Dopamine affects cellular immune functions during polymicrobial sepsis

Dopaminergic Inhibition of Human Neutrophils is Exerted Through D1-Like Receptors and Affected By Bacterial Infection

BACKGROUND

Dopamine (DA) affects immune functions in healthy subjects and during disease by acting on D1-like (D1 and D5) and D2-like (D2, D3 and D4) dopaminergic receptors (DR), however its effects on human polymorphonuclear leukocytes (PMN) are still poorly defined.

METHODS

We investigated DR expression in human PMN and the ability of DA to affect cell migration and reactive oxygen species (ROS) production. Experiments were performed on cells from healthy subjects (HS) and from patients (Pts) with bacterial infections as well, during the acute phase and after recovery. Some experiments were also performed in mice KO for the DRD5 gene.

RESULTS

PMN from HS express both D1-like and D2-like DR, and exposure to DA results in inhibition of activation-induced morphological changes, migration and ROS production which depend on the activation of D1-like DR. In agreement with these findings, DA inhibited migration of PMN obtained from wild-type mice, but not from DR D5 KO mice. In Pts with bacterial infections, during the febrile phase D1-like DR D5 on PMN were downregulated and DA failed to affect PMN migration. Both D1-like DR D5 expression and DA-induced inhibition of PMN migration were however restored after recovery.

CONCLUSION

Dopaminergic inhibition of human PMN is a novel mechanism which is likely to play a key role in the regulation of innate immunity. Evidence obtained in Pts with bacterial infections provides novel clues for the therapeutic modulation of PMN during infectious disease.

Integrative analysis of metabolomics and proteomics reveals amino acid metabolism disorder in sepsis

Background

Sepsis is defined as a systemic inflammatory response to microbial infections with multiple organ dysfunction. This study analysed untargeted metabolomics combined with proteomics of serum from patients with sepsis to reveal the underlying pathological mechanisms involved in sepsis.

Methods

A total of 63 patients with sepsis and 43 normal controls were enrolled from a prospective multicentre cohort. The biological functions of the metabolome were assessed by coexpression network analysis. A molecular network based on metabolomics and proteomics data was constructed to investigate the key molecules.

Results

Untargeted metabolomics analysis revealed widespread dysregulation of amino acid metabolism, which regulates inflammation and immunity, in patients with sepsis. Seventy-three differentially expressed metabolites (|log₂ fold change| > 1.5, adjusted P value < 0.05 and variable importance in the projection (VIP) > 1.5) that could predict sepsis were identified. External validation of the hub metabolites was consistent with the derivation results (area under the receiver operating characteristic curve (AUROC): 0.81–0.96/0.62–1.00). The pentose phosphate pathway was found to be related to sepsis-associated encephalopathy. Phenylalanine metabolism was associated with sepsis-associated acute kidney injury. The key molecular alterations of the multiomics network in sepsis compared to normal controls implicate acute inflammatory response, platelet degranulation, myeloid cell activation involved in immune response and phenylalanine, tyrosine and tryptophan biosynthesis, and arginine biosynthesis.

Conclusions

Integrated analysis of untargeted metabolomics and proteomics revealed characteristic metabolite and protein alterations in sepsis, which were mainly involved in inflammation-related pathways and amino acid metabolism. This study depicted the pathological characteristics and pathways involved in sepsis and potential therapeutic targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03320-y.

Anatomical and clinical implications of vagal modulation of the spleen

The vagus nerve coordinates most physiologic functions including the cardiovascular and immune systems. This mechanism has significant clinical implications because electrical stimulation of the vagus nerve can control inflammation and organ injury in infectious and inflammatory disorders. The complex mechanisms that mediate vagal modulation of systemic inflammation are mainly regulated via the spleen. More specifically, vagal stimulation prevents organ injury and systemic inflammation by inhibiting the production of cytokines in the spleen. However, the neuronal regulation of the spleen is controversial suggesting that it can be mediated by either monosynaptic innervation of the splenic parenchyma or secondary neurons from the celiac ganglion depending on the experimental conditions. Recent physiologic and anatomic studies suggest that inflammation is regulated by neuro-immune multi-synaptic interactions between the vagus and the splanchnic nerves to modulate the spleen. Here, we review the current knowledge on these interactions, and discuss their experimental and clinical implications in infectious and inflammatory disorders.

