A Novel Aza-MBP Altered Peptide Ligand for the Treatment of Experimental Autoimmune Encephalomyelitis.

Myelin basic protein (MBP) is a major target of T cells in lesions of multiple sclerosis (MS) patients and its animal model, experimental autoimmune encephalomyelitis (EAE). Interactions between the major histocompatibility complex II containing antigenic peptides and the T cell receptor activate CD4+ T cells that perpetuate EAE and MS. Previously reported data has shown that treating with an altered peptide ligand (APL) in which the normal antigenic peptide sequence of MBP has been slightly changed at T cell contact positions is helpful in reducing disease in both rodents and humans. The use of natural peptides, which are susceptible to protease degradation, requires high concentrations that can create hypersensitivity reactions. Our hypothesis is that APL containing aza substitutions, CH(R)-N- > N(R)N, could lead to improved protease resistance, reduced clinical disease scores, and a shift in T cell profile. In this study, several aza-APLs and control peptides were synthesized and screened for the best aza-APL candidate (3aza-APL) based on dissociation half time from major histocompatibility complex (MHC) class II, induction of IL-2 response, and resistance to degradation by proteases. The efficacy was then tested in vivo. Results indicate that 3aza-APL is superior to currently available APLs in terms of protease resistance and disease suppression in EAE mice. The 3aza-APL induced anti-inflammatory immune responses by altering key transcription factors and cytokine genes which regulate T cell subpopulations. These data suggest that the novel 3aza-APL has increased protease resistance property and is effective in reducing clinical and physiological signs of disease in EAE animals.

Use of methylene blue for refractory septic shock during continuous venovenous hemodiafiltration.

As an inhibitor of nitric oxide, methylene blue has been investigated as an alternative vasopressor in patients with septic shock refractory to catecholamine vasopressors and as an agent to maintain hemodynamic stability in patients receiving intermittent hemodialysis. However, to our knowledge, the use of methylene blue as a vasopressor in patents receiving continuous renal replacement therapy has not been evaluated. We describe a 56-year-old man who was receiving continuous venovenous hemodiafiltration (CVVHDF) for acute renal failure secondary to sepsis. After a difficult hospital stay for injuries sustained from a motor vehicle accident, the patient developed sepsis and subsequent renal failure. On hospital day 47, after an adequate course of antibiotics, the patient developed refractory shock while receiving norepinephrine, phenylephrine, vasopressin, and hydrocortisone. He was then given a continuous infusion of methylene blue, which increased his mean arterial pressure and allowed for weaning of the catecholamine vasopressors. Eight hours after the start of methylene blue, the CVVHDF filter failed, and the hemodiafiltration was stopped. Because the filter was blue, a sample of the patient's effluent was analyzed by using ultraviolet-visible spectroscopy. No methylene blue was detected in the sample, suggesting that the drug was not being removed by CVVHDF. Clinicians should use caution when they are considering the use of methylene blue in patients with refractory shock who are also receiving CVVHDF.