Decrease in cholesterol levels during the immunotherapy of cancer with interleukin-2

IL-2Rβγ signalling in lymphocytes promotes systemic inflammation and reduces plasma cholesterol in atherosclerotic mice

BACKGROUND AND AIMS

The relationship between inflammation and lipid metabolism is complex and bidirectional. Lymphocyte-driven inflammation has been shown to modulate both atherosclerotic plaque development and cholesterol levels, but the mechanisms are incompletely understood.

METHODS

The cardiometabolic effects of IL-2Rβγ signalling in atherosclerotic Apoe^-/- mice were investigated by treatment with an agonistic IL-2Rβγ-targeting IL-2/anti-IL-2 complex or a monoclonal anti-CD122 (IL-2Rβ) blocking antibody.

RESULTS

Administration of IL-2Rβγ agonistic IL-2/anti-IL-2 complexes to Apoe^-/- mice augmented opposing arms of the adaptive immune system. Expansion of effector/memory T cells and increased levels of circulating pro-inflammatory cytokines were observed along with elevated levels of regulatory T cells and IL-10. Notably, IL-2/anti-IL-2 treatment did not affect plaque size but decreased levels of plasma cholesterol. The cholesterol lowering effect of IL-2Rβγ agonism was not affected by anti-CD8 or anti-NK1.1 depleting antibody treatment but was contingent on the presence of adaptive immunity. Expression of multiple liver X receptor (LXR)-related genes, including Pltp and Srebp1c in the liver, was decreased by IL-2/anti-IL-2 treatment. Although IL-2Rβγ agonism lowered cholesterol levels, blocking IL-2Rβγ signalling using an anti-CD122 monoclonal antibody did not impact cholesterol levels or plaque burden in Apoe^-/- mice.

CONCLUSIONS

Elevated IL-2Rβγ signalling results in activation of both inflammatory and regulatory lymphocytes with a net zero effect on atherosclerosis and decreased plasma cholesterol levels. Changes in cholesterol levels were associated with reductions in hepatic LXR-related gene expression. Further studies are needed to investigate the clinical significance of IL-2 mediated modulation of hepatic LXR signalling in inflammatory disorders.

Effects of short-term melatonin administration on lipoprotein metabolism in normolipidemic postmenopausal women

OBJECTIVE

To investigate the effects of short-term administration of melatonin on lipoprotein metabolism in normolipidemic postmenopausal women.

METHODS

Fifteen such women received 6.0 mg melatonin daily for 2 weeks. Blood was sampled before and after treatment. We measured concentrations of total cholesterol and total triglyceride in the plasma, as well as the levels of cholesterol, triglyceride, and protein in the very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). Plasma apolipoprotein levels were determined by immunoturbidimetric assay. Activities of lipoprotein lipase, hepatic triglyceride lipase, and lecithin cholesterol acyltransferase were also determined by enzymatic analysis.

RESULTS

Melatonin administration significantly increased the plasma levels of triglyceride by 27.2% (P < 0.05), of VLDL-cholesterol by 37.2% (P < 0.01), of VLDL-triglyceride by 62.2% (P < 0.001), and of VLDL-protein by 30.0% (P < 0.05). However, the plasma total cholesterol level and the concentration of lipid and protein in LDL and HDL were not significantly affected. Melatonin significantly increased the plasma levels of apolipoprotein C-II by 29.5% (P < 0.005), of C-III by 17.1% (P < 0.001), and of E by 7.6% (P < 0.05). The plasma levels of apolipoprotein A-I, A-II, and B were not altered. Melatonin significantly inhibited the activity of lipoprotein lipase by -14.1% (P < 0.05), but did not significantly affect the activities of hepatic triglyceride lipase or of lecithin cholesterol acyltransferase.

CONCLUSIONS

Findings indicate that melatonin increases the plasma level of VLDL particles by inhibiting the activity of lipoprotein lipase, but may not affect the plasma levels of LDL and HDL particles in postmenopausal women with normolipidemia.

