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J M Lipton

Publications and source records attributed to J M Lipton.

At least 37 records · Page 2Linked to original sources
PubMed2000

Alpha-melanocyte-stimulating hormone peptides inhibit HIV-1 expression in chronically infected promonocytic U1 cells and in acutely infected monocytes.

The purpose of the present research was to determine if alpha-melanocyte-stimulating hormone (alpha-MSH) and its C-terminal tripeptide [alpha-MSH (11-13), KPV] alter HIV expression in infected cells. The results indicate that chronically HIV-1-infected promonocytic U1 cells produce alpha-MSH and that immunoneutralization of the endogenous peptide enhances HIV expression. Because U1 cells express the alpha-MSH receptor 1 (MC1R), an autocrine-inhibitory circuit based on the peptide and its receptor likely occurs in these cells. To determine effects of pharmacological concentrations of alpha-MSH peptides on HIV expression, we measured p24 antigen release by TNF-alpha-stimulated U1 cells exposed to a wide range of concentrations of synthetic alpha-MSH and KPV. Viral expression was reduced by both peptides. KPV also effectively reduced HIV replication in acutely infected monocyte-derived macrophages (MDM). The basis of the peptide influence on viral replication is at the transcriptional level; KPV inhibited activation of NF-kappaB that is known to enhance viral expression. Endogenous alpha-MSH likely contributes to natural defense against HIV. However, greater concentrations of synthetic peptide are much more effective in reducing HIV expression in infected cells.

DNA, Viral↗
PubMed1999

Autocrine alpha-melanocyte-stimulating hormone inhibits NF-kappaB activation in human glioma.

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) modulates inflammation by inhibiting production of proinflammatory cytokines. Using a plasmid vector encoding alpha-MSH, we examined whether autocrine alpha-MSH inhibits activation of the nuclear transcription factor NF-kappaB, a factor that is essential to expression of proinflammatory cytokines, in human glioma cells (A-172). Electrophoretic mobility shift assays of nuclear extracts demonstrated that NF-kappaB activation induced by lipopolysaccharide was inhibited in glioma cells transfected with alpha-MSH vector. Western blot analysis revealed that this inhibition was linked to preservation of expression of IkappaBalpha protein. Chloramphenicol acetyltransferase assay indicated that NF-kappaB-dependent reporter gene expression was suppressed in A-172 cells transfected with alpha-MSH vector. Finally, fluorescence staining confirmed that A-172 cells bear alpha-MSH receptors. The findings are consistent with the idea that, in central nervous system (CNS) inflammation, autocrine alpha-MSH exerts anti-inflammatory actions via modulation of NF-kappaB activation by preservation of IkappaBalpha protein. Based on this action of the peptide, it should be possible to treat neurodegenerative disease, stroke, encephalitis, trauma, and other CNS disorders that have an inflammatory component through gene therapy with alpha-MSH vector.

Autocrine Communication↗
PubMed1999

Inhibition of peripheral NF-kappaB activation by central action of alpha-melanocyte-stimulating hormone.

With the rise in the field of neuroimmunomodulation research, there is increased recognition of the influence of the nervous system and neuropeptides in peripheral disease. The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is a neuroimmunomodulatory agent that modulates production of proinflammatory cytokines and inhibits peripheral inflammation via actions on CNS receptors. We examined whether central alpha-MSH operates by inhibiting activation of the nuclear factor kappa B (NF-kappaB) that is essential to the expression of proinflammatory cytokines and development of inflammation in the periphery. Electrophoretic mobility shift assays of nuclear extracts from the murine foot pad injected with TNF-alpha demonstrated that centrally administered alpha-MSH does inhibit NF-kappaB activation. Western blot analysis revealed that this inhibition was linked to central alpha-MSH-induced preservation of expression of IkappaBalpha protein in the peripheral tissue. The NF-kappaB and IkappaBalpha effects were inhibited in mice with spinal cord transection. Intraperitoneal (i.p.) injection of the nonspecific beta-adrenergic receptor blocker propranolol, and of a specific beta2-adrenergic receptor antagonist, likewise prevented these effects of central alpha-MSH; blockade of cholinergic, alpha-adrenergic, or beta1-adrenergic receptors did not. Centrally administered alpha-MSH inhibited peripheral NF-kappaB activation and IkappaBalpha degradation even in mice with nonfunctional melanocortin 1 receptors (MC1R). These findings indicate that alpha-MSH can act centrally to inhibit NF-kappaB activation in peripheral acute inflammation via a descending neural pathway. The pathway involves beta2-adrenergic receptors, but does not require activation of MC1R within the brain.

