Volume 15 Issue 9, September 2009

Ian Lipkin, director of the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health, has helped identify close to 200 new viruses so far. Erica Westly spoke with Lipkin about how the viral discovery techniques he uses could help prevent future viral disease outbreaks, from swine flu to the unknown.

Vaccines work by training the immune system to target pathogens, but many types of shots need added substances called adjuvants to elicit a robust response. Despite the power of adjuvants, only one, called alum, is approved in the US. Charlotte Schubert looks at recent discoveries that could translate into a wider range of adjuvants and perhaps help provide future protection against diseases ranging from malaria to H1N1 'swine' flu.

Identification of an endogenous inhibitor of lymphatic vessel formation provides a glimpse at how lymphatic vessel growth is restrained (pages 1023–1030). The findings might be exploited to lower transplant rejection rates.

The primary cilium can keep cancer at bay, or it can instigate tumor development, according to studies in mice (pages 1055–1061 and 1062–1065). The outcome depends on the nature of the initiating event, which involves signaling through the Hedgehog pathway.

Obesity accelerates the aging of adipose tissue, a process only now beginning to come to light at the molecular level. Experiments in mice suggest that obesity increases the formation of reactive oxygen species in fat cells, shortens telomeres—and ultimately results in activation of the p53 tumor suppressor, inflammation and the promotion of insulin resistance (pages 1082–1087).

Before stem cell therapies become mainstream, several hurdles must be overcome. One challenge is developing air-tight approaches to assure that stem cell transplantation does not give rise to tumors. Another is finding safe ways to induce pluripotency in adult stem cells, which can then be used for transplantation. In Bedside to Bench, Evan Snyder and Rahul Jandial discuss the risks of tumorigenesis in stem cell therapies, and, in Bench to Bedside, Laura Clarke and Derek van der Kooy examine new ways to induce pluripotency.

Giovanni Monteleone and his colleagues show that the T cell-derived cytokine interleukin-21 is a new potential therapeutic target for psoriasis. Interleukin-21 seems to act directly on keratinocytes, stimulating them to proliferate and causing epidermal hyperplasia.

Enterotoxigenic Bacteroides fragilis, a bacterium from the intestinal flora, may promote colon tumor formation through a pathway that involves Stat3 expression and T helper type 17 immune responses.

Although endogenous inhibitors of blood vessel growth have been studied extensively, specific inhibitors of lymphatic vessel growth have not been identified. Albuquerque et al. now identify truncated, secreted versions of mouse and human VEGFR-2 receptors generated by alternative splicing. The mouse protein acts as an endogenous inhibitor of lymphatic vessel growth in the cornea and skin, and its administration had therapeutic effects in mouse models of corneal injury and transplantation.

Ischemia causes pericytes on brain microvessels to contract, obstructing erythrocyte transit even after blood flow is restored. This contraction, which depends on the production of oxygen and nitrogen radicals, represents a novel pathophysiological mechanism in stroke.

Suppression of the immune system could block autoimmune disease pathogenesis. Here Jacques Galipeau and his colleagues report that a fusion protein of two cytokines can induce immunosuppressive regulatory B cells. Transferring these cells into a mouse model of multiple sclerosis reduces disease in the mice.

Canonical Wnt signaling is known to be crucial in embryonic organ development. Joseph Gleeson and his colleagues now report that it is also important in the adult homeostasis of the kidney, especially after injury, and that disruption of this signaling pathway results in cystic kidney disease.

These two studies show that primary cilia can either mediate or suppress tumorigenesis in models of basal cell carcinoma and medulloblastoma, respectively, depending on the nature of the initial oncogenic event (pages 994–996) and (pages 1062–1065).

These two studies show that primary cilia can either mediate or suppress tumorigenesis in models of basal cell carcinoma and medulloblastoma, respectively, depending on the nature of the initial oncogenic event (pages 994–996) and (pages 1055–1061).

Dysregulation of osteoclasts, the cells that chew up bone, can lead to severe bone loss. Although many positive regulators of the differentiation of this cell type have been identified, few negative regulators have. Now, Masamichi Takami and colleagues have identified IRF-8 as an inhibitor of osteoclast formation and explore its role in disease.

The degenerative joint disease osteoarthritis is known to involve the activation of the protease ADAMTS-5. Now, Frank Echtermeyer and his colleagues have shown that the transmembrane proteoglycan syndecan-4 is responsible for this activation. They also show that genetic deletion of syndecan-4, or inhibition with a blocking antibody, reduces disease progression in a mouse model.

The mechanisms that lead to idiopathic pulmonary fibrosis, or lung scarring, is not clear. Victor Thannickal and his colleagues have now provided further insight by showing that induction of NOX4, an enzyme that creates reactive oxygen species, is required for the progression of the disease. Their findings suggest NOX4 as a potential target to treat this common ailment that currently has no proven treatment options.

A role for cell senescence and p53 in the development of insulin resistance (or prediabetes) has been obscure. Issei Komuro and colleagues now show that premature cell senescence occurs in the adipose tissue of obese mice and humans and that genetic deficiency of p53 is sufficient to prevent insulin resistance in mouse models of obesity, suggesting a new target to treat diabetes.

Jin and colleagues introduce a new chip-based system for the rapid identification and isolation of single antigen-specific antibody–secreting cells from human peripheral blood lymphocytes. The approach can be used to detect antibody-secreting cells for multiple antigens on the same chip and should have advantages over current technologies for isolating and producing human monoclonal antibodies of clinical significance.