Interleukin-2. A review of its pharmacological properties and therapeutic use in patients with cancer

Recombinant interleukin-2 (IL-2) products (e.g. aldesleukin, teceleukin) are nonglycosylated, modified forms of the endogenous compound. IL-2 acts as a pleiotropic mediator within the immune system, having a variety of effects via specific cell surface receptors. The interaction of IL-2 with the IL-2 receptor induces proliferation and differentiation of a number of T lymphocyte subsets, and stimulates a cytokine cascade that includes various interleukins, interferons and tumour necrosis factors. Antitumour effects of IL-2 appear to be mediated by its effects on natural killer, lymphokine-activated killer (LAK) and other cytotoxic cells. In vivo and in vitro effects of IL-2 seem to be dependent to a large extent on the environment; many studies have reported conflicting results, perhaps due to diverse populations of effector cells, the availability of other cytokines that have synergistic or inhibitory influences, and the dosage regimens used. The recombinant products appear to be biologically indistinguishable from native IL-2 in vitro and in vivo; the former induce minor antibody formation but this does not appear to alter functional properties. In patients with metastatic renal cell carcinoma, IL-2 therapy achieves average objective response rates of 20% (range 0 to 40%), with a complete response rate of about 5% (range 0 to 19%). Response duration varies considerably but can be durable (lasting for > 12 months), with some patients remaining in complete response for > 60 months. It is unclear at present whether higher dosage regimens improve clinical response, or whether combination therapy with other agents and/or adoptive therapy is beneficial. Survival duration may depend on the risk factors present, with poorer performance status and more than one site of metastases associated with shorter survival times. Patients with metastatic malignant melanoma receiving IL-2 as monotherapy show an average objective response rate of 13% (range 3 to 24%); however, objective response rate averages 30% (range 4 to 59%) when IL-2 is used in combination with other agents. Overall median survival appears to be about 10 months. Preliminary data indicate that IL-2 produces a lower response rate in patients with refractory colorectal carcinoma, ovarian cancer, bladder cancer, acute myeloid leukemia or non-Hodgkin's lymphoma. Adverse effects accompanying high dose, intravenous IL-2 therapy can be severe, with cardiovascular, pulmonary, haematological, hepatic, neurological, endocrine, renal and/or dermatological complications frequently requiring doses to be withheld.(ABSTRACT TRUNCATED AT 400 WORDS)

In vivo biological results of the association between interleukin-2 and interleukin-3 in the immunotherapy of cancer

The concomitant generation of macrophage-mediated suppressive events, as documented by the increase in neopterin and soluble interleukin-2 (IL-2) receptor (SIL-2R), and the enhanced production of cortisol, would represent the most investigated phenomena responsible for the reduced anticancer efficacy of IL-2 immunotherapy in humans. Based on our preliminary experimental studies suggesting a modulatory role of IL-3 on immune and endocrine effects induced by IL-2, a study was performed to evaluate the influence of IL-3 on biological effects of IL-2 cancer immunotherapy. We have evaluated 12 immunotherapeutic courses with IL-3 plus IL-2, which were performed in 6 patients with metastatic non-small cell lung cancer. The results were compared to those seen in 22 courses with IL-2 alone, carried out in 12 patients with metastatic non-small cell lung cancer. IL-3 was given intravenously at a daily dose of 1 microgram/kg/b.w. at 6 p.m. for 14 consecutive days, starting 7 days before IL-2. IL-2 was given subcutaneously at a dose of 3 million IU twice/daily for 5 days/week for 3 weeks. The increase in serum levels of the specific macrophage marker neopterin, induced by IL-2, was completely blocked by IL-3. The IL-2-induced SIL-2R rise was significantly lower during IL-3 plus IL-2 than under IL-2 alone. The increase in cortisol levels in response to IL-2 was neutralised by IL-3. The increase in lymphocyte, T lymphocyte, natural killer (NK) cell, activated T lymphocyte and eosinophil mean number was significantly higher during IL-3 plus IL-2 than during IL-2 alone. Episodes of fever, asthenia, anorexia, vomiting, anaemia and thrombocytopenia were significantly more frequent in patients receiving IL-2 alone than in those treated with IL-3 and IL-2. This preliminary study would suggest that IL-3 may improve the tolerability of IL-2 immunotherapy and enhance the biological antitumour properties of IL-2 by neutralising cortisol increase and macrophage-mediated suppressive events, with a following potential amplification of Il-2 anticancer efficacy.