HIV-related Death: Predicting Fatal Fungal Infections

In a study published in The Journal of Infectious Diseases, researchers from Albert Einstein College of Medicine of Yeshiva University have identified cells in blood that predict which HIV-positive individuals are most likely to develop deadly fungal meningitis, a major cause of HIV-related death. This form of meningitis affects more than 900,000 HIV-infected people globally—most of them in sub-Saharan Africa and other areas of the world where antiretroviral therapy for HIV is not available.A major cause of fungal meningitis is Cryptococcus neoformans, a yeast-like fungus commonly found in soil and in bird droppings. Virtually everyone has been infected with Cryptococcus neoformans, but a healthy immune system keeps the infection from ever causing disease.

The risk of developing fungal meningitis from Cryptococcus neoformans rises dramatically when people have weakened immunity, due to HIV infection or other reasons including the use of immunosuppressive drugs after organ transplantation, or for treating autoimmune diseases or cancer. Knowing which patients are most likely to develop fungal meningitis would allow costly drugs for preventing fungal disease to be targeted to those most in need. (In the U.S., the widespread use of antiretroviral therapy by HIV-infected people, and their preventive use of anti-fungal drugs, has dramatically reduced their rate of fungal meningitis from Cryptococcus neoformans to about 2%.)

In this study, Liise-anne Pirofski, M.D., describes a technique for predicting which HIV-infected patients are at greatest risk for developing fungal meningitis caused by Cryptococcus neoformans. Dr. Pirofski is chief in the division of infectious diseases at Einstein.

Dr. Pirofski and her colleagues counted the number of immune cells known as IgM memory B cells in the bloodstream of three groups of individuals: people infected with HIV who had a history of fungal meningitis caused by Cryptococcus neoformans; people infected with HIV but with no history of the disease; and those with no history of either HIV infection or the disease.

"We were astounded to find a profound difference in the level of these IgM memory B cells between the HIV-infected groups," said Dr. Pirofski. "The HIV-infected people with fungal meningitis caused by Cryptococcus neoformans had much lower levels of these cells."

The research team wanted to know if the lower levels of IgM memory B cells in certain HIV-infected individuals resulted from the fungal disease, or whether their reduced levels of these cells preceded their development of the disease.

To find out, Dr. Pirofski analyzed frozen blood samples taken from HIV-infected patients before they had developed fungal meningitis due to Cryptococcus neoformans. Years before these HIV-infected patients were diagnosed with meningitis, their blood had far fewer IgM memory B cells than HIV-infected patients who didn't come down with the disease. This suggests that some people are predisposed to develop fungal meningitis because they have low levels of IgM memory B cells that may be due to their genetic makeup.

These findings could be important for many other immunocompromised patients in addition to those infected with HIV. "We think that knowing whether transplant recipients or other patients taking immunosuppressive drugs have low numbers of IgM memory B cells could be useful in deciding which patients should receive antifungal drugs to prevent meningitis caused by Cryptococcus neoformans," says Dr. Pirofski.

Krishanthi Subramanian, Ph.D., who did her thesis work in Dr. Pirofski's laboratory, is the first author of the study.

Police Work Undermines Cardiovascular Health, Comparison To General Population Shows

It is well documented that police officers have a higher risk of developing heart disease: The question is why.In the most recent results coming out of one of the few long-term studies being conducted within this tightly knit society, University at Buffalo researchers have determined that underlying the higher incidence of subclinical atherosclerosis -- arterial thickening that precedes a heart attack or stroke -- may be the stress of police work.

"We took lifestyle factors that generally are associated with atherosclerosis, such as exercise, smoking, diet, etc., into account in our comparison between citizens and the police officers," said John Violanti, Ph.D., UB associate professor of social and preventive medicine, who has been studying the police force in Buffalo, N.Y., for 10 years.

"These lifestyle factors were statistically controlled for in the analysis. This led to the conclusion that it is not the 'usual' heart-disease-related risk factors that increase the risk in police officers. It is something else. We believe that 'something else' is the occupation of policing."

Results of the study appear in the June issue of the Journal of Occupational and Environmental Medicine.

Violanti and colleagues have been studying the role of cortisol, known as the "stress hormone," in these police officers to determine if stress is associated with physiological risk factors that can lead to serious health problems such as diabetes and cardiovascular disease.

In a study accepted for publication in Psychiatry Research that looked at the male-female differences in stress and signs of heart disease, Violanti found that female police officers had higher levels of cortisol when they awoke, and the levels remained high throughout the day. Cortisol normally is highest in the morning and decreases to its lowest point in the evening. The constantly high cortisol levels were associated with less arterial elasticity, a risk factor for heart disease, Violanti noted.

"When cortisol becomes dysregulated due to chronic stress, it opens a person to disease," he said. "The body becomes physiologically unbalanced, organs are attacked and the immune system is compromised as well. It's unfortunate, but that's what stress does to us."

In the current study, the researchers used carotid artery thickness to assess heart disease risk. Participants were 322 clinically healthy active-duty police officers from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study and 318 healthy persons from the ongoing UB Western New York Health Study matched to the officers by age.

