Effect of ciliary neurotrophic factor on body temperature and cerebrospinal fluid prostanoids in the cat

Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease

Besides the presence of amyloid beta (Aβ) plaques and neurofibrillary tangles, neurogenesis and synaptic plasticity are markedly impaired in Alzheimer's disease (AD) possibly contributing to cognitive impairment. In this context, neurotrophic factors serve as a promising therapeutic approach via utilization of regenerative capacity of brain to shift the balance from neurodegeneration to neural regeneration. However, besides more conventional "bystander" effect, to what extent can neurotrophic compounds affect underlying AD pathology remains questionable. Here we investigated the effect of chronic oral treatment with a ciliary neurotrophic factor (CNTF) derived peptidergic compound, P021 (Ac-DGGL(A)G-NH2), on disease pathology both at moderate and severe stages in a transgenic mouse model of AD. 3xTg-AD and wild type female mice were treated for 12months with P021 or vehicle diet starting at 9-10months of age. A significant reduction in abnormal hyperphosphorylation and accumulation of tau at known major AD neurofibrillary pathology associated sites was observed. The effect of P021 on Aβ pathology was limited to a significant decrease in soluble Aβ levels and a trend towards reduction in Aβ plaque load in CA1 region of hippocampus, consistent with reduction in Aβ generation and not clearance. This disease modifying effect was probably via increased brain derived neurotrophic factor (BDNF) expression mediated decrease in glycogen synthase kinase-3-β (GSK3β) activity we found in P021 treated 3xTg-AD mice. P021 treatment also rescued deficits in cognition, neurogenesis, and synaptic plasticity in 3xTg-AD mice. These findings demonstrate the potential of the neurotrophic peptide mimetic as a disease modifying therapy for AD.

The cytokine basis of cachexia and its treatment: are they ready for prime time?

Cachexia is a hypercatabolic condition that is often associated with the terminal stages of many diseases, in which the patient's resting metabolic rate is high and loss of muscle and fat tissue mass occur at an alarming rate. The patient also usually has concurrent anorexia, amplifying the wasting syndrome that is cachexia. The greater the extent of cachexia (regardless of underlying disease), the worse the prognosis. Efforts to treat cachexia over the years have fallen short of satisfactorily reversing the wasting syndrome. This article reviews the pathophysiology of cachexia, enumerating the different pro-inflammatory cytokines that contribute to the syndrome and attempting to illustrate their interwoven pathways. We also review the different treatments that have been explored, as well as the recent literature addressing the use of anti-cytokine therapy to treat cachexia.

Prostaglandin E2 in the pathogenesis of fever. An update

Prostaglandin E2 (PGE2) is recognized as a key intermediate in the sequence of events leading to fever. Normally undetectable or barely detectable in brain, it rises selectively on exposure to an infectious noxa and the attendant generation of pyrogenic cytokines outside and, in the case of interleukin (IL)-6, inside the brain. The mechanism by which pyrogens in the circulation promote the appearance of PGE2 within the confines of brain is not clear, and it is not known how PGE2 activation is selective with IL-6 being induced in brain. We have found that the cerebral microvasculature is not suitable as a source of PGE2 in response to blood-borne pyrogens. In addition, we show that IL-6 differs from other pyrogens in being able to stimulate specifically PGE2 synthesis. Nevertheless, brain-derived IL-6 does not appear to be necessary for PGE2 activation and the attendant fever. We conclude that signal-transducing mechanisms operating across the blood-brain barrier are most critical for the development of the febrile response to a systemic noxa.

Formation of interleukin-6 in the brain of the febrile cat: relationship to interleukin-1

Previous investigations have shown that interleukin-6 (IL-6), unlike other cytokines, is produced in larger amounts in the brain of the febrile animal regardless of the route, peripheral vs. central, of pyrogen administration. In addition, depending on the experimental condition IL-6 production may or may not require the prior induction of interleukin-1 (IL-1). The present study was carried out in the conscious cat to assess the importance of brain-derived IL-6 in the pathogenesis of fever and the interaction at that site between this cytokine and IL-1. IL-6 was detected in cerebrospinal fluid (CSF) collected at rest and its levels increased during the fever to intravenous (i.v.) endotoxin. The IL-6 elevation, but not the fever, was reversed by pretreatment with intracerebroventricular (i.c.v.) IL-1 receptor antagonist (hIL-1ra). Conversely, when pyrogens (endotoxin, IL-1) were given i.c.v., i.c.v. hIL-1ra reduced the fever without altering significantly the associated rise in CSF IL-6. We conclude that IL-6 is formed in brain in response to both i.v. and i.c.v. pyrogens; however, its formation, whether requiring the prior induction of IL-1 or not, does not appear to be critical for the development of the fever. Blood-borne IL-6, unlike brain-derived IL-6, may still play a role in fever as a trigger of signal-transducing mechanisms operating across the blood-brain barrier.