In this issue,Richard Gallo and his colleagues show that commensal bacteria on the skin can dampen inflammation resulting from injury. The cover image shows a colored scanning electron micrograph of the commensal bacteria Staphylococcus epidermidis. Credit: David Scharf/Photo Researchers, Inc.

During pulmonary hypertension there is arterial remodeling in the lung. In this issue, Patricia Thistlethwaite and her colleagues (page 1289) show that Notch3 promotes the development of human and rodent pulmonary hypertension and that Notch3 inhibition reverses the disease in mice. The image shows a pulmonary angiogram from a mouse with pulmonary hypertension treated with a blocker of Notch3 cleavage. Image courtesy of P. Thistlethwaite.

In this issue, Rakesh Jain, Brett Bouma and their coworkers develop a new type of intravital microscopy—termed optical frequency domain imaging—that they apply to visualize the tumor microvasculature and its response to antiangiogenic therapy. The cover image shows the vasculature surrounding human glioblastoma tumor cells transplanted into the brain of a mouse; the color of the vessels indicates depth, from superficial (yellow) to deep (red).

In this issue, Jayakrishna Ambati and his colleagues identify a secreted form of the VEGFR-2 receptor, generated by alternative splicing, as an endogenous inhibitor of lymphatic but not blood vessel growth. The cover image shows invasion of lymphatic vessels (green) into an injured mouse cornea deficient in secreted VEGFR-2. Blood vessels are shown in red.

Advances in HIV have transformed a fatal disease into a manageable illness, but many key questions remain. The cover shows numerous HIV-1 particles infecting a cultured HeLa cell, captured using a Hitachi SU6600 environmental scanning electron microscope. Image courtesy of T. Deerinck, K. Fitzpatrick, J. Guatelli and M. Ellisman, NMCIR, UCSD.

Rheumatoid arthritis results in the progressive destruction of the joints. In this issue, Jane Grogan and her colleagues show that targeted depletion of lymphotoxin-alphaexpressing Th1 and Th17 cells inhibits rheumatoid arthritis and other autoimmune diseases. The image is an electron micrograph of the damaged cartilage of the femur of a patient with arthritis. Credit: Moredun Animal Health Ltd./Science Photo Library.

Reduced levels of gastric acid results in poor calcium absorption from the diet and defects in bone homeostasis. On p 674 of this issue, Michael Amling and his colleagues show that deficiency in an ion pump subunit resulting in high gastric pH and poor osteoclast activity leads to osteopetrosis and rickets. The cover image is of multinucleated osteoclasts destroying bone in a non-decalcified section of human bone. The image is pseudocolored, with mineralized bone appearing orange. Photo: Michael Amling, Hamburg.

A high-salt diet, implicated in hypertension, leads to an accumulation of sodium ion in tissue. On p. 545 of this issue, Jens Titze and his coworkers describe a homeostatic response by which increased salt concentration upregulates VEGF-C production by macrophages, resulting in hyperplasia of lymphatic capillaries. The cover image is taken from a three-dimensional reconstruction of lymphatic vessels in the ear of a rat fed a high-salt diet. Lymphatic vessels (green) were stained by a podoplanin-specific antibody; cartilage (gray) was detected by its autofluorescence.

Targeting endothelial cell integrins has been pursued as a means to inhibit tumor angiogenesis. In this issue, Andrew Reynolds and his coworkers (p 392) reveal a potential pitfall to this strategy: low doses of αvα3/αvα5 integrin inhibitors lead to increased tumor angiogenesis and growth in mice. These effects may stem from increased recycling of the vascular endothelial growth factor receptor, VEGFR2, to the plasma membrane of endothelial cells. The cover image shows VEGFR2 staining (green) within vesicular structures in a tumor blood vessel in mice (laminin, red; nuclei, blue).

In this issue, Louis Picker and his colleagues (p 293) show that a replicating anti-SIV vaccine based on the persistently infecting cytomegalovirusa member of the herpes virus familycan increase the resistance of macaques to acquiring SIV infection. The authors attribute the protection to the generation of a robust effector memory T cell response. The cover image shows a colored transmission electron micrograph of a herpes virus particle (the virus envelope is not seen). Credit: Brian Megson, Centre for Infections/Health Protection Agency/Science Photo

Cerebral cavernous malformation (CCM) is a life-threatening disorder in which blood vessels in the brain dilate and frequently hemorrhage. In this issue, Kleaveland et al. (p 169) and Whitehead et al. (p 177) reveal underlying defects in endothelial cell signaling and function. On the cover, a color-enhanced magnetic resonance image of the brain shows multiple congenital malformations of the cerebral vasculature (red). Credit: Living Art Enterprises, LLC/Photo Researchers, Inc.

When neuronal migration stalls during brain development, subcortical band heterotopias, and epilepsy, may result. In this issue, Manent et al. (p 84) show that mispositioned neurons can be postnatally re-induced to migrate in vivo and that this normalizes seizure threshold in the mice. Cover image courtesy of Joseph LoTurco.