Removal of natural anti-αGal antibodies elicits protective immunity against Gram-negative bacterial infections

Antibody-dependent enhancement (ADE) of bacterial infections occurs when blocking or inhibitory antibodies facilitate the infectivity of pathogens. In humans, antibodies involved in ADE of bacterial infections may include those naturally produced against Galα1-3Galβ1-4GlcNAcβ (αGal). Here, we investigate whether eliminating circulating anti-αGal antibodies using a soluble αGal glycopolymer confers protection against Gram-negative bacterial infections. We demonstrated that the in vivo intra-corporeal removal of anti-αGal antibodies in α1,3-galactosyltransferase knockout (GalT-KO) mice was associated with protection against mortality from Gram-negative sepsis after cecal ligation and puncture (CLP). The improved survival of GalT-KO mice was associated with an increased killing capacity of serum against Escherichia coli isolated after CLP and reduced binding of IgG1 and IgG3 to the bacteria. Additionally, inhibition of anti-αGal antibodies from human serum in vitro increases the bactericidal killing of E. coli O86:B7 and multidrug-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa. In the case of E. coli O86:B7, there was also an improvement in bacteria opsonophagocytosis by macrophages. Both lytic mechanisms were related to a decreased binding of IgG2 to the bacteria. Our results show that protective immunity against Gram-negative bacterial pathogens can be elicited, and infectious diseases caused by these bacteria can be prevented by removing natural anti-αGal antibodies.

Did anomalous atmospheric circulation favor the spread of COVID-19 in Europe?

The current pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is having negative health, social and economic consequences worldwide. In Europe, the pandemic started to develop strongly at the end of February and beginning of March 2020. Subsequently, it spread over the continent, with special virulence in northern Italy and inland Spain. In this study we show that an unusual persistent anticyclonic situation prevailing in southwestern Europe during February 2020 (i.e. anomalously strong positive phase of the North Atlantic and Arctic Oscillations) could have resulted in favorable conditions, e.g., in terms of air temperature and humidity among other factors, in Italy and Spain for a quicker spread of the virus compared with the rest of the European countries. It seems plausible that the strong atmospheric stability and associated dry conditions that dominated in these regions may have favored the virus propagation, both outdoors and especially indoors, by short-range droplet and aerosol (airborne) transmission, or/and by changing social contact patterns. Later recent atmospheric circulation conditions in Europe (July 2020) and the U.S. (October 2020) seem to support our hypothesis, although further research is needed in order to evaluate other confounding variables. Interestingly, the atmospheric conditions during the Spanish flu pandemic in 1918 seem to have resembled at some stage with the current COVID-19 pandemic.

Did anomalous atmospheric circulation favor the spread of COVID-19 in Europe?

The current pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is having negative health, social and economic consequences worldwide. In Europe, the pandemic started to develop strongly at the end of February and beginning of March 2020. Subsequently, it spread over the continent, with special virulence in northern Italy and inland Spain. In this study we show that an unusual persistent anticyclonic situation prevailing in southwestern Europe during February 2020 (i.e. anomalously strong positive phase of the North Atlantic and Arctic Oscillations) could have resulted in favorable conditions, e.g., in terms of air temperature and humidity among other factors, in Italy and Spain for a quicker spread of the virus compared with the rest of the European countries. It seems plausible that the strong atmospheric stability and associated dry conditions that dominated in these regions may have favored the virus propagation, both outdoors and especially indoors, by short-range droplet and aerosol (airborne) transmission, or/and by changing social contact patterns. Later recent atmospheric circulation conditions in Europe (July 2020) and the U.S. (October 2020) seem to support our hypothesis, although further research is needed in order to evaluate other confounding variables. Interestingly, the atmospheric conditions during the Spanish flu pandemic in 1918 seem to have resembled at some stage with the current COVID-19 pandemic.

