Racial differences in phenotypic frailty assessment among general thoracic surgery patients.

Objectives: The American Association for Thoracic Surgery recommends using frailty assessments to identify patients at higher risk of perioperative morbidity and mortality. We evaluated what patient factors are associated with frailty in a thoracic surgery patient population. Methods: New patients aged more than 50 years who were evaluated in a thoracic surgery clinic underwent routine frailty screening with a modified Fried's Frailty Phenotype. Differences in demographics and comorbid conditions among frailty status groups were assessed with chi-square and Student t tests. Logistic regressions performed with binomial distribution assessed the association of demographic and clinical characteristics with nonfrail, frail, prefrail, and any frailty (prefrail/frail) status. Results: The study population included 317 patients screened over 19 months. Of patients screened, 198 (62.5%) were frail or prefrail. Frail patients undergoing thoracic surgery were older, were more likely single or never married, had lower median income, and had lower percent predicted diffusion capacity of the lungs for carbon monoxide and forced expiratory volume during 1 second (all P < .05). More non-Hispanic Black patients were frail and prefrail compared with non-Hispanic White patients (P = .003) and were more likely to score at least 1 point on Fried's Frailty Phenotype (adjusted odds ratio, 3.77; P = .02) when controlling for age, sex, number of comorbidities, median income, diffusion capacity of the lungs for carbon monoxide, and forced expiratory volume during 1 second. Non-Hispanic Black patients were more likely than non-Hispanic White patients to score points for slow gait and low activity (both P < .05). Conclusions: Non-Hispanic Black patients undergoing thoracic surgery are more likely to score as frail or prefrail than non-Hispanic White patients. This disparity stems from differences in activity and gait speed. Frailty tools should be examined for factors contributing to this disparity, including bias.

The Effect of Normothermic Machine Perfusion on the Immune Profile of Donor Liver.

Background: Normothermic machine perfusion (NMP) allows viability assessment and potential resuscitation of donor livers prior to transplantation. The immunological effect of NMP on liver allografts is undetermined, with potential implications on allograft function, rejection outcomes and overall survival. In this study we define the changes in immune profile of human livers during NMP. Methods: Six human livers were placed on a NMP device. Tissue and perfusate samples were obtained during cold storage prior to perfusion and at 1, 3, and 6 hours of perfusion. Flow cytometry, immunohistochemistry, and bead-based immunoassays were used to measure leukocyte composition and cytokines in the perfusate and within the liver tissue. Mean values between baseline and time points were compared by Student's t-test. Results: Within circulating perfusate, significantly increased frequencies of CD4 T cells, B cells and eosinophils were detectable by 1 hour of NMP and continued to increase at 6 hours of perfusion. On the other hand, NK cell frequency significantly decreased by 1 hour of NMP and remained decreased for the duration of perfusion. Within the liver tissue there was significantly increased B cell frequency but decreased neutrophils detectable at 6 hours of NMP. A transient decrease in intermediate monocyte frequency was detectable in liver tissue during the middle of the perfusion run. Overall, no significant differences were detectable in tissue resident T regulatory cells during NMP. Significantly increased levels of pro-inflammatory and anti-inflammatory cytokines were seen following initiation of NMP that continued to rise throughout duration of perfusion. Conclusions: Time-dependent dynamic changes are seen in individual leukocyte cell-types within both perfusate and tissue compartments of donor livers during NMP. This suggests a potential role of NMP in altering the immunogenicity of donor livers prior to transplant. These data also provide insights for future work to recondition the intrinsic immune profile of donor livers during NMP prior to transplantation.

Donor leukocyte trafficking during human ex vivo lung perfusion.

BACKGROUND: Ex vivo lung perfusion (EVLP) is used to assess and preserve lungs prior to transplantation. However, its inherent immunomodulatory effects are not completely understood. We examine perfusate and tissue compartments to determine the change in immune cell composition in human lungs maintained on EVLP. METHODS: Six human lungs unsuitable for transplantation underwent EVLP. Tissue and perfusate samples were obtained during cold storage and at 1-, 3- and 6-h during perfusion. Flow cytometry, immunohistochemistry, and bead-based immunoassays were used to measure leukocyte composition and cytokines. Mean values between baseline and time points were compared by Student's t test. RESULTS: During the 1st hour of perfusion, perfusate neutrophils increased (+22.2 ± 13.5%, p < 0.05), monocytes decreased (-77.5 ± 8.6%, p < 0.01) and NK cells decreased (-61.5 ± 22.6%, p < 0.01) compared to cold storage. In contrast, tissue neutrophils decreased (-22.1 ± 12.2%, p < 0.05) with no change in monocytes and NK cells. By 6 h, perfusate neutrophils, NK cells, and tissue neutrophils were similar to baseline. Perfusate monocytes remained decreased, while tissue monocytes remained unchanged. There was no significant change in B cells or T cell subsets. Pro-inflammatory cytokines (IL-1b, G-CSF, IFN-gamma, CXCL2, CXCL1 granzyme A, and granzyme B) and lymphocyte activating cytokines (IL-2, IL-4, IL-6, IL-8) increased during perfusion. CONCLUSIONS: Early mobilization of innate immune cells occurs in both perfusate and tissue compartments during EVLP, with neutrophils and NK cells returning to baseline and monocytes remaining depleted after 6 h. The immunomodulatory effect of EVLP may provide a therapeutic window to decrease the immunogenicity of lungs prior to transplantation.

Nanotraps for the containment and clearance of SARS-CoV-2.

SARS-CoV-2 enters host cells through its viral spike protein binding to angiotensin-converting enzyme 2 (ACE2) receptors on the host cells. Here, we show that functionalized nanoparticles, termed "Nanotraps," completely inhibited SARS-CoV-2 infection by blocking the interaction between the spike protein of SARS-CoV-2 and the ACE2 of host cells. The liposomal-based Nanotrap surfaces were functionalized with either recombinant ACE2 proteins or anti-SARS-CoV-2 neutralizing antibodies and phagocytosis-specific phosphatidylserines. The Nanotraps effectively captured SARS-CoV-2 and completely blocked SARS-CoV-2 infection to ACE2-expressing human cell lines and primary lung cells; the phosphatidylserine triggered subsequent phagocytosis of the virus-bound, biodegradable Nanotraps by macrophages, leading to the clearance of pseudotyped and authentic virus in vitro. Furthermore, the Nanotraps demonstrated an excellent biosafety profile in vitro and in vivo. Finally, the Nanotraps inhibited pseudotyped SARS-CoV-2 infection in live human lungs in an ex vivo lung perfusion system. In summary, Nanotraps represent a new nanomedicine for the inhibition of SARS-CoV-2 infection.