Mucins MUC5AC and MUC5B Are Variably Packaged in the Same and in Separate Secretory Granules

Rationale: MUC5AC (mucin 5AC, oligomeric gel-forming) and MUC5B (mucin 5B, oligomeric gel-forming) are the predominant secreted polymeric mucins in mammalian airways. They contribute differently to the pathogenesis of various muco-obstructive and interstitial lung diseases, and their genes are separately regulated, but whether they are packaged together or in separate secretory granules is not known. Objectives: To determine the packaging of MUC5AC and MUC5B within individual secretory granules in mouse and human airways under varying conditions of inflammation and along the proximal-distal axis. Methods: Lung tissue was obtained from mice stimulated to upregulate mucin production by the cytokines IL-1β and IL-13 or by porcine pancreatic elastase. Human lung tissue was obtained from donated normal lungs, biopsy samples of transplanted lungs, and explanted lungs from subjects with chronic obstructive pulmonary disease. MUC5AC and MUC5B were labeled with antibodies from different animal species or, in mice only, by transgenic chimeric mucin-fluorescent proteins and imaged using widefield deconvolution or Airyscan fluorescence microscopy. Measurements and Main Results: In both mouse and human airways, most secretory granules contained both mucins interdigitating within the granules. Smaller numbers of granules contained MUC5B alone, and even fewer contained MUC5AC alone. Conclusions: MUC5AC and MUC5B are variably stored both in the same and in separate secretory granules of both mice and humans. The high fraction of granules containing both mucins under a variety of conditions makes it unlikely that their secretion can be differentially controlled as a therapeutic strategy. This work also advances knowledge of the packaging of mucins within secretory granules to understand mechanisms of epithelial stress in the pathogenesis of chronic lung diseases.

Intermediary Role of Lung Alveolar Type 1 Cells in Epithelial Repair upon Sendai Virus Infection

The lung epithelium forms the first barrier against respiratory pathogens and noxious chemicals; however, little is known about how more than 90% of this barrier, made of AT1 (alveolar type 1) cells, responds to injury. Using the Sendai virus to model natural infection in mice, we find evidence that AT1 cells have an intermediary role by persisting in areas depleted of AT2 cells, upregulating IFN responsive genes, and receding from invading airway cells. Sendai virus infection mobilizes airway cells to form alveolar SOX2⁺ (Sry-box 2⁺) clusters without differentiating into AT1 or AT2 cells. Large AT2 cell-depleted areas remain covered by AT1 cells, which we name "AT2-less regions", and are replaced by SOX2⁺ clusters spreading both basally and luminally. AT2 cell proliferation and differentiation are largely confined to topologically distal regions and form de novo alveolar surface, with limited contribution to in situ repairs of AT2-less regions. Time-course single-cell RNA sequencing profiling and RNAscope validation suggest enhanced immune responses and altered growth signals in AT1 cells. Our comprehensive spatiotemporal and genomewide study highlights the hitherto unappreciated role of AT1 cells in lung injury-repair.

Immune Modulation to Improve Survival of Viral Pneumonia in Mice

Viral pneumonias remain global health threats, as exemplified in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, requiring novel treatment strategies both early and late in the disease process. We have reported that mice treated before or soon after infection with a combination of inhaled Toll-like receptor (TLR) 2/6 and 9 agonists (Pam2-ODN) are broadly protected against microbial pathogens including respiratory viruses, but the mechanisms remain incompletely understood. The objective of this study was to validate strategies for immune modulation in a preclinical model of viral pneumonia and determine their mechanisms. Mice were challenged with the Sendai paramyxovirus in the presence or absence of Pam2-ODN treatment. Virus burden and host immune responses were assessed to elucidate Pam2-ODN mechanisms of action and to identify additional opportunities for therapeutic intervention. Enhanced survival of Sendai virus pneumonia with Pam2-ODN treatment was associated with reductions in lung virus burden and with virus inactivation before internalization. We noted that mortality in sham-treated mice corresponded with CD8+ T-cell lung inflammation on days 11-12 after virus challenge, after the viral burden had declined. Pam2-ODN blocked this injurious inflammation by minimizing virus burden. As an alternative intervention, depleting CD8+ T cells 8 days after viral challenge also decreased mortality. Stimulation of local innate immunity within the lungs by TLR agonists early in disease or suppression of adaptive immunity by systemic CD8+ T-cell depletion late in disease improves outcomes of viral pneumonia in mice. These data reveal opportunities for targeted immunomodulation to protect susceptible human subjects.

