Jack C. Sipe

Cladribine in treatment of chronic progressive multiple sclerosis

Chronic progressive multiple sclerosis (MS) is a severely disabling demyelinating disease in which autoimmune processes seem to have a major role. The nucleoside drug cladribine is a potent lympholytic agent with few side-effects. We have studied its efficacy and safety in a randomised double-blind trial. 51 patients (48 entered as matched pairs) received four monthly courses of 0.7 mg/kg cladribine or placebo (saline) given through a surgically implanted central line. Neurologists with no knowledge of which medication the patient was receiving examined the patients monthly and noted two rating scale scores (Kurtzke and Scripps). Cerebrospinal fluid and brain magnetic resonance imaging (MRI) examinations were done at 6 and 12 months. Average neurological scores, demyelinated volumes on MRI, and concentrations of oligoclonal bands in cerebrospinal fluid were stable or improved in the patients receiving cladrabine but continued to deteriorate in patients on placebo. Mean paired (placebo minus matched cladribine) differences at 12 months relative to baseline were 1.0 (SE 0.4) for the Kurtzke scores, -13.9 (2.3) for the Scripps scores, 4.57 (1.17) mL for demyelinated volumes, and 7.3 (3.3) arbitrary units for concentrations of oligoclonal bands. Cladribine was generally well tolerated and clinically significant toxicity occurred in only 1 patient, in whom severe marrow suppression developed with complete recovery after several months. 1 patient died of newly acquired hepatitis B, an event unlikely to be related to cladribine. We conclude that the immunosuppressive drug cladribine influences favourably the course of chronic progressive MS.

A missense mutation in human fatty acid amide hydrolase associated with problem drug use

Problem drug use and dependence are neurobehavioral disorders of complex origin. Although environmental factors contribute to drug abuse and addiction, genetic factors also play a significant role estimated at 40–60% of the total risk. Nonetheless, the precise identities of human genes that confer vulnerability to problem drug use remain mostly unknown. Here, we describe a natural single nucleotide polymorphism in the human gene that encodes the principal endocannabinoid-inactivating enzyme, fatty acid amide hydrolase (FAAH), that in homozygous form is strongly associated with both street drug use and problem drug/alcohol use. This single nucleotide polymorphism results in a missense mutation (385C→A) that converts a conserved proline residue to threonine (Pro129→Thr), producing a FAAH variant that displays normal catalytic properties but an enhanced sensitivity to proteolytic degradation. Collectively, these results suggest that genetic mutations in FAAH may constitute important risk factors for problem drug use and support a potential link between functional abnormalities in the endogenous cannabinoid system and drug abuse and dependence.

A neurologic rating scale (NRS) for use in multiple sclerosis

A neurologic rating scale (NRS) has been developed for clinical assessment of MS patients. The scale has been tested on 250 MS patients. Assignment of the NRS score is based on assessment of each component of the neurologic examination and accurately reflects overall neurologic function. Clinical exacerbations are evident as significant deviations from baseline scores. There was close interexaminer correlation, with the range of variability no greater than 2.6%. The NRS is a simple, reliable, and sensitive scale that can be used with other objective measurements of neurologic function, such as neurophysiologic studies, in the clinical assessment of MS patients.

Overweight and obesity associated with a missense polymorphism in fatty acid amide hydrolase (FAAH)