All measurements were taken in the morning after a 12-hour fast. In addition to testing carotid thickness via ultrasound, investigators measured blood pressure, body size, cholesterol (both total and HDL) and glucose. They collected information on physical activity, symptoms of depression, alcohol consumption and smoking history. These are the factors that typically cause heart disease.

Results showed that police work was associated with increased subclinical cardiovascular disease -- there was more plaque build-up in the carotid artery -- compared to the general population that could not be explained by those conventional heart disease risk factors.

Subclinical atherosclerosis means that the disease shows progression but does not qualify yet as overt heart disease.

"In this case we examined the thickness of the carotid artery as an indicator of increasing risk for atherosclerosis," noted Violanti. "The plaque buildup was greater in police than the citizen population.

"In future work, we will measure the carotid artery thickness again to see how much it has increased. At some point in time, the thickness may reach a stage of possible blockage, which will require medical intervention and treatment. We think that police officers will likely reach that stage quicker than the general population."

P. Nedra Joseph, Ph.D., a former postdoctoral researcher at UB, now at the Centers for Disease Control and Prevention (CDC), is first author on the study. Additional contributors to the study were: from UB -- Richard Donahue, Ph.D., and Joan Dorn, Ph.D., from the UB School of Public Health and Health Professions; Michael E. Andrew, Ph.D., and Cecil M. Burchfiel, from the CDC; and Maurizio Trevisan, M.D., formerly of UB, now head of the University of Nevada Health Sciences System.

The BCOPS study is funded by the National Institute for Occupational Safety and Health.

‘Chemical Nose’ May Sniff Out Cancer Earlier

Using a “chemical nose” array of nanoparticles and polymers, researchers at the University of Massachusetts Amherst have developed a fundamentally new, more effective way to differentiate not only between healthy and cancerous cells but also between metastatic and non-metastatic cancer cells. It’s a tool that could revolutionize cancer detection and treatment, according to chemist Vincent Rotello and cancer specialist Joseph Jerry.An article describing Rotello and colleagues’ new chemical nose method of cancer detection appears in the June 23 issue of the journal Proceedings of the National Academy of Sciences online.

Currently, detecting cancer via cell surface biomarkers has taken what’s known as the “lock and key” approach. Drawbacks of this method include that foreknowledge of the biomarker is required. Also, as Rotello explains, a cancer cell has the same biomarkers on its surface as a healthy cell, but in different concentrations, a maddeningly small difference that can be very difficult to detect. “You often don’t get a big signal for the presence of cancer,” he notes. “It’s a subtle thing.”

He adds, “Our new method uses an array of sensors to recognize not only known cancer types, but it signals that abnormal cells are present. That is, the chemical nose can simply tell us something isn’t right, like a ‘check engine light,’ though it may never have encountered that type before.” Further, the chemical nose can be designed to alert doctors of the most invasive cancer types, those for which early treatment is crucial.

In blinded experiments in four human cancer cell lines (cervical, liver, testis and breast), as well as in three metastatic breast cell lines, and in normal cells, the new detection technique correctly indicated not only the presence of cancer cells in a sample but also identified primary cancer vs. metastatic disease.

In further experiments to rule out the possibility that the chemical nose had simply detected individual differences in cells from different donors, the researchers repeated the experiments in skin cells from three groups of cloned BALB /c mice: healthy animals, those with primary cancer and those with metastatic disease. Once again, it worked. “This result is key,” says Rotello. “It shows that we can differentiate between the the three cell types in a single individual using the chemical nose approach.”

Rotello’s research team, with colleagues at the Georgia Institute of Technology, designed the new detection system by combining three gold nanoparticles that have special affinity for the surface of chemically abnormal cells, plus a polymer known as PPE, or para-phenyleneethynylene. As the ‘check engine light,’ PPE fluoresces or glows when displaced from the nanoparticle surface.

By adding PPE bound with gold nanoparticles to human cells incubating in wells on a culture plate, the researchers induce a response called “competitive binding.” Cell surfaces bind the nanoparticles, displacing the PPE from the surface. This turns on PPE’s fluorescent switch. Cells are then identified from the patterns generated by different particle-PPE systems.

Rotello says the chemical nose approach is so named because it works like a human nose, which is arrayed with hundreds of very selective chemical receptors. These bind with thousands of different chemicals in the air, some more strongly than others, in the endless combination we encounter. The receptors report instantly to the brain, which recognizes patterns such as, for example, “French fries,” or it creates a new smell pattern.

Chemical receptors in the nose plus the brain’s pattern recognition skills together are incredibly sensitive at detecting subtly different combinations, Rotello notes. We routinely detect the presence of tiny numbers of bacteria in meat that’s going bad, for instance. Like a human nose, the chemical version being developed for use in cancer also remembers patterns experienced, even if only once, and creates a new one when needed.

For the future, Rotello says further studies will be undertaken in an animal model to see if the chemical nose approach can identify cell status in real tissue. Also, more work is required to learn how to train the chemical nose’s sensors to give more precise information to physicians who will be making judgment calls about patients’ cancer treatment. But the future is promising, he adds. “We’re getting complete identification now, and this can be improved by adding more and different nanoparticles. So far we’ve experimented with only three, and there are hundreds more we can make.”