Inducible epithelial resistance against acute Sendai virus infection prevents chronic asthma-like lung disease in mice

BACKGROUND AND PURPOSE

Respiratory viral infections play central roles in the initiation, exacerbation and progression of asthma in humans. An acute paramyxoviral infection in mice can cause a chronic lung disease that resembles human asthma. We sought to determine whether reduction of Sendai virus lung burden in mice by stimulating innate immunity with aerosolized Toll-like receptor (TLR) agonists could attenuate the severity of chronic asthma-like lung disease.

EXPERIMENTAL APPROACH

Mice were treated by aerosol with 1-μM oligodeoxynucleotide (ODN) M362, an agonist of the TLR9 homodimer, and 4-μM Pam2CSK4 (Pam2), an agonist of the TLR2/6 heterodimer, within a few days before or after Sendai virus challenge.

KEY RESULTS

Treatment with ODN/Pam2 caused ~75% reduction in lung Sendai virus burden 5 days after challenge. The reduction in acute lung virus burden was associated with marked reductions 49 days after viral challenge in eosinophilic and lymphocytic lung inflammation, airway mucous metaplasia, lumenal mucus occlusion and hyperresponsiveness to methacholine. Mechanistically, ODN/Pam2 treatment attenuated the chronic asthma phenotype by suppressing IL-33 production by type 2 pneumocytes, both by reducing the severity of acute infection and by down-regulating Type 2 (allergic) inflammation.

CONCLUSION AND IMPLICATIONS

These data suggest that treatment of susceptible human hosts with aerosolized ODN and Pam2 at the time of a respiratory viral infection might attenuate the severity of the acute infection and reduce initiation, exacerbation and progression of asthma.

Inducible epithelial resistance protects against acute viral infection and subsequent CD8+Tcell dependent lethal Immunopathology

Viral pneumonia leads to significant morbidity and mortality worldwide, demanding better understanding of the host immune response to infections for development of novel strategies to prevent respiratory infections. Our group has shown that mice treated with combination of Toll-like receptor (TLR) 2/6 and 9 agonists (Pam2-ODN) are protected against wide range of respiratory pathogens, including viruses. Mice challenged intra-pharyngeally with Sendai virus showed peak viral burden on day 5 and peak mortality on day 11, overlapping with increased lung CD8+Tcells. We hypothesized that mortality is associated with immunopathology caused by CD8+T cells. Pam2-ODN aerosolization one day prior to Sendai challenge reduced lung viral burden and reduced lung CD8+T cells on day 11 and enhanced mouse survival. Depletion of CD8+T cells before infection increased baseline virus susceptibility and enhanced viral replication in vivo, congruent with the known antiviral function of CD8+T cells. Pam2-ODN pre-treatment protected mice against death following viral challenge, even in the absence of CD8+T cells, reflecting antiviral responses induced directly from epithelial cells. Notably, depletion of CD8+T cells eight days after viral challenge also significantly enhanced survival of sham pre-treated mice, indicating rescue from CD8+T cell-mediated lethal immunopathology. Our findings definitively prove that CD8+T cells, although anti-viral in nature, promote lethal immunopathology that can be prevented by Pam2-ODN pre-treatment. Importantly, Pam2-ODN pre-treatment benefitted survival regardless of when CD8+T cells were depleted and may provide an opportunity to protect vulnerable populations against respiratory infections.

Toll-like receptor signalling protects against IL-33 led virus-induced asthmatic response in a Type I Interferon independent manner

Respiratory viruses are frequent causes of asthma development and exacerbations. However, there are gaps in understanding how viral infections cause immuno-pathology in the host leading to asthma progression. We have previously shown that mice treated with a combination of Toll-like receptor (TLR) 2/6 and 9 agonists (Pam2-ODN) are protected against broad range of respiratory infections induced by viruses, fungi and bacteria. Pam2-ODN treatment one day prior to virus infection leads to enhanced survival with reduced lung viral burden in mice. Further, Pam2-ODN pretreatment also inhibits acute lung pathology caused by CD8+ T cells and prevents chronic asthmatic phenotype of eosinophilia, airway hyperreactivity and mucus metaplasia. This protective effect was accompanied by reduced virus-driven lung IL-33, which is necessary to induce chronic asthmatic phenotype. Interestingly, Pam2-ODN does not induce increased production of Type I or III Interferons (IFN), nor does the protective response require intact interferon signaling. Transcriptome profiling of the mouse lungs in the chronic phase of infection led to identification of genes involved in airway remodelling, epithelial cell differentiation and chemokine signalling. More importantly, we identified genes from the Pam2-ODN treatment group that are involved in reversing the viral infection effect on day 49. Taken together, our findings reveal novel type I IFN independent mechanisms to prevent virus-induced asthma, and may provide an opportunity to protect vulnerable populations.

