Chronic and recurrent benign lymphadenopathy without constitutional symptoms associated with human herpesvirus-6B reactivation

EBV/HHV-6A dUTPases contribute to Myalgic Encephalomyelitis/Chronic-Fatigue-Syndrome pathophysiology by enhancing TFH cell differentiation and extrafollicular activities

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, debilitating multisystem illness of unknown etiology for which there is no cure and no diagnostic tests available. Despite increasing evidence implicating EBV and human herpesvirus-6A (HHV-6A) as potential causative infectious agents in a subset of ME/CFS patients, there are few mechanistic studies to address a causal relationship. In this study we examined a large ME/CFS cohort (n=351) and 77 controls and demonstrate a significant increase in activin A and IL-21serum levels, which correlated with seropositivity for antibodies to the EBV and HHV-6 protein deoxyuridine-triphosphate nucleotidohydrolase (dUTPase), but not CXCL13. These cytokines are critical for T follicular helper (TFH) cell differentiation, generation of high-affinity antibodies and long-lived plasma cells. Notably, ME/CFS serum was sufficient to drive TFH cell differentiation via an activin A-dependent mechanism. The lack of simultaneous CXCL13 increase with IL-21 indicates impaired TFH-function in ME/CFS. In vitro studies revealed that virus-dUTPases strongly induced activin A secretion while in vivo, EBV-dUTPase induced the formation of splenic marginal zone B and invariant NKTFH cells. Altogether, our data indicate abnormal germinal center (GC) activity in ME/CFS subjects and highlight a mechanism by which EBV and HHV6-dUTPases may alter GC and extrafollicular Ab responses.

Human Herpes Virus 6 (HHV-6)-associated Lymphadenitis: Pitfalls in Diagnosis in Benign and Malignant Settings

Human herpes virus 6 (HHV-6) is a member of the β-herpesvirinae subfamily. Most people acquire HHV-6 primary infection early in life and reactivation may occur, most often in immunocompromised individuals, leading to various clinical manifestations. HHV-6 infected cells may be identified in lymph nodes in both reactive and neoplastic conditions. Cases were retrieved from the hematopathology consultation service archives at National Institutes of Health from 2003 to 2017 in which infection by HHV-6 had been documented by immunohistochemical stains to HHV-6 gp60/110 envelope glycoprotein. Five cases of reactive lymphadenitis and 3 cases of lymphoma; 2 angioimmunoblastic T-cell lymphoma and 1 classic Hodgkin lymphoma, positive for HHV-6 were identified. The reactive lymph nodes showed marked paracortical hyperplasia and admixed large atypical lymphoid cells exhibiting pleomorphic nuclei, vesicular chromatin, and prominent eosinophilic intranuclear inclusions. Vascular proliferation and necrosis were also present, raising suspicion of peripheral T-cell lymphoma. The 3 cases of lymphoma showed similar viral inclusions, in addition to the characteristic features diagnostic of the lymphoma. Staining for HHV-6 was positive with a membranous and Golgi pattern and was restricted to cells with evident inclusions on hematoxylin and eosin. HHV-6 infected cells were positive for CD3 and CD4. HHV-6 lymphadenitis can present with morphologic atypia creating a diagnostic pitfall for lymphoma. In such cases, careful attention to the characteristic viral inclusions can lead to immunohistochemical analysis highlighting the replicating virus. In cases of lymphoma, identification of the inclusions is key in detecting the associated infection as well as in avoiding misinterpretation of the lymphoma subtype.

Lymphoproliferative Syndromes Associated with Human Herpesvirus-6A and Human Herpesvirus-6B

Human herpesvirus 6A and 6B (HHV-6A and HHV-6B) have been noted since their discovery for their T-lymphotropism. Although it has proven difficult to determine the extent to which HHV-6A and HHV-6B are involved in the pathogenesis of many diseases, evidence suggests that primary infection and reactivation of both viruses may induce or contribute to the progression of several lymphoproliferative disorders, ranging from benign to malignant and including infectious mononucleosis-like illness, drug induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS), and nodular sclerosis Hodgkin's lymphoma. Herein, we discuss the conditions associated with the lymphoproliferative capacity of HHV-6, as well as the potential mechanisms behind them. Continued exploration on this topic may add to our understanding of the interactions between HHV-6 and the immune system and may open the doors to more accurate diagnosis and treatment of certain lymphoproliferative disorders.

Blood biomarkers in adults with lymph node enlargement contribute to diagnostic significance of malignancy

Lymph node enlargement is a common presentation and has a possibility of malignancy like lymphoma that requires early diagnosis. This study aims to analyze the clinical characteristics of these patients and finds out useful predictors of malignant diseases. We retrospectively investigated 81 patients with lymph node enlargement between July 2, 2014 and May 17, 2016. The characteristics and laboratory findings were evaluated combining with the final diagnosis. The diagnoses were malignancy in 51 patients and benign lymphadenopathy in 30 patients. Increased beta2-microglobulin (B2M) (P = 0.012) was found to be associated with malignant diseases, and level of 3699.5 μg/L was used as a cut-off value to differentiate the malignancies from benign diseases, offering 63.4% sensitivity and 87.0% specificity. Immunoglobulin G (IgG) (P = 0.038) levels were significantly lower in malignant group, whose receiver operating characteristic curve showed that level of 1121.5 mg/dl had sensitivity and specificity as 58.5% and 82.6%. Moreover, through analysis of cytokines, we found interleukin-10 (IL-10) levels were elevated in malignant group compared with benign group. Serum B2M and IgG levels were concluded to be useful parameters for predicting malignancies. Besides, increased IL-10 levels indicated a higher risk of malignancy in some way.

Chemokines encoded by herpesviruses

Viruses use diverse strategies to elude the immune system, including copying and repurposing host cytokine and cytokine receptor genes. For herpesviruses, the chemokine system of chemotactic cytokines and receptors is a common source of copied genes. Here, we review the current state of knowledge about herpesvirus-encoded chemokines and discuss their possible roles in viral pathogenesis, as well as their clinical potential as novel anti-inflammatory agents or targets for new antiviral strategies.