Relation between lymphocyte subpopulations and pineal function in patients with early or metastatic cancer

Immunoregulatory role of melatonin in cancer

Melatonin is a ubiquitous indole amine that plays a fundamental role in the regulation of the biological rhythm. Disrupted circadian rhythm alters the expression of clock genes and deregulates oncogenes, which finally promote tumor development and progression. An evidence supporting this notion is the higher risk of developing malignancies among night shift workers. Circadian secretion of the pineal hormone also synchronizes the immune system via a reciprocal association that exists between the immune system and melatonin. Immune cells are capable of melatonin biosynthesis in addition to the expression of its receptors. Melatonin induces big changes in different immune cell proportions, enhances their viability and improves immune cell metabolism in the tumor microenvironment. These effects might be directly mediated by melatonin receptors or indirectly through alterations in hormonal and cytokine release. Moreover, melatonin induces apoptosis in tumor cells via the intrinsic and extrinsic pathways of apoptosis, while it protectsthe immune cells. In general, melatonin has a profound impact on immune cell trafficking, cytokine production and apoptosis induction in malignant cells. On such a basis, using melatonin and resynchronization of sleep cycle may have potential implications in immune function enhancement against malignancies, which will be the focus of the present paper.

Melatonin and inflammation-Story of a double-edged blade

Melatonin is an immune modulator that displays both pro- and anti-inflammatory properties. Proinflammatory actions, which are well documented by many studies in isolated cells or leukocyte-derived cell lines, can be assumed to enhance the resistance against pathogens. However, they can be detrimental in autoimmune diseases. Anti-inflammatory actions are of particular medicinal interest, because they are observed in high-grade inflammation such as sepsis, ischemia/reperfusion, and brain injury, and also in low-grade inflammation during aging and in neurodegenerative diseases. The mechanisms contributing to anti-inflammatory effects are manifold and comprise various pathways of secondary signaling. These include numerous antioxidant effects, downregulation of inducible and inhibition of neuronal NO synthases, downregulation of cyclooxygenase-2, inhibition of high-mobility group box-1 signaling and toll-like receptor-4 activation, prevention of inflammasome NLRP3 activation, inhibition of NF-κB activation and upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). These effects are also reflected by downregulation of proinflammatory and upregulation of anti-inflammatory cytokines. Proinflammatory actions of amyloid-β peptides are reduced by enhancing α-secretase and inhibition of β- and γ-secretases. A particular role in melatonin's actions seems to be associated with the upregulation of sirtuin-1 (SIRT1), which shares various effects known from melatonin and additionally interferes with the signaling by the mechanistic target of rapamycin (mTOR) and Notch, and reduces the expression of the proinflammatory lncRNA-CCL2. The conclusion on a partial mediation by SIRT1 is supported by repeatedly observed inhibitions of melatonin effects by sirtuin inhibitors or knockdown.

Relationship of nocturnal melatonin levels to duration and course of multiple sclerosis

Multiple sclerosis (MS) is the most common of the demyelinating diseases of the CNS. The clinical course and prognosis of the disease are variable. Characteristically, the illness tends to progress in a series of relapses and remissions. Over the years there is a tendency for the patient to enter a phase of slow and steady deterioration of neurologic function. In about 10%-20% of patients, the course of the disease is not punctuated by a fluctuating course, but rather by an inexorable progression from the onset. The pineal gland has been implicated recently in the pathogenesis and clinical course of MS. Since MS is generally a chronic progressive disorder, we predicted an association between duration of illness and the activity of the pineal gland. To investigate this hypothesis further, we studied nocturnal plasma melatonin levels in relation to duration of illness in a cohort of 32 MS patients (4 men, 28 women; mean age: 41.1 years; SD = 11.1; mean duration of illness: 13.1 years; SD = 12.4) randomly selected from consecutive hospital admissions to a Neurology service for exacerbation of symptoms. For the purpose of comparison, we also studied in the sample serum prolactin levels. The cohort included 7 patients in whom the duration of illness since onset of first neurological symptoms was < or = 5 years (mean: 3.0 years +/- 1.1) and a cohort of 25 patients in whom the duration of illness was > 5 years (mean: 15.6 years +/- 12.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of morphine withdrawal syndrome on endo-oligopeptidase (EC 3.4.22.19) activity

Endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was examined in several areas of the central nervous system (CNS) as well as in the immune and endocrine tissues of rats chronically treated with morphine and submitted to naloxone-induced withdrawal. A specific fluorogenic substrate was used to determine the endopeptidase 22.19 activity. A non-uniform increase in endopeptidase 22.19 activity was detected in the CNS. The highest increase in endopeptidase 22.19 specific activity was found in the dorsal hippocampus (about 3.5-fold higher than control), followed by occipital and frontal cortex, substantia nigra, thalamus and hypothalamus. In peripheral tissues, a significant decrease of endopeptidase 22.19 was observed in the pineal gland, whereas the morphine withdrawal syndrome caused a slight but significant increase in lymphoid tissues such as lymph nodes and thymus. These findings are indicative of a possible participation of endopeptidase 22.19 in naloxone-induced withdrawal.