Platelet Munc13-4 regulates hemostasis, thrombosis and airway inflammation

Platelet degranulation is crucial for hemostasis and may participate in inflammation. Exocytosis in platelets is mediated by SNARE proteins and should be controlled by Munc13 proteins. We found that platelets express Munc13-2 and -4. We assessed platelet granule exocytosis in Munc13-2 and -4 global and conditional knockout (KO) mice, and observed that deletion of Munc13-4 ablates dense granule release and indirectly impairs alpha granule exocytosis. We found no exocytic role for Munc13-2 in platelets, not even in the absence of Munc13-4. In vitro, Munc13-4-deficient platelets exhibited defective aggregation at low doses of collagen. In a flow chamber assay, we observed that Munc13-4 acted as a rate-limiting factor in the formation of thrombi. In vivo, we observed a dose-dependency between Munc13-4 expression in platelets and both venous bleeding time and time to arterial thrombosis. Finally, in a model of allergic airway inflammation, we found that platelet-specific Munc13-4 KO mice had a reduction in airway hyper-responsiveness and eosinophilic inflammation. Taken together, our results indicate that Munc13-4-dependent platelet dense granule release plays essential roles in hemostasis, thrombosis and allergic inflammation.

On the (N, Z) dependence of the second-order Møller-Plesset correlation energies for closed-shell atomic systems

Accurate Møller-Plesset (MP2) correlation energies calculated by means of the variational-perturbation and the finite-element methods are presented for several members of the Cu(+) isoelectronic series (N = 28), which represent closed-shell systems containing for the first time the 3d(10)-electron configuration and, consequently, closed M-shell. Total MP2 energies as well as their inner- and inter-shell components are reported for Cu(+), Zn(2+), Ge(4+), Kr(8+), Sr(10+), and Cd(20+). We found that for these ions the Z-dependence of the total MP2 energies is significantly weaker than for the members of the Ar-like series. The origin of this fact is rationalized by a detailed analysis performed at the levels of the shell- and inter-shell contributions to the MP2 energies. To get, for the first time, more general information about the (N, Z) characteristics of the MP2 energies for closed-shell atomic systems, we compare the Z-dependence of the Cu(+)-like systems with the MP2 energies calculated for other isoelectronic series. The weak Z-dependence is found for the He-, Ne-, and Cu(+)-like series, which consist of atoms having perfectly closed-shell K-, KL-, and KLM-electronic structures, respectively. In turn, for the Be-, Mg-, and Ar-series, the Z-dependence is considerably stronger.

The dynamics of the C + PH3 reaction: a theoretical study

The C + PH(3) reaction is one of the simplest gas-phase processes which can produce molecular species containing P-C bonds. It could be of astrophysical importance and a reference for other phosphine reactions with carbon-containing molecular radicals. The dynamical aspects have been studied theoretically by quasi-classical trajectory methods in order to determine its rate as a function of the temperature, the branching ratios, and the molecular mechanisms. We have obtained a T(0.2) dependence of the capture rate. The total rate is affected by the existence of relatively high-lying saddle points for the isomerization of the CPH(3) complex but get a value of 0.82·10(-10) cm(3) s(-1) at 300 K, which is considered quite high for a neutral-neutral reaction and higher than those of similar reactions. Moreover, the total rate presents a weak dependence with the temperature. Our results indicate that several products containing P-C bonds are formed, the main reaction channel being the generation of HPCH + H.

