Yuval Tal

Cellular Heparan Sulfate Participates in the Metabolism of Prions

During prion diseases, the host protein PrPC is refolded into an abnormal conformer “prion” PrPSc. Histological and pharmacological data have suggested that glycosaminoglycans may be involved in the development of prion diseases. Here we present the first direct evidence that cellular glycosaminoglycans play a role in the biogenesis of PrPSc in prion-infected ScN2a cells. When ScN2a cells were incubated with estradiol β-d-xyloside to inhibit the glycosylation of proteoglycans, PrPSc was vastly reduced. Treating ScN2a-M cells with heparinase III, but not with heparinase I or chondroitinase ABC, caused a profound reduction of PrPSc. In contrast, neither the amount of PrPC nor its subcellular distribution were affected as assayed by immunofluorescence microscopy and flotation procedures. In vitro treatment of ScN2a membranes with heparinase III at either neutral or acidic pH did not reduce the level of protease-resistant PrPSc. The inhibitor of sulfation, sodium chlorate, vastly reduces PrPSc in ScN2a cells (Gabizon, R., Meiner, Z., Halimi, M., and Ben-Sasson, S. A. (1993) J. Cell. Physiol. 157, 319–325). Both soluble heparan sulfate and chondroitin sulfate partially restored the level of PrPSc in chlorate-treated cells. We conclude that heparinase III-sensitive, presumably undersulfated, cellular heparan sulfate plays a significant role in the biogenesis of PrPSc in ScN2a cells.

Modulation of proteinase-K resistant prion protein by prion peptide immunization.

Prion diseases are caused by conformational alterations in the prion protein (PrP). The immune system has been assumed to be non‐responsive to the self‐prion protein, therefore, PrP autoimmunity has not been investigated. Here, we immunized various strains of mice with PrP peptides, some selected to fit the MHC class II‐peptide binding motif. We found that specific PrP peptides elicited strong immune responses in NOD, C57BL/6 and A/J mice. To test the functional effect of this immunization, we examined the expression of proteinase‐K‐resistant PrP by a scrapie‐infected tumor transplanted to immunized syngeneic A/J mice. PrP peptide vaccination did not affect the growth of the infected tumor transplant, but significantly reduced the level of protease‐resistant PrP. Our results demonstrate that self‐PrP peptides are immunogenic in mice and suggest that this immune response might affect PrP‐scrapie levels in certain conditions.

Complete Freund's adjuvant immunization prolongs survival in experimental prion disease in mice

We recently reported that immunization of mice with certain self‐prion protein peptides induced specific T‐cell and B‐cell immune responses; importantly, this immunization was associated with a decrease in the number of protease‐resistant PrPSc particles recoverable in a transplanted, scrapie‐infected syngeneic tumor. The present study was carried out to determine whether immunization with the immunogenic PrP peptides might influence the natural history of experimental scrapie in mice. We immunized C57BL/6 mice with self‐prion peptides in complete Freunds adjuvant (CFA) or with CFA alone as a control and then infected the mice with mouse‐adapted scrapie by injection either intraperitoneally or intracerebrally. We report here that immunization with CFA, irrespective of whether prion peptides were present in the inoculum, resulted in marked prolongation of survival of the mice, whether the challenge was intracerebral or intraperitoneal. Mice in the immunized and control groups that died contained equivalent amounts of PrPSc. Thus, CFA immunization has a therapeutic effect in experimental scrapie in mice, possibly by reducing the rate of PrPSc accumulation in the brain.

Cogan's Syndrome—Clinical Guidelines and Novel Therapeutic Approaches

Cogans syndrome (CS) is a rare chronic inflammatory disorder, classically characterized by interstitial keratitis and sensorineural hearing loss. Recurrent episodes of inner ear disease might result in deafness. In some patients, it may also be accompanied by systemic vasculitis. Diagnosis of CS is often missed or delayed due to its rarity, the nonspecific clinical signs at onset, and the lack of a confirmatory diagnostic test. The mechanisms responsible for CS are unknown; however, in the last decade, the pathogenesis has been somewhat elucidated, suggesting that the disease is a result of inner ear autoimmunity. The autoimmune hypothesis postulates the triggering of the disease by a viral infection via a number of mechanisms, which are mainly as follows: antigenic mimicry, self-perpetuating inflammation by cytokine release, and unveiling hidden epitopes. Aside from its clinical resemblance to other autoimmune disorders, some autoantigen has apparently been identified, namely, CD148 and connexine 26. Treatment should begin as early as possible. While treatment is based primarily on glucocorticoids, there is no standard alternative for patients who respond poorly. Failure of conventional treatment could lead to profound sensorineural hearing loss. From the limited data we have, infliximab seems to be the most promising biological remedy, enabling steroid tapering and leading to improvement in auditory/ocular disease, with better results when administered in early stages. Proposed guidelines for the use of infliximab in CS are found in the last table of the review, in an attempt to define the proper timing for initiating infliximab treatment in order to avoid permanent disability.

