B cell activity is impaired in human and mouse obesity and is responsive to an essential fatty acid upon murine influenza infection

Obesity is associated with increased risk for infections and poor responses to vaccinations, which may be due to compromised B cell function. However, there is limited information about the influence of obesity on B cell function and underlying factors that modulate B cell responses. Therefore, we studied B cell cytokine secretion and/or Ab production across obesity models. In obese humans, B cell IL-6 secretion was lowered and IgM levels were elevated upon ex vivo anti-BCR/TLR9 stimulation. In murine obesity induced by a high fat diet, ex vivo IgM and IgG were elevated with unstimulated B cells. Furthermore, the high fat diet lowered bone marrow B cell frequency accompanied by diminished transcripts of early lymphoid commitment markers. Murine B cell responses were subsequently investigated upon influenza A/Puerto Rico/8/34 infection using a Western diet model in the absence or presence of docosahexaenoic acid (DHA). DHA, an essential fatty acid with immunomodulatory properties, was tested because its plasma levels are lowered in obesity. Relative to controls, mice consuming theWestern diet had diminished Ab titers whereas theWestern diet plus DHA improved titers. Mechanistically, DHA did not directly target B cells to elevate Ab levels. Instead, DHA increased the concentration of the downstream specialized proresolving lipid mediators (SPMs) 14-hydroxydocosahexaenoic acid, 17-hydroxydocosahexaenoic acid, and protectin DX. All three SPMs were found to be effective in elevating murine Ab levels upon influenza infection. Collectively, the results demonstrate that B cell responses are impaired across human and mouse obesity models and show that essential fatty acid status is a factor influencing humoral immunity, potentially through an SPM-mediated mechanism

Differential enzymatic activity of common haplotypic versions of the human acidic Mammalian chitinase protein

FWN – Publicaties zonder aanstelling Universiteit Leide

Astronomical Distance Determination in the Space Age: Secondary Distance Indicators

The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)