Bayesian network analysis of multi-compartmentalized immune responses in a murine model of sepsis and direct lung injury

Abstract Background Inflammatory disease processes involve complex and interrelated systems of mediators. Determining the causal relationships among these mediators becomes more complicated when two, concurrent inflammatory conditions occur. In those cases, the outcome may also be dependent upon the timing, severity and compartmentalization of the insults. Unfortunately, standard methods of experimentation and analysis of data sets may investigate a single scenario without uncovering many potential associations among mediators. However, Bayesian network analysis is able to model linear, nonlinear, combinatorial, and stochastic relationships among variables to explore complex inflammatory disease systems. In these studies, we modeled the development of acute lung injury from an indirect insult (sepsis induced by cecal ligation and puncture) complicated by a direct lung insult (aspiration). To replicate multiple clinical situations, the aspiration injury was delivered at different severities and at different time intervals relative to the septic insult. For each scenario, we measured numerous inflammatory cell types and cytokines in samples from the local compartments (peritoneal and bronchoalveolar lavage fluids) and the systemic compartment (plasma). We then analyzed these data by Bayesian networks and standard methods. Results Standard data analysis demonstrated that the lung injury was actually reduced when two insults were involved as compared to one lung injury alone. Bayesian network analysis determined that both the severity of lung insult and presence of sepsis influenced neutrophil recruitment and the amount of injury to the lung. However, the levels of chemoattractant cytokines responsible for neutrophil recruitment were more strongly linked to the timing and severity of the lung insult compared to the presence of sepsis. This suggests that something other than sepsis-driven exacerbation of chemokine levels was influencing the lung injury, contrary to previous theories. Conclusions To our knowledge, these studies are the first to use Bayesian networks together with experimental studies to examine the pathogenesis of sepsis-associated lung injury. Compared to standard statistical analysis and inference, these analyses elucidated more intricate relationships among the mediators, immune cells and insult-related variables (timing, compartmentalization and severity) that cause lung injury. Bayesian networks are an effective tool for evaluating complex models of inflammation.http://deepblue.lib.umich.edu/bitstream/2027.42/113666/1/13104_2015_Article_1488.pd

Differences in normal values for murine white blood cell counts and other hematological parameters based on sampling site

Objective and design: The effect of blood sampling site on the hemogram and neutrophil adhesion molecules was examined in BALB/c mice.¶ Materials and methods: Blood samples were drawn from the tail, eye, and heart during anesthesia with ketamine and xylazine. Cell numbers were quantified with an automated counter and flow cytometry was used to quantify CD11b and CD18.¶ Results: Total white blood cell (WBC) counts were highest from tail, lower from eye, and significantly lower from heart blood. In general, differences between tail and heart counts reflected changes in all cell types. RBCs, platelets and hematocrits were significantly increased in tail compared to heart blood. Although CD18 levels were not different, CD11b was significantly higher on neutrophils from tail compared to heart blood.¶ Conclusions: In anesthetized BALB/c mice, sampling site readily influences blood counts and neutrophil CD11b. The findings underscore the need to standardize sampling site when measuring these parameters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41822/1/11-50-10-523_10500523.pd

Short‐wave infrared light imaging measures tissue moisture and distinguishes superficial from deep burns

Existing clinical approaches and tools to measure burn tissue destruction are limited resulting in misdiagnosis of injury depth in over 40% of cases. Thus, our objective in this study was to characterize the ability of short‐wave infrared (SWIR) imaging to detect moisture levels as a surrogate for tissue viability with resolution to differentiate between burns of various depths. To accomplish our aim, we constructed an imaging system consisting of a broad‐band Tungsten light source; 1,200‐, 1,650‐, 1,940‐, and 2,250‐nm wavelength filters; and a specialized SWIR camera. We initially used agar slabs to provide a baseline spectrum for SWIR light imaging and demonstrated the differential absorbance at the multiple wavelengths, with 1,940 nm being the highest absorbed wavelength. These spectral bands were then demonstrated to detect levels of moisture in inorganic and in vivo mice models. The multiwavelength SWIR imaging approach was used to diagnose depth of burns using an in vivo porcine burn model. Healthy and injured skin regions were imaged 72 hours after short (20 seconds) and long (60 seconds) burn application, and biopsies were extracted from those regions for histologic analysis. Burn depth analysis based on collagen coagulation histology confirmed the formation of superficial and deep burns. SWIR multispectral reflectance imaging showed enhanced intensity levels in long burned regions, which correlated with histology and distinguished between superficial and deep burns. This SWIR imaging method represents a novel, real‐time method to objectively distinguishing superficial from deep burns.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154351/1/wrr12779_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154351/2/wrr12779.pd

