Effects of β2adrenoceptor agonists on T-cell subpopulations

Reciprocal modulation of helper Th1 and Th17 cells by the β2-adrenergic receptor agonist drug terbutaline

Catecholamine hormones are powerful regulators of the immune system produced by the sympathetic nervous system (SNS). They regulate the adaptive immune system by altering T-cell differentiation into T helper (Th) 1 and Th2 cell subsets, but the effect on Th17 cells is not known. Th17 cells, defined, in part, by chemokine receptor CCR6 and cytokine interleukin (IL)-17A, are crucial for mediating certain pathogen-specific responses and are linked with several autoimmune diseases. We demonstrated that a proportion of human Th17 cells express beta 2-adrenergic receptor (β2AR), a G protein-coupled receptor that responds to catecholamines. Activation of peripheral blood mononuclear cells, which were obtained from venous blood drawn from healthy volunteers, with anti-cluster of differentiation 3 (CD3) and anti-CD28 and with a β2-agonist drug, terbutaline (TERB), augmented IL-17A levels (P < 0.01) in the majority of samples. TERB reduced interferon gamma (IFNγ) indicating that IL-17A and IFNγ are reciprocally regulated. Similar reciprocal regulation was observed with dbcAMP. Proliferation of Th cells was monitored by carboxyfluorescein diacetate N-succinimidyl ester labeling and flow cytometry with antibody staining for CD3 and CD4. TERB increased proliferation by a small but significant margin (P < 0.001). Next, Th17 cells (CD4⁺ CXCR3^- CCR6⁺ ) were purified using an immunomagnetic positive selection kit, which removes all other mononuclear cells. TERB increased IL-17A from purified Th17 cells, which argues that TERB acts directly on Th17 cells. Thus, hormone signals from the SNS maintain a balance of Th cells subtypes through the β2AR.

Impact of Aging and Cytomegalovirus on Immunological Response to Influenza Vaccination and Infection

The number of people over the age of 60 is expected to double by 2050 according to the WHO. This emphasizes the need to ensure optimized resilience to health stressors in late life. In older adults, influenza is one of the leading causes of catastrophic disability (defined as the loss of independence in daily living and self-care activities). Influenza vaccination is generally perceived to be less protective in older adults, with some studies suggesting that the humoral immune response to the vaccine is further impaired in cytomegalovirus (CMV)-seropositive older people. CMV is a β-herpes virus infection that is generally asymptomatic in healthy individuals. The majority of older adults possess serum antibodies against the virus indicating latent infection. Age-related changes in T-cell-mediated immunity are augmented by CMV infection and may be associated with more serious complications of influenza infection. This review focuses on the impact of aging and CMV on immune cell function, the response to influenza infection and vaccination, and how the current understanding of aging and CMV can be used to design a more effective influenza vaccine for older adults. It is anticipated that efforts in this field will address the public health need for improved protection against influenza in older adults, particularly with regard to the serious complications leading to loss of independence.

Pharmacological targeting of allergen-specific T lymphocytes

Allergic disorders are the result of a complex pathophysiology, involving major cellular lineages and a multitude of humoral factors of the innate and adaptive immune system, and have the tendency to involve multiple organs. Consequently, even standard pharmacological treatment of allergies is rarely specific but usually targets more than one pathway/cellular system at a time. Accordingly, many of the classic anti-allergic drugs have a critical impact also on T helper cells, which are pivotal not only during the sensitization but also the maintenance phase of allergic diseases. Recent years have seen a dramatic increase of novel drugs with the potency to interfere, more or less specifically, with T lymphocyte function, which might, possibly together with classic anti-allergic drugs, help harnessing one of the central cellular players in allergic responses. A major theme in the years to come will be a thoughtful combination of previously established with recently developed treatment modalities.

Surgery as a double-edged sword: a clinically feasible approach to overcome the metastasis-promoting effects of surgery by blunting stress and prostaglandin responses

Surgery remains an essential therapeutic approach for most solid malignancies, including breast cancer. However, surgery also constitutes a risk factor for promotion of pre-existing micrometastases and the initiation of new metastases through several mechanisms, including the release of prostaglandins and stress hormones (e.g., catecholamines and glucocorticoids). However, the perioperative period also presents an opportunity for cell mediated immunity (CMI) and other mechanisms to eradicate or control minimal residual disease, provided that the deleterious effects of surgery are minimized. Here, we discuss the key role of endogenous stress hormones and prostaglandins in promoting the metastatic process through their direct impact on malignant cells, and through their deleterious impact on anti-cancer CMI. We further discuss the effects of anesthetic techniques, the extent of surgery, pain alleviation, and timing within the menstrual cycle with respect to their impact on tumor recurrence and physiological stress responses. Last, we suggest an attractive perioperative drug regimen, based on a combination of a cyclooxygenase (COX)-2 inhibitor and a β-adrenergic blocker, which we found effective in attenuating immune suppression and the metastasis-promoting effects of surgery in several tumor models. This regimen is clinically applicable, and could potentially promote disease free survival in patients operated for breast and other types of cancer.

