Water mobility and microstructure evolution in the germinating Medicago truncatula seed studied by NMR relaxometry. A revisited interpretation of multicomponent relaxation

The water status of Medicago truncatula Gaertn. seed was followed by low-field NMR relaxometry during germination with and without oryzalin or fusicoccin used as growth modulators. T1 and T2 relaxation times and proportions P1 and P2 were determined on fresh, frozen, and freeze-thawed samples to characterize changes in water dynamics and compartmentation and in the nonfreezing water fraction. The results demonstrate that low-field NMR relaxometry allowed differentiating germination phases and events occurring during them as well as perturbations related to the presence of growth modulators. The results provide clear evidence that the classical multicomponent relaxation interpretation cannot directly relate T2 components and morphological compartments in biological tissue

J Virol

In this placebo-controlled phase II randomized clinical trial, 103 HIV-1 infected patients under c-ART (combined antiretroviral treatment) were randomized 2:1 to receive 3 doses of DNA GTU-MultiHIV B (coding for Rev, Nef, Tat, Gag and gp160) at Week (W)0, W4 and W12 followed by 2 doses of LIPO-5 vaccine containing long peptides from Gag, Pol and Nef at W20 and W24 or placebos. Analytical treatment interruption (ATI) was performed between W36 to W48.At W28, vaccinees experienced an increase in functional CD4(+) T cell responses measured (P\textbackslashtextless0.001 for each cytokine compared to W0) predominantly against Gag and Pol/Env and an increase in HIV-specific CD8(+) T cells producing IL-2 and TNF-α (P=0.001 and 0.013, respectively), predominantly against Pol/Env and Nef. However, analysis of T cell subsets by mass cytometry in a subpopulation showed an increase of W28/W0 ratio for memory CD8(+) T cells co-expressing exhaustion and senescence markers such as PD-1/TIGIT (P=0.004) and CD27/CD57 (P=0.044) in vaccinees compared to placebo. During ATI, all patients experienced viral rebound with a maximum observed HIV RNA level at W42 (median: 4.63 log(10) cp/ml; IQR 4.00-5.09) without any difference between arms. No patient resumed c-ART for CD4 cell count drop. Globally, the vaccine strategy was safe. However, a secondary HIV transmission during ATI was observed.These data show that the prime-boost combination of DNA and LIPO-5 vaccines elicited broad and polyfunctional T cells. The contrast between the quality of immune responses and the lack of potent viral control underscores the need of combined immunomodulatory strategies.IMPORTANCE In this placebo-controlled phase II randomized clinical trial, we evaluated the safety and immunogenicity of a therapeutic prime-boost vaccine strategy using a recombinant DNA vaccine (GTU®-MultiHIV B clade) followed by a boost vaccination by a lipopeptide vaccine (HIV-LIPO-5) in HIV-infected patients while on combined antiretroviral therapy. We show that this prime-boost strategy is well tolerated, consistently with previous studies in HIV-1 infected individuals and healthy volunteers who received each vaccine component individually. Compared to placebo group, vaccines elicited strong and polyfunctional HIV-specific CD4(+) and CD8(+) T cell responses. However, these immune responses presenting some qualitative defects were not able to control viremia following antiretroviral treatment interruption as no difference in HIV viral rebound was observed in vaccine and placebo groups. Several lessons were learned from these results pointing out the urgent need to combine the vaccine strategies with other immune-based interventions

J Clin Immunol

We report a longitudinal analysis of the immune response associated with a fatal case of COVID-19 in Europe. This patient exhibited a rapid evolution towards multiorgan failure. SARS-CoV-2 was detected in multiple nasopharyngeal, blood, and pleural samples, despite antiviral and immunomodulator treatment. Clinical evolution in the blood was marked by an increase (2–3-fold) in differentiated effector T cells expressing exhaustion (PD-1) and senescence (CD57) markers, an expansion of antibody-secreting cells, a 15-fold increase in γδ T cell and proliferating NK-cell populations, and the total disappearance of monocytes, suggesting lung trafficking. In the serum, waves of a pro-inflammatory cytokine storm, Th1 and Th2 activation, and markers of T cell exhaustion, apoptosis, cell cytotoxicity, and endothelial activation were observed until the fatal outcome. This case underscores the need for well-designed studies to investigate complementary approaches to control viral replication, the source of the hyperinflammatory status, and immunomodulation to target the pathophysiological response. The investigation was conducted as part of an overall French clinical cohort assessing patients with COVID-19 and registered in clinicaltrials.gov under the following number: NCT04262921

[Natural polymers according to NMR data: cross-relaxation in hydrated collagen macromolecules from two connective tissues].

Spin-lattice relaxation and cross-relaxation in oriented and randomly oriented collagen fibers from two connective tissues (15-month-old calf and 8-year-old steer) at a water content of 0.6 g H2O/g dry matter were studied. Collagens were chosen according to different numbers of covalent nonreducible cross-links, which increase during the life of the animal. The spin-lattice relaxation curves for all the collagens after a 180 degree-tau-90 degree pulse sequence were described by two exponential components. The dependences of two components of spin lattice relaxation time and their populations on the length of the 180 degree-pulse were obtained. On the basis of data of Goldman-Shen sequence and the two-phase model, the populations of proton fractions (p(w) and p(c)) as well as the rates of transfer of magnetization between water protons and collagen protons (k(w) and k(c)) were calculated. No significant difference between k(w) (k(c)) in oriented and randomly oriented fibers as well as in fibers with different cross-linking was found. The estimates of the cross-relaxation times for low cross-link collagen and high cross-link one were done. The correlation times of dipole-dipole interactions for both connective tissues were calculated using the cross-relaxation theory

[Natural polymers according to NMR data: cross-relaxation in hydrated collagen macromolecules from two connective tissues].

Spin-lattice relaxation and cross-relaxation in oriented and randomly oriented collagen fibers from two connective tissues (15-month-old calf and 8-year-old steer) at a water content of 0.6 g H2O/g dry matter were studied. Collagens were chosen according to different numbers of covalent nonreducible cross-links, which increase during the life of the animal. The spin-lattice relaxation curves for all the collagens after a 180 degree-tau-90 degree pulse sequence were described by two exponential components. The dependences of two components of spin lattice relaxation time and their populations on the length of the 180 degree-pulse were obtained. On the basis of data of Goldman-Shen sequence and the two-phase model, the populations of proton fractions (p(w) and p(c)) as well as the rates of transfer of magnetization between water protons and collagen protons (k(w) and k(c)) were calculated. No significant difference between k(w) (k(c)) in oriented and randomly oriented fibers as well as in fibers with different cross-linking was found. The estimates of the cross-relaxation times for low cross-link collagen and high cross-link one were done. The correlation times of dipole-dipole interactions for both connective tissues were calculated using the cross-relaxation theory

Study of collagen using liquid and solid

This work describes the applications of high resolution 13C liquid and solid Nuclear Magnetic Resonance (NMR) to the study of collagen with various degrees of cross-linking. The 13C solid NMR spectra, after treatement by the Maximum Entropy Method, and the relaxation times T1 measurements allow us to emphasize cross-links differences between theses native, dry and insoluble fibrillar proteins