Azathioprine as a therapeutic alternative for refractory chronic urticaria

Chronic urticaria (CU) affects up to 1% of the general population. Its impact on quality of life is immense, and patients might require multiple drugs to control symptoms. The main therapeutic challenge in the treatment of CU is to maintain symptomatic control while minimizing the use of glucocorticosteroids and their plethora of side effects.

Autologous stem cell transplantation in a rare multicentric Castleman disease of the plasma cell variant

We present a case of a 52-year-old male who was evaluated due to anorexia, persistent diarrhea, weight loss, and liver enzyme elevations, with no hematologic laboratory abnormalities. Imaging modalities revealed several tissue lesions involving the pancreas, the right kidney, and an axillary lymph node. Diagnosis of Castleman disease was reached only due to the tissue obtained from the lymph node. Chemotherapy and immunosuppression led to a short remission. The patient underwent autologous stem cell transplantation, and has since been in remission. This case demonstrates the cryptogenic and chameleon-like nature of Castleman disease. Challenges in treating Castleman disease patients reflect current limitations and the need for a greater understanding of disease pathogenesis.

Hypersensitivity Reactions to Rituximab: 53 Successful Desensitizations in 7 Patients with Severe, Near-Fatal Reactions

Rituximab is a chimeric antibody instrumental in the treatment of numerous hematological malignancies. A plethora of clinical manifestations are associated with acute hypersensitivity reactions (HSRs) to rituximab. Whether the HSRs are due to immunocytotoxicity or allergic responses, conventional desensitization procedures such as the 12-step protocol are usually effective. Nevertheless, rare, life-threatening immunocytotoxic reactions, as well as delayed reactions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and Drug Reaction with Eosinophilia and Systemic Symptoms, are considered absolute contraindications to the desensitization procedure. Here, we report our experience with hematological patients who had experienced severe, near-fatal, immediate HSRs to rituximab. A “modified desensitization” protocol was used, using intense premedication before the 12-step desensitization procedure. Following severe HSRs to previous rituximab infusions, 7 patients were admitted to the Hadassah Hematology Department in an attempt to resume rituximab treatment. Patients were included on the basis of the severity of the initial reaction and on their disease status mandating the administration of rituximab. Immediate HSRs were classified according to Brown’s Grading System. This research is a retrospective study (institutional ethical committee approval no. 0230-15-HMO). The patients’ status and the HSR details before admission to our department are presented in Table I. In 6 of 7 patients, the primary HSR occurred on the first exposure to rituximab. Owing to the severity of the primary disease, repeated rituximab administration was attempted in 5 of 7 patients and failed. Despite slower administration, premedication, and an attempt to desensitize (in patient 3), all patients presented severe HSRs. Five patients experienced cardiovascular collapse; 2 (3 and 6) had anaphylactic shock, necessitating intensive care unit hospitalization, 1 of which (6) suffered a complete cardiac arrest, mandating cardiovascular resuscitation. The 12-step desensitization protocol, previously described, uses successive increments in the concentration of the drug and

Autoimmune Inner Ear Disease: Immune Biomarkers, Audiovestibular Aspects, and Therapeutic Modalities of Cogan’s Syndrome

Cogans syndrome (CS) is a rare autoimmune disorder characterized by audiovestibular dysfunction and ocular inflammation. Currently, there is no specific serum autoantibody used in the diagnostic workup of CS. Treatment is based on immunosuppressive agents, mainly corticosteroids as first-line choice. Recently, novel therapeutic modalities in CS have emerged. These include tumor necrosis factor-α inhibitors and other biologicals. Despite medical treatment, hearing loss may progress to irreversible bilateral profound SNHL in approximately half of CS patients resulting in candidacy for cochlear implantation (CI). Due to the inflammatory nature of the disease that is causing endosteal reaction with partial obliteration or complete neoossification of the intracochlear ducts, early CI is recommended. CI provides excellent and stable hearing rehabilitation with high score of word and sentence recognition. In this review, we will discuss different aspects of CS including clinical presentation, diagnosis, treatment, and future directives.

Methylphenidate prolongs symptom-free period of experimental prion disease in mice.

http://dx.doi.org/10.1016/j.jns.2015.02.040 0022-510X/© 2015 Elsevier B.V. All rights reserved. We wish to report an observation regarding the effects of RitalinTM (methylphenidate, MP) on the course of prion disease in mice. Prions [1] propagate by refolding host protein PrP into PrP, a process occurring on lipid ‘rafts’. We studied MP because it reduces serum cholesterol [2] and elevates serum dehydroepiandrosterone (DHEA) [3], and as we have found that DHEA reduces PrP in prion-infected neuro2A cells (in preparation). (See Fig. 1.)