Towards benchmark second-order correlation energies for large atoms. II. Angular extrapolation problems

We have studied the use of the asymptotic expansions (AEs) for the angular momentum extrapolation (to l --> infinity) of atomic second-order Moller-Plesset (MP2) correlation energies of symmetry-adapted pairs (SAPs). The AEs have been defined in terms of partial wave (PW) increments to the SAP correlation energies obtained with the finite element MP2 method (FEM-MP2), as well as with the variational perturbation method in a Slater-type orbital basis. The method employed to obtain AEs from PW increments is general in the sense that it can be applied to methods other than MP2 and, if modified, to molecular systems. Optimal AEs have been determined for all types of SAPs possible in large atoms using very accurate FEM PW increments up to lmax = 45. The impact of the error of the PW increments on the coefficients of the AEs is computed and taken into account in our procedure. The first AE coefficient is determined to a very high accuracy, whereas the second involves much larger errors. The optimum l values (lopt) for starting the extrapolation procedures are determined and their properties, interesting from the practical point of view, are discussed. It is found that the values of the first AE coefficients obey expressions of the type derived by Kutzelnigg and Morgan [J. Chem. Phys. 96, 4484 (1992); 97, 8821(E) (1992)] for He-type systems in the bare-nucleus case provided they are modified by fractional factors in the case of triplet and unnatural singlet SAPs. These expressions give extremely accurate values for the first AE coefficient both for the STO and the FEM Hartree-Fock orbitals. We have compared the performance of our angular momentum extrapolations with those of some of the principal expansion extrapolations performed with correlation consistent basis sets employed in the literature and indicated the main sources of inaccuracy.

Towards benchmark second-order correlation energies for large atoms: Zn[sup 2+] revisited

To provide very accurate reference results for the second-order Møller-Plesset (MP2) energy and its various components for Zn(2+), which plays for 3d-electron systems a similar role as Ne for smaller atoms and molecules, we have performed extensive calculation by two completely different implementations of the MP2 method: the finite element method (FEM) and the variation-perturbation (VP) method. The FEM and VP calculations yield partial wave contributions up to l(max)=45 and 12, respectively. Detailed comparison of all FEM and VP energy components for l(max)=12 has disclosed an extraordinary similarity, which justifies using the present results as benchmarks. The present correlation energies are compared with other works. The dependability of an earlier version of FEM, already applied to very large closed-shell atoms, is confirmed. It has been found that for larger atoms the accuracy of the analytical Hartree-Fock results has an impact on the accuracy of the MP2 energies greater than for smaller atoms. Fields of applications of the present results in studies of various electron correlation effects in 3d-electron atoms and molecules are indicated.

Design of gradient-index microlenses for stacked planar optics

The refractive-index profiles of planar matrix microlenses that result from the Luneburg lens theory turn out to yield considerable aberrations. The presented modification of the design process enables satisfactory suppression of the focusing errors.

New method for designing the stigmatically imaging gradient-index lenses of spherical symmetry

The general solution presented here yields smooth, continuous, and monotonic refractive-index profiles for Luneburg-Morgan lenses with a boundary index of N > 1. The new formula incorporates an original apparent-immersing method as well as the continuous-deflection-function concept recently developed by one of the authors for the description of waveguide lenses.

Quasi-analytical ray tracing through the generalized Luneburg lens

A new method of ray tracing through an inhomogeneous lens with radial symmetry of the refractive-index distribution is proposed that consists of a parametric determination of the polar coordinates of the current ray position.

Liquid feed passage route into stomach compartments, influence of abomasal infusions on plasma glucose, and supplementation of dry rations with liquid feeds from lick-wheel feeders

Passage route into stomach compartments of liquid feeds containing a marker was studied by feeding a liquid supplement and molasses from a lick-wheel feeder and by infusing the liquid supplement into the reticulorumen 30 min prior to sampling contents of the reticulorumen and abomasum and 4 h prior to sampling blood for plasma glucose. Recovery from reticulorumen and concentration of marker in abomasal ingesta gave no evidence of rumen bypass, this supported by a gross correlation of .92 between rumen ammonia nitrogen and nonprotein nitrogen intake from liquid feeds. Plasma glucose values were not different. Preinfusion and postinfusion plasma glucose values were similar for abomasal infusion of about 454 g of molasses, 20% crude protein liquid supplement, and for the basal diet. Values were lower for abomasal infusion of the 35% crude protein liquid supplement (Pro-Lix) than for the 20% crude protein liquid supplement. When complete rations containing 11.5, 13.0, and 14.5% crude protein were supplemented with either molasses or a 20% crude protein liquid supplement fed from lick-wheel feeders, intake averaged .53 and .34 kg per animal daily for the respective liquid feeds. There was no effect on milk yield, solids-corrected milk, milk fat content, protein content, solids-not-fat percent, or body weight change. There was an interaction of protein level and liquid feeds in which plasma glucose was increased by liquid feeds in higher but not in lower protein diets.