1β-induced inflammatory pathway activation in DA neurons and rescues subsequent apoptosis via β-arrestin2 interacting with protein kinases, such as JNK and suppressing their phosphorylation. Furthermore, β-arrestin2 knockout abolishes the anti-inflammatory and neuroprotective effects of UNC9995 in PD mouse model, supporting that UNC9995 is a β-arrestin2-biased Drd2 agonist and revealing its novel function in PD treatment. Collectively, this work illustrates that Drd2 agonist UNC9995 prevents DA neuron degeneration in PD and provides a new strategy for developing the β-arrestin2-biased ligands in the therapy of NDDs.

Estrogen Deficiency and Colonic Function: Surgical Menopause and Sex Differences in Angiotensin and Dopamine Receptor Interaction

The physiopathological mechanisms that regulate menopausal and sex differences in colonic transit, inflammatory processes, and efficacy of treatments have not been clarified. The dopaminergic system and renin–angiotensin system coexist in the gut and regulate different processes such as motility, absorption/secretion, and inflammation. We investigated the changes in expression of major angiotensin and dopamine receptors in the colon of male, female, and ovariectomized female mice. Possible interaction between both systems was investigated using male and female mice deficient (ko) for major angiotensin and dopamine receptors. In wild-type mice, colonic tissue from females showed lower angiotensin type 1/angiotensin type 2 ratio (an index of pro-inflammatory/anti-inflammatory renin–angiotensin system balance), lower dopamine D1 and D2 receptor expression, and lower levels of pro-inflammatory and pro-oxidative markers relative to males. Interestingly, ovariectomy increased the expression of pro-inflammatory angiotensin type 1 receptor expression and decreased anti-inflammatory angiotensin type 2 receptor expression, increased D1 and D2 receptor expression, and increased the levels of pro-inflammatory and pro-oxidative markers. Ovariectomy-induced changes were blocked by estrogen replacement. The present results suggest a mutual regulation between colonic angiotensin and dopamine receptors and sex differences in this mutual regulation. Estrogen regulates changes in both angiotensin and dopamine receptor expression, which may be involved in sex- and surgical menopause-related effects on gut motility, permeability, and vulnerability to inflammatory processes.

Activation of α7nACh receptor protects against acute pancreatitis through enhancing TFEB-regulated autophagy

Acute pancreatitis (AP) is associated with impaired acinar cell autophagic flux, intracellular zymogen activation, cell necrosis and inflammation. Activation of the cholinergic system of vagus nerve has been shown to attenuate AP, but the effect of organ-intrinsic cholinergic system on pancreatitis remains unknown. In this study, we aim to examine the effect of α7 nicotinic acetylcholine receptor (α7nAChR) stimulation within the pancreas during AP. In vivo, AP was induced by caerulein plus LPS or ethanol plus palmitoleic acid in mice. In vitro, pancreatic acini were isolated and subjected to cholecystokinin (CCK) stimulation. Mice or acini were pre-treated with PNU-282987 (selective α7nAChR agonist) or methyllycaconitine citrate salt (selective α7nAChR antagonist). Pancreatitis severity, acinar cell injury, autophagic flux, and transcription factor EB (TFEB) pathway were analyzed. Both caerulein plus LPS in vivo and CCK in vitro led to an up-regulation of α7nAChR, indicating activation of pancreas-intrinsic α7nAChR signaling during AP. PNU-282987 decreased acinar cell injury, trypsinogen activation and pancreatitis severity. Conversely, methyllycaconitine citrate salt increased acinar cell injury and aggravated AP. Moreover, activation of α7nAChR by PNU-282987 promoted autophagic flux as indicated by reduced p62, increased LysoTracker staining and decreased number of autolysosomes with undegraded contents. Furthermore, PNU-282987 treatment significantly increased TFEB activity in pancreatic acinar cells. α7nAChR activation also attenuated pancreatic inflammation and NF-κB activation. Our results showed that activation of α7nAChR protected against experimental pancreatitis through enhancing TFEB-mediated acinar cell autophagy, suggesting that activation of pancreas-intrinsic α7nAChR may serve as an endogenous protective mechanism during AP.

