Impaired monocyte cyclic AMP responses and monocyte cytotoxicity in atopic dermatitis

Esophageal candidiasis as a complication of inhaled corticosteroids

BACKGROUND

Oropharyngeal candidiasis is a well-described side effect of inhaled corticosteroids. Nevertheless, few cases of esophageal candidiasis have been reported.

OBJECTIVE

To present a patient with esophageal candidiasis associated with inhaled corticosteroids.

METHODS

Case report.

RESULTS

Our patient is a 70-year-old white woman with a 20-year history of intrinsic asthma, well controlled on triamcinolone acetonide 400 micrograms, ipratropium bromide 36 micrograms, and pirbuterol acetate 400 micrograms, each inhaled four times daily. She reported no oral steroid use for > 4 years and that she always rinsed her mouth following triamcinolone acetonide inhalation. The patient had gastritis with peptic ulcer disease in the past and developed worsening dyspeptic pain and heartburn. Following discontinuation of cimetidine and initiation of ranitidine without improvement, esophagogastroduodenoscopy was performed. Several small white patches in the mid and distal esophagus could not be removed with pressure. A biopsy confirmed the diagnosis of candidal esophagitis. Following a 4-week course of fluconazole, the patient was clinically improved and follow-up esophagogastroduodenoscopy was normal. There was no evidence of underlying cellular immunosuppression, malignancy, or diabetes mellitus and no history of recent antibiotic usage. Delayed skin tests revealed 5 x 5 mm induration to dermatophytin. Delayed hypersensitivity to Candida and mumps tests was absent. There was strong in vitro lymphocyte transformation and a positive immediate skin test response to Candida. ELISA for human immunodeficiency virus was negative. T and B cell counts were normal with CD4 = 630/mm3, CD8 = 520/mm3, and absolute B cell = 120/mm3. It is possible that this patient's immediate hypersensitivity response to Candida suppressed her delayed response. Candidal esophagitis is a rare, yet important, complication of inhaled corticosteroid use.

CONCLUSION

Immunocompetent patients on inhaled corticosteroids with medically unresponsive symptoms of esophagitis should be investigated for esophageal candidiasis.

Eicosanoids and essential fatty acid modulation in chronic disease and the chronic fatigue syndrome

Abnormalities of Essential Fatty Acid (EFA) incorporation into phospholipid are found in chronic diseases. More recently changes in circulating EFA metabolites (EFAM) together with EFAM hypo-responsiveness of immune cells and EFAM production from cells have been found associated with disease. We hypothesize that changes in ratio of EFAMs are the normal physiological responses to stressors, but when stressors are excessive or prolonged, EFAM systems may become unpredictably hypo-responsive owing to factors such as receptor down regulation and substrate depletion. In time, many homeostatic system become deranged and held in that state by minor stressors. Literature review of chronic fatigue syndrome (CFS) shows hyper and hypo-responsiveness in immune function, several Hypothalamo-Pituitary (HP) axes and sympathetic nervous system, all relatable to dysfunctional changes in EFA metabolism. For the first time, we explain chronic immune system activation and hypo-responsive immune function in CFS; through EFAMs. Dietary EFA modulation (DEFA) can alter ratios of both membrane EFAs and produced EFAMs, and if maintained can restore hypo-responsive function. We discuss dietary strategies and relevance in CFS, and a case series of CFS patients applying DEFA with other titrated published managements which saw 90% gaining improvement within 3 months and more than 2/3 fit for full time duties. This hypothesis and DEFA may have relevance in other chronic conditions.

Functional desensitization of monocytes from patients with multiple sclerosis due to prostaglandin E

We previously showed that monocytes from patients with multiple sclerosis (MS) produce increased prostaglandin E (PGE) in tissue culture. In this paper we show that monocytes from patients with chronic progressive MS are less sensitive to agents which stimulate PGE synthesis than healthy controls. MS cells are equally sensitive to PG inhibitors. MS monocytes have increased levels of cellular cyclic AMP and are less sensitive to PGE-mediated increases in cAMP. Depressed monocyte natural cytotoxicity was found to be correlated with cellular cAMP. Functional desensitization of monocytes and decreased sensitivity to PGE signals may be related to chronic exposure to prostaglandin E.

Atopic dermatitis: a defect of intracellular secondary messenger systems?

