JCI table of contents July 1, 2005

06/23/05

EDITOR'S PICK

Eliminating bacterial infections out of thin air

When microorganisms invade the body, immune mechanisms kick in to fight them off. The infected tissues typically show depleted oxygen levels, and a protein called HIF-1 alpha regulates this. Interestingly, the cells responsible for destroying the foreign pathogens are effective in this low-oxygen environment. In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Randall Johnson and collegues from UCSD show for the first time that induction of the HIF-1 pathway can act as a "super-antibiotic", accelerating the killing of bacteria in conditions typical of those found during bacterial infection and sepsis.

The authors show that regulation of HIF-1 is required for immune defense against bacterial infection. They also show that bacteria killing is increased under conditions of low oxygen due to HIF-1 upregulation, and that bacterial infection upregulates HIF-1. In fact, upregulation of HIF-1 enhances expression of bactericidal agents and killing of bacteria.

This reveals that a novel approach to treating bacterial infection is by increasing the killing capacity of cells of the innate immune system. In a related commentary, Kol Zarember and Harry Melach write, "By dissecting the role of HIF-1 in innate immune defenses, the study…introduces new targets for therapeutic immunomodulation."

TITLE: HIF-1alpha expression regulates the bactericidal capacity of phagocytes

AUTHOR CONTACT:
Randall Johnson
University of California, San Diego, La Jolla, CA USA
Phone: 858 822-0509; E-mail: rsjohnson@ucsd.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=23865

ACCOMPANYING COMMENTARY:

Title: HIF-1alpha: a master regulator of innate host defenses?

AUTHOR CONTACT:
Harry L. Malech
NIAID, National Institutes Of Health, Bethesda, MD USA
Phone: 301-480-6916; Fax: 301-402-0789; E-mail: hmalech@nih.gov

View the PDF of this article at: https://www.the-jci.org/article.php?id=25740

PHYSIOLOGY

Muscles in obesity have problems choosing fuel

In obese and diabetic people, fat and carbohydrate oxidation by skeletal muscle is disrupted, contributing to insulin resistance. In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Barbara Ukropcova and colleagues from Pennington Biomedical Research Center examine whether the ability of skeletal muscle to oxidize fat in vitro is representative of the donor's metabolic characteristics.

The authors find that skeletal muscle cells, cultured in a controlled environment for up to 5 weeks, isolated from the endocrine and nutritional influences of their donor, retained their donor's metabolic characteristics. This suggests that defects in switching between fat oxidation and carbohydrate oxidation, possibly due to genetic defects in skeletal muscle, contribute to obesity and insulin resistance. The authors show that fuel preference in muscle cells is abnormal in young healthy obese individuals.

In an accompanying commentary, David Kelley writes, "these findings support the concept that the capacity of skeletal muscle to oxidize fat under appropriate physiological conditions is related to leanness, aerobic fitness, and insulin sensitivity."

TITLE: Dynamic Changes in Fat Oxidation in Human Primary Myocytes Mirror Metabolic Characteristics of the Donor

AUTHOR CONTACT:
Barbara Ukropcova
Pennigton Biomedical Research Center, Baton Rouge, LA USA
Phone: 225-763-2726; Fax: 225-763-2525; E-mail: UkropcB@pbrc.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=24332

ACCOMPANYING COMMENTARY:

TITLE: Skeletal muscle fat oxidation: timing and flexibility are everything

AUTHOR CONTACT:
David Kelley
University of Pittsburgh School of Medicine, Pittsburgh, PA USA
Phone: 412-692-2848; Fax: 412-692-2165; E-mail: Kelley@msx.dept-med.pitt.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=25758

PHYSIOLOGY

A new stem cell niche – no kidneying around

A common disease of the kidney is acute renal failure (ARF) that causes kidney damage and abnormal function. The kidney is capable of some regeneration and it was previously thought that stem cells from the bone marrow were at least partially responsible for this repair. Two new JCI studies now challenge this hypothesis.

In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Jeremy Duffield and colleagues from Harvard study kidney repair in mice harboring markers in their bone marrow. The researchers show that bone marrow-derived cells do not contribute to kidney repair after ARF. The marked cells were not incorporated into the injured kidney. The authors hypothesize that endogenous kidney cells instead are responsible for the repair seen. The second study, by Fangming Lin and colleagues from University of Texas, also shows that cells within the kidney are the main source of kidney repair. Moreover, injection of bone marrow cells does not make any significant contribution to functional or structural recovery.

In an accompanying commentary, Diane Kraus and Lloyd Cantley write, "the majority of the cells that…repair the injured tubules came from an endogenous cell population, rather than from bone marrow-derived cells." These results support the premise that the kidney has a stem cell niche of its own.

