Research Corner: PAH-Associated Conditions: Systemic Sclerosis and HIV

Research Corner: PAH-Associated Conditions: Systemic Sclerosis and HIV

08.19.2016

Contributed by Mohamad Taha, PH Researcher

In this issue of the Research Corner, we will address some questions regarding medical conditions that can be associated with pulmonary arterial hypertension (PAH), with a focus on systemic sclerosis and HIV associated PAH.   

Can other diseases lead to development of PAH?

Sadly, yes. According to the most recent classification, PAH can appear associated to several disorders:

  • Connective tissue diseases - diseases affecting connective tissue, mainly joints and skin such as scleroderma and lupus 
  • HIV infection - infectious virus that leads to immunodeficiency
  • Portal hypertension - increased pressure in the portal venous system that comes from the stomach, intestine, spleen and pancreas(i.e. abdominal blood supply from the intestine to the liver), also known as portopulmonary hypertension (POPH)
  • Congenital heart diseases - problems with the heart anatomy/structure present at birth
  • Schistosomiasis infection - a disease caused by a parasitic worm common in Africa, Asia, and South America

What is systemic sclerosis?

Systemic sclerosis (SSc) is multi-systemic connective tissue disease that is characterized by extensive vascular abnormalities, auto-immunity (the immune system attacks the owner’s body), inflammation, and fibrosis (thickening and scarring of connective tissue). SSc can affect many organs, such as the skin and joints, but can also affect the lungs and heart.

Why can I develop PAH if I have SSc?

The exact mechanism of how SSc can lead to SSc-PAH is still not clear. However, it is generally believed that a combination of lung inflammation and immune cells attacking the endothelial cells (cells lining blood vessels) in the lungs could be a major factor.

How prevalent is SSc-PAH and how does the treatment strategy change?

Patients with associated SSc-PAH account for 15-30% of all PAH population, and display a worse prognosis than patients with idiopathic PAH (IPAH) or familial PAH (FPAH). Currently, therapeutic tools for the treatment of SSc-PAH are the same as those used to treat IPAH patients, while new therapies targeting inflammation and the immune system are being developed.

What is HIV?

Human immunodeficiency virus (HIV) is a virus that targets and kills a specific cell type within the human immune system. These cells (called: CD4 helper T-cells) are part of the body’s response to infection; thus, when HIV kills them, patients may develop acquired immunodeficiency syndrome (AIDS). In other words, HIV cripples the immune system and makes it very difficult to fight the simplest of infections.  

Why can I develop PAH if I have HIV?

 It is believed that some of the viral proteins can lead to endothelial cell injury in the lungs, as well as increased cell division of smooth muscle cells, two factors contributing to PAH development. It is also possible for HIV to increase inflammation and immune system dysregulation (immune system not working properly), thus contributing to the development of PAH.   

How prevalent is HIV-PAH and how does the treatment strategy change?

Around 0.5% of patients with HIV develop PAH. Treatment of HIV-PAH follows guidelines for treatment of IPAH, while HIV is managed with antiviral therapies (also known as HAART).

References:

Simonneau et al. “Updated Clinical Classification of Pulmonary Hypertension.” Journal of the American College of Cardiology (2013) 62:D34–41.

Sobanski et al. “Current Approaches to the Treatment of Systemic-Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH).” Current Rheumatology Reports (2016) 18:10.

Chinello and Petrosillo. “Pharmacological Treatment of HIV-Associated Pulmonary Hypertension.” Expert Review of Clinical Pharmacology (2016) 9(5):715.

Please always keep in mind that while I can provide you with a small insight into PH research, you should always be able to get answers from your Pulmonary Hypertension Specialist, who is more familiar with your specific case and your treatment history. 

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