IMPORTANCE Sepsis is a heterogeneous syndrome. Identification of distinct clinical phenotypes may allow more precise therapy and improve care. OBJECTIVE To derive sepsis phenotypes from clinical data, determine their reproducibility and correlation with host-response biomarkers and clinical outcomes, and assess the potential causal relationship with results from randomized clinical trials (RCTs). DESIGN, SETTINGS, AND PARTICIPANTS Retrospective analysis of data sets using statistical, machine learning, and simulation tools. Phenotypes were derived among 20 189 total patients (16 552 unique patients) who met Sepsis-3 criteria within 6 hours of hospital presentation at 12 Pennsylvania hospitals (2010-2012) using consensus k means clustering applied to 29 variables. Reproducibility and correlation with biological parameters and clinical outcomes were assessed in a second database (2013-2014; n = 43 086 total patients and n = 31 160 unique patients), in a prospective cohort study of sepsis due to pneumonia (n = 583), and in 3 sepsis RCTs (n = 4737). EXPOSURES All clinical and laboratory variables in the electronic health record. MAIN OUTCOMES AND MEASURES Derived phenotype (α, β, γ, and δ) frequency, host-response biomarkers, 28-day and 365-day mortality, and RCT simulation outputs. RESULTS The derivation cohort included 20 189 patients with sepsis (mean age, 64 [SD, 17] years; 10 022 [50%] male; mean maximum 24-hour Sequential Organ Failure Assessment [SOFA] score, 3.9 [SD, 2.4]). The validation cohort included 43 086 patients (mean age, 67 [SD, 17] years; 21 993 [51%] male; mean maximum 24-hour SOFA score, 3.6 [SD, 2.0]). Of the 4 derived phenotypes, the α phenotype was the most common (n = 6625; 33%) and included patients with the lowest administration of a vasopressor; in the β phenotype (n = 5512; 27%), patients were older and had more chronic illness and renal dysfunction; in the γ phenotype (n = 5385; 27%), patients had more inflammation and pulmonary dysfunction; and in the δ phenotype (n = 2667; 13%), patients had more liver dysfunction and septic shock. Phenotype distributions were similar in the validation cohort. There were consistent differences in biomarker patterns by phenotype. In the derivation cohort, cumulative 28-day mortality was 287 deaths of 5691 unique patients (5%) for the α phenotype; 561 of 4420 (13%) for the β phenotype; 1031 of 4318 (24%) for the γ phenotype; and 897 of 2223 (40%) for the δ phenotype. Across all cohorts and trials, 28-day and 365-day mortality were highest among the δ phenotype vs the other 3 phenotypes (P < .001). In simulation models, the proportion of RCTs reporting benefit, harm, or no effect changed considerably (eg, varying the phenotype frequencies within an RCT of early goal-directed therapy changed the results from >33% chance of benefit to >60% chance of harm). CONCLUSIONS AND RELEVANCE In this retrospective analysis of data sets from patients with sepsis, 4 clinical phenotypes were identified that correlated with host-response patterns and clinical outcomes, an...

Recombinant mouse interleukin 10 (IL-10) was exceedingly potent at suppressing the ability of mouse peritoneal macrophages (m phi) to release tumor necrosis factor alpha (TNF-alpha). The IC50 of IL-10 for the suppression of TNF-alpha release induced by 0.5 microgram/ml lipopolysaccharide was 0.04 +/- 0.03 U/ml, with as little as 1 U/ml suppressing TNF-alpha production by a factor of 21.4 +/- 2.5. At 10 U/ml, IL-10 markedly suppressed m phi release of reactive oxygen intermediates (ROI) (IC50 3.7 +/- 1.8 U/ml), but only weakly inhibited m phi release of reactive nitrogen intermediates (RNI). Since TNF-alpha is a T cell growth and differentiation factor, whereas ROI and RNI are known to inhibit lymphocyte function, it is possible that m phi exposed to low concentrations of IL-10 suppress lymphocytes. m phi deactivated by higher concentrations of IL-10 might be permissive for the growth of microbial pathogens and tumor cells, as TNF-alpha, ROI, and RNI are major antimicrobial and tumoricidal products of m phi. IL-10's effects on m phi overlap with but are distinct from the effects of the two previously described cytokines that suppress the function of mouse m phi, transforming growth factor beta and macrophage deactivation factor. Based on results with neutralizing antibodies, all three m phi suppressor factors appear to act independently.

The roles of nitric oxide (NO) in numerous disease states have generated considerable discussion over the past several years. NO has been labeled as the causative agent in different pathophysiological mechanisms, yet appears to protect against various chemical species such as those generated under oxidative stress. Similarly, NO appears to exert a dichotomy of effects within the multistage model of cancer. Chronic inflammation can lead to the production of chemical intermediates, among them NO, which in turn can mediate damage to DNA. Yet, NO also appears to be critical for the tumoricidal activity of the immune system. Furthermore, NO can also have a multitude of effects on other aspects of tumor biology, including angiogenesis and metastasis. This report will discuss how the chemistry of NO may impact the initiation and progression stages of cancer.

