Current Drug Targets - Immune, Endocrine & Metabolic Disorders - Volume 4, Issue 1, 2004

Our perception of the function of the pineal gland and its hormone melatonin has attained a new dimension during the last decade. Through melatonin, the pineal becomes a principal organ present in vertebrates involved in the control of rhythmic adaptations to daily and seasonal cycles. Melatonin is synthesized and secreted during the dark period of the light / dark cycle. The rhythmic nocturnal melatonin secretion is directly generated by the circadian clock and is entrained to a 24-hour period by the light-dark cycle. The periodic secretion of melatonin may be used as a circadian mediator to any system than can “read” the message. Melatonin acts as an arm of the circadian clock, giving a timerelated signal to a number of body functions; one of them is the circadian organization of the immune response. This review discusses melatonin role in rheumatoid arthritis. Animal studies employing Freund's complete mycobacterial adjuvant (FCA) as a model of rheumatoid arthritis are described. Immune and neuroendocrine circadian rhythms were examined in FCA-injected rats, both in the preclinical phase of arthritis (2-3 days after FCA injection) as well as in the acute phase of the disease (18 days after FCA injection). In arthritic rats, the 24-h organization of immune and neuroendocrine responses becomes altered. Significant effects of immune response on diurnal rhythmicity of adenohypophysial and hypophysiotropic hormones occurred in arthritic rats. Melatonin treatment prevented alteration of 24-h rhythms of serum ACTH, prolactin and luteinizing hormone in rats injected with FCA. In addition, melatonin treatment prevented alteration of the 24-h variation in hypothalamic monoamine transmitter turnover during the preclinical phase of Freund's adjuvant arthritis in rats. A comparison between the inflammatory and immune responses elicited by physiological and pharmacological doses of melatonin in FCA arthritis is reported. Pinealectomized rats exhibited a significantly less pronounced inflammatory response, which was restored to normal by a low melatonin dose (0.3 μg / ml of drinking water), whereas a high melatonin dose (30 μg / ml) that resulted in a 50- 60-fold increase in plasma melatonin, augmented the inflammatory and immune response. These results should be considered in the light of recent reports that rheumatoid arthritis patients have increased nocturnal plasma levels of melatonin and that their synovial macrophages respond to melatonin with an increased cytokine production.

CD26 is a 110 kDa surface-bound ectopeptidase with intrinsic dipeptidyl peptidase IV (DPP IV) activity, which has multiple biological functions. In this review, we will focus specifically on work demonstrating that CD26 has a key role in immune function as a T cell activation molecule and a regulator of the functional effect of selected biological factors through its DPP IV enzyme activity. As further evidence of the important role played by this multifaceted molecule in immune regulation, we will also discuss experimental attempts from our laboratory and others to influence immunemediated conditions through CD26 monoclonal antibodies and DPP IV activity with various agents, including anti-CD26 monoclonal antibodies and DPP IV chemical inhibitors. Of special significance from a clinical perspective is also CD26 effect on glucose metabolism through its DPP IV activity and its potential role as a therapeutic target in diabetes. In addition, we will review recent studies that describe the physical and functional interaction of CD26 with other essential cellular structures and the biological consequences of their association. In particular, we will present recent data from our laboratory that demonstrates the correlation between CD26, especially its DPP IV activity, and the key nuclear protein topoisomerase II alpha, an interaction that has important clinical implications. In summary, we will examine the biology of the multifaceted CD26 / DPP IV molecule, focusing particularly on its function in immune regulation and its potential role as a molecular target for novel treatment modalities for a number of disease states, ranging from autoimmune diseases, diabetes to malignancies.