Glucose Activates Vagal Control of Hyperglycemia and Inflammation in Fasted Mice

Sepsis is a leading cause of death in hospitalized patients. Many experimental treatments may have failed in clinical trials for sepsis, in part, because they focused on immune responses of healthy animals that did not mimic the metabolic settings of septic patients. Epidemiological studies show an association between metabolic and immune alterations and over 1/3 of septic patients are diabetic, but the mechanism linking these systems is unknown. Here, we report that metabolic fasting increased systemic inflammation and worsened survival in experimental sepsis. Feeding and administration of glucose in fasted mice activated the vagal tone without affecting blood pressure. Vagal stimulation attenuated hyperglycemia and serum TNF levels in sham but only hyperglycemia in splenectomized mice. Vagal stimulation induced the production of dopamine from the adrenal glands. Experimental diabetes increased hyperglycemia and systemic inflammation in experimental sepsis. Fenoldopam, a specific dopaminergic type-1 agonist, attenuated hyperglycemia and systemic inflammation in diabetic endotoxemic mice. These results indicate that glucose activates vagal control of hyperglycemia and inflammation in fasted septic mice via dopamine.

Dopaminergic Control of Inflammation and Glycemia in Sepsis and Diabetes

Most preclinical treatments for sepsis failed in clinical trials in part because the experimental models of sepsis were performed on healthy animals that do not mimic septic patients. Here, we report that experimental diabetes worsens glycemia, inflammation, and mortality in experimental sepsis. Diabetes increases hyperglycemia, systemic inflammation, and mortality in sepsis. Diabetes exacerbates serum tumor necrosis factor (TNF) levels in sepsis by increasing splenic TNF production. Both serum from diabetic mice and glucose increase cytokine production in splenocytes. Anti-inflammatory treatments cannot control hyperglycemia and are less effective in diabetic patients. By contrast, dopaminergic agonist type-1, fenoldopam, attenuates hyperglycemia, and systemic inflammation in diabetic septic mice by inhibiting splenic p65NF-kB phosphorylation. Fenoldopam inhibits TNF production in splenocytes even at high glucose concentrations and inhibits the canonical NF-kB pathway by inhibiting p65RelA and p50NF-kB1 phosphorylation without affecting the non-canonical NF-kB proteins. Treatment with fenoldopam rescues diabetic mice from established polymicrobial peritonitis even when the treatment is started after the onset of sepsis. These results suggest that dopaminergic agonists can control hyperglycemia, systemic inflammation and provide therapeutic advantages for treating diabetic patients with sepsis in a clinically relevant time frame.

The implication of neuronimmunoendocrine (NIE) modulatory network in the pathophysiologic process of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder implicitly marked by the substantia nigra dopaminergic neuron degeneration and explicitly characterized by the motor and non-motor symptom complexes. Apart from the nigrostriatal dopamine depletion, the immune and endocrine study findings are also frequently reported, which, in fact, have helped to broaden the symptom spectrum and better explain the pathogenesis and progression of PD. Nevertheless, based on the neural, immune, and endocrine findings presented above, it is still difficult to fully recapitulate the pathophysiologic process of PD. Therefore, here, in this review, we have proposed the neuroimmunoendocrine (NIE) modulatory network in PD, aiming to achieve a more comprehensive interpretation of the pathogenesis and progression of this disease. As a matter of fact, in addition to the classical motor symptoms, NIE modulatory network can also underlie the non-motor symptoms such as gastrointestinal, neuropsychiatric, circadian rhythm, and sleep disorders in PD. Moreover, the dopamine (DA)-melatonin imbalance in the retino-diencephalic/mesencephalic-pineal axis also provides an alternative explanation for the motor complications in the process of DA replacement therapy. In conclusion, the NIE network can be expected to deepen our understanding and facilitate the multi-dimensional management and therapy of PD in future clinical practice.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

Differential Response of Dopamine Mediated by β-Adrenergic Receptors in Human Keratinocytes and Macrophages: Potential Implication in Wound Healing

OBJECTIVE

Dopamine is an immunomodulatory neurotransmitter. In the skin, keratinocytes and macrophages produce proinflammatory cytokines and metalloproteinases (MMPs) which participate in wound healing. These cells have a catecholaminergic system that modulates skin pathophysiologic processes. We have demonstrated that dopamine modulates cytokine production in keratinocytes via dopaminergic and adrenergic receptors (ARs). The aim of this study was to evaluate the effect of dopamine and its interaction with β-ARs in human HaCaT keratinocytes and THP-1 macrophages. We evaluated the production of inflammatory mediators implicated in wound healing.

