ATG16L1 protects from interferon-γ-induced cell death in the small intestinal crypt

The breakdown of the intestinal mucosal barrier is thought to underlie the progression to Crohn disease (CD), whereby numerous risk factors contribute. For example, a genetic polymorphism of the autophagy gene ATG16L1, associated with an increased risk of developing CD, contributes to the perturbation of the intestinal epithelium. We examined the role of Atg16l1 in protecting the murine small intestinal epithelium from T-cell-mediated damage using the anti-CD3 model of enteropathy. Our work showed that mice specifically deleted for Atg16l1 in intestinal epithelial cells (IECs) (Atg16l1^ΔIEC) had exacerbated intestinal damage, characterized by crypt epithelial cell death, heightened inflammation, and decreased survival. Moreover, Atg16l1 deficiency delayed the recovery of the intestinal epithelium, and Atg16l1-deficient IECs were impaired in their proliferative response. Pathology was largely driven by interferon (IFN)-γ signaling in Atg16l1^ΔIEC mice. Mechanistically, although survival was rescued by blocking tumor necrosis factor or IFN-γ independently, only anti-IFN-γ treatment abrogated IEC death in Atg16l1^ΔIEC mice, thereby decoupling IEC death and survival. In summary, our findings suggest differential roles for IFN-γ and tumor necrosis factor in acute enteropathy and IEC death in the context of autophagy deficiency and suggest that IFN-γ-targeted therapy may be appropriate for patients with CD with variants in ATG16L1.

Intestinal epithelial autophagy protects from cytokine-driven mortality and IFNγ-dependent cell death in acute small intestinal injury

Crohn’s disease (CD) is characterized by a breakdown of the intestinal mucosal barrier. A genetic polymorphism of the autophagy gene ATG16L1 is associated with increased risk of developing CD, and it impairs the protective and regenerative functions of the intestinal epithelium. Autophagy acts as a regulator of cell death and has been implicated in the protection from both necroptosis and apoptosis in the epithelium.

Our work showed that mice specifically deleted for Atg16l1 in intestinal epithelial cells (Atg16l1ΔIEC) had exacerbated T cell-mediated intestinal damage in the model of anti-CD3 enteropathy compared to wild-type mice, which was characterized by crypt epithelial cell death and heightened inflammation. Moreover, Atg16l1 deficiency delayed the recovery of the intestinal epithelium, and Atg16l1-deficient IECs were impaired in their proliferative response. Pathology and mortality were largely driven by microbiota-dependent expression of Ifng, Tnf, and type I IFN response genes in Atg16l1ΔIEC mice. Mechanistically, while survival was rescued by blocking these cytokine pathways independently, only anti-IFNγ treatment abrogated intestinal epithelial cell (IEC) death in Atg16l1ΔIEC mice, thereby decoupling IEC death and survival. In summary, our findings suggest differential roles for IFNγ, TNF, and type I IFN in acute enteropathy and IEC death in the context of autophagy deficiency.

Supported by grants from CIHR (MOP-12353, FDN-14333) and NSERC (RGPIN-201).

Technical note: Determination of acidity in whole raw milk: comparison of results obtained by two different analytical methods

In Argentina, one analytical method is usually carried out to determine acidity in whole raw milk: the Instituto Nacional de Racionalización de Materiales standard (no. 14005), based on the Dornic method of French origin. In a national and international regulation, the Association of Official Analytical Chemists International method (no. 947.05) is proposed as the standard method of analysis. Although these methods have the same foundation, there is no evidence that results obtained using the 2 methods are equivalent. The presence of some trends and discordant data lead us to perform a statistical study to verify the equivalency of the obtained results. We analyzed 266 samples and the existence of significant differences between the results obtained by both methods was determined.

Investigations of patients of health care workers infected with HIV. The Centers for Disease Control and Prevention database

OBJECTIVE

To assess the risk for transmission of the human immunodeficiency virus (HIV) from an infected health care worker to patients.

DESIGN

Survey of investigators from health departments, hospitals, and other agencies who had elected to notify patients who had received care from health care workers infected with HIV.

MEASUREMENTS

Information was collected about infected health care workers, their work practices, their patients' HIV test results, procedures that they did on those of their patients who were tested for HIV, and patient notification procedures.

RESULTS

As of 1 January 1995, information about investigations of 64 health care workers infected with HIV was reported to the Centers for Disease Control and Prevention; HIV test results were available for approximately 22,171 patients of 51 of the 64 health care workers. For 37 of the 51 workers, no seropositive patients were reported among 13,063 patients tested for HIV. For the remaining 14 health care workers, 113 seropositive patients were reported among 9108 patients. Epidemiologic and laboratory follow-up did not show any health care worker to have been a source of HIV for any of the patients tested.

CONCLUSION

Despite limitations, these data are consistent with previous assessments that state that the risk for transmission of HIV from a health care worker to a patient is very small. These data also support current recommendations that state that retrospective patient notification need not be done routinely.

HIV transmission in the health-care setting. Risks to health-care workers and patients

Transmission of HIV from patients to health care workers (HCWs) has been documented. Data from surveillance projects and epidemiologic studies provide the basis for evaluation of the risk of HIV transmission in health care settings. Strategies to further reduce this risk should focus on prevention of blood contacts between HCWs and patients through the use of universal precautions and implementation of new or modified medical devices, techniques, and personal protective equipment.