Acute Disease↗
PubMed1999

Mechanisms of antiinflammatory action of alpha-MSH peptides. In vivo and in vitro evidence.

alpha-Melanocyte stimulating hormone (alpha-MSH) modulates all forms of inflammation by acting on peripheral inflammatory cells, glial inflammatory cells, and on CNS receptors that activate descending antiinflammatory neural pathways. The multiple actions of this ancient peptide suggest that there is no singular biochemical mechanism through which it exerts its antiinflammatory activity. However, research on IL-10 deficient and Agouti protein hypersecreting mice provide new insights into the actions of the peptide in living animals. Studies of cultured human astrocytes, whole murine brain, and human monocyte/macrophages indicate that a primary effect of the peptide is modulation of activation of the nuclear transcription factor kappa B. The latter influence may underlie the established reduction of gene expression and production of proinflammatory peptides and inducible nitric oxide by alpha-MSH peptides.

Agouti Signaling Protein↗
PubMed1999

alpha-MSH in systemic inflammation. Central and peripheral actions.

Until recently, inflammation was believed to arise from events taking place exclusively in the periphery. However, it is now clear that central neurogenic influences can either enhance or modulate peripheral inflammation. Therefore, it should be possible to improve treatment of inflammation by use of antiinflammatory agents that reduce peripheral host responses and inhibit proinflammatory signals in the central nervous system (CNS). One such strategy could be based on alpha-melanocyte stimulating hormone (alpha-MSH). Increases in circulating TNF-alpha and nitric oxide (NO), induced by intraperitoneal administration of endotoxin in mice, were modulated by central injection of a small concentration of alpha-MSH. Inducible nitric oxide synthase (iNOS) activity and iNOS mRNA in lungs and liver were likewise modulated by central alpha-MSH. Increase in lung myeloperoxidase (MPO) activity was significantly less in lungs of mice treated with central alpha-MSH. Proinflammatory agents induced by endotoxin were significantly greater after blockade of central alpha-MSH. The results suggest that antiinflammatory influences of neural origin that are triggered by alpha-MSH could be used to treat systemic inflammation. In addition to its central influences, alpha-MSH has inhibitory effects on peripheral host cells, in which it reduces release of proinflammatory mediators. alpha-MSH reduces chemotaxis of human neutrophils and production of TNF-alpha, neopterin, and NO by monocytes. In research on septic patients, alpha-MSH inhibited release of TNF-alpha, interleukin-1 beta (IL-1 beta), and interleukin-8 (IL-8) in whole blood samples in vitro. Combined central and peripheral influences can be beneficial in treatment of sepsis.

Animals↗
PubMed1999

Alpha-MSH peptides inhibit production of nitric oxide and tumor necrosis factor-alpha by microglial cells activated with beta-amyloid and interferon gamma.

Alpha-melanocyte stimulating hormone (alpha-MSH) is an ancient tridecapeptide with potent inhibitory activity in all major forms of inflammation. The anti-inflammatory message sequence of alpha-MSH resides in the COOH-terminal tripeptide alpha-MSH[11-13]. We tested the influence of alpha-MSH[1-13] and of alpha-MSH[11-13] in a cultured murine microglia cell line known to produce nitric oxide (NO(-)(2)) and tumor necrosis factor (TNFalpha) when stimulated with beta-amyloid protein (Abeta). Melanocortin peptides significantly inhibited release of both NO(-)(2) and TNFalpha into cell-free supernatants from microglia stimulated with Abeta[1-42] or Abeta[25-35] peptides and interferon gamma (IFNgamma). Northern blot analysis demonstrated that alpha-MSH[1-13] and alpha-MSH[11-13] inhibited accumulation of inducible nitric oxide synthase (iNOS) and TNFalpha mRNA was triggered by Abeta stimulation. Abeta/microglial interaction is believed to promote the progression of inflammatory and neurodegenerative changes in senile plaques in Alzheimer's disease. Our data indicate that alpha-MSH peptides might be used to modulate the local response of the brain to Abeta deposition in this neurodegenerative disease.