Expression of alpha-AR subtypes in T lymphocytes and role of the alpha-ARs in mediating modulation of T cell function

OBJECTIVES

Previous work in our laboratory has shown that alpha-adrenoreceptors (alpha-ARs) and beta-ARs exist on lymphocytes from functional profile, and that the receptors mediate the regulation of lymphocyte function by catecholamines. In the present study, we directly examined the expression of alpha-AR subtypes, alpha(1)-AR and alpha(2)-AR mRNAs, in T lymphocytes and explored the roles of the alpha-AR subtypes and intracellular signal transduction mechanisms linked to the receptors in mediating the modulation of T lymphocyte function.

METHODS

T lymphocytes from mesenteric lymph nodes of rats were purified by using a nylon wool column. Reverse transcription polymerase chain reaction was used to detect the expression of alpha(1)-AR and alpha(2)-AR mRNAs in the freshly isolated T cells and the mitogen concanavalin A (Con A)-activated lymphocytes. Colorimetric methylthiazoletetrazolium assay was employed to measure lymphocyte proliferation induced by Con A. Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) levels in the Con A-stimulated lymphocyte culture supernatants were examined by enzyme-linked immunosorbent assay.

RESULTS

T cells expressed both alpha(1)-AR and alpha(2)-AR mRNAs. The expression of both alpha(1)-AR and alpha(2)-AR mRNAs was significantly higher in the Con A-activated lymphocytes than in the resting lymphocytes. Phenylephrine, a selective alpha(1)-AR agonist, had no evident effect on lymphocyte proliferation nor on IFN-gamma and IL-4 production induced by Con A. However, the selective alpha(2)-AR agonist clonidine attenuated Con A-induced lymphocyte proliferation as well as IFN-gamma and IL-4 production. The inhibited lymphocyte proliferation and IFN-gamma and IL-4 production by clonidine were blocked by yohimbine, an alpha(2)-AR antagonist. Either phospholipase C inhibitor U-73122 or protein kinase C inhibitor chelerythrine partially prevented the suppressive effect of clonidine on Con A-stimulated lymphocyte proliferation and IL-4 production.

CONCLUSIONS

T lymphocytes express both alpha(1)-ARs and alpha(2)-ARs, but only the alpha(2)-ARs participate in the suppressive modulation of lymphocyte proliferation and cytokine production in vitro. The inhibitory effect of alpha(2)-AR stimulation on lymphocyte function is partially mediated via the phospholipase C-protein kinase C pathway.

Interleukin-10-secreting "regulatory" T cells induced by glucocorticoids and beta2-agonists

Greater clinical benefit in controlling the symptoms of asthma is frequently observed through combining moderate doses of inhaled glucocorticoids together with long-acting beta(2)-agonists, as compared with increasing glucocorticoid dosage alone. To address in vitro whether glucocorticoids plus beta(2)-agonists, compared with glucocorticoids alone, have greater inhibitory activity on CD4+ T cell responses to allergen, peripheral blood CD4+ T cell responses to allergen were compared in the presence or absence of the glucocorticoid fluticasone proprionate and the short- and long-acting beta(2)-agonists salbutamol and salmeterol, respectively. Fluticasone proprionate inhibited interleukin (IL)-5 and IL-13 and enhanced IL-10 synthesis in allergen-stimulated cultures in a concentration-dependent manner. Salmeterol, but not salbutamol, inhibited IL-5 and IL-13 and enhanced IL-10 synthesis in these cultures. When used in combination the two drugs demonstrated an additive effect on this pattern of cytokine production. Allergen-specific T cell lines induced in the presence of salmeterol and fluticasone proprionate inhibited IL-5 and IL-13 production by allergen-specific Th2 cell lines in an IL-10-dependent manner. Thus fluticasone proprionate and salmeterol increased IL-10 and reduced Th2 cytokine synthesis additively in allergen stimulated human CD4+ T cells.

Differential control of TH1 versus TH2 cell responses by the combination of low-dose steroids with beta2-adrenergic agonists

BACKGROUND

Combination treatment with steroids and long-acting beta2-agonists provides greater asthma control than simply increasing the dose of steroids.

OBJECTIVE

Although the effects of combination treatment with steroids and long-acting beta2-agonists have been attributed to their anti-inflammatory and bronchodilator effects, the ability of this combination to act synergistically on T cells has not been explored.