Molecular markers of putative spermatogonial stem cells in the domestic cat

Spermatogonial stem cells (SSCs) are an important tool for fertility preservation and species conservation. The ability to expand SSCs by in vitro culture is a crucial premise for their use in assisted reproduction. Because SSCs represent a small proportion of the germ cells in the adult testis, culture success is aided by pre-enrichment through sorting techniques based on cell surface-specific markers. Given the importance of the domestic cat as a model for conservation of endangered wild felids, herein we sought to examine culture conditions as well as molecular markers for cat SSCs. Using a cell culture medium for mouse SSCs supplemented with glial cell-derived neurotrophic factor (GDNF), germ cells from prepuberal cat testes remained viable in culture for up to 43 days. Immunohistochemistry for promyelocytic leukaemia zinc finger (PLZF) protein on foetal, prepuberal and adult testis sections revealed a pattern of expression consistent with the labelling of undifferentiated spermatogonia. Fluorescence-activated cell sorting (FACS) with an antibody against epithelial cell adhesion molecule (EPCAM) was used to sort live cells. Then, the gene expression profile of EPCAM-sorted cells was investigated through RT-qPCR. Notably, EPCAM (+) cells expressed relatively high levels of CKIT (CD117), a surface protein typically expressed in differentiating germ cells but not SSCs. Conversely, EPCAM (-) cells expressed relatively high levels of POU domain class 5 transcription factor 1 (POU1F5 or OCT4), clearly a germ line stem cell marker. These results suggest that cat SSCs would probably be found within the population of EPCAM (-) cells. Future studies should identify additional surface markers that alone or in combination can be used to further enrich SSCs from cat germ cells.

Risk of tuberculosis after lung transplantation: the value of pretransplant chest computed tomography and the impact of mTOR inhibitors and azathioprine use

BACKGROUND

It is necessary to determine the incidence and risk factors for tuberculosis (TB), as well as strategies to assess and treat latent tuberculosis infection (LTBI) in lung transplant recipients.

METHODS

A retrospective cohort study of 398 lung transplant recipients was performed. Episodes of TB were studied and the incidence rate was calculated. Logistic regression analysis was used to analyze specific variables as potential risk factors for TB.

RESULTS

Median follow-up was 558 days (range 1-6636). Six cases (1.5%) of TB were documented in 398 transplant patients. The incidence density of TB was 406.3 cases/10(5) patient-years (95% confidence interval [CI] 164.7-845), which is higher than in the general population (13.10 cases/10(5) person-years). All cases occurred in the period 1993-2006, when the tuberculin skin test (TST) and treatment of LTBI in positive TST patients were not part of the protocol. Pretransplant computed tomography (CT) showed residual lesions in 50% of patients who developed TB, although the TST was negative and the chest radiograph was inconclusive. Multivariate analysis identified the presence of residual lesions in the pretransplant chest CT (odds ratio [OR] 11.5, 95% CI 1.9-69.1, P = 0.008), use of azathioprine (OR 10.6, 95% CI 1.1-99.1, P = 0.038), and use of everolimus (OR 6.7, 95% CI 1.1-39.8, P = 0.036) as independent risk factors for TB.

CONCLUSIONS

Residual lesions in the pretransplant chest CTs and the use of azathioprine and mTOR inhibitors are associated with the risk of TB.

Factors related to the development of CMV-specific CD8+ T cell response in CMV-seropositive solid organ transplant candidates

This cross-sectional study analyzes factors associated with the development of CMV-specific CD8+ response, measured by IFNg production after cytomegalovirus (CMV) peptide stimulation, in CMV-seropositive solid organ transplantation candidates. A total of 114 candidates were enrolled, of whom 22.8% (26/114) were nonreactive (IFNγ < 0.2 IU/mL). Multivariate logistic regression analysis showed that age, HLA alleles and organ to be transplanted were associated with developing CMV-specific CD8+ immunity (reactive; IFNγ ≥ 0.2 IU/mL). The probability of being reactive was higher in candidates over 50 than in those under 50 (OR 6.33, 95%CI 1.93-20.74). Candidates with HLA-A1 and/or HLA-A2 alleles had a higher probability of being reactive than those with non-HLA-A1/non-HLA-A2 alleles (OR 10.97, 95%CI 3.36-35.83). Renal candidates had a higher probability of being reactive than lung (adjusted OR 8.85, 95%CI 2.24-34.92) and liver candidates (OR 4.87, 95%CI 1.12-21.19). The AUC of this model was 0.84 (p < 0.001). Positive and negative predictive values were 84.8% and 76.9%, respectively. In renal candidates longer dialysis was associated with an increased frequency of reactive individuals (p = 0.040). Therefore, although the assessment of CMV-specific CD8+ response is recommended in all R+ candidates, it is essential in those with a lower probability of being reactive, such as non-renal candidates, candidates under 50 or those with non-HLA-A1/non-HLA-A2 alleles.