Amyloid beta-Peptides↗
PubMed1999

Systemically administered alpha-melanocyte-stimulating peptides inhibit NF-kappaB activation in experimental brain inflammation.

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) and its C-terminal tripeptide alpha-MSH11-13 modulate production of proinflammatory cytokines and inhibit inflammation. We examined whether systemic alpha-MSH and alpha-MSH11-13 inhibit activation of the nuclear transcription factor, nuclear factor kappa B (NF-kappaB), a factor that is essential to expression of proinflammatory cytokines, in experimental murine brain inflammation induced by lipopolysaccharide. Electrophoretic mobility shift assays of nuclear extracts demonstrated that parenteral alpha-MSH inhibited NF-kappaB activation. Western blot analysis revealed that this inhibition was linked to alpha-MSH-induced preservation of expression of IkappaBalpha protein in the brain. The effects of alpha-MSH on NF-kappaB and IkappaBalpha were paralleled by pretreatment with alpha-MSH11-13. Similar effects of the two peptides were observed in mice with nonfunctional melanocortin 1 receptors (MC1R), ruling out the possibility that this receptor subtype is essential to the influence on NF-kappaB. These findings indicate that alpha-MSH peptides given systemically can inhibit NF-kappaB activation induced in acute brain inflammation even in the absence of MC1R.

Animals↗
PubMed1999

Nucleoside analogues in the therapy of Langerhans cell histiocytosis: a survey of members of the histiocyte society and review of the literature.

BACKGROUND: Previous reports have suggested activity of the nucleoside analogues 2-chlorodeoxyadenosine (2-CdA) and 2'-deoxycoformycin (2'-DCF) in Langerhans cell histiocytosis (LCH). PROCEDURE: To assess the efficacy of 2-CdA and 2'-DCF as salvage therapy for LCH, a survey of members of the Histiocyte Society and a literature review were undertaken. Twenty-three patients treated with 2-CdA and 4 treated with 2'-DCF were found, age range 2 months to 49 years. RESULTS: All 15 survey patients had multiorgan involvement, and 14 were heavily pretreated. Doses of 2-CdA ranged from 0.1 mg/kg/day continuous infusion for 5-7 days (majority of patients) to 13 mg/m(2)/day for 5 days, for 1-6 courses. One of the 15 patients had an early death, 5 had no response (NR), 3 had partial response (PR), and 6 achieved complete response (CR). Among 8 published patients, 7 achieved stable CR and 1 NR. Among 4 patients treated with 2'-DCF (4 mg/m(2)/week for 8 weeks then q 2 weekly), 2 achieved CR for 16+ and 18+ months and 2 PR for 2 and 5 months. Toxicity consisted mainly of combined myelo- and immunosuppression but no significant infections occurred and there were no toxic deaths. A cumulative thrombocytopenia was noted, which in 1 case took up to 6 months to resolve. Transient gastrointestinal toxicity and elevation of liver enzymes was seen, and 2 patients developed renal tubular acidosis. The peripheral neuropathy reported in adult patients receiving high doses was not seen. CONCLUSIONS: 2-CdA and 2'-DCF appear to have a useful role in LCH and are worthy of prospective trial in patients unresponsive to routine therapy.

Adolescent↗
PubMed1999

alpha-melanocyte-stimulating hormone inhibits NF-kappaB activation and IkappaBalpha degradation in human glioma cells and in experimental brain inflammation.

