Lysosomes drive the piecemeal removal of mitochondrial inner membrane.

Mitochondrial membranes define distinct structural and functional compartments. Cristae of the inner mitochondrial membrane (IMM) function as independent bioenergetic units that undergo rapid and transient remodelling, but the significance of this compartmentalized organization is unknown1. Using super-resolution microscopy, here we show that cytosolic IMM vesicles, devoid of outer mitochondrial membrane or mitochondrial matrix, are formed during resting state. These vesicles derived from the IMM (VDIMs) are formed by IMM herniation through pores formed by voltage-dependent anion channel 1 in the outer mitochondrial membrane. Live-cell imaging showed that lysosomes in proximity to mitochondria engulfed the herniating IMM and, aided by the endosomal sorting complex required for transport machinery, led to the formation of VDIMs in a microautophagy-like process, sparing the remainder of the organelle. VDIM formation was enhanced in mitochondria undergoing oxidative stress, suggesting their potential role in maintenance of mitochondrial function. Furthermore, the formation of VDIMs required calcium release by the reactive oxygen species-activated, lysosomal calcium channel, transient receptor potential mucolipin 1, showing an interorganelle communication pathway for maintenance of mitochondrial homeostasis. Thus, IMM compartmentalization could allow for the selective removal of damaged IMM sections via VDIMs, which should protect mitochondria from localized injury. Our findings show a new pathway of intramitochondrial quality control.

Under the Radar: Strategies Used by Helicobacter pylori to Evade Host Responses.

The body depends on its physical barriers and innate and adaptive immune responses to defend against the constant assault of potentially harmful microbes. In turn, successful pathogens have evolved unique mechanisms to adapt to the host environment and manipulate host defenses. Helicobacter pylori (Hp), a human gastric pathogen that is acquired in childhood and persists throughout life, is an example of a bacterium that is very successful at remodeling the host-pathogen interface to promote a long-term persistent infection. Using a combination of secreted virulence factors, immune subversion, and manipulation of cellular mechanisms, Hp can colonize and persist in the hostile environment of the human stomach. Here, we review the most recent and relevant information regarding how this successful pathogen overcomes gastric epithelial host defense responses to facilitate its own survival and establish a chronic infection.

Updated joint ESPGHAN/NASPGHAN guidelines for management of Helicobacter pylori infection in children and adolescents (2023).

BACKGROUND: Evolving epidemiological data and increasing antibiotic resistance mandate an update of the European and North American Societies of Pediatric Gastroenterology, Hepatology and Nutrition guidelines. METHODS: Certainty of evidence and strength of recommendations were rated by experts according to the Grading of Recommendation Assessment, Development, and Evaluation approach. PICO (patient population, intervention, comparator, and outcome) questions were developed and voted on by the group. Recommendations were formulated using the Evidence to Decision framework. RESULTS: The current literature supports many of the previous recommendations and several new recommendations. Invasive testing with strain antimicrobial susceptibility analysis is recommended for the diagnosis and selection of eradication therapy for H. pylori infection. Molecular methods are acceptable for detection of infection and of antibiotic resistance in gastric biopsy specimens. Reliable, noninvasive tests can be used as a screening method for children with history of gastric cancer in a first-degree relative. When investigating causes of chronic immune thrombocytopenic purpura, testing for H. pylori is no longer recommended. When investigating other diseases such as inflammatory bowel disease, celiac disease, or eosinophilic esophagitis, specific diagnostic biopsies for H. pylori infection are not indicated. However, if H. pylori is an incidental finding, treatment may be considered after discussing the risks and benefits. Treatment should be based on antibiotic antimicrobial susceptibility testing and, if unavailable, regimens containing clarithromycin should be avoided. CONCLUSIONS: Due to decreasing prevalence of infection, increasing challenges with antibiotic resistance, and emerging evidence regarding complications of infection, clinicians must be aware of these recommended changes to appropriately manage H. pylori infection and its clinical sequelae in children.