Experience of the Reina Sofia hospital in lobar lung transplantation

The number of patients awaiting lung transplantation has steadily increased over the past decade, but the number of donors has remained relatively stable. Owing to the increasing scarcity of donor lungs, especially for pediatric and small adult recipients, advanced operative strategies for the use of larger grafts for smaller recipients have been developed. Size matching between donors and recipients represents one of the organ distribution criteria widely accepted by lung transplantation teams. However, in some cases it is not possible to allocate a donor to the corresponding size-compatible recipient. To avoid possible complications derived from the implantation of oversized lungs into smaller recipients, various methods of downsizing are applied for cadaveric donor lungs, such as lobar transplantation. We review our experience in 6 patients undergoing volume reduction of the lung graft by lobar resection at the time of transplantation. Graft volume reduction by anatomic resection (lobar transplantation) is a reliable and safe procedure to overcome size disparities between the donor and the recipient of a lung transplant, and thus to maximize the number of donors.

Results of lung transplantation in idiopathic pulmonary fibrosis patients

Lung transplantation (OLT) remains the only available therapy for patients with end-stage idiopathic pulmonary fibrosis (IPF). The objective of this study was to review our experience of OLT for end-stage IPF (IPFLT) patients, seeking to identify variables associated with survival for comparison with outcomes of other indications for LT (OILT). From October 1993 to December 2009, we performed 310 consecutive OLT in 301 patients for treatment of various end-stage pulmonary conditions. The indications for OLT were: IPF (n=89, 30.5%) chronic obstructive pulmonary disease (n=82), cystic fibrosis (n=80), bronchiectasis (n=12), alfa-1-antitrypsin deficit (n=6), primary pulmonary hypertension (n=4), bronchiolitis obliterans (n=4), other conditions (n=15). We observed significant differences in the actuarial survival between the IPFLT and the OILT groups particularly at the expense of worse perioperative 30-day and early 1-year mortality in the IPFLT group. Upon univariate and multivariate analyses, the need for cardiopulmonary bypass, previous recipient ventilator dependence, and donor age>50 years were all associated with poorer survival rates among IPF patients. In our experience, survival did not differ between patients who underwent a single versus a bilateral sequential lung transplant (BSLT); however, BSLT cases were associated with short-term damage but long-term survival. The functional results in the IPFLT group were excellent. We observed significant improvements in the values of arterial oxygen pressure (PaO2), arterial carbon dioxide pressure (PaCO2), forced vital capacity (FVC%) and forced expiratory volume in 1 second (FEV1%) at 6, 12, and 36 months compared to their pretransplant baseline results.

[Utility of 3D computed tomography for the surgical planning of pelvic fractures]

BACKGROUND

To determine the utility of 3D computed tomography for the preoperative planning of pelvic rim fractures assessing possible changes in fracture classification as well as in the surgical indication itself.

METHODS

We retrospectively reviewed patients who had undergone surgery for complex pelvic fractures during a 15-month period. The mechanism of injury was recorded and the availability of a multi-slice spiral volumetric CT scan was requested as a preoperative study.

