Expression of cytotoxic T-lymphocyte antigen 4 on CD4+ and CD8+ T cells is increased in acute lung injury

Machine Learning-Based Discovery of a Gene Expression Signature in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To identify differentially expressed genes and networks from the airway cells within 72 hours of intubation of children with and without pediatric acute respiratory distress syndrome. To test the use of a neutrophil transcription reporter assay to identify immunogenic responses to airway fluid from children with and without pediatric acute respiratory distress syndrome.

DESIGN

Prospective cohort study.

SETTING

Thirty-six bed academic PICU.

PATIENTS

Fifty-four immunocompetent children, 28 with pediatric acute respiratory distress syndrome, who were between 2 days to 18 years old within 72 hours of intubation for acute hypoxemic respiratory failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We applied machine learning methods to a Nanostring transcriptomics on primary airway cells and a neutrophil reporter assay to discover gene networks differentiating pediatric acute respiratory distress syndrome from no pediatric acute respiratory distress syndrome. An analysis of moderate or severe pediatric acute respiratory distress syndrome versus no or mild pediatric acute respiratory distress syndrome was performed. Pathway network visualization was used to map pathways from 62 genes selected by ElasticNet associated with pediatric acute respiratory distress syndrome. The Janus kinase/signal transducer and activator of transcription pathway emerged. Support vector machine performed best for the primary airway cells and the neutrophil reporter assay using a leave-one-out cross-validation with an area under the operating curve and 95% CI of 0.75 (0.63-0.87) and 0.80 (0.70-1.0), respectively.

CONCLUSIONS

We identified gene networks important to the pediatric acute respiratory distress syndrome airway immune response using semitargeted transcriptomics from primary airway cells and a neutrophil reporter assay. These pathways will drive mechanistic investigations into pediatric acute respiratory distress syndrome. Further studies are needed to validate our findings and to test our models.

Insights into the immuno-pathogenesis of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a clinical syndrome associated with oxygenation failure resulting from a direct pulmonary or indirect systemic insult. It is a complex etiological phenomenon involving an array of immune cells acting in a delicate balance between pathogen clearance and immunopathology. There is emerging evidence of the involvement of different immune cell types in ARDS pathogenesis. This includes polarization of alveolar macrophages (AMs), neutrophil netosis, the pro-inflammatory response of T helper 17 subsets, and the anti-inflammatory and regenerative role of T regulatory cell subsets. Knowledge of these pathogenic mechanisms has led to translational opportunities, for example, research in the use of methylprednisolone, DNAse, aspirin, keratinocyte growth factor and in the development of stem cell therapy for ARDS. Discovering subgroups of patients with ARDS afflicted with homogenous pathologic mechanisms can provide prognostic and/or predictive insight that will enable precision medicine. Lastly, new high dimensional immunomic technologies are promising tools in evaluating the host immune response in ARDS and will be discussed in this review.

Mycobacterium leprae upregulates IRGM expression in monocytes and monocyte-derived macrophages

Leprosy is caused by the infection of Mycobacterium leprae, which evokes a strong inflammatory response and leads to nerve damage. Immunity-related GTPase family M protein (IRGM) plays critical roles in controlling inflammation. The objective of the study was to investigate whether IRGM is involved in the infection of M. leprae. Levels of IRGM were assessed in M. leprae-infected CD4(+) T cells, monocytes, and monocyte-derived macrophages. Data revealed that both protein and mRNA levels of IRGM were increased in monocytes after M. leprae infection. Interestingly, monocyte-derived macrophages showed more prominent IRGM expression with M. leprae infection, whereas the bacteria did not affect IRGM in CD4(+) T cells. Furthermore, we assessed levels of IRGM in CD4(+) T cells and monocytes from 78 leprosy patients and 40 healthy controls, and observed upregulated protein level of IRGM in the monocytes from leprosy patients. Also, IRGM expression was inversely correlated with the severity of the disease. These findings suggested a close involvement of IRGM in M. leprae infection and indicated a potential mechanism of defending M. leprae infection.