O-GalNAcylation of RANTES Improves Its Properties as a Human Immunodeficiency Virus Type 1 Entry Inhibitor.

Many human proteins have the potential to be developed as therapeutic agents. However, side effects caused by direct administration of natural proteins have significantly slowed expansion of protein therapeutics into the clinic. Post-translational modifications (PTMs) can improve protein properties, but because of significant knowledge gaps, we are considerably limited in our ability to apply PTMs to generate better protein therapeutics. Here, we seek to fill the gaps by studying the PTMs of a small representative chemotactic cytokine, RANTES. RANTES can inhibit HIV-1 infection by competing with it for binding to receptor CCR5 and stimulating CCR5 endocytosis. Unfortunately, RANTES can induce strong signaling, leading to severe inflammatory side effects. We apply a chemical biology approach to explore the potential of post-translationally modified RANTES as safe inhibitors of HIV-1 infection. We synthesized and systematically tested a library of RANTES isoforms for their ability to inhibit inflammatory signaling and prevent HIV-1 infection of primary human cells. Through this research, we revealed that most of the glycosylated variants have decreased inflammation-associated properties and identified one particular glyco variant, a truncated RANTES containing a Galß1-3GalNAc disaccharide α-linked to Ser4, which stands out as having the best overall properties: relatively high HIV-1 inhibition potency but also weak inflammatory properties. Moreover, our results provided a structural basis for the observed changes in the properties of RANTES. Taken together, this work highlights the potential importance of glycosylation as an alternative strategy for developing CCR5 inhibitors to treat HIV-1 infection and, more generally, for reducing or eliminating unwanted properties of therapeutic proteins.

CCL5 as an adjuvant for cancer immunotherapy.

IMPORTANCE OF THE FIELD: To date cancer immunotherapy has only achieved limited clinical efficacy, thus more efficient immunotherapeutic approaches need to be explored. The CC chemokine CCL5 plays a role in chemoattraction and activation of immune cells implying its potential clinical application as an adjuvant for boosting anti-tumor immunity, although an effect on carcinogenesis and tumor cell invasiveness is also reported to be associated with CCL5. AREAS COVERED IN THIS REVIEW: Recent progress in exploiting CCL5 as an adjuvant for cancer prevention and treatment, and updated understanding on how CCL5 is involved in tumor invasiveness and carcinogenesis. WHAT THE READER WILL GAIN: CCL5 represents a natural adjuvant for enhancing anti-tumor immune responses. However, animal experiments and clinical reports suggest that CCL5 plays a role in carcinogenesis and invasiveness of tumor cells. Therefore, a CCL5-based cancer therapeutic approach needs to avoid the CCL5-associated potential detrimental effects. TAKE HOME MESSAGE: CCL5 has a pre-eminent role in chemotaxis and activation of a wide spectrum of immune cells. CCL5 functions as an adjuvant to boost anti-tumor immunity by diverse protocols such as co-immunization of recombinant CCL5 protein with tumor-associated antigen, vaccination with CCL-5-expressing tumor cells, or viral vector delivery of CCL5 cDNA into growing tumor. CCL5 may also promote tumor cell survival, proliferation and invasion by different mechanisms.

Cytokine cascade in sepsis.

Sepsis is associated with an exacerbated production of both pro- and anti-inflammatory cytokines, which are detectable within the bloodstream. Their 'half-angel, half-devil' properties are fully illustrated in sepsis. While they are a prerequisite to fight infection, their overzealous production is deleterious. The highest levels are found in plasma of non-surviving patients: they are markers and causative agents of poor outcome. Only the level of the chemokine RANTES is inversely associated with the APACHE II score (r = -0.7; p = 0.02) and low levels are associated with poor outcome. The link, interplay and network of cytokines taking place during sepsis are illustrated by the correlations between the levels of most pro- and anti-inflammatory cytokines. Excessive release of anti-inflammatory cytokines may be associated with the immunodysregulation observed in sepsis. However, despite the presence of huge amounts of anti-inflammatory cytokines and molecules targeting specifically interleukin-1 (IL-1) (i.e. IL-1 receptor antagonist) and tumour necrosis factor (TNF) (i.e. soluble TNF receptors), there is no indication that their levels are sufficient to counteract fully these proinflammatory cytokines. TNF was initially thought to be the 'hub of the cytokine network'. Although TNF contributes towards favouring the production of many other cytokines within a complex cascade, there are numerous examples to illustrate that its presence is not a prerequisite for these productions.