Role of CARD9 in inflammatory signal pathway of peritoneal macrophages in severe acute pancreatitis

Previous studies revealed that caspase recruitment domain protein 9 (CARD9) was involved in severe acute pancreatitis (SAP) inflammation and that interfering with its expression in vivo could inhibit inflammation. However, the specific mechanism is unknown. This study aimed to discover the related signal pathways of CARD9 in macrophages. SiRNA interference technology was used in vivo and in vitro to detect CARD9‐related signal pathways in peritoneal macrophages. Furthermore, Toll‐like receptor 4 (TLR4) and membrane‐associated C‐type lectin‐1 (Dectin‐1) pathways in macrophages were activated specially to looking for the upstream signal path of CARD9. Results showed up‐regulation of CARD9 expression in peritoneal macrophages of SAP rats (P < .05). CARD9 siRNA alleviated inflammatory cytokines, and inhibited the phosphorylation of NF‐κB and p38MAPK in peritoneal macrophages in vivo or in vitro. Meanwhile, CARD9 siRNA reduced the concentration of CARD9 and Bcl10 in peritoneal macrophages, and TLR4 and Dectin‐1 took part in CARD9 signal pathways in macrophages. In conclusion, there is an inflammation signal pathway comprised of TLR4/Dectin‐1‐CARD9‐NF‐κB/p38MAPK activated in macrophages in SAP. Blockade of CARD9 expression in macrophages can effectively alleviate SAP inflammation.

Dopamine D2 receptor activator quinpirole protects against trypsinogen activation during acute pancreatitis via upregulating HSP70

Trypsinogen activation is the hallmark of acute pancreatitis (AP) independent of intra-acinar NF-κB activation and inflammation. We previously found that dopamine (DA) receptor 2 (DRD2) activation controls inflammation during AP via PP2A-dependent NF-κB activation. In this study, we sought to examine whether DRD2 signaling mediates trypsinogen activation and the underlying mechanisms. Pancreatic acinar cells were stimulated with cholecystokinin-8 in vitro. AP was induced by intraperitoneal injections of caerulein and LPS or l-arginine. Pancreatitis severity was assessed biochemically and histologically. We found that activation of DRD2 by quinpirole, a potent DRD2 agonist, resulted in the reduction of trypsinogen activation and the upregulation of HSP70 in vitro and in vivo. Mechanistically, we found that quinpirole induced dephosphorylation of heat shock factor 1 (HSF1), a master transcription factor of HSP70, leading to increased nuclear translocation of HSF1 in a PP2A-dependent pathway. Furthermore, DRD2 activation restored lysosomal pH and, therefore, maintained lysosomal cathepsin B activity in a HSP70-dependent manner. VER155008, a potent HSP70 antagonist, abolished the protective effects observed with DRD2 activation in vitro and in two experimental models of AP. Our data showed that besides controlling NF-κB activation, DRD2 activation prevented trypsinogen activation during acute pancreatitis via PP2A-dependent upregulation of HSP70 and further support that DRD2 agonist could be a promising therapeutic strategy for treating AP.NEW & NOTEWORTHY The current study demonstrated that activation of DRD2 by quinpirole protects against trypsinogen activation in the in vitro and in vivo setting of acute pancreatitis by upregulating HSP70 and restoring lysosomal degradation via a PP2A-dependent manner, therefore leading to reduced pancreatic injury. These findings provide a new mechanistic insight on the protective effect of DRD2 activation in acute pancreatitis.

Losartan improves visceral sensation and gut barrier in a rat model of irritable bowel syndrome

BACKGROUND

Lipopolysaccharide (LPS) or repeated water avoidance stress (WAS) induces visceral allodynia and colonic hyperpermeability via corticotropin-releasing factor (CRF) and proinflammatory cytokines, which is considered to be a rat irritable bowel syndrome (IBS) model. As losartan is known to inhibit proinflammatory cytokine release, we hypothesized that it improves these visceral changes.

METHODS

The threshold of visceromotor response (VMR), that is, abdominal muscle contractions induced by colonic balloon distention was electrophysiologically measured in rats. Colonic permeability was determined in vivo by quantifying the absorbed Evans blue in colonic tissue for 15 minutes spectrophotometrically.

KEY RESULTS

Lipopolysaccharide (1 mg kg^-1 ) subcutaneously (s.c.) reduced the threshold of VMR and increased colonic permeability. Losartan (5-25 mg kg^-1  s.c.) for 3 days inhibited these changes in a dose-dependent manner. Moreover, repeated WAS (1 hour daily for 3 days) or intraperitoneal injection of CRF (50 µg kg^-1 ) induced the similar visceral changes as LPS, which were also eliminated by losartan. These effects by losartan in LPS model were reversed by GW9662 (a peroxisome proliferator-activated receptor-γ [PPAR-γ] antagonist), N^G -nitro-L-arginine methyl ester (a nitric oxide [NO] synthesis inhibitor), or naloxone (an opioid receptor antagonist). Moreover, it also inhibited by sulpiride (a dopamine D₂ receptor antagonist) or domperidone (a peripheral dopamine D₂ antagonist).

