Impact of siRNA-Mediated Cofilin-1 Knockdown and Obesity Associated Microenvironment on the Motility of Natural Killer Cells.

The anti-tumor capacity of natural killer (NK) cells heavily relies on their ability to migrate towards their target cells. This process is based on dynamic actinrearrangement, so-called actin treadmilling, andis tightly regulated by proteins such as cofilin-1. The aim of the present study was to identify the role of cofilin-1 (CFL-1) in the migratory behavior of NK cells and to investigate a possible impact of an obesity-associated micromilieu on these cells, as it is known that obesity correlates with various impaired NK cell functions. CFL-1 was knocked-down via transfection of NK-92 cells with respective siRNAs. Obesity associated micromilieu was mimicked by incubation of NK-92 cells with adipocyte-conditioned medium from human preadipocyte SGBS cells or leptin. Effects on CFL-1 levels, the degree of phosphorylation to the inactive pCFL-1 as well as NK-92 cell motility were analyzed. Surprisingly, siRNA-mediated CFL-1 knockdown led to a significant increase of migration, as determined by enhanced velocity and accumulated distance of migration. No effect on CFL-1 nor pCFL-1 expression levels, proportion of phosphorylation and cell migratory behavior could be demonstrated under the influence of an obesity-associated microenvironment. In conclusion, the results indicate a significant effect of a CFL-1 knockdown on NK cell motility.

Effects of obesity on NK cells in a mouse model of postmenopausal breast cancer.

Obesity is a widely spread disease and a crucial risk factor for malign disorders, including breast cancer of women in the postmenopause. Studies demonstrated that in case of obesity crucial natural killer (NK) cell functions like combating tumor cells are affected. This study aims to analyze NK cells and NK cell receptor expression of obese mice in a model for postmenopausal breast cancer. Therefore, female BALB/c mice were fed either a high fat or a standard diet. Thereafter, ovaries were ectomized and a syngeneic and orthotopical injection of 4T1-luc2 mouse mammary tumor cells into the mammary adipose tissue pad was performed. Obese mice showed increased body weights and visceral fat mass as well as increased levels of leptin and IL-6 in plasma. Moreover, compared to the lean littermates, tumor growth was increased and the NKp46-expression on circulating NK cells was decreased. Furthermore, the activating NK cell receptor NKG2D ligand (MULT1) expression was enhanced in adipose tissue of obese tumor bearing mice. The present study gives novel insights into gene expression of NK cell receptors in obesity and aims to promote possible links of the obesity-impaired NK cell physiology and the elevated breast cancer risk in obese women.

Leptin affects filopodia and cofilin in NK-92 cells in a dose- and time-dependent manner.

Hyperleptinemia, associated with obesity, is related with immune dysfunction and carcinogenesis. Natural Killer (NK) cells, a major component of the innate immune system are mediators of anti-tumor immunity and the most actively migrating cells among leukocytes. Actin rearrangement, promoted by cofilin plays a central role in cellular migration. Leptin affects the phosphorylation-dependent activity of cofilin and thus actin remodeling. We used human NK-92 cells to explore the in vitro effects of leptin on co-localization of cofilin and F-actin and on morphological changes in NK cells. NK-92 cells were incubated with different leptin concentrations (10 and 100 ng/mL) for 30 min and 24 h and immunocytochemically stained. Results demonstrate a dose- and time-dependent influence of leptin on cellular morphology. Utilizing confocal microscopy, we observed that the co-localization of cofilin-1 and F-actin was slightly influenced by leptin. In summary, the present study demonstrates an impact of a physiological leptin stimulation on the filopodia length, and a time-dependent effect on the co-localization of cofilin and F-actin in NK-92 cells.

[Dealing with diagnostic uncertainty in general practice]. / Umgang mit diagnostischer Unsicherheit in der Hausarztpraxis.

In general, the prevalence of diseases is low in primary care. Therefore, the positive predictive value of diagnostic tests is lower than in hospitals where patients are highly selected. In addition, the patients present with milder forms of disease; and many diseases might hide behind the initial symptom(s). These facts lead to diagnostic uncertainty which is somewhat inherent to general practice. This narrative review discusses different sources of and reasons for uncertainty and strategies to deal with it in the context of the current literature. Fear of uncertainty correlates with higher diagnostic activities. The attitude towards uncertainty correlates with the choice of medical speciality by vocational trainees or medical students. An intolerance of uncertainty, which still increases as medicine is making steady progress, might partly explain the growing shortage of general practitioners. The bio-psycho-social context appears to be important to diagnostic decision-making. The effect of intuition and heuristics are investigated by cognitive psychologists. It is still unclear whether these aspects are prone to bias or useful, which might depend on the context of medical decisions. Good communication is of great importance to share uncertainty with the patients in a transparent way and to alleviate shared decision-making. Dealing with uncertainty should be seen as an important core component of general practice and needs to be investigated in more detail to improve the respective medical decisions.