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) modulates production of proinflammatory cytokines in brain tissue and in peripheral inflammatory cells. Transcription of the genes for these proinflammatory cytokines is regulated by the nuclear factor kappaB (NF-kappaB). NF-kappaB is also activated by proinflammatory cytokines. Degradation of the cytoplasmic inhibitor IkappaBalpha protein results in activation of NF-kappaB. Because of increasing evidence that NF-kappaB is involved in brain injury and inflammation and neurodegenerative disease, we examined whether alpha-MSH inhibits activation of NF-kappaB and limits degradation of IkappaBalpha protein induced by lipopolysaccharide (LPS) in human glioma cells (A-172) and in mouse brain. Electrophoretic mobility shift assays of nuclear extracts from A-172 cells and whole mouse brains stimulated with LPS revealed that alpha-MSH does suppress NF-kappaB activation. Western blot analysis demonstrated that alpha-MSH preserved expression of IkappaBalpha protein in vitro (glioma cells) and in vivo (brain tissue). Chloramphenicol acetyltransferase assay indicated that alpha-MSH suppresses NF-kappaB-dependent reporter gene expression induced by LPS in A-172 cells. The findings are consistent with the possibility that the anti-inflammatory action of alpha-MSH in CNS inflammation occurs via modulation of NF-kappaB activation by peptide-induced inhibition of degradation of IkappaBalpha protein.

Animals↗
PubMed1999

Elevated concentrations of plasma alpha-melanocyte stimulating hormone are associated with reduced disease progression in HIV-infected patients.

To determine whether concentrations of the anti-inflammatory peptide alpha-melanocyte stimulating hormone (alpha-MSH) are associated with accelerated or reduced disease progression in patients with HIV infection, plasma concentrations of alpha-MSH and two other anticytokine molecules, interleukin-1 receptor antagonist (IL-1 ra) and soluble tumor necrosis factor receptor (s TNF r), were taken repeatedly from HIV-positive patients over a 1-year period. Samples from 87 patients were collected by using special precautions to ensure accurate measurement of the peptide. Alpha-MSH concentrations were determined by radioimmunoassay; IL-1 ra and s TNF r concentrations were measured by using enzyme-linked immunosorbent assays. Clinical and immunologic variables were recorded to determine whether there is an association between cytokine antagonist concentrations and disease progression. Elevated concentrations of circulating alpha-MSH were associated with reduced progression of the disease. Circulating alpha-MSH was greater in non-progressors than in progressors; the association between elevated alpha-MSH and reduced disease progression was even more pronounced in patients with baseline CD4+ T cell counts less than 200/microL. No such association was observed for the other two anticytokine molecules, and there was no significant correlation between the plasma concentration of either cytokine antagonist and alpha-MSH. The present evidence and previous findings indicate that elevated concentrations of alpha-MSH are associated with reduced disease progression in HIV-infected patients.

Adult↗
PubMed1999

alpha-MSH and its receptors in regulation of tumor necrosis factor-alpha production by human monocyte/macrophages.

The hypothesis that macrophages contain an autocrine circuit based on melanocortin [ACTH and alpha-melanocyte-stimulating hormone (alpha-MSH)] peptides has major implications for neuroimmunomodulation research and inflammation therapy. To test this hypothesis, cells of the THP-1 human monocyte/macrophage line were stimulated with lipopolysaccharide (LPS) in the presence and absence of alpha-MSH. The inflammatory cytokine tumor necrosis factor (TNF)-alpha was inhibited in relation to alpha-MSH concentration. Similar inhibitory effects on TNF-alpha were observed with ACTH peptides that contain the alpha-MSH amino acid sequence and act on melanocortin receptors. Nuclease protection assays indicated that expression of the human melanocortin-1 receptor subtype (hMC-1R) occurs in THP-1 cells; Southern blots of RT-PCR product revealed that additional subtypes, hMC-3R and hMC-5R, also occur. Incubation of resting macrophages with antibody to hMC-1R increased TNF-alpha concentration; the antibody also markedly reduced the inhibitory influence of alpha-MSH on TNF-alpha in macrophages treated with LPS. These results in cells known to produce alpha-MSH at rest and to increase secretion of the peptide when challenged are consistent with an endogenous regulatory circuit based on melanocortin peptides and their receptors. Targeting of this neuroimmunomodulatory circuit in inflammatory diseases in which myelomonocytic cells are prominent should be beneficial.

