Stelara struck: a case of noninfectious pneumonitis secondary to ustekinumab.

BACKGROUND: We describe a case of acute hypoxic respiratory failure due to drug induced lung disease secondary to ustekinumab, which is a monoclonal antibody used to treat psoriasis, psoriatic arthritis, and inflammatory bowel disease. CASE PRESENTATION: A 33-year-old man with a history of Crohn's disease presented with fevers, myalgias, and abdominal pain, and subsequently developed acute hypoxemic respiratory failure approximately 2 weeks after restarting ustekinumab for his Crohn's disease. Cross-sectional chest imaging showed ground glass opacities and bilateral consolidations. Due to progressive hypoxia, he ultimately required intubation and mechanical ventilation. Broad infectious and autoimmune work up was negative, making drug induced interstitial lung disease (DILD) the leading consideration. He was treated with high dose steroids with dramatic improvement in his respiratory status. At follow up, his imaging findings had largely resolved, and his pulmonary function tests were normal. CONCLUSIONS: For patients presenting with acute hypoxic respiratory failure, it is critical to identify the underlying cause. In addition to testing for common respiratory infections that can cause respiratory failure, patients should also be evaluated for risk factors for developing atypical or opportunistic infections as well as inflammatory pneumonitis. Due to receiving ustekinumab, our patient was both at risk for developing an opportunistic infection as well as DILD. Although rare, DILD is a recognized toxicity of ustekinumab. Ustekinumab can cause significant lung injury, as in our patient, but with steroids and avoidance of future doses of the medication, our patient demonstrated good recovery. Reassuring outcomes have similarly been described in the literature; however, this case provides further details about outcomes with long-term follow-up clinical, imaging, and pulmonary function testing data available. We recommend consideration of high dose steroids for these patients for whom DILD is suspected.

Inhibition of glutamine metabolism accelerates resolution of acute lung injury.

Despite recent advances, acute respiratory distress syndrome (ARDS) remains a severe and often fatal disease for which there is no therapy able to reduce the underlying excessive lung inflammation or enhance resolution of injury. Metabolic programming plays a critical role in regulating inflammatory responses. Due to their high metabolic needs, neutrophils, macrophages, and lymphocytes rely upon glutamine metabolism to support activation and function. Additionally, during times of physiologic stress, nearly all cells, including fibroblasts and epithelial cells, require glutamine metabolism. We hypothesized that inhibiting glutamine metabolism reduces lung inflammation and promotes resolution of acute lung injury. Lung injury was induced by instilling lipopolysaccharide (LPS) intratracheally. To inhibit glutamine metabolism, we administered a glutamine analogue, 6-diazo-5-oxo-L-norleucine (DON) that binds to glutamine-utilizing enzymes and transporters, after injury was well established. Treatment with DON led to less lung injury, fewer lung neutrophils, lung inflammatory and interstitial macrophages, and lower levels of proinflammatory cytokines and chemokines at 5 and/or 7 days after injury. Additionally, DON led to earlier expression of the growth factor amphiregulin and more rapid recovery of LPS-induced weight loss. Thus, DON reduced lung inflammation and promoted resolution of injury. These data contribute to our understanding of how glutamine metabolism regulates lung inflammation and repair, and identifies a novel target for future therapies for ARDS and other inflammatory lung diseases.

Etiology and treatment of cough in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease of dysregulated wound healing leading to unremitting scarring and loss of lung function. The predominant symptoms are dyspnea on exertion and a persistent dry cough. For patients with IPF, cough is more than just bothersome; it has a significant negative impact on quality of life and is a marker of disease severity and progression. The etiology of cough in IPF is unclear but may be due to architectural distortion of the lungs, increased sensitivity of the cough reflex, airway inflammation, or changes in mucus production and clearance. There also may be an overlap between IPF cough and cough due to other common etiologies such as asthma, gastroesophageal reflux disease, upper airway cough syndrome, and medications. There are no approved therapies to specifically treat IPF cough, and recently approved medications for IPF have not been evaluated in cough. Few clinical trials have focused on treatments for IPF cough. To date, there is only one randomized, placebo control therapeutic study for IPF cough with thalidomide, which significantly reduced IPF cough and improved quality of life. Two additional cohort studies report that interferon-α and prednisolone also decrease IPF cough. However, no medication is approved to treat IPF cough. Currently, the mainstay of therapy for IPF cough is standard cough suppressants, which have limited efficacy and often intolerable side effects. Future studies are needed to determine an effective therapy to alleviate this particularly debilitating symptom and improve overall quality of life for patients suffering with IPF.

Deletion of mTORC1 Activity in CD4+ T Cells Is Associated with Lung Fibrosis and Increased γδ T Cells.

Pulmonary fibrosis is a devastating, incurable disease in which chronic inflammation and dysregulated, excessive wound healing lead to progressive fibrosis, lung dysfunction, and ultimately death. Prior studies have implicated the cytokine IL-17A and Th17 cells in promoting the development of fibrosis. We hypothesized that loss of Th17 cells via CD4-specific deletion of mTORC1 activity would abrogate the development of bleomycin-induced pulmonary fibrosis. However, in actuality loss of Th17 cells led to increased mortality and fibrosis in response to bleomycin. We found that in the absence of Th17 cells, there was continued production of IL-17A by γδ T cells. These IL-17A+ γδ T cells were associated with increased lung neutrophils and M2 macrophages, accelerated development of fibrosis, and increased mortality. These data elucidate the critical role of IL-17A+ γδ T cells in promoting chronic inflammation and fibrosis, and reveal a novel therapeutic target for treatment of pulmonary fibrosis.