CONCLUSION & INFERENCES

Losartan prevented visceral allodynia and colonic hyperpermeability in rat IBS models. These actions may be PPAR-γ-dependent and also mediated by the NO, opioid, and dopamine D₂ pathways. Losartan may be useful for IBS treatment.

BRD4 Inhibition Protects Against Acute Pancreatitis Through Restoring Impaired Autophagic Flux

Impaired autophagy has been shown to play a critical role in experimental and human acute pancreatitis (AP). However, the mechanism for transcriptional regulation of autophagy remains largely unknown. In this study, we aim to explore the role of BRD4 (bromodomain-containing protein 4), a transcriptional repressor of autophagy, during AP. Changes in pancreatic BRD4 expression and the effect of BRD4 inhibition were measured in mice with AP (induced by caerulein and ethanol and palmitoleic acid) and in isolated pancreatic acinar cells stimulated with cholecystokinin (CCK). Pancreatitis severity was evaluated by serum amylase and pancreatic histopathology. The autophagic flux, the fusion of autophagosome and lysosome, and lysosomal degradation were evaluated. Sirtuin 1 (SIRT1) expression and the effect of SIRT1 inhibition were assessed. We found that pancreatic BRD4 expression was upregulated during various models of AP. BRD4 inhibition reduced CCK-stimulated pancreatic acinar cell injury and pro-inflammatory expression in vitro and protected against two models of experimental AP. Mechanistically, BRD4 inhibition restored impaired autophagic flux via promoting autophagosome-lysosome fusion and lysosomal degradation. BRD4 inhibition also upregulated SIRT1 and inhibition of SIRT1 reversed the effects of BRD4 inhibition on autophagic flux. Our data suggest that BRD4 is a potential therapeutic target for treating AP.

Inhibition of Matrix Metalloproteinase with BB-94 Protects against Caerulein-Induced Pancreatitis via Modulating Neutrophil and Macrophage Activation

Methods

AP was induced in Balb/C mice by ten hourly intraperitoneal injections of caerulein (100 μg/kg) and LPS (5 mg/kg). The MMP inhibitor, BB-94 (20 mg/kg) was intraperitoneally administered 30 min before AP induction. Pancreatitis was confirmed by histology and serum amylase and lipase. Expression of pancreatic proinflammatory mediators and NF-κB activation were assessed. Bone marrow-derived neutrophils (BMDNs) and macrophages (BMDMs) were isolated. BMDNs were activated by phorbol 12-myristate 13-acetate (PMA, 50 ng/ml) and neutrophil reactive oxygen species (ROS) production was recorded. BMDMs were stimulated with 10 ng/ml IFN-γ and 100 ng/ml LPS to induce M1 macrophage polarization.

Results

Pancreatic MMP-9 was markedly upregulated and serum MMP-9 was increased in caerulein-induced pancreatitis. Inhibition of MMP with BB-94 ameliorated pancreatic tissue damage and decreased the expression of proinflammatory cytokines (TNFα and IL-6) or chemokines (CCL2 and CXCL2) and NF-κB activation. Furthermore, using isolated BMDNs and BMDMs, we found that inhibition of MMP with BB-94 markedly decreased neutrophil ROS production, inhibited inflammatory macrophage polarization and NF-κB activation.

Conclusions

Our results showed that inhibition of MMP with BB-94 protected against pancreatic inflammatory responses in caerulein-induced pancreatitis via modulating neutrophil and macrophage activation.

