Role of epithelial barrier function in inducing type 2 immunity following early-life viral infection.

Background: Preschool wheeze attacks triggered by recurrent viral infections, including respiratory syncytial virus (RSV), are associated with an increased risk of childhood asthma. However, mechanisms that lead to asthma following early-life viral wheezing remain uncertain.

Methods: To investigate a causal relationship between early-life RSV infections and onset of type 2 immunity, we developed a neonatal murine model of recurrent RSV infection, in vivo and in silico, and evaluated the dynamical changes of altered airway barrier function and downstream immune responses, including eosinophilia, mucus secretion and type 2 immunity.

C3 Drives Inflammatory Skin Carcinogenesis Independently of C5.

Nonmelanoma skin cancer such as cutaneous squamous cell carcinoma (cSCC) is the most common form of cancer and can occur as a consequence of DNA damage to the epithelium by UVR or chemical carcinogens. There is growing evidence that the complement system is involved in cancer immune surveillance; however, its role in cSCC remains unclear. Here, we show that complement genes are expressed in tissue from patients with cSCC, and C3 activation fragments are present in cSCC biopsies, indicating complement activation.

C1q restrains autoimmunity and viral infection by regulating CD8 T cell metabolism.

Deficiency of C1q, the initiator of the complement classical pathway, is associated with the development of systemic lupus erythematosus (SLE). Explaining this association in terms of abnormalities in the classical pathway alone remains problematic because C3 deficiency does not predispose to SLE. Here, using a mouse model of SLE, we demonstrate that C1q, but not C3, restrains the response to self-antigens by modulating the mitochondrial metabolism of CD8 T cells, which can themselves propagate autoimmunity.