Too Much Fat, Too Little Fat

Everyone wants to lose weight at the beginning of the year, and fat’s role in overall metabolism is a popular topic in the scientific and popular press. I see numerous computer popups advertising how to decrease my girth. I never click.

Now, Science and Arthritis and Rheumatology report intriguing physiological and pathological roles of fat, increasing our respect for and interest in the adipocyte.

Bleomycin injections have been used for many years to model systemic sclerosis. Recent findings show that the adipocytes in the mouse dermis are decreased after bleomycin injections and that this is associated with increased myofibroblasts that retain adipocyte markers (Marangoni et al, 2014). Therefore, thinking about human systemic sclerosis one now should consider signaling pathways that may affect adipocytes and trigger transdifferentiation . . . An important finding for stimulating New Year’s thinking. At first glance, this could be fat cells doing harm to the host.

Dermal adipocytes in the mouse can help the host (a mouse) during cutaneous infection with Staphylococcus aureus (Zhang et al, 2015). The adipocytes increase during cutaneous infection, and, more importantly, produce cathelicidin, an antimicrobial peptide. If adipose proliferation is prevented in the transgenic model, the antimicrobial peptide is impaired.

These two studies will no doubt increase interest in adipocytes and their roles in infections and inflammation.

The differences between mouse and human skin adipocytes have been recently summarized (Driskell et al, 2014).

 

REFERENCES:

Driskell RR, Jahoda CAB, Chuong CM (2014) Defining dermal adipose tissue. Exp Derm 23:629-31

 

Marangoni RG, Korman B, Wei J, et al (2014) Myofibroblasts in cutaneous fibrosis originate from adiponectin-positive intradermal progenitors. Arthritis Rheumatol. doi: 10.1002/art.38990. [Epub ahead of print]

 

Zhang LJ, Guerrero-Juarez CF, Hata T, et al (2015) Innate immunity. Dermal adipocytes protect against invasive Staphylococcus aureus skin infection. Science 347:67-71

 

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