CCL2 disrupts the adherens junction: implications for neuroinflammation.

Alterations to blood-brain barrier (BBB) adhesion molecules and junctional integrity during neuroinflammation can promote central nervous system (CNS) pathology. The chemokine CCL2 is elevated during CNS inflammation and is associated with endothelial dysfunction. The effects of CCL2 on endothelial adherens junctions (AJs) have not been defined. We demonstrate that CCL2 transiently induces Src-dependent disruption of human brain microvascular endothelial AJ. ß-Catenin is phosphorylated and traffics from the AJ to PECAM-1 (platelet endothelial cell adhesion molecule-1), where it is sequestered at the membrane. PECAM-1 is also tyrosine-phosphorylated, an event associated with recruitment of the phosphatase SHP-2 (Src homology 2 domain-containing protein phosphatase) to PECAM-1, ß-catenin release from PECAM-1, and reassociation of ß-catenin with the AJ. Surface localization of PECAM-1 is increased in response to CCL2. This may enable the endothelium to sustain CCL2-induced alterations in AJ and facilitate recruitment of leukocytes into the CNS. Our novel findings provide a mechanism for CCL2-mediated disruption of endothelial junctions that may contribute to BBB dysfunction and increased leukocyte recruitment in neuroinflammatory diseases.

PrPC, the cellular isoform of the human prion protein, is a novel biomarker of HIV-associated neurocognitive impairment and mediates neuroinflammation.

Of the 33 million people infected with the human immunodeficiency virus (HIV) worldwide, 40-60% of individuals will eventually develop neurocognitive sequelae that can be attributed to the presence of HIV-1 in the central nervous system (CNS) and its associated neuroinflammation despite antiretroviral therapy. PrP(C) (protease resistant protein, cellular isoform) is the nonpathological cellular isoform of the human prion protein that participates in many physiological processes that are disrupted during HIV-1 infection. However, its role in HIV-1 CNS disease is unknown. We demonstrate that PrP(C) is significantly increased in both the CNS of HIV-1-infected individuals with neurocognitive impairment and in SIV-infected macaques with encephalitis. PrP(C) is released into the cerebrospinal fluid, and its levels correlate with CNS compromise, suggesting it is a biomarker of HIV-associated neurocognitive impairment. We show that the chemokine (c-c Motif) Ligand-2 (CCL2) increases PrP(C) release from CNS cells, while HIV-1 infection alters PrP(C) release from peripheral blood mononuclear cells. Soluble PrP(C) mediates neuroinflammation by inducing astrocyte production of both CCL2 and interleukin 6. This report presents the first evidence that PrP(C) dysregulation occurs in cognitively impaired HIV-1-infected individuals and that PrP(C) participates in the pathogenesis of HIV-1-associated CNS disease.

Diagnostic and therapeutic challenges of EBV-positive mucocutaneous ulcer: a case report and systematic review of the literature.

BACKGROUND: Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a recently recognized B cell lymphoproliferative disorder that is driven by latent EBV infection and causes discrete ulcerations in the oropharynx, gastrointestinal tract, and skin. Local attenuation of immunosurveillance associated with iatrogenic immunosuppressant use, primary immunodeficiency, or age-associated immunosenescence has been implicated as a predisposing factor. This disorder is likely under reported, as it was only first defined in 2010 and shares histological features with other B-cell proliferative neoplasms. The first case series that described EBVMCU suggested that EBVMCU is generally self-limited and is likely to resolve without treatment. Since that publication, additional cases have been reported that describe a more heterogeneous clinical course, often requiring aggressive therapy. We now systematically review all published cases of EBVMCU and detail a case of aggressive and progressive EBVMCU, including diagnostic and management challenges, as well as successful treatment with radiation therapy. CASE PRESENTATION: A forty-nine year old woman presented with painful and debilitating multifocal oral EBVMCU that initially responded to four weekly doses of rituximab. Her disease relapsed within 3 months and continued to progress and cause significant morbidity. She was successfully treated with local external beam radiation therapy of 30 Gy in 15 fractions, with duration of response of at least 6 months. CONCLUSIONS: We suggest that although many patients with EBVMCU experience a self-limited course, for others EBVMCU can be a debilitating, persistent disorder that requires aggressive therapy to prevent disease progression. CD20- and CD30-directed antibody therapy, local radiation therapy, local surgical excision, systemic chemotherapy, and a combination of these therapies have all been successfully used to treat EBVMCU with high rates of durable clinical remission. As EBVMCU is not currently included in the 2008 WHO classification of lymphoproliferative disorders and no evidence-based guidelines or expert opinions have been proposed to guide therapy, this case report and systematic review provides a foundation on which to guide therapeutic decisions.