August 2026 Research Update

This month added a small amount of real-world detail about how PAP is treated over time, but the evidence is limited to individual patient stories. One report described improvement after combining whole lung lavage (washing out the lungs) with inhaled sargramostim (a GM-CSF medicine) in autoimmune PAP. Another described a long-term autoimmune PAP case where scarring changes were a concern, and lung capacity stayed relatively stable during treatment with nintedanib, while one measure of gas transfer still declined. [1] [2]

In the vaping-exposed autoimmune PAP case, the person had GM-CSF autoantibodies confirming the autoimmune form and needed repeat whole lung lavage when breathing tests and oxygen levels worsened. After lavage and ongoing nebulized sargramostim, breathing test results and exercise tolerance improved, showing a course of ups and downs with treatment support. The authors also raised vaping as a possible trigger in this individual, but a single case cannot show cause and effect. [1]

In the long-standing autoimmune PAP case with a progressive fibrosing pattern (scarring-like changes), nintedanib was started after a period of decline. Over 2 years, forced vital capacity (a measure of how much air can be blown out) stayed relatively stable and symptoms improved, while diffusion capacity (a measure of oxygen transfer) continued to fall. The report highlights how difficult it can be to tell scarring progression apart from returning PAP activity using imaging and other measures over time. [2]

For patients, these reports mainly add context about what treatment journeys can look like rather than providing proof that one approach works better than another. The lavage plus inhaled sargramostim case shows that improvement in breathing and exercise tolerance can occur after combined care in autoimmune PAP, even if repeat procedures are needed. The nintedanib case shows that when scarring-like changes are suspected in someone with autoimmune PAP, different lung tests can move in different directions, which can complicate understanding what is driving symptoms. Because both are single-patient reports, the findings may matter most as background knowledge and for future research, not as a basis for broad expectations. [1] [2]

This month reinforced that PAP is not one single situation, and the same scan patterns can happen for different reasons. Case reports described PAP appearing alongside a serious lung infection in an infant with an inherited immune disorder, and PAP developing as a secondary problem in an autoimmune muscle disease where it resembled worsening interstitial lung disease. Together, these cases emphasize that finding the underlying cause matters because the right next steps depend on whether PAP is autoimmune, secondary to another condition, or complicated by infection. [3] [4]

In a 4-month-old infant, PAP was found together with Pneumocystis jirovecii pneumonia, and this combination led to genetic testing that identified a novel CD40LG variant causing X-linked hyper-IgM syndrome (an immune system disorder). The infant improved after ventilatory support, high-dose trimethoprim-sulfamethoxazole, and intravenous immunoglobulin, and later imaging also improved. This case shows how infection and immune deficiency can be central to the story when PAP appears early in life. [3]

Another report described secondary PAP in a person with anti-MDA5 dermatomyositis, presenting in a way that resembled progression of interstitial lung disease rather than a new diagnosis. The main message was the diagnostic challenge: PAP can mimic other lung problems in symptoms and imaging, especially in people who already have an autoimmune disease affecting the lungs. The summary did not provide detailed outcomes, so how the condition changed over time in this case is unclear. [4]

For patients and caregivers, these cases help clarify why PAP workups often focus on the underlying cause, especially when PAP occurs in infants, in people with immune system conditions, or in people with autoimmune diseases. They also show that similar scan findings can reflect infection, PAP itself, or other lung disease activity, which can make the path to a clear explanation slower than expected. What remains uncertain is how often these specific situations occur, because case reports cannot estimate risk or predict what will happen for most people. This information matters most for understanding the range of reasons PAP can occur and why the diagnosis sometimes requires looking beyond the lungs. [3] [4]

A laboratory study this month provided a clearer biological explanation for how PAP-like changes can develop when lung "cleanup" cells (alveolar macrophages) cannot survive or function well. In mice, turning off mTOR signaling in certain immune cells led to fewer alveolar macrophages, poorer cleanup of material in the lungs, fat buildup inside these cells, and PAP-like lung pathology. Similar changes were seen when mice were given temsirolimus, a drug that inhibits mTOR, supporting the idea that this pathway helps keep alveolar macrophages healthy. [5]

The same study connected mTOR activity to specific cell survival and fat-handling programs. When mTOR signaling was lost, cells had lower PPARgamma (a regulator of fat processing) and lower levels of pro-survival Bcl-2 family proteins, and more signs of cell death. In simple terms, this suggests that when this pathway is disrupted, the lung cells responsible for clearing surfactant may die off and leave material behind. [5]

For patients, this is early research in mice and in lab-grown cells, so it does not predict how any one person will do. What it adds now is a more concrete picture of one way PAP-like buildup can happen: problems with the survival and fat processing of alveolar macrophages can drive the lung filling process. What remains uncertain is how often mTOR disruption plays a role in human PAP, and whether measuring or modifying this pathway would be useful in people. For now, it mainly matters as background research that could shape future studies of causes and possible targets. [5]