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Biomedical subjects

Peter A Calabresi

Publications and source records attributed to Peter A Calabresi.

24 records · Page 2Linked to original sources

Diagnosis and management of multiple sclerosis.

Multiple sclerosis, an idiopathic inflammatory disease of the central nervous system, is characterized pathologically by demyelination and subsequent axonal degeneration. The disease commonly presents in young adults and affects twice as many women as men. Common presenting symptoms include numbness, weakness, visual impairment, loss of balance, dizziness, urinary bladder urgency, fatigue, and depression. The diagnosis of multiple sclerosis should be made by a physician with experience in identifying the disease. Diagnosis should be based on objective evidence of two or more neurologic signs that are localized to the brain or spinal cord and are disseminated in time and space (i.e., occur in different parts of the central nervous system at least three months apart). Magnetic resonance imaging with gadolinium contrast, especially during or following a first attack, can be helpful in providing evidence of lesions in other parts of the brain and spinal cord. A second magnetic resonance scan may be useful at least three months after the initial attack to identify new lesions and provide evidence of dissemination over time. It is critical to exclude other diseases that can mimic multiple sclerosis, including vascular disease, spinal cord compression, vitamin B12 deficiency, central nervous system infection (e.g., Lyme disease, syphilis), and other inflammatory conditions (e.g., sarcoidosis, systemic lupus erythematosus, Sjögren's syndrome). Symptom-specific drugs can relieve spasticity, bladder dysfunction, depression, and fatigue. Five disease-modifying treatments for multiple sclerosis have been approved by the U.S. Food and Drug Administration. These treatments are partially effective in reducing exacerbations and may slow progression of disability.

Adjuvants, Immunologic↗

Kv1.3-blocking 5-phenylalkoxypsoralens: a new class of immunomodulators.

The lymphocyte potassium channel Kv1.3 is widely regarded as a promising new target for immunosuppression. To identify a potent small-molecule Kv1.3 blocker, we synthesized a series of 5-phenylalkoxypsoralens and tested them by whole-cell patch clamp. The most potent compound of this series, 5-(4-phenylbutoxy)psoralen (Psora-4), blocked Kv1.3 in a use-dependent manner, with a Hill coefficient of 2 and an EC50 value of 3 nM, by preferentially binding to the C-type inactivated state of the channel. Psora-4 is the most potent small-molecule Kv1.3 blocker known. It exhibited 17- to 70-fold selectivity for Kv1.3 over closely related Kv1-family channels (Kv1.1, Kv1.2, Kv1.4, and Kv1.7) with the exception of Kv1.5 (EC50, 7.7 nM) and showed no effect on human ether-a-go-go-related channel, Kv3.1, the calcium-activated K+ channels (IKCa1, SK1-SK3, and BKCa), or the neuronal NaV1.2 channel. In a test of in vivo toxicity in rats, Psora-4 did not display any signs of acute toxicity after five daily subcutaneous injections at 33 mg/kg body weight. Psora-4 selectively suppressed the proliferation of human and rat myelin-specific effector memory T cells with EC50 values of 25 and 60 nM, respectively, without persistently suppressing peripheral blood naive and central memory T cells. Because autoantigen-specific effector memory T cells contribute to the pathogenesis of T cell-mediated autoimmune diseases such as multiple sclerosis, Psora-4 and other Kv1.3 blockers may be useful as immunomodulators for the therapy of autoimmune disorders.

Adjuvants, Immunologic↗

Kinetics of CCR7 expression differ between primary activation and effector memory states of T(H)1 and T(H)2 cells.

We explored the kinetics of CCR7 expression on T(H)1 and T(H)2 polarized cells as well as on antigen-specific T cell lines at various stages of differentiation. A striking pattern of early (days 7-14) inducible CCR7 expression was seen preferentially on primary T(H)1 cell lines, as compared to T(H)2 cells, and was dependent on the strength and duration of the T cell receptor signal. Upon repeated restimulation (days 21-28) and differentiation, a switch occurred in which T(H)2 cells had high CCR7 expression, whereas T(H)1 cells lost CCR7 expression. Chronic (8 weeks and later) effector memory cell lines were 95% CCR7 negative. These data demonstrate an ordered pattern of CCR7 expression that suggest more rapid priming of T(H)1 cells in the lymph node, and delayed priming with prolonged CCR7 expression during T(H)2 responses, and may have implications for tracking T(H)1 effector T cells ex vivo in autoimmune diseases.