METHODS

Cells were stimulated with dopamine in the absence or presence of the β-adrenergic antagonist propranolol. Wound closure, MMP activity, and the production of IL-8, IL-1β, and IκB/NFκB pathway activation were determined in stimulated cells.

RESULTS

Dopamine did not affect the wound closure in human keratinocytes, but diminished the propranolol stimulatory effect, thus delaying cell migration. Similarly, dopamine significantly decreased MMP-9 activity and the propranolol-induced MMP activity. Dopamine significantly increased the p65-NFκB subunit levels in the nuclear extracts, which were reduced in the presence of propranolol in keratinocytes. On the other hand, dopamine significantly increased MMP-9 activity in THP-1 macrophages, but did not modify the propranolol-increased enzymatic activity. Dopamine significantly increased IL-8 production in human macrophages, an effect that was partially reduced by propranolol. Dopamine did not modify the p65-NFκB levels in the nuclear extracts in THP-1 macrophages.

CONCLUSION

We suggest that the effect of dopamine via β-ARs depends on the physiological condition and the cell type involved, thus contributing to either improve or interfere with the healing process.

Dopamine receptor DR2 expression in B cells is negatively correlated with disease activity in rheumatoid arthritis patients

OBJECTIVE

Dopamine receptor (DR) signaling is involved in the pathogenesis of autoimmune diseases. We aimed to measure the expression levels of DR1-5 on B cells from patients with rheumatoid arthritis (RA) and to analyze the relationship between DRs and clinical manifestations, inflammatory biomarkers, functional status and disease activity.

METHODS

A total of 29 patients with RA, 12 healthy donors and 12 patients with osteoarthritis (OA) were recruited in this study. Flow cytometry was used to measure the levels of DR1-5 expressed on B cells. The relationships between B cell DR expressions and clinical features in RA patients were analyzed using the Spearman correlation test.

RESULTS

The expression levels of B cell DR1-5 in both the RA and OA groups were lower than those in healthy controls. After 3 months of medication, all five receptors were elevated in RA patients, with DR2 and DR3 being significantly increased from the baseline. DR2 expression on B cells was negatively correlated with inflammatory biomarkers and disease activity.

CONCLUSION

RA patients had lower expression level of DR2 on B cells compared to the healthy controls, and the level of DR2 negatively correlated with the disease activity. DR2 and DR3 might be novel predictors of patient responses to disease modifying antirheumatic drug therapy.

Influence of metoclopramide on abdominal wall healing in rats subjected to colonic anastomosis in the presence of peritoneal sepsis induced

PURPOSE

To evaluate the effects of metoclopramide on abdominal wall healing in rats in the presence of sepsis.

METHODS

40 rats divided into two groups of twenty animals, subdivided into two subgroups of 10 animals each: group (E) - treated with metoclopramide, and saline-treated control group. The two groups were divided into subgroups of 10 to be killed on the 3rd day (n = 10) or day 7 (n = 10) after surgery. Sepsis was induced by cecal ligation and puncture. We performed also the section and anastomosis in left colon. The synthesis of the abdominal wall was made with 3-0 silk thread. We measured the breaking strength of the abdominal wall and made the histopathological evaluation.

RESULTS

on 3rd day postoperative, the average breaking strength in the E group was 0.83 ± 0.66 and in group C was 0.35 ± 0.46 (p = 0.010). On the seventh day, the breaking strength in group E was 11.44 ± 5.07, in group C 11.66 ± 7.38 (p = 1.000). The E7 group showed lower inflammatory infiltration, foreign body reaction, fibrin than control.

CONCLUSION

animals treated with metoclopramide had a higher resistance of the abdominal wall on the 3rd postoperative day.

Inotrope and vasopressor therapy of septic shock

The ultimate goals of hemodynamic therapy in shock are to restore effective tissue perfusion and to normalize cellular metabolism. In sepsis, both global and regional perfusion must be considered. In addition, mediators of sepsis can perturb cellular metabolism, leading to inadequate use of oxygen and other nutrients despite adequate perfusion; one would not expect organ dysfunction mediated by such abnormalities to be corrected by hemodynamic therapy. Despite the complex pathophysiology of sepsis, an underlying approach to its hemodynamic support can be formulated that is particularly pertinent with respect to vasoactive agents. Both arterial pressure and tissue perfusion must be taken into account when choosing therapeutic interventions and the efficacy of hemodynamic therapy should be assessed by monitoring a combination of clinical and hemodynamic parameters. It is relatively easy to raise blood pressure, but somewhat harder to raise cardiac output in septic patients. How to optimize regional blood and microcirculatory blood flow remains uncertain. Specific end points for therapy are debatable and are likely to evolve. Nonetheless, the idea that clinicians should define specific goals and end points, titrate therapies to those end points, and evaluate the results of their interventions on an ongoing basis remains a fundamental principle. The practice parameters were intended to emphasize the importance of such an approach so as to provide a foundation for the rational choice of vasoactive agents in the context of evolving monitoring techniques and therapeutic approaches.

