Circulating free DNA in the plasma of individuals with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant syndrome whose characteristic manifestations include benign neurofibromas, yet NF1 is also associated with a high risk of cancer. Measurements of circulating free plasma DNA (cfDNA) are gaining wider applicability in cancer diagnostics, targeting of therapy, and monitoring of therapeutic response. Individuals with NF1 are likely to be followed up using this method, but the effects of NF1 and neurofibromas on cfDNA levels are not known. We studied peripheral blood samples from 19 adults with NF1 and 12 healthy controls. The cfDNA was isolated from plasma with QIAamp Circulating Nucleic Acid Kit and quantified using the Qubit 2.0 Fluorometer. The cfDNA concentration of each sample was normalized relative to the plasma protein concentration. The normalized median concentration of cfDNA in plasma was 19.3 ng/ml (range 6.6–78.6) among individuals with NF1 and 15.9 ng/ml (range 4.8–47.0) among controls (p = .369). Individuals with NF1 who also had plexiform neurofibroma (pNF) showed non‐significantly elevated cfDNA concentration compared to individuals with NF1 and without known pNF (median 25.4 vs. 18.8 ng/ml, p = .122). The effect of NF1 on cfDNA seems to be relatively small and NF1 is therefore unlikely to hamper the use of cfDNA‐based assays.</p

Mast Cells in Human Cutaneous Neurofibromas: Density, Subtypes, and Association with Clinical Features in Neurofibromatosis 1

Background: Cutaneous neurofibromas (cNFs) are hallmarks of neurofibromatosis 1 (NF1) and cause the main disease burden in adults with NF1. Mast cells are a known component of cNFs. However, no comprehensive characterization of mast cells in cNFs is available, and their contributions to cNF growth and symptoms such as itch are not known.Methods: We collected 60 cNFs from ten individuals with NF1, studied their mast cell proteinase content, and compared the mast cell numbers to selected clinical features of the tumors and patients. The tumors were immunolabeled for the mast cell markers CD117, tryptase, and chymase, and the percentage of immunopositive cells was determined using computer-assisted methods.Results: The median proportions of positive cells were 5.5% (range 0.1-14.4) for CD117, 4.0% (1.2-7.0) for tryptase, and 5.0% (1.1-15.9) for chymase. The median densities of cells immunopositive for CD117, tryptase, and chymase were 280, 243, and 250 cells/mm2, respectively. Small tumors, growing tumors, and tumors from patients below the median age of 33 years displayed a high proportion of mast cells. Cells expressing both tryptase and chymase were the predominant mast cell type in cNFs, followed by cells expressing chymase only.Conclusion: The results highlight the abundance of mast cells in cNFs and that their number and subtypes clearly differ from those previously reported in unaffected skin.</p

Characterization of Mast Cells in Human Cutaneous Neurofibromas

Neurofibromatosis type 1 (NF1) is an autosomal dominant syndrome predisposing to malignancies. Most of the adult NF1 patients exhibit cutaneous neurofibromas (cNFs) which are derived from peripheral nerves in the skin. Although cNFs never undergo a malignant transformation, they reduce the quality of life of persons with NF1. One of the cell types present in cNFs are mast cells. These immune effectors can have both anti- and protumorigenic effects in cancer, and they might play an important functional role in neurofibromas as well. Mast cells are classified into three subtypes based on their protease content: the MC(T), the MC(C) and the MC(TC) types. A commonly used surface marker for mast cells is CD117 (c-Kit). The aim of this study was to quantify and characterize mast cells in human cNFs using antibodies to CD117 and the two mast cell proteases – chymase and tryptase. 60 cNF tissue samples from 10 NF1 patients were immunolabeled. The digitized sections were annotated, and positive cells within each tumor were counted. Finally, the total number of cells present in each tumor section was divided by the section area. The mean densities of cells positive for CD117, chymase and tryptase observed in cNFs were 271 (95% CI: 227 to 318), 270 (95% CI: 225 to 318) and 259 (95% CI: 223 to 297) cells/mm2, respectively. Growing tumors appeared to have higher mast cell densities than those with an unknown growth status. To conclude, mast cells can be considered as a prevalent cell type in human cNFs.Tyypin 1 neurofibromatoosi (NF1) on autosominen, vallitsevasti periytyvä oireyhtymä, joka altistaa pahanlaatuisille muutoksille. Suurimmalla osalla aikuisista NF1-potilaista esiintyy kutaanisia neurofibroomia, jotka saavat alkunsa ihon ääreishermoista. Vaikka nämä kasvaimet eivät koskaan muutu pahanlaatuisiksi, ne heikentävät NF1-potilaiden elämänlaatua. Yksi kutaanisissa neurofibroomissa esiintyvistä solutyypeistä ovat syöttösolut. Nämä immuunivaikuttajat voivat syövässä sekä hillitä että edistää kasvaimen kasvua, ja niillä saattaa olla tärkeä toiminnallinen merkitys myös neurofibroomissa. Syöttösolut jaetaan proteaasisisältönsä mukaisesti kolmeen alatyyppiin: MC(T)-, MC(C)- ja MC(TC)-tyyppeihin. Yleisesti käytetty syöttösolujen pintamarkkeri on CD117 (c-Kit). Tämän tutkimuksen tavoitteena oli määrittää ja karakterisoida ihmisen kutaanisten neurofibroomien syöttösoluja käyttämällä CD117:lle ja kahdelle syöttösoluproteaasille – kymaasille ja tryptaasille – spesifisiä vasta-aineita. Kymmeneltä NF1-potilaalta saaduille 60 kutaaniselle neurofibroomanäytteelle suoritettiin vasta-ainevärjäys. Digitalisoidut leikkeet annotoitiin, ja kunkin kasvaimen positiiviset solut laskettiin. Lopuksi kunkin kasvainalueen kokonaissolumäärä jaettiin alueen pinta-alalla. Kutaanisten neurofibroomien CD117-, kymaasi- ja tryptaasipositiivisten solujen keskimääräiset tiheydet olivat 271 (95% CI: 227–318), 270 (95% CI: 225–318) ja 259 (95% CI: 223–297) solua/mm2. Kasvavissa kasvaimissa syöttösolujen tiheydet osoittautuivat suuremmiksi kuin kasvutilanteeltaan tuntemattomissa kasvaimissa. Syöttösoluja voidaan pitää yleisenä solutyyppinä ihmisen kutaanisissa neurofibroomissa