Malaria inhibits surface expression of complement receptor 1 in monocytes/macrophages, causing decreased immune complex internalization.

Complement receptor 1 (CR1) expressed on the surface of phagocytic cells binds complement-bound immune complexes (IC), playing an important role in the clearance of circulating IC. This receptor is critical to prevent accumulation of IC, which can contribute to inflammatory pathology. Accumulation of circulating IC is frequently observed during malaria, although the factors contributing to this accumulation are not clearly understood. We have observed that the surface expression of CR1 on monocytes/macrophages and B cells is strongly reduced in mice infected with Plasmodium yoelii, a rodent malaria model. Monocytes/macrophages from these infected mice present a specific inhibition of complement-mediated internalization of IC caused by the decreased CR1 expression. Accordingly, mice show accumulation of circulating IC and deposition of IC in the kidneys that inversely correlate with the decrease in CR1 surface expression. Our results indicate that malaria induces a significant decrease on surface CR1 expression in the monocyte/macrophage population that results in deficient internalization of IC by monocytes/macrophages. To determine whether this phenomenon is found in human malaria patients, we have analyzed 92 patients infected with either P. falciparum (22 patients) or P. vivax (70 patients) , the most prevalent human malaria parasites. The levels of surface CR1 on peripheral monocytes/macrophages and B cells of these patients show a significant decrease compared with uninfected control individuals in the same area. We propose that this decrease in CR1 plays an essential role in impaired IC clearance during malaria.

Endoscopic endonasal resection of clival xanthoma: case report and literature review.

Bone xanthoma is an extremely rare and benign tumor in terms of its nature and growth over time. We describe the first case coexisting with ventriculomegaly secondary to aqueduct stenosis (non-tumoral hydrocephalus), the second xanthoma of the clivus described to date. The patient was a 51-year-old woman with headaches and absence seizures. Axial T1-weighted MRI showed a well-demarcated, hypointense, osteolytic, 25 × 18 × 15 mm lesion with cortical erosion located at the right margin of the clivus. Sagittal T2-weighted MRI demonstrated a hypointense mass without associated edema. Sagittal gadolinium-enhanced T1-weighted MRI showed contrast uptake with a partially hypointense rim. The increased ventricular size without periventricular edema was associated with aqueduct stenosis, and there was no contiguity with the tumor. A neuronavigation image-guided transsphenoidal approach was chosen to perform a macroscopically complete resection. Intraoperative histopathological study showed a chordoma of the clivus. Exhaustive postsurgical study revealed the benign nature of a bone xanthoma. Given the finding of a clival lesion, the differential diagnosis is essentially with other malignant entities with a rapidly fatal outcome, such as metastases, or with a possible invasive evolution, such as clivus chordomas. This report describes the clinical, radiological, and pathological keys for such differentiation in order to avoid unnecessarily aggressive treatment with ablative surgery and radiotherapy.

Acceleration of the DNA methylation clock among lynch syndrome-associated mutation carriers.

BACKGROUND: DNA methylation (DNAm) age metrics have been widely accepted as an epigenetic biomarker for biological aging and disease. The purpose of this study is to assess whether or not individuals carrying Lynch Syndrome-associated mutations are affected in their rate of biological aging, as measured by the epigenetic clock. METHODS: Genome-wide bisulfite DNA sequencing data were generated using DNA from CD4 + T-cells obtained from peripheral blood using 27 patient samples from Lynch syndrome families. Horvath's DNAm age model based on penalized linear regression was applied to estimate DNAm age from patient samples with distinct clinical and genetic characteristics to investigate cancer mutation-related aging effects. RESULTS: Both Lynch mutation carriers and controls exhibited high variability in their estimated DNAm age, but regression analysis showed steeper slope for the Lynch mutation carriers. Remarkably, six Lynch Syndrome-associated mutation carriers showed a strong correlation to the control group, and two sisters carrying Lynch Syndrome-associated mutations, with no significant difference in lifestyle and similar chronological age, were assigned very different DNAm age. CONCLUSIONS: Future studies will be required to explore, in larger patient populations, whether specific epigenetic age acceleration is predictive of time-to-cancer development, treatment response, and survival. Epigenetic clock DNAm metrics may be affected by the presence of cancer mutations in the germline, and thus show promise of potential clinical utility for stratified surveillance strategies based on the relative risk for imminent emergence of tumor lesions in otherwise healthy Lynch Syndrome-associated mutation carriers.