RESULTS

Ten cases (58%) were pelvic rim fractures and 7 were acetabular fractures. The mean ISS was 23.82 (9-50), and 82.3% of cases were severe traumas (ISS > 16). After the CT scan was obtained, the initial classification of the fracture was changed in four cases (23.5%), without any changes in the surgical indication. An artifact was detected in the volumetric reconstruction but it did not limit the surgeon's interpretation.

CONCLUSION

Tridimensional CT-based modeling is very helpful in the surgical planning of pelvic fractures and is a complement of the plain X-rays.

[Tumor necrosis factor as a biomarker of infection in total knee arthroplasty]

BACKGROUND

Thanks to defense mechanisms, organisms have had to adapt themselves to an adverse natural setting that causes acute and chronic stress. This adaptive response that tries to protect the cells against lethal insults uses its own defense systems.

MATERIAL AND METHODS

Prospective, observational, descriptive pilot study with analytic components to determine the baseline preoperative TNF levels of 35 patients undergoing total knee arthroplasty due to gonarthrosis. Ten patients with a diagnosis of infected total knee arthroplasty were also included. In order to find differences and possible associations, the Mann-Whitney U test or the Fisher test was used to compare the variables between the non-infected group of patients and the group with the infection complication.

RESULTS

We found a statistically significant difference; higher levels of fibrinogen, erythrocyte sedimentation rate, C-reactive protein, TNF-alpha and temperature were found in the infected patients; temperature was not clinically relevant.

CONCLUSIONS

In the absence of a diagnostic specificity, the combined determinations of acute phase reactants may be useful to detect the presence and intensity of the inflammatory and infectious processes.

Cardiac tamponade secondary to pneumopericardium after lung transplantation: a case report

Pneumopericardium is a rare cause of cardiac tamponade. It is an exceptional complication of lung transplantation. We have presented a case of a patient with cystic fibrosis who experienced cardiac tamponade secondary to a tension pneumopericardium during the postoperative course after lung transplantation. Dehiscence of the bronchial suture line was confirmed by fiberoptic bronchoscopy.

Evaluation of Patients Referred for Lung Transplantation: Fourteen Years Experience

We present a descriptive study of patients referred as candidates for lung transplantation in the last 14 years. The 837 requests were evaluated stepwise in three phases: phase I, derivation report; phase II, outpatient evaluation; and phase III, inpatient evaluation. Chronic obstructive pulmonary disease was the most common reason for referral (31%). Cystic fibrosis was the referral disease with the best transplanted/referred relation (57%) and pulmonary fibrosis was the disease that had the highest mortality (39.7% of all deaths). Forty-three percent of all patients reached phase III and 29% were transplanted. Mortality on the waiting list was 3.7%. The most important causes of exclusion were inadequate indications and the presence of severe associated diseases. The mean study was 44 days. Knowledge of the natural history, local factors that influence organ availability, expected time on the waiting list, and disease progression allow optimization of this therapeutic option.

Comparative analysis of the morphological, cytochemical, immunophenotypical, and functional characteristics of normal human peripheral blood lineage(-)/CD16(+)/HLA-DR(+)/CD14(-/lo) cells, CD14(+) monocytes, and CD16(-) dendritic cells

