The Bacteria that are Good for Us

Chains of StreptococciSalmonella. Streptococcus. Shigella. The most well-known bacteria are those that cause disease. Our relationship with them is one of combat. With good reason, we look for ways to avoid encountering them and to eliminate them when we do meet.

But not all bacteria are bad for us. Of course we have known for years that we are colonized by harmless bacteria, but recently, studies on the human microbiome have revealed many surprising things about these bacterial tenants. Studies are showing that the teeming multitudes of organisms living in and on the human body are not just harmless bystanders, but complex, interrelated communities that can have profound effects on our health.

Three studies published last week in Science add more to the growing body of microbiome surprises, showing that certain gut bacteria are not only good for us, but may even be required for the effectiveness of some anti-cancer immunotherapies.

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Improved Method for the Rapid Analysis of Monoclonal Antibodies Using IdeS

ides_abTherapeutic monoclonal antibodies (MAbs) are inherently heterogeneous due to a wide range of both enzymatic and chemical modifications, such as oxidation, deamidation and glycosylation which may occur during expression, purification or storage. For identification and functional evaluation of these modifications, stability studies
are typically performed by employing stress conditions such as exposure to chemical oxidizers, elevated pH and temperature.

To characterize MAbs, a variety of analytical techniques are chosen, such as size exclusion chromatography and ion exchange chromatography. However, due to the large size of the intact MAbs, these methods lack structural resolution. Often, the chromatographic peaks resolved by SEC and IEC methods are collected and further analyzed by peptide mapping to obtain more detailed information. Peptide mapping, in which antibodies are cleaved into small peptides through protease digestion followed by LC–MS/MS analysis, is generally the method of choice for detection and quantitation of site-specific modifications. However sample preparation and lengthy chromatographic separation make peptide mapping impractical for the analysis of large numbers of samples. In contrast to peptide mapping analysis, the middle-down approach offers the advantage of high-throughput and specificity for antibody characterization.

Limited proteolysis of IgG molecules by the IdeS enzyme has been introduced for antibody characterization due to its high cleavage specificity and simple digestion procedure. Continue reading

Unexpected connections: Gut bacteria influence immunotherapy outcomes

Over the last few years, human microbiome studies have revealed fascinating connections between our colonizing microorganisms and ourselves—including associations between gut bacterial populations and obesity, disease susceptibility, and even mood. The relationship between us and our microbial colonists—once considered completely benign, is now being revealed as an intricate, complicated partnership with the potential to redefine who “we” are in fundamental ways.

Two papers published back-to-back in the November 27 issue of Science add further to this growing body of knowledge—reporting a new and unexpected connection between gut bacterial species and the effectiveness of cancer immunotherapies in mice. The work suggests one reason why such treatments are effective in some circumstances, but not others. Both papers report that the presence of specific bacterial populations may be required for the efficacy of certain treatments, and raise the intriguing question “Could the composition of bacteria in the gut be manipulated to enhance the effectiveness of cancer treatments?” Continue reading

Characterizing Immune-Modulating Antibodies Using Bioluminescence

Immune checkpoint pathways such as PD-1/PD-L1 and CTLA-4 are promising new immunotherapy targets for the treatment of cancer and autoimmunity. Immune checkpoint reporter-based bioassays provide a simple, consistent, and reliable cell-based assay to measure Ab function throughout the drug development pipeline.

The brief chalk talk below describes the assay principals of the reporter-based bioassay that monitors the functional blockade of PD-1/PD-L1 interactions.

Removing Cancer’s Cloak of Invisibility

Copyright Promega.

Copyright Promega.

For decades scientists have been trying to harness the power of our immune system to fight cancer cells. It is not impossible to imagine that our immune system, which is sophisticated enough to fight against a multitude of invaders that threaten our health, should be able to tackle a deadly disease such as cancer. This formed the basis of testing a new type of cancer treatment known as immunotherapy. Immunotherapy for cancer means developing treatments to harness your immune system and using your own immune system to fight the cancerous cells.

But in reality it was hard to make this work. Because, as scientists discovered recently, cancer outsmarts the immune system by wearing a kind of “invisibility cloak”. Cancer is able to fool the immune system from recognizing that it is the enemy and in effect keeps the immune system from destroying it.

In a breakthrough discovery scientists have found a way around this treachery.

The breakthrough is in therapies called ‘checkpoint inhibitors’. Checkpoint inhibitors block the mechanisms that allow some tumor cells to evade the immune system. The drugs ensure that cancer cells are no longer be shielded from the immune system defenses, but are instead recognized as “foreign”. Continue reading