BACKGROUND:The brain endogenous cannabinoid system modulates reward and craving pathways and consequently may affect body weight. A naturally occurring missense polymorphism in the gene encoding fatty acid amide hydrolase (FAAH), the primary enzyme for inactivation of endocannabinoids, is associated with problem drug use.AIMS:To investigate the relationship between the FAAH cDNA 385 A/A (P129T) polymorphism and overweight disorders in subjects of multiple ethnic backgrounds attending a medical screening clinic.SUBJECTS:A total of 2667 subjects of white, black and Asian ancestry were genotyped and stratified by a standardized clinic-based assessment of body mass index (BMI, weight in kilograms/(height in meters)2 or kg/m2).METHODS:Subjects were genotyped for the FAAH cDNA 385 C → A polymorphism using allele-specific oligonucleotide hybridization methods by investigators blinded to all clinical information. BMI was calculated based on exact clinical measurements and World Health Organization ranges were used to stratify subjects. Statistical methods included the Fisher exact test, Mann–Whitney U-test and multivariable logistic regression analysis.RESULTS:The homozygous FAAH 385 A/A genotype was significantly associated with overweight and obesity in white subjects (P=0.005) and in black subjects (P=0.05) but not in a small group of Asians. The median BMI for all subjects was significantly greater in the FAAH 385 A/A genotype group compared to heterozygote and wild-type groups (P=0.0001). In white subjects, there was an increasing frequency of the FAAH 385 A/A genotype with increasing BMI categories of overweight (P=0.02) and obese (P=0.006) with the same trend in black subjects.CONCLUSIONS:These results suggest a role for the FAAH 385 A/A missense polymorphism as an endocannabinoid risk factor in overweight/obesity and may provide indirect evidence to support cannabinoid antagonist treatment strategies in overweight disorders.

Systemic alpha‐interferon therapy of multiple sclerosis

A randomized, double-blind, placebo-controlled crossover study tested the efficacy of natural alpha interferon in altering exacerbating-remitting MS. Twenty-four patients with frequent exacerbations were treated for 6-month periods, beginning with either 5 × l06 IU of interferon daily or placebo. A 6-month washout period followed each treatment. Exacerbation rates were reduced during interferon and placebo phases compared with pre-study rates; a greater reduction occurred on interferon, particularly following placebo, possibly reflecting a learning phenomenon. Fifteen patients with a strictly exacerbating-remitting course had fewer and milder exacerbations on interferon compared with those on placebo, whereas 9 patients with a progressive component continued to have active disease. These results suggest that interferon might reduce exacerbations in certain patients and indicate guidelines for future trials of interferon in MS.

Reduced endocannabinoid immune modulation by a common cannabinoid 2 (CB2) receptor gene polymorphism: possible risk for autoimmune disorders

Immune system responsiveness results from numerous factors, including endogenous cannabinoid signaling in immunocytes termed the “immunocannabinoid” system. This system can be an important signaling pathway for immune modulation. To assess the immunomodulating role of the cannabinoid 2 (CB2) receptor, we sought polymorphisms in the human gene, identified a common dinucleotide polymorphism, and investigated its effect on endocannabinoid‐induced inhibition of T lymphocyte proliferation. The CB2 cDNA 188–189 GG/GG polymorphism predicts the substitution of glutamine at amino acid position 63 by arginine. T lymphocytes from CB2 188–189 GG/GG homozygotes had approximately twofold reduction of endocannabinoid‐induced inhibition of proliferation compared with cells from CB2 188–189 AA/AA homozygotes. In GG/GG subjects, the reduced endocannabinoid inhibitory response was highly significant for N‐arachidonylglycine and nearly significant for 2‐arachidonylglycerol, and a specific CB2 receptor antagonist partially blocked these effects. Also, patients with autoimmune diseases had an increased prevalence of the homozygous GG/GG genotype. Collectively, these results demonstrate reduced endogenous fatty acid amide immunomodulatory responses in individuals with the CB2 188–189 GG/GG genotype and suggest that this CB2 gene variation may be a risk factor for autoimmunity. The results also support the proposition that the CB2 receptor may represent a novel pharmacological target for selective agonists designed to suppress autoreactive immune responses while avoiding CB1 receptor‐mediated cannabinoid adverse effects.

Brain iron metabolism and neurodegenerative disorders.