Adrenocorticotropic Hormone↗
PubMed1998

Mechanisms of antiinflammatory action of the neuroimmunomodulatory peptide alpha-MSH.

The antiinflammatory effects of alpha-melanocyte-stimulating hormone (alpha-MSH) molecules, specifically alpha-MSH(1-13) and its COOH-terminal tripeptide alpha-MSH(11-13), are well established. The peptides have been effective in tests of all major models of inflammation, and more recent tests have been extended to include experimental inflammatory bowel disease, CNS ischemia/reperfusion injury, and bacterial endotoxin-induced inflammation within the brain. The broad effectiveness of alpha-MSH molecules in all major types of inflammation indicates that the peptides exert actions that are very basic to the inflammatory process. Three general mechanisms of antiinflammatory action of alpha-MSH molecules have been identified: inhibition of production of inflammatory mediators by, or inhibition of inflammatory actions of, peripheral host cells; inhibition of peripheral inflammation induced by actions on melanocortin receptors within the brain; inhibition of CNS inflammation by local action of the peptides. It appears that alpha-MSH molecules have multiple actions that modulate the primitive inflammatory response.

Animals↗
PubMed1998

The neuropeptide alpha-MSH in HIV infection and other disorders in humans.

We measured plasma concentration of alpha-melanocyte-stimulating hormone (alpha-MSH), a proopiomelanocortin derivative that modulates pyrogenic and proinflammatory effects of cytokines, in infectious and inflammatory disorders in humans to learn if changes in this peptide take place in naturally occurring disease. alpha-MSH was elevated in HIV-infected patients of the CDC groups III and IV. Although the peptide increased in the circulation of normal subjects injected with endotoxin, it was reduced in patients with septic syndrome. alpha-MSH was found in the synovial fluid of arthritis patients, and its concentration was greater in the forms of arthritis marked by greater inflammation. We found that alpha-MSH is increased in the circulation of patients with acute myocardial infarction receiving thrombolytic therapy. Plasma concentrations of alpha-MSH is increased in the circulation of patients with acute myocardial infarction receiving thrombolytic therapy. Plasma concentrations of alpha-MSH were lower in healthy elderly subjects than in young controls. Because an excess of proinflammatory cytokines can have detrimental effects, we investigated the influences of alpha-MSH on the production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in HIV-infected patients and in patients with septic syndrome. Production of these cytokines in whole-blood samples stimulated with endotoxin was significantly reduced by treatment of blood with alpha-MSH. alpha-MSH has been injected into at least 106 human subjects to study its effects on pituitary function, menstrual bleeding, and tanning. The peptide was always well tolerated. alpha-MSH administration could open new perspectives in treatment of inflammatory diseases in humans.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Melanocortin peptides inhibit production of proinflammatory cytokines and nitric oxide by activated microglia.

Inflammatory processes contribute to neurodegenerative disease, stroke, encephalitis, and other central nervous system (CNS) disorders. Activated microglia are a source of cytokines and other inflammatory agents within the CNS and it is therefore important to control glial function in order to preserve neural cells. Melanocortin peptides are pro-opiomelanocortin-derived amino acid sequences that include alpha-melanocyte-stimulating hormone (alpha-MSH) and adrenocorticotropic hormone (ACTH). These peptides have potent and broad anti-inflammatory effects. We tested effects of alpha-MSH (1-13), alpha-MSH (11-13), and ACTH (1-24) on production of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and nitric oxide (NO) in a cultured murine microglial cell line (N9) stimulated with lipopolysaccharide (LPS) plus interferon gamma (IFN-gamma). Melanocortin peptides inhibited production of these cytokines and NO in a concentration-related fashion, probably by increasing intracellular cAMP. When stimulated with LPS + IFN-gamma, microglia increased release of alpha-MSH. Production of TNF-alpha, IL-6, and NO was greater in activated microglia after innmunoneutralization of endogenous alpha-MSH. The results suggest that alpha-MSH is an autocrine factor in microglia. Because melanocortin peptides inhibit production of pro-inflammatory mediators by activated microglia they might be useful in treatment of inflammatory/degenerative brain disorders.

