Long-term Monocyte Dysfunction after Sepsis in Humanized Mice Is Related to Persisted Activation of Macrophage-Colony Stimulation Factor (M-CSF) and Demethylation of PU.1, and It Can Be Reversed by Blocking M-CSF In Vitro or by Transplanting Naïve Autologous Stem Cells In Vivo

The duration of post-sepsis long-term immune suppression is poorly understood. Here, we focused on the role of monocytes (MO) as the pivotal cells for long-term regulation of post-sepsis milieu. Lost ability of MO to adapt is seen in several acute conditions, but it is unclear for how long MO aberrancy post-sepsis can persist. Interestingly, the positive feedback loop sustaining secretion of macrophage-colony stimulation factor (M-CSF) can persist even after resolution of sepsis and significantly alters performance of MO. Here, we investigated the activation of M-CSF, and it as critical regulator of PU.1 in mice surviving 28 days after sepsis. Our primary readout was the ability of MO to differentiate into dendritic cells (DCs; MO→iDC) in vitro since this is one of the critical processes regulating a successful transition from innate to acquired immunity. We utilized a survival modification of the cecal ligation and puncture (CLP) model of sepsis in humanized mice. Animals were sacrificed 28 days after CLP (tCLP+28d). Untouched (CONTR) or sham-operated (SHAM) animals served as controls. Some animals received rescue from stem cells originally used for grafting 2 weeks after CLP. We found profound decrease of MO→iDC in the humanized mice 28 days after sepsis, demonstrated by depressed expression of CD1a, CD83, and CD209, diminished production of IL-12p70, and depressed ability to stimulate T cells in mice after CLP as compared to SHAM or CONTR. In vitro defect in MO→iDC was accompanied by in vivo decrease of BDCA-3+ endogenous circulating DC. Interestingly, post-CLP MO had persistent activation of M-CSF pathway, shown by exaggerated secretion of M-CSF, activation of PU.1, and demethylation of SPII. Neutralization of the M-CSF in vitro reversed the post-CLP MO→iDC aberration. Furthermore, transplantation of naïve, autologous stem cell-derived MO restored CLP-deteriorated ability of MO to become DC, measured as recovery of CD1a expression, enhanced production of IL-12p70, and ability of IL-4 and GM-CSF MO to stimulate allogeneic T cells. Our results suggest the role of epigenetic mediated M-CSF aberration in mediating post-sepsis immune system recovery

The clinical and immunological performance of 28 days survival model of cecal ligation and puncture in humanized mice

<div><p>Sepsis triggers a coordinated and thorough immune system response with long-term unfavorable sequelae after the initial insult. Long-term recovery from sepsis has garnered increasing attention recently, but a lack of suitable animal models impairs progress in this area. Our study, therefore, aimed to address the performance of the immune system in a survivable model of sepsis (cecal ligation and sepsis; CLP) for up to 28 d after the initial injury in humanized mice. Our model mimics human sepsis with weight loss and post-sepsis hypothermia. Within the first 7 d of sepsis, the M1 inflammatory cell subtype predominated, as evidenced by increased CD16 expression, but at 28 d, a mixed population of M1 and M2 inflammatory cells emerged, as evidenced by increased secretion of transforming growth factor TGFβ and CD206 expression. This change was accompanied by normalized production of interleukin (IL)-6, tumor necrosis factor TNFα and IL-10 at 28 d. Furthermore, the ability of MO to become regulatory DC or the frequency of endogenous DC were severely affected at 28 days. Thus, sepsis results in profound and persistent changes in the function of myeloid cells up to 28 days after CLP demonstrating the persistence of the new acquired immunological features long after resolution of the sepsis.</p></div

Natural history of CLP in humanized mice.

<p>We observed a significant decrease in animal mortality (A). Most deaths occurred either shortly after surgery or two weeks after the initial insult. Animals who died prematurely exhibited a significant drop in temperature at 6 (p = 0.0043) and 18 h (p = 0012) after CLP, while survivors were able to regain their core temperatures, at least partially (C). Also, the drop in weight was more pronounced in animals dying prematurely (p = 0.025) (C). A strong correlation was observed between drop in temperature at six h and weight loss post-CLP (<i>r</i>^<i>2</i> = 0.37;p = 0.023) (D).</p

Flow cytometry in MO after CLP suggests an M1-to-M2 shift.

<p>Post-CLP, a late increase in expression of TGFβ/LAP (Mean Fluorescence Intensity (MFI); <i>p</i> = 0.047) and CD206 (<i>p</i> = 0.049) was seen. In contrast, expression of CD16 was increased only shortly after CLP MFI (<i>p</i> = 0.022) compared to pre-CLP expression levels.</p

Changes in temperature and weight as compare to the time before the surgery.

