Microglial nodules in the normal-appearing white matter have been suggested as the earliest stage(s) of multiple sclerosis (MS) lesion formation. Such nodules are characterized by an absence of leukocyte infiltration, astrogliosis or demyelination, and may develop into active demyelinating MS lesions. Although the etiology of MS is still not known, inflammation and autoimmunity are considered to be the central components of this disease. Previous studies provide evidence that Wallerian degeneration, occurring as a consequence of structural damage in MS lesions, might be responsible for observed pathological abnormalities in connected normal-appearing white matter. As innate immune cells, microglia/macrophages are the first to react to even minor pathological changes in the CNS. Biopsy tissue from 27 MS patients and autopsy and biopsy tissue from 22 normal and pathological controls were analyzed to determine the incidence of microglial nodules. We assessed MS periplaque white matter tissue from early disease stages to determine whether microglial nodules are associated with altered axons. With immunohistochemical methods, the spatial relation of the two phenomena was visualized using HLA-DR antibody for MHC II expression by activated microglia/macrophages and by applying antibodies against damaged axons, i.e., SMI32 (non-phosphorylated neurofilaments) and amyloid precursor protein as well as neuropeptide Y receptor Y1, which marks axons undergoing Wallerian degeneration. Our data demonstrate that the occurrence of microglial nodules is not specific to MS and is associated with degenerating as well as damaged axons in early MS. In addition, we show that early MS microglial nodules exhibit both pro- and antiinflammatory phenotypes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-013-1082-0) contains supplementary material, which is available to authorized users.

Background In brain tissues from multiple sclerosis (MS) patients, clusters of activated HLA-DR-expressing microglia, also referred to as preactive lesions, are located throughout the normal-appearing white matter. The aim of this study was to gain more insight into the frequency, distribution and cellular architecture of preactive lesions using a large cohort of well-characterized MS brain samples. Methods Here, we document the frequency of preactive lesions and their association with distinct white matter lesions in a cohort of 21 MS patients. Immunohistochemistry was used to gain further insight into the cellular and molecular composition of preactive lesions. Results Preactive lesions were observed in a majority of MS patients (67%) irrespective of disease duration, gender or subtype of disease. Microglial clusters were predominantly observed in the vicinity of active demyelinating lesions and are not associated with T cell infiltrates, axonal alterations, activated astrocytes or blood–brain barrier disruption. Microglia in preactive lesions consistently express interleukin-10 and TNF-α, but not interleukin-4, whereas matrix metalloproteases-2 and −9 are virtually absent in microglial nodules. Interestingly, key subunits of the free-radical-generating enzyme NADPH oxidase-2 were abundantly expressed in microglial clusters. Conclusions The high frequency of preactive lesions suggests that it is unlikely that most of them will progress into full-blown demyelinating lesions. Preactive lesions are not associated with blood–brain barrier disruption, suggesting that an intrinsic trigger of innate immune activation, rather than extrinsic factors crossing a damaged blood–brain barrier, induces the formation of clusters of activated microglia.

OBJECTIVES Pancreatic cancer (PC) is a lethal malignancy that lacks specific diagnostic markers. The present study explores the diagnostic potential of the most differentially overexpressed secretory mucin MUC5AC alone and in combination with CA19-9 using multi-center training and validation sets. METHODS The expression of MUC5AC in benign pancreatic pathologies, PC precursor lesions, primary PC tissues and metastatic lesions was evaluated by immunohistochemistry. Circulating MUC5AC levels were measured using sandwich ELISA assay developed in-house, and CA19-9 was measured using radioimmunoassay. A combined training set (n =346) was used to evaluate the diagnostic (n =241) and predictive (n =105, total samples 201 from pre- and post-surgical and chemotherapy set) significance of MUC5AC. Results were further validated with a pre-defined cut-off value using independent sets from the Mayo Clinic (n =94) and the University of Pittsburgh Medical Center (n =321). RESULTS Tissue expression analyses indicated the de novo expression of MUC5AC in pancreatic intraepithelial precursor lesions 1A (PanIN1A); the expression was maintained through all stages of progression to invasive adenocarcinoma. The median circulating MUC5AC levels in patients with resectable early-stage PC (EPC) (stage 1/2; 67.2 ng/ml, IQR: 23.9–382.1) and unresectable late-stage PC (LPC) (stage 3/4; 389.7 ng/ml, IQR: 87.7–948.6) were significantly higher compared with (P-value ≤0.0001) benign controls (BC) (7.2 ng/ml, IQR: 0.4–26.5) and (P-value ≤0.0001) chronic pancreatitis (CP) controls (8.4 ng/ml, IQR: 1.5–19.2). In the diagnostic training set (n =241), MUC5AC efficiently differentiated EPC from healthy controls (HC) (83%/80% sensitive (SN)/specific (SP)), BC (67%/87% SN/SP), and CP (83%/77% SN/SP). Independent validation sets from the Mayo Clinic and UPMC confirmed the diagnostic potential of MUC5AC to differentiate EPC from BC (68%/73%; 65%/83%) and CP (68%/79%; 65%/72%). Furthermore, MUC5AC and CA19-9 combination significantly improved (p-value < 0.001) the diagnostic accuracy for differentiating resectable cases from controls. CONCLUSIONS MUC5AC is a valuable diagnostic biomarker, either alone or in combination with CA19-9, to differentiate PC from CP and benign controls.