Adrenocorticotropic Hormone↗
PubMed1998

Melanocortin peptides inhibit production of proinflammatory cytokines in blood of HIV-infected patients.

Melanocortins are proopiomelanocortin-derived peptides that include adrenocorticotropic hormone [ACTH (1-39)], alpha-melanocyte-stimulating hormone [alpha-MSH (1-13)], and related amino acid sequences. Melanocortin peptides have potent antiinflammatory/anticytokine activity. Because cytokines such as interleukin 1 (IL-1) and tumor necrosis factor (TNF) can be detrimental in HIV-infected patients, we investigated the effects of melanocortins on production of IL-1 and TNF alpha in the blood of HIV patients. Cytokine production was measured in whole blood samples stimulated with LPS in the presence or absence of alpha-MSH (1-13), alpha-MSH (11-13), ACTH (1-24), or ACTH (1-39). Melanocortins reduced production of both cytokines in a concentration-dependent fashion. In separate experiments on normal peripheral blood mononuclear cells (PBMC), alpha-MSH (1-13) inhibited production of IL-1 beta and TNF alpha induced by HIV envelope glycoprotein gp 120. These results suggest that stimulation of melanocortin receptors in inflammatory cells could be a novel way to reduce production of cytokines that promote HIV replication.

Adrenocorticotropic Hormone↗
PubMed1998

Does the duration of cardiopulmonary bypass or aortic cross-clamp, in the absence of blood and/or blood product administration, influence the IL-6 response to cardiac surgery?

UNLABELLED: Cardiopulmonary bypass (CPB) induces a systemic inflammatory response characterized by release of proinflammatory cytokines, including interleukin 6 (IL-6). Recent reports suggest that plasma IL-6 is increased after CPB. Previous studies evaluating the influence of duration of CPB and/or aortic cross-clamp time on the release of IL-6 are conflicting. Infusion of blood and blood products during these studies may have influenced plasma concentrations of proinflammatory cytokines by inducing host cell (monocyte) activation and IL-6 release. The purpose of our investigation was to determine, in an environment free from blood and/or blood product administration, the influence of duration of CPB and/or aortic cross-clamp on the magnitude of the IL-6 response in patients undergoing cardiac surgery. We prospectively evaluated plasma IL-6 levels preinduction (T0) and at sternal closure in 16 patients undergoing CPB (coronary artery bypass grafting, n = 9; valvular cardiac surgery, n = 7) to determine whether there is a correlation between the absolute increase in IL-6 and the duration of CPB or aortic cross-clamp time. None of the patients received blood and/or blood products during the study to control for the introduction of additional activated cells and soluble mediators, including IL-6. The results demonstrate that the magnitude of the IL-6 response to CPB is positively correlated with the duration of CPB but not with duration of aortic cross-clamp. It seems that induction of IL-6 release is part of a normal response to CPB and does not depend on activation of host cells during prolonged aortic cross-clamp. The activation or presence of inflammatory cytokines associated with administration of blood and/or blood products could have influenced previously published investigations relating the influence of duration of CPB and/or aortic cross-clamp time to the magnitude of the IL-6 response. IMPLICATIONS: This study found a positive correlation between the magnitude of the interleukin 6 response to cardiopulmonary bypass and duration of cardiopulmonary bypass (but not duration of aortic cross-clamp) when measurements were made in the absence of blood/blood product transfusion. Future studies evaluating strategies to reduce cytokine responses to cardiopulmonary bypass should therefore control for cardiopulmonary bypass duration.

Adult↗