We have discovered that the mosquito Anopheles stephensi, a natural vector of human malaria, limits parasite development with inducible synthesis of nitric oxide (NO). Elevated expression of A. stephensi NO synthase (NOS), which is highly homologous to characterized NOS genes, was detected in the midgut and carcass soon after invasion of the midgut by Plasmodium. Early induction is likely primed by bacterial growth in the blood meal. Later increases in A. stephensi NOS expression and enzyme activity occurred at the beginning of sporozoite release. Circulating levels of nitrite͞ nitrate, end-products of NO synthesis, were significantly higher in Plasmodium-infected mosquitoes. Dietary provision of the NOS substrate L-arginine reduced Plasmodium infections in A. stephensi. In contrast, dietary provision of a NOS inhibitor significantly increased parasite numbers in infected mosquitoes, confirming that A. stephensi limits Plasmodium development with NO.

SummaryActivated mouse peritoneal macrophages produce nitric oxide (NO) via a nitric oxide synthase that is inducible by interferon 3, (IFN-7): iNOS. We have studied the mechanisms by which transforming growth factor ~1 (TGF-~) suppresses IFN-7-stimulated NO production. TGF-~/ treatment reduced iNOS specific activity and iNOS protein in both cytosolic and particulate fractions as assessed by Western blot with monospecific anti-iNOS immunoglobulin G. TGF-~ reduced iNOS mRNA without affecting the transcription ofiNOS by decreasing iNOS mRNA stability. Even after iNOS was already expressed, TGF-~ reduced the amount of iNOS protein.This was due to reduction ofiNOS mRNA translation and increased degradation ofiNOS protein.The potency of TGF-B as a deactivator of NO production (50% inhibitory concentration, 5.6 _+ 2 pM) may reflect its ability to suppress iNOS expression by three distinct mechanisms: decreased stability and translation of iNOS mRNA, and increased degradation of iNOS protein. This is the first evidence that iNOS is subject to other than transcriptional regulation. ecent appreciation of the role of endogenously generated nitric oxide (NO) 2 in the physiology and pathophysiology of every organ system raises interest in mechanisms by which NO production may be regulated (1). This question assumes additional significance in view of the ability of NO to kill or damage cells (2).Constitutive isoforms of NO synthase (chiOS) are expressed in neurons and endothelium. These enzymes produce small amounts of NO over several minutes in response to agonists that elevate intracellular Ca 2 + (1). press an inducible isoform of NO synthase (iNOS) that produces relatively large amounts of NO over many hours without dependence on secretagogues. Nothing is known to regulate iNOS after it has been induced (1).Suppression of iNOS expression was first shown in macrophages exposed to TGF-B (16). These results were confirmed 1 Yoram Vodovotz and Christian Bogdan contributed equally to the e~periments described in this work.2 Abbreviations used in this paper: cNOS, constitutive isoforms of nitric oxide synthase; FAD, ravin adenine dinucleotide; GAPDH, glyr.eraldehyde-3-phosphate dehydrogenase; iNOS, inducible isoform of nitric oxide synthase; NADPH, 3-nicotinamide-adenine dinucleotide phosphate; NO, nitric oxide.

No abstract

The quoted references are mostly recent reviews of significant relevance. eNOS, endothelial isoform of nitric oxide synthase (NOS); iNOS, inducible form of NOS; NO, nitric oxide.

We propose a mathematical model for mitochondria-dependent apoptosis, in which kinetic cooperativity in formation of the apoptosome is a key element ensuring bistability. We examine the role of Bax and Bcl-2 synthesis and degradation rates, as well as the number of mitochondrial permeability transition pores (MPTPs), on the cell response to apoptotic stimuli. Our analysis suggests that cooperative apoptosome formation is a mechanism for inducing bistability, much more robust than that induced by other mechanisms, such as inhibition of caspase-3 by the inhibitor of apoptosis (IAP). Simulations predict a pathological state in which cells will exhibit a monostable cell survival if Bax degradation rate is above a threshold value, or if Bax expression rate is below a threshold value. Otherwise, cell death or survival occur depending on initial caspase-3 levels. We show that high expression rates of Bcl-2 can counteract the effects of Bax. Our simulations also demonstrate a monostable (pathological) apoptotic response if the number of MPTPs exceeds a threshold value. This study supports our contention, based on mathematical modeling, that cooperativity in apoptosome formation is critically important for determining the healthy responses to apoptotic stimuli, and helps define the roles of Bax, Bcl-2, and MPTP vis-à-vis apoptosome formation.