Dopamine and renal function and blood pressure regulation

Dopamine is an important regulator of systemic blood pressure via multiple mechanisms. It affects fluid and electrolyte balance by its actions on renal hemodynamics and epithelial ion and water transport and by regulation of hormones and humoral agents. The kidney synthesizes dopamine from circulating or filtered L-DOPA independently from innervation. The major determinants of the renal tubular synthesis/release of dopamine are probably sodium intake and intracellular sodium. Dopamine exerts its actions via two families of cell surface receptors, D1-like receptors comprising D1R and D5R, and D2-like receptors comprising D2R, D3R, and D4R, and by interactions with other G protein-coupled receptors. D1-like receptors are linked to vasodilation, while the effect of D2-like receptors on the vasculature is variable and probably dependent upon the state of nerve activity. Dopamine secreted into the tubular lumen acts mainly via D1-like receptors in an autocrine/paracrine manner to regulate ion transport in the proximal and distal nephron. These effects are mediated mainly by tubular mechanisms and augmented by hemodynamic mechanisms. The natriuretic effect of D1-like receptors is caused by inhibition of ion transport in the apical and basolateral membranes. D2-like receptors participate in the inhibition of ion transport during conditions of euvolemia and moderate volume expansion. Dopamine also controls ion transport and blood pressure by regulating the production of reactive oxygen species and the inflammatory response. Essential hypertension is associated with abnormalities in dopamine production, receptor number, and/or posttranslational modification.

Norepinephrine or Dopamine for Septic Shock

Received July 30, 2010, and in revised form September 14, 2010. Accepted for publication September 20, 2010. Background: There is debate as to the vasopressor agent of choice in patients with septic shock. According to current guidelines either dopamine or norepinephrine may be considered as the first-line agent for the management of refractory hypotension of septic shock. Objective: The aim of this systematic review was to evaluate randomized clinical trials which compared norepinephrine versus dopamine in critically ill patients with septic shock or in a population of critically ill patients with shock predominantly secondary to sepsis. Data Sources: MEDLINE, Embase, Scopus, Cochrane Register of Controlled Trials and citation review of relevant primary and review articles. Study Selection: Randomized clinical trials that compared norepinephrine with dopamine in critically ill adults with sepsis and reported the 28-day or in-hospital mortality. Data Extraction: We abstracted data on study design, study setting, patient population, 28-day mortality or in-hospital mortality, rate of arrhythmias, hospital length of stay, and ICU length of stay. Data Synthesis: Six studies met our inclusion criteria. These studies included a total of 2043 participants, with 995 in the norepinephrine and 1048 in the dopamine groups. There were 479 (48%) deaths in the norepinephrine group and 555 (53%) deaths in the dopamine group. There was statistically significant superiority of norepinephrine over dopamine for the outcome of in-hospital or 28-day mortality: pooled RR: 0.91 (95% CI 0.83 to 0.99; P = .028). We also found a statistically significant decrease in the rate of cardiac arrhythmias in the norepinephine group as compared to the dopamine group: pooled RR: 0.43 (95% CI 0.26 to 0.69; P ≤ .001). A subgroup analysis that pooled studies in which all the randomized patients had septic shock demonstrated that norepinephrine improved in-hospital or 28-day mortality; however, the results were no longer statistically significant. Conclusions: The analysis of the pooled studies that included a critically ill population with shock predominantly secondary to sepsis showed superiority of norepinephrine over dopamine for in-hospital or 28-day mortality.

cDNA cloning and induction of tyrosine hydroxylase gene from the diamondback moth, Plutella xylostella

We cloned a full-length tyrosine hydroxylase cDNA from the integument of the diamondback moth, Plutella xylostella. In the phylogenetic tree, tyrosine hydroxylase (PxTH) clustered with the other lepidopteran THs. Serine residues in the PxTH sequence, namely Ser(24), Ser(31), Ser(35), Ser(53), and Ser(65), were predicted to be the target sites for phosphorylation based on PROSITE analysis. In particular, Ser(35) of PxTH is highly conserved across a broad phylogenetic range of animal taxa including rat and human. Western blot analysis using both PxTH-Ab1 and PxTH-Ab2 polyclonal antibodies verified the expression of PxTH in all life cycle stages of P. xylostella, namely the larval, pupal, and adult stages. To examine the possible immune function of PxTH in P. xylostella, PxTH gene expression was investigated by RT-PCR and western blotting analysis after challenging P. xylostella with bacteria. PxTH expression was elevated 1 h post-infection and was continued till 12 h of post-infection relative to control larvae injected with sterile water.