METHODS

PBMCs from control subjects and allergic asthmatic patients were stimulated with PHA in the presence of low doses of fluticasone propionate (FP) with or without salmeterol for 72 hours. The inhibition of T-cell proliferation, cytokine production, and glucocorticoid receptor translocation was measured.

RESULTS

Both groups showed a similar degree of inhibition of PHA-induced T-cell proliferation with FP (inhibitory concentration of 50% approximately 10(-9) mol/L) alone. Use of lower concentrations of FP (10(-12) to 10(-11) mol/L) in combination with salmeterol (10(-10) to 10(-7) mol/L) in control subjects provided similar inhibition of proliferation. This combination treatment was associated with significantly greater glucocorticoid receptor translocation into the cell nucleus compared with that seen with FP alone (10(-12) mol/L; P <.01). In contrast, FP-salmeterol failed to act synergistically in asthmatic patients. The 2-drug combination significantly inhibited production of TNF-alpha and IFN-gamma in both groups (P <.05) but failed to inhibit TH2 cytokine (IL-5 and IL-13) production by PBMCs from asthmatic patients. Because allergic inflammation is associated with increased levels of cellular phosphodiesterases that might degrade salmeterol-induced cyclic adenosine monophosphate, rolipram (10(-6) mol/L), a phosphodiesterase 4 inhibitor, was added to the FP-salmeterol combination. This triple combination of drugs enhanced inhibitory activity of low-dose steroids on T-cell proliferation in asthmatic patients and inhibited IL-13 production.

CONCLUSION

These data suggest that beta2-agonists in combination with low doses of steroids can suppress T-cell proliferation and TH1 cytokine production from healthy individuals, but suppression of T cells with a combination of FP and salmeterol in asthmatic patients requires inhibition of phosphodiesterases.

Relationship between changes in interferon-gamma production by peripheral blood T cells and changes in peak expiratory flow rate in patients with chronic stable asthma

BACKGROUND

Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity.

OBJECTIVE

To investigate the relationship between changes in IFN-gamma production by peripheral blood T cells and changes in lung function in chronic stable asthmatics.

METHODS

Sixteen patients with chronic stable moderate asthma aged 35-65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-gamma, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Patients with increased IFN-gamma changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P < 0.05) PEFR compared with those with decreased IFN-gamma changes. The changes in IFN-gamma production and IFN-gamma: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P < 0.02; Rs = 0.63, P < 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively.

CONCLUSIONS

These findings suggest that IFN-gamma may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma.

Modulation of T-cell function by (R)- and (S)-isomers of albuterol: anti-inflammatory influences of (R)-isomers are negated in the presence of the (S)-isomer

BACKGROUND

beta(2)-Adrenergic agonists interact with specific receptors on T lymphocytes to mediate anti-inflammatory activities. However, anti-inflammatory effects are not observed when beta(2)-adrenergic agonists are administered in vivo as racemates.

OBJECTIVE

We hypothesized that anti-inflammatory influences are mediated by the (R)-isomer and are masked in the additional presence of the (S)-isomer.

METHODS

Antigen-specific T-cell lines were generated in the presence of recombinant human IL-2 and tetanus with or without varying concentrations of (R)- and (S)-isomers of albuterol alone or in combination. Parallel lines were generated in the presence of propranolol. Cells were briefly pulsed with PHA and evaluated for proliferation, apoptosis, and cytokine secretion.

RESULTS

(R)-Albuterol significantly inhibited T-cell proliferation (77.0% +/- 9.7% of control at 10(-8) mol/L and 61.1% +/- 9.0% at 10(-7) mol/L). No influence was observed with (S)-albuterol alone. However, the addition of (S)-albuterol to (R)-albuterol mediated a dose-dependent increase in proliferation. At equivalent concentrations of the 2 isomers, proliferation was unchanged from the control, whereas at 10(-6) mol/L (S)-albuterol, proliferation was enhanced. Both the inhibitory effects of (R)-albuterol alone and the stimulating influence of (R)- plus (S)-albuterol were blocked in the additional presence of propranolol. (R)-Albuterol at 10(-8) mol/L inhibited IL-2 and IFN-gamma production. Racemic albuterol (10(-8) mol/L each) had no influence on cytokine production; however, the combination of 10(-8) mol/L (R)-albuterol with 10(-6) (S)-albuterol stimulated production of IL-2 and IL-13. No effects were observed on apoptosis or cell viability.

CONCLUSION

These studies confirm the beta-adrenergic receptor-specific anti-inflammatory effects of (R)-albuterol. The racemate had minimal influences on proliferation or cytokine production. The presence of excess (S)-albuterol resulted in proinflammatory influences. We hypothesize that the (S)-isomer functions as an inverse agonist to switch the function of the beta(2)-adrenergic receptor.