Nef is one of the six regulatory proteins coded by the Human Immunodeficiency Virus (HIV)-1 and -2, and by the Simian Immunodeficiency Virus (SIV). Accumulating experimental evidences indicate that Nef is required for the optimal infectivity of HIV viral particles, and that it plays a critical role in the AIDS pathogenesis progressing. We previously cloned and sequenced a functionally defective HIV-1 genome (F12HIV-1) whose nef gene showed a rather unusual feature, i.e. its expression blocks the HIV-1 release by interfering with the viral assembling / release. Such a striking phenotype appeared to be the result of three amino acid substitutions, and coupled with the loss of the most part of the Nef functions described for the wild type counterpart. The F12Nef properties encouraged the designing of new strategies of anti HIV-1 gene therapy we afforded by recovering an inducible lentivirus vector expressing F12Nef as the cytoplasmic domain of a transmembrane fusion protein including a selectable marker (i.e. the Nerve Growth Factor receptor) as the ecto- and transmembrane domains. As expected, the expression of such a chimeric protein resulted in a potent protection of transduced cells from the HIV-1 spread. In sum, and surprisingly enough, we generated a reagent effectively counteracting the HIV-1 replication through the combination of a slightly mutated AIDS pathogenetic factor together with a lentivirus vector, i.e. the result of artifactual modifications of the HIV-1 genome.

There is accumulating evidence that local anesthetics have immunological properties in addition to their direct anesthetic activity. Because local anesthetics are often used together with blood vessel contraction drugs, such as epinephrine and felypressin in the clinical setting, we have examined possible abilities of both local anesthetic alone including lidocaine, mepivacaine, procaine, prilocaine and tetracaine, and local anesthetics with blood vessel contraction drugs including lidocaine with epinephrine and prilocaine with felypressin on the functions related to natural immunity in neutrophils and macrophages. In contrast, lidocaine, mepivacaine, procaine, prilocaine and tetracaine all inhibited adhesion, chemotaxis, phagocytosis, and the production of superoxide anion and hydrogen peroxide by neutrophils and macrophages. Lidocaine with epinephrine and prilocaine with felypressin were effective in significantly inhibiting adhesion, chemotaxis, phagocytosis, and the production of hydrogen peroxide by neutrophils and macrophages. Interestingly, lidocaine with epinephrine potentiated the production of superoxide anion, whereas prilocaine with felypressine inhibited the production, irrespective of cells. In addition, epinephrine potentiated the production of superoxide anion, whereas epinephrine inhibited the production of hydrogen peroxide as well as lidocaine with epinephrine. This potentiation by epinephrine was not prevented by adrenergic antagonists. Furthermore, superoxide dismutase potentiated the production of hydrogen peroxide, which was in part prevented by epinephrine. These results suggest that local anesthetics may inhibit the functions related to natural immunity in neutrophils and macrophages. In addition, lidocaine with epinephrine evidently differs from prilocaine with felypressine regarding the molecular mechanisms underlying the modulation of superoxide anion production by neutrophils and macrophages.

Esters of o-phthalic acid are widely distributed in the ecosystem. The phthalate acid esters (PAE's) are used as plasticizers in enormous quantities for a variety of industrial uses in the formulation of plastics. They are also used as solvents in certain industrial processes and as vehicles for pesticides and have been described as being among the most abundant man-made environmental pollutants. Plasticizers have been shown to elute at a constant rate from plastic products to the environment. Increasing chemical use needs a better understanding of how these pollutants may affect human health. In particular, certain members of this chemical class, such as di-[2-ethylhexyl]-phthalate (DEHP), have been shown to cause reproductive and developmental toxicity and are suspected to be endocrine disruptors.

The advent of proteomics has brought with it the hope of discovering novel biomarkers that can be used to diagnose diseases, predict susceptibility, and monitor progression. Much of this effort has focused on the mass spectral identification of the thousands of proteins that populate complex biosystems such as serum and tissues. A revolutionary approach termed proteomic pattern analysis has emerged as an effective method for the early diagnosis of diseases such as ovarian, breast, and prostate cancer. Proteomic pattern analysis relies on the pattern of proteins observed and does not rely on the identification of a traceable biomarker. Utilizing this technology, hundreds of clinical samples per day can be analyzed with the potential to be a novel, highly sensitive diagnostic tool for the early detection of diseases or as a predictor of response to therapy.

