Inactivation of the Sts enzymes promotes resistance to lethal Staphylococcus aureus infection.

Staphylococcus aureus is a highly infective Gram-positive bacterial pathogen that causes a wide range of diseases in both healthy and immunocompromised individuals. It can evade host immune defenses by expressing numerous virulence factors and toxins. Coupled with the inability of the human host to develop protective immunity against S. aureus, the emergence of antibiotic-resistant strains complicates treatment options. The non-canonical Sts phosphatases negatively regulate signaling pathways in varied immune cell types. To determine the role of the Sts proteins in regulating host responses to a Gram-positive microorganism, we investigated the response of mice lacking Sts expression to S. aureus infection. Herein, we demonstrate that Sts -/- animals are significantly resistant to lethal intravenous doses of S. aureus strain USA300. Resistance is characterized by significantly enhanced survival and accelerated bacterial clearance in multiple peripheral organs. Infected Sts -/- animals do not display increased levels of cytokines TNFα, IFNγ, and IL-6 in the spleen, liver, and kidney during the early stages of the infection, suggesting that a heightened pro-inflammatory response does not underlie the resistance phenotype. In vivo ablation of mononuclear phagocytes compromises the Sts -/- enhanced CFU clearance phenotype. Additionally, Sts -/- bone marrow-derived macrophages demonstrate significantly enhanced restriction of intracellular S. aureus following ex vivo infection. These results reveal the Sts enzymes to be critical regulators of host immunity to a virulent Gram-positive pathogen and identify them as therapeutic targets for optimizing host anti-microbial responses.

The Sts Proteins: Modulators of Host Immunity.

The suppressor of TCR signaling (Sts) proteins, Sts-1 and Sts-2, are a pair of closely related signaling molecules that belong to the histidine phosphatase (HP) family of enzymes by virtue of an evolutionarily conserved C-terminal phosphatase domain. HPs derive their name from a conserved histidine that is important for catalytic activity and the current evidence indicates that the Sts HP domain plays a critical functional role. Sts-1HP has been shown to possess a readily measurable protein tyrosine phosphatase activity that regulates a number of important tyrosine-kinase-mediated signaling pathways. The in vitro catalytic activity of Sts-2HP is significantly lower than that of Sts-1HP, and its signaling role is less characterized. The highly conserved unique structure of the Sts proteins, in which additional domains, including one that exhibits a novel phosphodiesterase activity, are juxtaposed together with the phosphatase domain, suggesting that Sts-1 and -2 occupy a specialized intracellular signaling niche. To date, the analysis of Sts function has centered predominately around the role of Sts-1 and -2 in regulating host immunity and other responses associated with cells of hematopoietic origin. This includes their negative regulatory role in T cells, platelets, mast cells and other cell types, as well as their less defined roles in regulating host responses to microbial infection. Regarding the latter, the use of a mouse model lacking Sts expression has been used to demonstrate that Sts contributes non-redundantly to the regulation of host immunity toward a fungal pathogen (C. albicans) and a Gram-negative bacterial pathogen (F. tularensis). In particular, Sts-/- animals demonstrate significant resistance to lethal infections of both pathogens, a phenotype that is correlated with some heightened anti-microbial responses of phagocytes derived from mutant mice. Altogether, the past several years have seen steady progress in our understanding of Sts biology.

Blood Test Increases Colorectal Cancer Screening in Persons Who Declined Colonoscopy and Fecal Immunochemical Test: A Randomized Controlled Trial.

BACKGROUND & AIMS: The septin 9 blood test is indicated for colorectal cancer screening in individuals who decline first-line tests, but participation in this context is unclear. We conducted a randomized controlled trial to compare reoffering colonoscopy and fecal immunochemical test (FIT) alone versus also offering the blood test among individuals who declined colonoscopy and FIT. METHODS: Screen-eligible Veterans aged 50-75 years who declined colonoscopy and FIT within the previous 6 months were randomized to letter and telephone outreach to reoffer screening with colonoscopy/FIT only (control), or additionally offering the blood test as a second-line option (intervention). The primary outcome was completion of any screening test within 6 months. The secondary outcome was completion of a full screening strategy within 6 months, including colonoscopy for those with a positive noninvasive test. RESULTS: Of 359 participants who completed follow-up, 9.6% in the control group and 17.1% in the intervention group completed any screening (7.5% difference; P = .035). Uptake of colonoscopy and FIT was similar in the 2 groups. The full screening strategy was completed in 9.0% and 14.9% in the control and intervention groups, respectively (5.9% difference; P = .084). CONCLUSIONS: Among individuals who previously declined colonoscopy and FIT, offering a blood test as a secondary option increased screening by 7.5% without decreasing uptake of first-line screening options. However, completion of a full screening strategy did not increase. These findings indicate that a blood test is a promising method to improve colorectal cancer screening, but obtaining a timely colonoscopy after a positive noninvasive test remains a challenge (ClincialTrials.gov number, NCT03598166).

Treatment of Metastatic Castration-resistant Prostate Cancer With Abiraterone and Enzalutamide Despite PSA Progression.

BACKGROUND/AIM: National guidelines offer little guidance on the use of PSA progression (PSA increase as defined below) as a clinical endpoint in metastatic castration-resistant prostate cancer (mCRPC). The aim of the study was to examine treatment patterns/outcomes with abiraterone (abi)/enzalutamide (enza) throughout PSA progression and near the end of life (EOL). PATIENTS AND METHODS: Cases of mCRPC treated with abi or enza from the New York Veterans Affairs (VA) from 6/2011-8/2017 were reviewed. Regression analyses were conducted to identify factors associated with continuation of abi/enza treatment up to the EOL, and survival. RESULTS: Of 184 patients, 72 received abi alone, 28 received enza alone, and 84 received both. Treatment was changed for PSA progression alone in 39.1% (abi) and 25.7% (enza) of patients. A total of 37 patients (20%) received abi/enza within 1 month before death, 30% of whom were receiving hospice services. Older patients and black patients were less likely to receive abi/enza up to the EOL. CONCLUSION: Abi/enza are frequently discontinued for PSA progression alone and continued at EOL. The clinical benefit of these practices warrants additional study.