Iron, an essential element for central nervous system (CNS) function, has frequently been found to accumulate in brain regions that undergo degeneration in neurological diseases such as Alzheimer disease, Parkinson disease, Friedreich ataxia and other disorders. However, the precise role of iron in the cause of many neurodegenerative diseases is unclear. To assist in understanding the potential importance of iron in CNS disease, this review summarizes the present knowledge in the areas of CNS iron metabolism, homeostasis and disregulation of iron balance caused by mutations in genes encoding proteins involved in iron transport, storage and metabolism. This review encompasses neurodegenerative disorders associated with both iron overload and deficiency to highlight areas where iron misregulation is likely to be important in the pathophysiology of several human brain diseases.

Cladribine for multiple sclerosis: review and current status

In the 1990s, cladribine was developed as an adenosine deaminase-resistant nucleoside analog with selective lymphotoxic specificity in the hope that it might become useful in the treatment of some lymphoid neoplasms and autoimmune disorders. Several clinical trials demonstrated very significant effectiveness and safety of cladribine in the cure of hairy-cell leukemia, and the control of many other lymphoid malignancies. Cladribine was also extensively tested in selected autoimmune disorders, most notably in multiple sclerosis, with evidence of efficacy, tolerability and acceptable side effects/toxicity. The previous clinical studies and current status of cladribine for the treatment of multiple sclerosis are considered in this drug profile. In January 2005, Serono and IVAX announced plans to initiate a Phase III study of a specially formulated oral tablet of cladribine (Mylinax®, Serono and IVAX) for the treatment of relapsing forms of multiple sclerosis. The proposed study will be the first large multicenter randomized controlled clinical trial of oral cladribine in multiple sclerosis.

Biomarkers of endocannabinoid system activation in severe obesity.

Background Obesity is a worldwide epidemic, and severe obesity is a risk factor for many diseases, including diabetes, heart disease, stroke, and some cancers. Endocannabinoid system (ECS) signaling in the brain and peripheral tissues is activated in obesity and plays a role in the regulation of body weight. The main research question here was whether quantitative measurement of plasma endocannabinoids, anandamide, and related N-acylethanolamines (NAEs), combined with genotyping for mutations in fatty acid amide hydrolase (FAAH) would identify circulating biomarkers of ECS activation in severe obesity. Methodology/Principal Findings Plasma samples were obtained from 96 severely obese subjects with body mass index (BMI) of ≥40 kg/m2, and 48 normal weight subjects with BMI of ≤26 kg/m2. Triple-quadrupole mass spectroscopy methods were used to measure plasma ECS analogs. Subjects were genotyped for human FAAH gene mutations. The principal analysis focused on the FAAH 385 C→A (P129T) mutation by comparing plasma ECS metabolite levels in the FAAH 385 minor A allele carriers versus wild-type C/C carriers in both groups. The main finding was significantly elevated mean plasma levels of anandamide (15.1±1.4 pmol/ml) and related NAEs in study subjects that carried the FAAH 385 A mutant alleles versus normal subjects (13.3±1.0 pmol/ml) with wild-type FAAH genotype (p = 0.04), and significance was maintained after controlling for BMI. Conclusions/Significance Significantly increased levels of the endocannabinoid anandamide and related NAEs were found in carriers of the FAAH 385 A mutant alleles compared with wild-type FAAH controls. This evidence supports endocannabinoid system activation due to the effect of FAAH 385 mutant A genotype on plasma AEA and related NAE analogs. This is the first study to document that FAAH 385 A mutant alleles have a direct effect on elevated plasma levels of anandamide and related NAEs in humans. These biomarkers may indicate risk for severe obesity and may suggest novel ECS obesity treatment strategies.

Primary intracranial hypotension and bilateral isodense subdural hematomas

A 39-year-old woman with headache and an organic mental syndrome was found to have primary intracranial hypotension (PIH). Bilateral isodense subdural hematomas were discovered in association with an absence of detectable CSF pressure on two lumbar punctures. This case study emphasizes that PIH is not an entirely benign condition and that intracranial hemorrhage may accompany persistent intracranial hypotension.