Atherosclerotic vascular disease is among the most frequent causes of death worldwide. Current therapeutic strategies concentrate mainly on lowering of low-density lipoprotein (LDL) cholesterol and an impressive reduction in the risk for cardiovascular morbidity and mortality has been achieved. Inflammatory mechanisms are more and more recognized to play an important role in vascular disease as inflammatory markers correlate with prognosis in acute and chronic coronary artery disease. HDL cholesterol exerts antiinflammatory effects on the vasculature. Moreover, HDL is an antioxidant, inhibits thrombogenesis, and has pro-fibrinolytic properties. Last but not least, HDL mediates reverse cholesterol transport. These pleiotropic effects make HDL an ideal therapeutic target for novel therapeutic strategies specifically aiming at HDL elevation for the prevention and treatment of atherosclerotic vascular disease.

The issue of a possible relationship between type 2 diabetes and cancer is still debated. Such chronic diseases show a high incidence in the general population. In their pathophysiology both genetic and environmental factors are involved, inducing important modifications of metabolism. Diabetes is associated to profound metabolic alterations, such as hyperinsulinemia and insulin resistance, which are common in various diseases, i.e. obesity, hypertension, dyslipidemia and hyperuricemia. Those illnesses form the so-called metabolic syndrome. Insulin resistance, hyperestrinism and the associated hyperandrogenism may play a role in the onset of some malignancies, such as endometrium cancer, breast cancer and prostate cancer. Low plasma levels of IGF-1 are able to reduce the risk of cancer in type 2 diabetes patients. This goal can be obtained with preventive measures, as physical activity, diet and drugs that can reduce insulin resistance (metformin and thiazolidinediones).

Interleukin-1α (IL-1α) plays an important role(s) in the regulation of immune and inflammatory responses. The testis is an immunologically privileged organ and the variety of effects exerted by IL-1α on this organ have yet to be explored in detail. The aim of the present review is to describe our current view of the paracrine role played by IL-1α in testicular physiology. Testicular IL-1α is expressed during development, primarily in Sertoli cells, appearing in rats for the first time 20 days after birth. This cytokine is microheterogeneous, consisting of three molecular species with molecular weights of 45, 24 and 17 KDa. The 17KDa form represents mature IL-1α, while the 24-KDa IL-1α has been shown by our research group to be an alternately spliced form of the 45-KDa pro-IL-1α. IL-1α was observed to stimulate the proliferation of immature Sertoli cells with higher efficacy than FSH. IL-1α was also found to exert mitogenic effects both on isolated peritubular cells and germ cells. Furthermore, isoforms of IL-1α were seen to stimulate basal testosterone production in immature Leydig cells, but not in the corresponding adult cells. This effect involved induction of the steroidogenic acute regulatory (StAR) protein and positively regulation by p38 MAPK. Recently, we have observed positive interactions between IL-1α and hormones of the GH / IGF-I system that lead to enhanced androgen production by the Leydig cell. In conclusion, our findings suggest that isoforms of IL-1α may serve as paracrine mediators, alone or in concert with other factors, that support proper testicular cell functioning and, thereby, reproduction and fertility.

The hypothalamic neuropeptide corticotropin-releasing hormone (CRH) is produced by several tissues of the female reproductive system. It is also secreted at inflammatory sites and possesses potent pro-inflammatory properties influencing both innate and acquired immune processes. Uterine CRH participates in local immune early pregnancy phenomena, such as decidualization of endometrial strom a and protection of the fetus from maternal immune system. This is maintained through induction of the expression of apoptotic FasL on invasive extravillous trophoblast and maternal decidual cells at the fetal-maternal interface. Furthermore, CRH increases apoptosis of activated T lymphocytes through FasL induction participating in the process of implantation and early pregnancy. Female rats treated with the non-peptidic CRH receptor 1 (CRHR1) specific antagonist antalarmin, in the first 6 days of gestation, have undergone a decrease of endometrial implantation sites and live embryos and markedly diminished endometrial FasL expression.