HIV positive people on ART have impaired alveolar immunity

Gareth Hardy, HIV i-Base

Professor Paul Collini from University of Sheffield presented some interesting immunological results that suggest that macrophages in the lungs of HIV positive people may be impaired, even after viral suppression on ART.

The risk of invasive,pneumococcal disease and declining lung function contributing to conditions such as chronic obstructive pulmonary disease (COPD) are increased in HIV positive people, even during the ART era. Dr Collini investigated whether there is a persistently altered virologic and immunologic environment in the lung during ART that impairs apoptosis-associated pneumococcal killing by alveolar macrophages.

In this study HIV positive people were either ART naive or had an undetectable viral load for a median of 87 months. The researchers found that alveolar macrophages had an impaired ability to kill pneumococci bacteria and that even in people on ART there is a persistent lymphocytosis in the alveoli of the lung. A much higher proportion of these cells were CD8 T cells than is the case in healthy control subjects.

Since HIV infection of macrophages in the lung is minimal, Dr Collini proposed that this pathology might have an indirect mechanism.

The researchers then demonstrated that despite ART, the HIV protein gp120 persists in the lung and is detectable in broncho-alveolar lavage fluid. They further demonstrated that treatment of macrophages with gp120 inhibits their ability to kill cells infected with pneumococcus.

In conclusion, alveolar macrophages have an impaired apoptotic response to pneumococci and the immune environment of the lung fails to correct ART, possibly playing a role in HIV-associated lung disease.

Reference:

Collini P et al. Healthy HIV sero-positive individuals have impaired alveolar immunity despite HAART. 22nd Annual BHIVA Conference, 19-22 April 2016, Manchester. Oral abstract O10.
http://www.bhiva.org/documents/Conferences/2016Manchester/Presentations/160421/PaulCollini.pdf (PDF slides)
http://www.bhiva.org/160421PaulCollini.aspx (webcast)

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