ST. JUDE CHILDREN'S RESEARCH HOSPITAL
EDITOR'S CHOICE IN IMMUNOLOGY
A. Kamei et al., “Exogenous remodeling of lung resident macrophages protects against infectious consequences of bone marrow-suppressive chemotherapy,” PNAS, doi:10.1073/pnas.1607787113, 2016.
Chemotherapy wipes out cancerous cells and dividing normal cells alike, often particularly damaging those in bone marrow that produce white blood cells. As a patient’s immune system is weakened, even minor infections can become life-threatening. Researchers are exploring ways to circumvent this problem by “remodeling” the immune system prior to chemotherapy.
Below the radar
Akinobu Kamei of St. Jude Children’s Research Hospital and his colleagues identified a class of white blood cell that only becomes active in the lungs of mice following vaccination for a common bacterial strain that causes pneumonia. Like some other immune cells in the lungs, these so-called vaccine-induced macrophages, or ViMs, do not originate in bone marrow, but reside solely in the lungs, likely having derived from progenitor cells in the lungs during embryogenesis.
The St. Jude team found that ViMs are not decimated by chemotherapy like other immune cells—in fact, their numbers don’t dip at all. It’s not clear how ViMs manage this feat, says Kamei, but mice that were vaccinated before chemotherapy, triggering ViMs, survived bacterial infections at much higher rates than unvaccinated mice.
“The future plan,” says Kamei, “is to induce lung tissue [immune] remodeling to compensate for bone marrow suppression after chemotherapy.” Immunology researcher Sandro Vento of Nazarbayev University in Kazakhstan pointed out in an email to The Scientist that the animal-model work is only preliminary. “This is an initial study which opens a new area of research, and it will be important to understand the mechanisms which allow vaccine-induced macrophages to survive chemotherapy.”