HIV-associated lipodystrophy is a condition characterized by loss of

subcutaneous fat The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and macro ...

associated with infection with HIV.

Presentation

HIV-associated lipodystrophy commonly presents with fat loss in face, buttocks, arms and legs. There is also fat ''accumulation'' in various body parts. Patients often present with "buffalo hump"-like fat deposits in their upper backs. Breast size of patients (both male and female) tends to increase. In addition, patients develop abdominal obesity.

Cause

The exact mechanism of HIV-associated

lipodystrophy Lipodystrophy syndromes are a group of genetic or acquired disorders in which the body is unable to produce and maintain healthy fat tissue. The medical condition is characterized by abnormal or degenerative conditions of the body's adipose tissue. ...

is not fully elucidated. There is evidence indicating both that it can be caused by anti-retroviral medications and that it can be caused by HIV infection in the absence of anti-retroviral medication.

Evidence implicating anti-retroviral medications

On the one hand, lipodystrophy seems to be mainly due to HIV-1

protease inhibitors Protease inhibitors (PIs) are medications that act by interfering with enzymes that cleave proteins. Some of the most well known are antiviral drugs widely used to treat HIV/AIDS and hepatitis C. These protease inhibitors prevent viral replicat ...

. Interference with

lipid metabolism Lipid metabolism is the synthesis and degradation of lipids in cells, involving the breakdown or storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes. In anim ...

is postulated as

pathophysiology Pathophysiology ( physiopathology) – a convergence of pathology with physiology – is the study of the disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is ...

. Also, the development of lipodystrophy is associated with specific

nucleoside reverse transcriptase inhibitor Reverse-transcriptase inhibitors (RTIs) are a class of antiretroviral drugs used to treat HIV infection or AIDS, and in some cases hepatitis B. RTIs inhibit activity of reverse transcriptase, a viral DNA polymerase that is required for replicatio ...

s (NRTI). Mitochondrial toxicity is postulated to be involved in the

pathogenesis Pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Greek πάθος ''pat ...

associated with NRTI.

Evidence implicating HIV infection alone

On the other hand, there is evidence that

HIV-1 The subtypes of HIV include two major types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). HIV-1 is related to viruses found in chimpanzees and gorillas living in western Africa, while HIV-2 viruses are related to viruses found in the sooty mangabey ...

infection on its own contributes to the development of the lipodystrophic

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (biology), morphology or physical form and structure, its Developmental biology, developmental proc ...

by interfering with some key genes of

adipocyte Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. Adipocytes are derived from mesenchymal stem cells which give rise to adipocytes through adipogenesis. I ...

differentiation and

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used t ...

function on patients which have not received antiretroviral treatment.

Management

GHRH analogs such as

tesamorelin Tesamorelin (INN) (trade name Egrifta SV) is a synthetic form of growth-hormone-releasing hormone (GHRH) which is used in the treatment of HIV-associated lipodystrophy, approved initially in 2010. It is produced and developed by Theratechnologie ...

can be used to treat HIV-associated lipodystrophy.

Prognosis

Reversion of lipodystrophy does not occur after withdrawal of protease inhibitors.

References

External links

{{Authority control Conditions of the subcutaneous fat HIV/AIDS