Breed-specific pro-inflammatory cytokine production as a predisposing factor for susceptibility to sepsis in the dog

Objective : To determine whether 2 dog breeds with a high risk for parvoviral enteritis, a disease associated with sepsis, produce stronger pro-inflammatory cytokine responses to a stimulus than dogs with a lower risk. Design : Blinded comparison. Setting : University outpatient clinic. Animals : Healthy, unrelated, purebred Doberman Pinschers ( n =10) and Rottweilers ( n =9) with age-matched mixed-breed dogs ( n =7). Interventions : Heparinized, whole-blood samples were collected from each dog and incubated for 6 hours with lipopolysaccharide. Plasma was collected, and bioassays were used to determine the concentrations of TNF-Α and IL-6. The mean values obtained from the high-risk breeds were compared with the mean obtained from the mixed-breeds. Measurements and main results : The mean TNF-Α production from dogs with a high risk for parvoviral enteritis (1321±161 pg/mL; Doberman Pinscher and Rottweiler) was greater ( P <0.05) than that from lower risk, mixed-breed dogs (674±186 pg/mL). There were no differences in TNF-Α levels between Doberman (1128±247 pg/mL) and Rottweiler (1563±pg/mL) breeds or between any breeds with regard to IL-6 production. Conclusions : The magnitude of TNF-Α production by peripheral blood monocytes was the greatest in the dogs with breed-related risk for parvoviral enteritis. However, additional studies are needed to prove a causal relationship between high TNF and predilection for parvoviral enteritis. Regardless, breed appears to be a predisposing factor for variations in cytokine production that could impact the host response to infection and other inflammatory insults.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71791/1/j.1476-4431.2006.00215.x.pd

Immunopathologic Alterations in Murine Models of Sepsis of Increasing Severity

We investigated inflammatory and physiologic parameters in sepsis models of increasing lethality induced by cecal ligation and puncture (CLP). Mice received imipenem for antibiotic therapy, and groups were sacrificed at 2, 4, 8, 12, 16, 20, and 24 h after CLP. The severity of sepsis increased with needle puncture size (lethality with 18-gauge puncture [18G], 100%; 21G, 50%; 25G, 5%; sham treatment, 0%). While the temperature (at 12 h) and the activity and diurnal rhythm (at day 4) of the 25G-treated CLP group recovered to normal, the 21G and 18G treatment groups exhibited severe hypothermia along with decreased activities. A direct correlation was also observed between the severity of sepsis and cytokine (interleukin 1β [IL-1β], tumor necrosis factor [TNF], IL-6, and IL-10) concentrations in both the peritoneum and the plasma. There were substantially higher cytokine levels in the more severe CLP models than in the sham-treated one. Peritoneal and plasma TNF levels were always less than 40 pg/ml in all models. None of the cytokines in the septic mice peaked within the first hour, which is in contrast to the results of most endotoxin models. Chemokine (KC and macrophage inflammatory protein 2) profiles also correlated with the severity of sepsis. Except for the chemokines, levels of inflammatory mediators were always higher at the site of inflammation (peritoneum) than in the circulation. Our study demonstrated that sepsis of increasing severity induced increased cytokine levels both within the local environment (peritoneum) and systemically (plasma), which in turn correlated with morbidity and mortality