Systemic neutrophilia observed during anaphylactic shock in rats is inhibited by dopaminergic antagonists

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.

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.

Dopaminergic Regulation of Innate Immunity: a Review

Dopamine (DA) is a neurotransmitter in the central nervous system as well as in peripheral tissues. Emerging evidence however points to DA also as a key transmitter between the nervous system and the immune system as well as a mediator produced and released by immune cells themselves. Dopaminergic pathways have received so far extensive attention in the adaptive branch of the immune system, where they play a role in health and disease such as multiple sclerosis, rheumatoid arthritis, cancer, and Parkinson's disease. Comparatively little is known about DA and the innate immune response, although DA may affect innate immune system cells such as dendritic cells, macrophages, microglia, and neutrophils. The present review aims at providing a complete and exhaustive summary of currently available evidence about DA and innate immunity, and to become a reference for anyone potentially interested in the fields of immunology, neurosciences and pharmacology. A wide array of dopaminergic drugs is used in therapeutics for non-immune indications, such as Parkinson's disease, hyperprolactinemia, shock, hypertension, with a usually favorable therapeutic index, and they might be relatively easily repurposed for immune-mediated disease, thus leading to innovative treatments at low price, with benefit for patients as well as for the healthcare systems.

The prognostic value of the neutrophil/lymphocyte ratio in patients with snake bites for clinical outcomes and complications

Introduction

Snake bites have cardiotoxicity, neurotoxic, myotoxic, nephrotoxic, and hemotoxic features. The neutrophil/lymphocyte ratio (NLR) provides valuable information for the determination of the diagnosis and prognosis of various diseases. In this study, we aimed to investigate the relationship between NLR with the development of complications and duration of hospital stay in snakebite cases.

Method

In this study, 107 patients with snakebite complaints that applied to a tertiary care university hospital between 2011 and 2014 were retrospectively reviewed. The control group compromised of 107 age-and gender-matched healthy subjects. These patients were examined using their previous laboratory results, bite areas pictures, geographic location, and analysis of complications that developed during the hospitalization.

Results

Patients in our snake bites group (n = 107), included males (64%) and females (36%). When NLR1–NLR2, NLR1–NLR3, and NLR2–NLR3 were compared, a statistically significant difference was found (p < 0.001). No mortality was observed in our patients. In cases of snakebites, 4.67% of the patients underwent finger amputation. Compartment syndrome occurred in 3.73% of patients. In one case that developed compartment syndrome, a finger amputation was made. When 8 patients with a complication were compared with patients having snakebite but no complication, the initial NLR was found to be higher and statistically significant (p = 0.042). The average length of stay of patients in the hospital was 9 days. In the analysis of the correlation between the duration of hospitalization and NLR, the patients with a high level of NLR were found to have a longer hospital stay compared to lower NLR levels (p = 0.012).

Conclusion

NLR was significantly increased in patients that developed complications and needed a longer stay in the hospital.

Sleep enhances the human antibody response to hepatitis A vaccination

OBJECTIVE

The common belief that sleep supports immune defense has received surprisingly little direct experimental support. The antibody response to vaccination provides a valid tool to assess the influence of sleep on adaptive immune functioning in humans, which is also clinically relevant.

METHODS

Two groups of healthy humans (N = 19) not previously infected with hepatitis A virus (HAV) were studied. On the night after primary vaccination with inactivated HAV, which took place at 0900 hours, one group had regular sleep. The other group stayed awake, and did not sleep before 2100 hours the following day. HAV antibody titers were measured repeatedly until 28 days after vaccination. Plasma hormone concentrations and white blood cell (WBC) subset counts were determined on the night and day after vaccination.

RESULTS

Subjects who had regular sleep after vaccination, displayed a nearly two-fold higher HAV antibody titer after 4 weeks than subjects staying awake on this night (p=.018). Compared with wakefulness, sleep after vaccination distinctly increased release of several immune-stimulating hormones including growth hormone, prolactin, and dopamine (p <.01). Concentrations of thyrotropin, norepinephrine, and epinephrine were lowered by sleep (p <.02), whereas sleep only marginally influenced WBC subset counts.

CONCLUSIONS

Data suggest that sleep compared with sleep deprivation on the night after vaccination improves the formation of antigen-specific immune defense as reflected by antibody production in humans. Sleep presumably acts by inducing a hormonal environment in secondary lymphoid tissues, enhancing lymphocyte proliferation and differentiation and finally antibody synthesis. Results underscore the importance of sleep for immunocompetence.

The tripeptide FEG ameliorates systemic inflammatory responses to rat intestinal anaphylaxis

BACKGROUND

Food allergies are generally associated with gastrointestinal upset, but in many patients systemic reactions occur. However, the systemic effects of food allergies are poorly understood in experimental animals, which also offer the opportunity to explore the actions of anti-allergic drugs. The tripeptide D-phenylalanine-D-glutamate-Glycine (feG), which potentially alleviates the symptoms of systemic anaphylactic reactions, was tested to determine if it also reduced systemic inflammatory responses provoked by a gastric allergic reaction.

RESULTS

Optimal inhibition of intestinal anaphylaxis was obtained when 100 microg/kg of feG was given 20 min before the rats were challenged with antigen. The increase in total circulating neutrophils and accumulation of neutrophils in the heart, developing 3 h and 24 h, respectively, after antigen challenge were reduced by both feG and dexamethasone. Both anti-inflammatory agents reduced the increase in vascular permeability induced by antigen in the intestine and the peripheral skin (pinna), albeit with different time courses. Dexamethasone prevented increases in vascular permeability when given 12 h before antigen challenge, whereas feG was effective when given 20 min before ingestion of antigen. The tripeptide prevented the anaphylaxis induced up regulation of specific antibody binding of a cell adhesion molecule related to neutrophil activation, namely CD49d (alpha4 integrin).

CONCLUSIONS

Aside from showing that intestinal anaphylaxis produces significant systemic inflammatory responses in non-intestinal tissues, our results indicate that the tripeptide feG is a potent inhibitor of extra-gastrointestinal allergic reactions preventing both acute (30 min) and chronic (3 h or greater) inflammatory responses.