<p>Changes in temperature and weight as compare to the time before the surgery.</p

High Temperature CO₂‑in-Water Foams Stabilized with Cationic Quaternary Ammonium Surfactants

The design of surfactants for stabilizing CO₂-in-water (brine) (C/W) foams at high temperature is challenging given the low density (solvent strength) of CO₂, limited surfactant solubility in brine, and a lack of knowledge of the interfacial and rheological properties. Herein, the tail length of trimethylammonium cationic surfactants was optimized to provide the desired phase behavior and interfacial properties for formation and stabilization of the C/W foams. The headgroup was properly balanced with a C_12–14 hydrocarbon tail to achieve aqueous solubility in 22% total dissolved solids (TDS) brine up to 393 K (120 °C) along with high surfactant adsorption (area/surfactant molecule of 154 Ų) at the CO₂–water (C–W) interface which reduced the interfacial tension from ∼40 mN/m to ∼6 mN/m. For C_12–14N­(CH₃)₃Cl, these properties enabled stabilization of a C/W foam with an apparent viscosity of 14 mPa·s at 393 K in both a crushed calcium carbonate packed bed (75 μm² or 76 Darcy) and a capillary tube downstream of the bed. In addition, the partition coefficient of the surfactant between oil and 22% TDS (255 kg/m³) brine was less than 0.15, which would be beneficial for minimizing the loss of the surfactant to an oil phase in applications including enhanced oil recovery and hydraulic fracturing

CO₂‑in-Water Foam at Elevated Temperature and Salinity Stabilized with a Nonionic Surfactant with a High Degree of Ethoxylation

The utilization of nonionic surfactants for stabilization of CO₂ foams has been limited by low aqueous solubilities at elevated temperatures and salinities. In this work, a nonionic surfactant C_12–14(EO)₂₂ with a high degree of ethoxylation resulted in a high cloud point temperature of 83 °C even in 90 g/L NaCl brine. Despite the relatively high hydrophilic–CO₂-philic balance, the surfactant adsorption at the C–W interface lowered the interfacial tension to ∼7 mN/m at a CO₂ density of ∼0.85 g/mL, as determined with captive bubble tensiometry. The adsorption was sufficient to stabilize a CO₂-in-water (C/W) foam with an apparent viscosity of ∼7 cP at 80 °C, essentially up to the cloud point temperature, in the presence of 90 g/L NaCl brine in a 30 darcy sand pack. In a 1.2 darcy glass bead pack, the apparent viscosity of the foam in the presence of 0.8% total dissolved solids (TDS) brine reached the highest viscosity of ∼350 cP at 60% foam quality (volume percent CO₂) at a low superficial velocity of 6 ft/day. Shear-thinning behavior was observed in both the glass bead pack and the sand pack irrespective of the permeability difference. In addition, C_12–14(EO)₂₂ stabilized C/W foam with an apparent viscosity of 80–100 cP in a 49 mdarcy dolomite core formed through a coinjection and a surfactant-alternating-gas process. The dodecane–0.8% TDS brine partition coefficient for C_12–14(EO)₂₂ was below 0.1 at 40 °C and 1 atm. The formation of strong foam in the porous media and the low oil–brine partition coefficient indicate C_12–14(EO)₂₂ has potential for CO₂-enhanced oil recovery

Supramolecular arrangement of protein in nanoparticle structures predicts nanoparticle tropism for neutrophils in acute lung inflammation

Myerson JW, Patel PN, Rubey KM, et al. Supramolecular arrangement of protein in nanoparticle structures predicts nanoparticle tropism for neutrophils in acute lung inflammation. Nature Nanotechnology. 2022;17(1):86-97.This study shows that the supramolecular arrangement of proteins in nanoparticle structures predicts nanoparticle accumulation in neutrophils in acute lung inflammation (ALI). We observed homing to inflamed lungs for a variety of nanoparticles with agglutinated protein (NAPs), defined by arrangement of protein in or on the nanoparticles via hydrophobic interactions, crosslinking and electrostatic interactions. Nanoparticles with symmetric protein arrangement (for example, viral capsids) had no selectivity for inflamed lungs. Flow cytometry and immunohistochemistry showed NAPs have tropism for pulmonary neutrophils. Protein-conjugated liposomes were engineered to recapitulate NAP tropism for pulmonary neutrophils. NAP uptake in neutrophils was shown to depend on complement opsonization. We demonstrate diagnostic imaging of ALI with NAPs; show NAP tropism for inflamed human donor lungs; and show that NAPs can remediate pulmonary oedema in ALI. This work demonstrates that structure-dependent tropism for neutrophils drives NAPs to inflamed lungs and shows NAPs can detect and treat ALI