TITLE: Restoration of tubular epithelial cells during repair of the post ischemic kidney is independent of bone marrow stem cells

AUTHOR CONTACT:
Jeremy Duffield
Harvard Institutes of Medicine, Boston, MA USA
Phone: 617-525-5914; Fax: 617-525-5830; E-mail: jduffield@rics.bwh.harvard.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=22593

TITLE: Intrarenal Cells, not Bone Marrow-Derived Cells, are the Major Source for Regeneration in Post-ischemic Kidney

AUTHOR CONTACT:
Fangming Lin
University of Texas Southwestern Medical Center, Dallas, TX USA
Phone: 214-648-3438; Fax: 214-648-2034; E-mail: fangming.lin@utsouthwestern.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=23015

ACCOMPANYING COMMENTARY:

TITLE: Heating up the stem cell controversy: protection rather than differentiation in the kidney tubule?

AUTHOR CONTACT:
Lloyd G. Cantley
Yale University School of Medicine, New Haven, CT USA
Phone: 203-785-7110; Fax: 203-785-4904; E-mail: lloyd.cantley@yale.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=25540

PHYSIOLOGY

A new way to keep blood pressure under control

Chromogranin A (CHGA) is a hormone-like molecule that is overexpressed in hereditary hypertension, but its precise role in the disease was unclear. In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Sushil Mahata and colleagues from UCSD describe several novel phenotypes observed in mice lacking CHGA, and establish a role for this protein in hormone and neurotransmitter storage and release in vivo.

The mice had elevated blood pressure that could be restored to normalcy by treating the mice with human CHGA, demonstrating that the human gene plays a role in autonomic control of blood pressure. An accompanying commentary by Taeyoon Kim and Y. Peng Loh states that one important clinical implication of this work is that CHGA may be used as a therapeutic agent for treating hypertension in humans.

TITLE: Targeted ablation of the chromogranin A gene: Elevated blood pressure rescued by the human ortholog

AUTHOR CONTACT:
Sushil Mahata
University of California, San Diego, La Jolla, CA USA
Phone: 858-552-8585 x2637; Fax: 858-642-6425; E-mail: smahata@ucsd.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=24354

ACCOMPANYING COMMENTARY:

TITLE: Chromagranin A: a surprising link between granule biogenesis and hypertension

AUTHOR CONTACT:
Y. Peng Loh
NICHD, NIH, Bethesda, MD USA
Phone: 301-496-3239; Fax: 301-496-9939; E-mail: lohp@mail.nih.gov

View the PDF of this article at: https://www.the-jci.org/article.php?id=25706

PHYSIOLOGY

Unraveling the regulation of renin

Renin is a protein that controls blood pressure and is increased in many cardiovascular diseases and kidney diseases. Liver X Receptors (LXR) are members of the nuclear hormone receptor family that play a role in lipid metabolism, inflammation and immunity. In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Victor Dzau and colleagues from Duke University establish the role of LXR alpha and LXR beta as regulators of renin. The data provide information for the development of novel selective modulators of LXR alpha and beta for several disorders including hypertension and heart failure.

TITLE: Liver X Receptors alpha and beta regulate renin expression in vivo

AUTHOR CONTACT:
Victor Dzau
Duke University, Durham, NC USA
Phone: 919-684-2255; Fax: 919-681-7020; E-mail: victor.dzau@duke.edu

View the PDF of this article at: https://www.the-jci.org/article.php?id=24594

GENETICS

Cause of deadly skin disease found to be in the genes

Harlequin ichthyosis (HI) is a severe skin disease that is usually lethal in newborns. A dense scale that covers the skin, with abnormal facial features, characterizes it. The cause of HI was previously unknown. In a new study appearing in the July 1 print issue of The Journal of Clinical Investigation, Masashi Akiyama and colleagues from Hokkaido University report that mutations in a protein called ABCA12 are responsible for HI.

In this study, the authors show that ABCA12 is a lipid transporter in skin cells. They identify 5 mutations in 4 HI families.

In an accompanying commentary, Alain Hovnanian writes, "these results should allow for early prenatal diagnosis of HI and lend hope to the possibility of a specific treatment for this devastating disorder."

TITLE: Mutations in lipid transporter ABCA12 in harlequin ichthyosis and functional recovery by corrective gene transfer

AUTHOR CONTACT:
Masashi Akiyama
Hokkaido University Graduate School of Medicine, Sapporo, Japan Phone: 81-117161161; Fax: 81-117067820; E-mail: akiyama@med.hokudai.ac.jp

View the PDF of this article at: https://www.the-jci.org/article.php?id=24834

ACCOMPANYING COMMENTARY:

TITLE: Harlequin ichthyosis unmasked: a defect of lipid transport

AUTHOR CONTACT:
Alain Hovnanian
Purpan Hospital, INSERM Toulouse, France
Phone: 33-561-158-432; Fax: 33-561-499-036; E-mail: alain.hovnanian@toulouse.inserm.fr

View the PDF of this article at: https://www.the-jci.org/article.php?id=25736

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