Establishing GPCR Targets of hMAO Active Anthraquinones from Cassia obtusifolia Linn Seeds Using In Silico and In Vitro Methods

The present study examines the effect of human monoamine oxidase active anthraquinones emodin, alaternin (=7-hydroxyemodin), aloe-emodin, and questin from Cassia obtusifolia Linn seeds in modulating human dopamine (hD₁R, hD₃R, and hD₄R), serotonin (h5-HT_1AR), and vasopressin (hV_1AR) receptors that were predicted as prime targets from proteocheminformatics modeling via in vitro cell-based functional assays, and explores the possible mechanisms of action via in silico modeling. Emodin and alaternin showed a concentration-dependent agonist effect on hD₃R with EC₅₀ values of 21.85 ± 2.66 and 56.85 ± 4.59 μM, respectively. On hV_1AR, emodin and alaternin showed an antagonist effect with IC₅₀ values of 10.25 ± 1.97 and 11.51 ± 1.08 μM, respectively. Interestingly, questin and aloe-emodin did not have any observable effect on hV_1AR. Only alaternin was effective in antagonizing h5-HT_1AR (IC₅₀: 84.23 ± 4.12 μM). In silico studies revealed that a hydroxyl group at C1, C3, and C8 and a methyl group at C6 of anthraquinone structure are essential for hD₃R agonist and hV_1AR antagonist effects, as well as for the H-bond interaction of 1-OH group with Ser192 at a proximity of 2.0 Å. Thus, based on in silico and in vitro results, hV_1AR, hD₃R, and h5-HT_1AR appear to be prime targets of the tested anthraquinones.

Myeloid-specific dopamine D2 receptor signalling controls inflammation in acute pancreatitis via inhibiting M1 macrophage

BACKGROUND AND PURPOSE

Macrophage infiltration and activation is a critical step during acute pancreatitis (AP). We have shown that pancreas-specific D₂ receptor signalling protects against AP severity. As it is unclear to what extent myeloid-specific D₂ receptor mediates AP, we investigated the role of myeloid-specific D₂ receptor signalling in AP.

EXPERIMENTAL APPROACH

Using wild-type and LysM^+/cre D₂ ^fl/fl mice, AP was induced by l-arginine, caerulein and LPS. Murine bone marrow-derived macrophages and human peripheral blood mononuclear cells (PBMCs) were isolated, cultured and then induced to M1 phenotype. AP severity was assessed by measurements of serum amylase and lipase and histological grading. Macrophage phenotype was assessed by flow cytometry and qRT-PCR. NADPH oxidase-induced oxidative stress and NF-κB and NLRP3 inflammasome signalling pathways were also evaluated.

KEY RESULTS

We found that dopaminergic system was activated and dopamine reduced inflammatory cytokine expression in M1-polarized macrophages from human PBMCs. Dopaminergic synthesis was also activated, but D₂ receptor expression was down-regulated in M1-polarized macrophages from murine bone marrows. During AP, myeloid-specific D₂ receptor deletion worsened pancreatic injury, systematic inflammation and promoted macrophages to M1 phenotype. Furthermore, M1 macrophages from LysM^+/cre D₂ ^fl/fl mice exhibited increased NADPH oxidase-induced oxidative stress and enhanced NF-κB and NLRP3 inflammasome activation. D₂ receptor activation inhibited M1 macrophage polarization, oxidative stress-induced NF-κB and NLRP3 inflammasome activation.

CONCLUSION AND IMPLICATIONS

Our data for the first time showed that myeloid-specific D₂ receptor signalling controls pancreatic injury and systemic inflammation via inhibiting M1 macrophage, suggesting D₂ receptor activation might serve as therapeutic target for AP.

Bridelia speciosa Müll.Arg. Stem bark Extracts as a Potential Biomedicine: From Tropical Western Africa to the Pharmacy Shelf

Bridelia species have been used in traditional African medicine for the management of diverse human ailments. In the current work, the detailed phytochemical profiles of the extracts of the stem bark of B. speciosa were evaluated and the antioxidant and enzyme inhibitory properties of the extracts were assessed. The anti-bacterial and anti-mycotic effects of the extracts were evaluated against selected pathogen strains. Additionally, the anti-proliferative effects were studied on the liver cancer HepG2 cell line. Finally, the putative protective effects were assessed on isolated rat liver that was challenged with lipopolysaccharide (LPS). The results revealed the presence of 36 compounds in the ethyl acetate extract, 44 in the methanol extract, and 38 in the water extract. Overall, the methanol extract showed the highest antioxidant activity, particularly in LPS-stimulated rat liver. Additionally, this extract exerted the highest antimycotic effect on C. albicans, whereas the water extract showed a promising anti-proliferative effect on liver cancer HepG2 cells. The methanol extract was also the most active as enzyme inhibitor, against acetylcholinesterase and butyrylcholinesterase. The current study appraises the antioxidant and enzyme inhibition properties of B. speciosa methanol extract and showed that this specie could be a promising source of biologically active phytochemicals, with potential health uses.