The clinical manifestations of atopic dermatitis comprise a complex mixture of pharmacological, physiological and immunological responses. Circumstantial evidence suggests that atopic disease may arise consequent upon the migration of bone marrow-derived cells into the target tissue of skin or respiratory mucosa. Mediator release from such cells has been shown to be abnormal in atopic dermatitis, and itch, the hallmark of the disease, may be the result of chronic inflammatory mediator release into the skin. Abnormal release of mediators has been shown to correlate with inadequate nucleotide control of cell function. In particular, elevated cyclic AMP-specific PDE activity causing cyclic AMP hyporesponsiveness has been found in peripheral blood mononuclear leucocytes in atopic dermatitis. Investigation of this pathway has led to the discovery of additional abnormalities of other secondary messenger systems, including abnormalities of protein kinase C activity and of inositol activation. The biochemical abnormalities may be a consequence of down-regulation of the second messenger systems because of chronic exposure to low levels of inflammatory mediators, but may themselves subsequently permit further mediator release. They may provide a biochemical mechanism for many of the immunological abnormalities seen in atopic dermatitis. In particular, they offer a biochemical explanation for the paradox of increased type 1-mediated immunity and diminished cell-mediated immunity commonly observed in this complex disease.

Monocyte localization of elevated cAMP phosphodiesterase activity in atopic dermatitis

Patients with atopic dermatitis (AD) manifest a number of immune abnormalities which correlate with in vitro defects including lymphocyte transformation, chemotaxis, and cytotoxicity. Past studies have shown reduced leukocyte cyclic 3',5'-adenosine monophosphate (cAMP) levels after exposure to adenylate cyclase-active agonists, and we have demonstrated that this results from increased catabolism due to elevated cAMP-phosphodiesterase activity. These results were obtained in preparations containing mixtures of lymphocytes and monocytes. In order to determine more precisely the cellular site of the defect we have separated the leukocytes into lymphocyte- and monocyte-enriched preparations using either Percoll-gradient centrifugation or adherence isolation. Both techniques yielded over 93% pure lymphocytes, whereas the former yielded 64% monocytes compared with the latter method which generated 94% pure monocytes. Atopic monocytes, obtained by either technique, consistently showed elevated phosphodiesterase activity compared with those of the nonatopic monocytes. Such differences were not evident in lymphocyte preparations from normal and atopic subjects. In spite of the increased rate of cAMP degradation in atopic leukocytes, the resting cAMP levels do not differ from those of normal subjects. We questioned whether this is caused by increased cAMP synthesis and evaluated cellular adenylate cyclase activity. We found no evidence in AD cells for an increased rate of adenylate cyclase catalysis, either basal activity or after stimulation by forskolin. Therefore, the resting cAMP levels must have been compensated by other mechanisms. Impaired cyclic nucleotide metabolism in atopic monocytes may affect a number of immunologic and inflammatory reactions and could account for many of the clinical abnormalities in atopic diseases.

Abnormal monocyte cytotoxicity and cyclic-AMP levels in systemic sclerosis

Monocyte antibody-dependent cell-mediated cytotoxicity (ADCC) was compared to intrinsic cyclic-adenosine-monophosphate (cAMP) levels in 14 patients with systemic sclerosis. Depressed monocyte cytotoxicity was observed. Elevated cAMP levels (2-5 times) in resting monocytes were found in 5 patients; the rest had normal cAMP values. Monocyte ADCC was inversely correlated to cellular cAMP content (r = -0.6659, P less than 0.02). Scleroderma patients with high basal cAMP levels showed impaired responses to beta-adrenergic stimulation but not to prostaglandin E (PGE1) and histamine. Patients with normal basal cAMP levels showed no defect in beta-adrenergic responses. No close correlation between monocyte abnormality and clinical state was found.

Divergent effects of methylxanthines and adenylate cyclase agonists on monocyte cytotoxicity and cyclic AMP levels

The effects of theophylline, isobutylmethylxanthine (IBMX), prostaglandin E1 (PGE1), and isoproterenol on monocyte antibody-dependent cytotoxicity (ADCC) were compared with their effects on monocyte cyclic adenosine 3':5'-monophosphate (cAMP) levels. Theophylline (2 mmol/l) halved ADCC and gave a 2-fold increase in cAMP levels. At concentrations not elevating cAMP theophylline inhibited ADCC significantly. In comparison, incubation of monocytes with IBMX, PGE1 and isoproterenol ADCC was only modestly inhibited while these agents gave larger increments (3- to 8-fold) in cAMP levels than theophylline did. Low concentrations of IBMX (50 mumol/l) elevated cAMP without affecting monocyte ADCC whereas PGE1 and isoproterenol inhibited ADCC dose-dependently comparable to increases in cAMP. However, in doses giving similar inhibition of ADCC addition of PGE1 resulted in larger cAMP increments than isoproterenol. The effects of IBMX, PGE1 and isoproterenol was dependent on target cell to effector cell ratio and increased during preincubation with the agents. The inhibition of ADCC by the agents was accompanied by a depressed monocyte lysozyme release and depressed activation of hexose monophosphate shunt. However, only theophylline affected monocyte attachment to sensitized target cells. These results argue against the general inverse relationship between cAMP content and inhibition of monocyte ADCC and demonstrate that theophylline independent on increases in cAMP inhibits ADCC probably by abrogation of monocyte binding activity.