Pineal calcification and its relationship to the fatigue of multiple sclerosis

Fatigue is one of the most common clinical features of multiple sclerosis (MS) and is a frequent cause of disability. The pathogenesis of fatigue remains obscure. It may result from impaired propagation of action potentials in areas of demyelination. Other contributors may be mental depression, immobility, and physical disability. The fatigue of MS may be relieved by diverse pharmacological drugs such as amantadine and pemoline, but the mechanisms by which these agents act to ameliorate fatigue are unknown. Attention has been focused recently on the relationship between MS and the pineal gland and evidence has been presented to implicate the pineal gland and melatonin in the pathogenesis of the disease. To investigate this relationship further, we studied in 47 MS patients (mean age: 41.6 +/- 9.9 yrs; mean duration of illness: 13.6 +/- 12.6 yrs) the association between fatigue and incidence of pineal calcification (PC) on CT scan, which is thought to reflect past secretory activity of the gland. For comparison, we also evaluated the incidence of choroid plexus calcification (CPC) in these patients. The sample included 20 patients who experienced ongoing, debilitating fatigue during the course of the disease. 27 patients who did not complain of fatigue served as controls. The two groups were not distinguishable with respect to age, sex, age of onset, chronicity, course (relapsing-remitting vs. chronic progressive), and severity of the disease (ambulatory vs. immobile), as well as the incidence of affective illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple sclerosis: the role of the pineal gland in its timing of onset and risk of psychiatric illness

The incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. It has been suggested, therefore, that the clinical manifestation of MS is dependent upon having passed the pubertal period. Since pineal melatonin secretion declines from childhood to puberty and as melatonin is an immunomodulator, we have proposed that the dramatic decline in melatonin secretion just prior to the onset of the physical manifestations of puberty may disrupt immune responses resulting in either reactivation of the infective agent or in an increased susceptibility to post-pubertal infection. The fall in melatonin secretion during pre-puberty may also increase the susceptibility of these patients to affective disorder which is associated with lower melatonin secretion and the presence of a phase-advance of their biological rhythms. We predicted, therefore, a higher incidence of affective disorder in patients with pubertal or post-pubertal onset of MS compared to those in whom the disease manifested later. To test this hypothesis, we studied the incidence of affective disorder in relation to age of onset of first neurological symptoms in 31 MS patients, 6 of whom manifested symptoms of MS prior to age 18 (mean = 16.8 years). All patients with pubertal onset MS and only 48% of the control group had an affective disorder. The pubertal onset patients also had a significantly lower nocturnal melatonin levels and a lower incidence of pineal calcification on CT scan. These findings thus support the hypothesis implicating the pineal gland in the timing of onset of MS and in the risk for the development of affective disorder.

Clinical aspects of the melatonin action: impact of development, aging, and puberty, involvement of melatonin in psychiatric disease and importance of neuroimmunoendocrine interactions

During the last decade we have learned much on physiological changes in the secretion of the pineal hormone melatonin (MLT) in man. Reportedly, there is little or no MLT secreted before age 3 months. Then MLT production commences, becomes circadian, and reaches highest nocturnal levels at the age of 1-3 years. During all of childhood nocturnal peak levels drop progressively by 80% until adult levels are reached. This alteration appears to be the consequence of increasing body size in face of constant MLT production during childhood. The biological significance of this MLT alteration is presently unknown. Because of conceptual considerations, major depressive syndrome (MDS) and seasonal affective disorder (SAD) have been in the focus of pineal research for several years. Although in these disorders alterations in MLT levels could not be substantiated, light therapy, a consequence of this research, was discovered as an effective treatment for SAD and perhaps for MDS. In addition, there is some recent evidence for low MLT levels in schizophrenia. Finally, the potential effect of MLT in neuroimmunoendocrine interactions is presently explored. Reportedly, in vitro studies and animal experiments give evidence for a modulatory role of MLT in the immune response. However, the exact way of this possible action of MLT remains to be clarified. Clinical studies are too scant for a meaningful estimation of MLT's involvement in human neuroimmunoendocrine interactions.

A brief survey of pineal gland-immune system interrelationships

The present paper summarizes evidence that support the hypothesis of the existence of bilateral interactions between pineal gland and the immune system. Both in vivo and in vitro experiments show that the pineal gland, via its hormone melatonin, enhances immune function. Mechanisms involved in this immunostimulatory effect are not well understood, but some evidence suggests the existence of specific binding sites for melatonin on immune cells. Moreover, the release of opioid peptides and interleukin-2 by T-helper cells may also participate in this mechanism by activating, at least natural killer activity and antibody-dependent cellular cytotoxicity. Some immune signals, i.e., gamma-interferon, may be involved in regulating pineal function, thereby representing a regulatory mechanism in the opposite direction. The physiological and clinical significance of these data remains to be studied.

The role of a thymus-pineal axis in an immune mechanism of aging

The Immune Theory of Aging cannot explain the cause of immune decline. It is hypothesized that the pineal gland acting in utero and during neonatal life in altricial mammals serves as a component of the immune system. Evidence in support of the presence of a thymus-pineal axis is presented. It is postulated that the pineal gland carries a considerable burden of immunological defense during maturation of the thymus, and also acts in the programming of the immune system. By relating thymus and immune function to the pineal and its known role as a neuroendocrine transducer for the entrainment and control of biorhythms, a consilence is developed between the role of the immune system in senescence and the pineal function in biorhythmicity. The relationships developed thus permit an extension of the immune theory as regards causative mechanisms.