Immune checkpoint inhibitor associated diarrhoea.

A man in his 80s was undergoing immunotherapy with pembrolizumab, an anti-PD-1 monoclonal antibody, following his diagnosis of adenocarcinoma of primary lung origin. 24 weeks into treatment, the patient reported experiencing loose stools associated with malaise and poor appetite but no further symptoms. This progressed in frequency and a clinical diagnosis of grade 2 immune checkpoint inhibitor colitis was made. Management with oral prednisolone was commenced but symptoms persisted. Common enteric infections had been ruled out, as were coeliac disease and hyperthyroidism. Flexible sigmoidoscopy and colonoscopy results were not in keeping with colitis, having revealed normal looking mucosa. Following this, a faecal elastase level was found to be low. A diagnosis of pembrolizumab-induced pancreatic exocrine insufficiency was made, and stool frequency and consistency swiftly improved following the use of pancreatic enzyme replacement therapy.

Consequences of maternal psychological stress during pregnancy for the risk of asthma in the offspring.

Asthma is a common lung condition that makes breathing difficult through the inflammation and constriction of the lung airways. Epidemiological evidence supports the presence of a positive association between prenatal maternal psychological stress (PMPS) and asthma in the offspring, suggesting the disease may have developmental origins. T-helper 2 (Th2) cells are a major subtype of T-helper cells, producing Th2 cytokines, which may be the main drivers of asthma symptoms. A Th2 dominant blood cytokine profile may therefore indicate an increased risk of asthma, as studies have shown a link between PMPS and a T-helper 2 (Th2) cytokine profile in offspring. The mechanism by which PMPS may cause Th2 cytokine dominance in the offspring is unclear. Epigenetic modifications in utero can lead to long-lasting effects that persist postnatally and have therefore been implicated in this relationship. Increased maternal blood cortisol levels due to PMPS may increase transfer of cortisol to the foetus, where the temporarily increased levels may induce changes in the epigenome. Evidence from animal studies suggests that genes controlling cytokine production in T cells can be epigenetically modified in a way that increases Th2 cytokine production. Other evidence suggests that methylation of the NR3C1 gene decreases hippocampal glucocorticoid receptor expression, leading to decreased negative regulation of the hypothalamus-pituitary-adrenal axis. This can increase cortisol production which has been shown to increase Th2 cytokine production. Therefore, the link between PMPS and a Th2 offspring cytokine profile, mediated through epigenetic changes, may explain the positive relationship between PMPS and asthma in the offspring.