On the mechanism of enhanced monocyte and neutrophil cytotoxicity in severe psoriasis

Monocyte and neutrophil function assessed as antibody-dependent cell-mediated cytotoxicity (ADCC) using IgG-sensitizing human erythrocytes as target cells was enhanced in patients with severe psoriasis when compared to healthy controls. We found significant correlation between increased monocyte ADCC and increased neutrophil ADCC, No differences in basal cAMP levels and cAMP responses during initiation of the ADCC reaction was observed between psoriatics and normals. Also degranulation determined as lysozyme release during ADCC was normal. In contrast, the increase in ADCC was significantly correlated to an enhanced hexose monophosphate shunt activation in the effector cells during the cytotoxic reaction. Activity of enzymes responsible for the respiratory burst was not altered in psoriasis since superoxide production after stimulation with phorbol myristate acetate was normal. Likewise, oxygen consumption and degranulation following phagocytosis of opsonized zymosan particles in neutrophils was found normal in psoriasis. Since monocytes showed increased binding of IgG-sensitized erythrocytes these data indicate that the enhanced monocyte and neutrophil ADCC is caused by an enhancement of the respiratory burst possibly induced by increased Fc receptor activity.

Enhanced monocyte and neutrophil cytotoxicity and normal cyclic nucleotide levels in severe psoriasis

Eighteen patients with active psoriasis were investigated for antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by monocytes and neutrophil leukocytes. Patients with extensive psoriatic lesions showed increased ADCC whereas patients with minimal psoriasis had normal monocyte and neutrophil function. After clinical remission the ADCC became normal. No stimulatory factors in psoriatic serum could be demonstrated. The increased monocyte and neutrophil cytotoxicity in severe psoriasis is not explained by altered cyclic nucleotide levels as cAMP and cGMP levels were normal in psoriatic monocytes and neutrophils showing both increased and normal ADCC. Our results indicate that increased ADCC is secondary to the psoriatic activity.

Dialyzable leukocyte extract stimulates cAMP in T gamma lymphocytes

Dialyzable leukocyte extract (DLE) from human blood leukocytes gave a 3- to 8-fold increase in the cAMP concentration after addition to purified lymphocytes. No significant change in cGMP was observed. When purified lymphocytes were separated into T cells and non-T cells by an E-AET rosette technique the cAMP response was most pronounced in T cells. When further separating T lymphocytes into T cells with Fc receptors for IgG and T cells with Fc receptors for IgM (T gamma and T mu lymphocytes), the increase in cAMP following stimulation was specifically conferred to T gamma lymphocytes. Our findings may support the concept that DLE activates T gamma lymphocytes, leading to an increase in suppressor cell function.

Monocyte-mediated antibody-dependent cytotoxicity. Modulation by Glycolysis and insulin

In suspensions of purified human monocytes from 14 healthy persons the antibody-dependent cell-mediated cytotoxicity (ADCC), the lactate release, and the glucose uptake were studied. In non-stimulated monocytes ADCC correlated with lactate release and glucose uptake. Following addition of insulin a dose-related rise in ADCC, lactate release, and glucose uptake was observed. For each of the three processes the maximal insulin effect was about 30%. Most of the stimulation was seen within the physiological concentration range of insulin, and the insulin concentration resulting in 50% of the maximal effect was nearly the same for ADCC, lactate release, and glucose uptake (about 100 pM). The insulin stimulation of ADCC correlated with the stimulation of lactate release and glucose uptake. An inverse correlation between the ADCC of non-stimulated monocytes and the insulin stimulation of ADCC was demonstrated. No relationship was found between monocyte maturity and any of the three variables of monocyte function, either with or without insulin. These results indicate that, for normal monocytes, the cytotoxic capacity is closely related to the glycolysis.

Antibody-dependent monocyte-mediated cytotoxicity in atopic dermatitis. Relation to clinical state and cyclic AMP response

Antibody-dependent monocyte-mediated cytotoxicity was investigated in adult patients with atopic dermatitis. In patients with active dermatitis monocyte cytotoxicity was reduced. Serial studies of individual patients demonstrated that a reduced cytotoxicity in clinical exacerbation did not normalize during clinical remission. The reduced monocyte cytotoxicity was not caused by an abnormal influence of lymphocytes. During the cytotoxicity reaction a rapid and transient elevation of monocyte cyclic AMP occurred. In atopic dermatitis this elevation was decreased, but no relation was found between the monocyte cytotoxicity and the cyclic AMP response in these patients.