Antigen Presentation↗

The voltage-gated Kv1.3 K(+) channel in effector memory T cells as new target for MS.

Through a combination of fluorescence microscopy and patch-clamp analysis we have identified a striking alteration in K(+) channel expression in terminally differentiated human CCR7(-)CD45RA(-) effector memory T lymphocytes (T(EM)). Following activation, T(EM) cells expressed significantly higher levels of the voltage-gated K(+) channel Kv1.3 and lower levels of the calcium-activated K(+) channel IKCa1 than naive and central memory T cells (T(CM)). Upon repeated in vitro antigenic stimulation, naive cells differentiated into Kv1.3(high)IKCa1(low) T(EM) cells, and the potent Kv1.3-blocking sea anemone Stichodactyla helianthus peptide (ShK) suppressed proliferation of T(EM) cells without affecting naive or T(CM) lymphocytes. Thus, the Kv1.3(high)IKCa1(low) phenotype is a functional marker of activated T(EM) lymphocytes. Activated myelin-reactive T cells from patients with MS exhibited the Kv1.3(high)IKCa1(low) T(EM) phenotype, suggesting that they have undergone repeated stimulation during the course of disease; these cells may contribute to disease pathogenesis due to their ability to home to inflamed tissues and exhibit immediate effector function. The Kv1.3(high)IKCa1(low) phenotype was not seen in glutamic acid decarboxylase, insulin-peptide or ovalbumin-specific and mitogen-activated T cells from MS patients, or in myelin-specific T cells from healthy controls. Selective targeting of Kv1.3 in T(EM) cells may therefore hold therapeutic promise for MS and other T cell-mediated autoimmune diseases.

Adult↗

Considerations in the treatment of relapsing-remitting multiple sclerosis.

Disease-modifying drugs are available in the United States for the treatment of relapsing-remitting multiple sclerosis (RRMS), including interferon (IFN) beta-1a, IFNbeta-1b, and glatiramer acetate. Another formulation of IFNbeta-1a is available in Europe, Canada, and other countries. Mitoxantrone is also indicated for the treatment of worsening forms of RRMS and secondary progressive (SP) MS. In addition to reductions in annual relapse rates and other measures of clinical disability, the disease-modifying drugs appear to reduce MRI measures of disease activity. Available data suggest that the efficacy of disease-modifying therapy is sustained for at least for 4 to 6 years. Results of clinical drug trials have been used as a rationale to support treatment of early MS with a disease-modifying drug. Other medical therapies are used in the management of RRMS, including treatments to help manage MS-related symptoms such as spasticity and bladder dysfunction, and corticosteroids to hasten recovery from acute relapses. In some situations, interventions are used to minimize side effects of disease-modifying drug therapy. Several currently marketed treatments, including IV immunoglobulin, methotrexate, and azathioprine, are being evaluated as treatments for RRMS in combination with the approved therapies. Investigational compounds, including oral formulations of glatiramer acetate and interferon, are in various stages of development.

Brain↗

Chemokine receptor expression on MBP-reactive T cells: CXCR6 is a marker of IFNgamma-producing effector cells.

Cytokine-polarized T cells have distinct chemokine receptor (CKR) expression patterns associated with their cytokine secretion profiles. In order to investigate this paradigm in autoreactive human T cells, we have determined the CKR expression pattern of myelin basic protein (MBP)-reactive T cell lines (TCL) and compared these profiles to those of TCL-generated in response to tetanus toxoid (TT). Expression of CXCR6 and CXCR3 on TCL was significantly positively correlated with IFNgamma, and inversely correlated with IL-5 production. TT TCL had significantly higher expression of CCR7(-)/CD45RA(-) T effector memory (Tem) cells than MBP TCL. However, in MBP-specific TCL, CXCR6 was found to be the best marker of conversion to the Tem phenotype. CXCR6 and CXCR3 are likely to be important in the migration of effector memory T cells in Th1-mediated inflammatory diseases such as multiple sclerosis (MS).

Biomarkers↗