Metabolic syndrome is a low-grade systemic inflammatory condition

An increase in proinflammatory cytokines, a decrease in endothelial nitric oxide and adiponectin levels and an alteration in hypothalamic peptides and gastrointestinal hormones that regulate satiety, hunger and food intake all occur in metabolic syndrome. Consumption of a diet that is energy dense and rich in saturated and trans-fats by pregnant women and lactating mothers, in childhood and adult life may trigger changes in the hypothalamic and gut peptides and hormones. Such changes modulate immune response and inflammation and lead to alterations in the hypothalamic 'bodyweight/appetite/satiety set point' and result in the initiation and development of the metabolic syndrome. Roux-en-gastric bypass induces weight loss, decreases the levels of cytokines and restores hypothalamic neuropeptides and gut hormones and the hypothalamic bodyweight/appetite/satiety set point to normal. Thus, metabolic syndrome is a low-grade systemic inflammatory condition with its origins in the perinatal period and childhood.

The immunoregulatory role of dopamine: an update

The neurotransmitter dopamine (DA) is an important molecule bridging the nervous and immune systems. DA through autocrine/paracrine manner modulates the functions of immune effector cells by acting through its receptors present in these cells. DA also has unique and opposite effects on T cell functions. Although DA activates naïve or resting T cells, but it inhibits activated T cells. In addition, changes in the expression of DA receptors and their signaling pathways especially in T cells are associated with altered immune functions in disorders like schizophrenia and Parkinson's disease. These results suggest an immunoregulatory role of DA. Therefore, targeting DA receptors and their signaling pathways in these cells by using DA receptor agonists and antagonists may be useful for the treatment of diseases where DA induced altered immunity play a pathogenic role.

Inotrope and vasopressor therapy of septic shock

When fluid administration fails to restore an adequate arterial pressure and organ perfusion in patients with septic shock, therapy with vasoactive agents should be initiated. The ultimate goals of such therapy in shock are to restore effective tissue perfusion and to normalize cellular metabolism. The efficacy of hemodynamic therapy in sepsis should be assessed by monitoring a combination of clinical and hemodynamic parameters. Although specific end points for therapy are debatable, and therapies will inevitably evolve as new information becomes available, the idea that clinicians should define specific goals and end points, titrate therapies to those end points, and evaluate the results of their interventions on an ongoing basis remains a fundamental principle.

Pharmacological optimization of tissue perfusion

After fluid resuscitation, vasoactive drug treatment represents the major cornerstone for correcting any major impairment of the circulation. However, debate still rages as to the choice of agent, dose, timing, targets, and monitoring modalities that should optimally be used to benefit the patient yet, at the same time, minimize harm. This review highlights these areas and some new pharmacological agents that broaden our therapeutic options.

[Is there still a place for dopamine in the paediatric critical care setting?]

Dopamine is mostly used in patients with cardiogenic or septic shock, but its place in critical care medicine is often questioned. Dopamine, of which pharmacology in children is variable, is prescribed for its inotropic effect, associated with an increase in cardiac output and at a lesser degree blood pressure. Beneficial effects (need for renal replacement therapy and mortality) of low dose in patients at risk of, or with acute renal failure are not demonstrated. Dopamine has numerous potential deleterious effects on local circulations (pulmonary, cerebral, coronary and cutaneous), respiratory function, gastroduodenal motility, endocrine function (further depression of the hypothalamic-pituitary axis induced by stress) and immunity (partially due to decreased production of prolactin). Finally, in shocked adults dopamine infusion might be associated with an increase in mortality rate. Dopamine remains the most prescribed catecholamine, either in adults or children. It still is one of the first line drug included in the recent recommendations for the treatment of septic shock (norepinephrine tends to replace it), cardiogenic shock (dobutamine is the first drug), severe head trauma, and organ donor in cerebral death. In conclusion, if dopamine is today less used, there is no proof that its deleterious effects are associated with an excess of mortality. Thus, dopamine still is part of the stock of drugs that act on the cardiocirculatory system (but for how long?).