Human peripheral blood (PB) CD14(lo)/HLA-DR(+) cells were initially described as a subset of mature monocytes. Recently, it has been suggested that these represent a part of a new subset of dendritic cells (DC), characterized by the coexpression of MDC-8/HLA-DR/CD16. The aim of the present paper was to analyze the morphological, cytochemical, phenotypical, and functional characteristics of PB CD16(+)/HLA-DR(+) cells compared to both PB CD14(+) monocytes and CD16(-) DC. In contrast to CD14(+) monocytes, purified CD16(+)/HLA-DR(+) cells displayed cytoplasmic veils and lacked cytoplasmic myeloperoxidase and alpha-naphthyl acetate esterase. Normal human PB CD16(+)/HLA-DR(+) cells also displayed phenotypic characteristics different from those of CD14(+) monocytes: they lacked the CD64 Fcgamma receptor, showed lower levels of CD32, and expressed higher amounts of CD16 compared to CD14(+) monocytes. They also displayed a different pattern of expression of other antigens, including CD14, HLA-DR, CD45RA, CD45RO, complement receptors and complement regulatory surface proteins, adhesion and costimulatory molecules, and cytokine receptors, among others. When compared to CD16(-) DC, CD16(+)/HLA-DR(+) cells showed reactivity for CD16, dim positivity for CD14, higher expression of both Ig- and complement-receptors and lower reactivity for HLA-DR, adhesion, and costimulatory molecules (with the exception of CD86). The CD16(+)/HLA-DR(+) cell subset displayed a higher Ig/complement-mediated phagocytic/oxidative activity than CD16(-) DC, although this activity was significantly lower than that of mature monocytes. Regarding cytokine production at the single cell level, LPS plus IFN-gamma-stimulated PB CD16(+)/HLA-DR(+) cells produced significant amounts of IL1beta, IL6, IL12, TNFalpha, and IL8; however, the percentage of cytokine-producing cells and the amount of cytokine/cell were lower in CD16(+)/HLA-DR(+) cells than in CD14(+) monocytes. In addition, upon comparing CD16(+)/HLA-DR(+) cells with CD33(+++)/CD16(-) DC, we found that the percentage of cytokine-producing cells and the amount of cytokine/cell were significantly different in both cell subsets. In summary, our results show that CD16(+)/HLA-DR(+) cells clearly display different morphologic, cytochemical, immunophenotypical, and functional characteristics compared to both mature monocytes and CD16(-) DC. Interestingly, these cells are more frequent than other DC in normal human adult PB and cord blood samples, while they are less represented in normal bone marrow.

Flow cytometric analysis of cytokine production by normal human peripheral blood dendritic cells and monocytes: comparative analysis of different stimuli, secretion-blocking agents and incubation periods

In this paper, we comparatively analyze the effects of the following different stimuli on the production and intracellular accumulation of the interleukin (IL)-1 beta, IL-6, IL-12, tumor necrosis factor-alpha (TNF-alpha), and IL-8 inflammatory cytokines in both normal human peripheral blood (PB) dendritic cell (DC) subsets and monocytes: lipopolysaccharide (LPS) versus Staphylococcus aureus cowan I (SAC) in the presence or absence of interferon-(IFN)-gamma-, cytokine secretion-blocking agents (brefeldin A alone versus brefeldin A plus monensin), and incubation periods (6, 12, and 24 h). For this purpose, a four-color multiple-staining direct immunofluorescence technique analyzed by flow cytometry was systematically used in all experiments (n = 19). Our results show that after stimulation, an important proportion of each of the two CD33(+) myeloid DC subsets as well as the monocytes produce significant amounts of all cytokines analyzed under each of the experimental conditions assayed. In contrast, CD33(-/+lo) lymphoplasmocytoid DC failed to produce detectable levels of any of the above-mentioned cytokines under the same stimulatory conditions. Upon comparing the different stimuli used, LPS was associated with higher percentages of cytokine-producing cells compared with SAC, especially within the CD33(hi) DC subset; interestingly, the addition of IFN-gamma enhanced the response of monocytes to both LPS and SAC. As regards the secretion-blocking agents, brefeldin A alone was superior to the combination of brefeldin A and monensin. This is because it was frequently associated with both a higher percentage of cytokine-positive cells and greater amounts of detectable cytokines per cell. Sequential analysis of cytokine production by PB DC and monocytes after 6, 12, and 24 h of cell culture showed that after 6 h, an increased cell death rate existed among DC, which became even undetectable at 24 h, in the absence of a significant increase in cytokine secretion. In summary, our results show that from the experimental conditions assayed in this paper, to induce cytokine production by normal human DC and monocytes, maximum response is obtained once PB samples are stimulated for 6 h with LPS (with or without IFN-gamma) in the presence of brefeldin A alone.

The hippocampus and flexible spatial knowledge in rats

Lesions to the hippocampal system in rats result in a profound impairment of place or locale spatial learning although other learning strategies remain unaltered. The main objective of the present study was to investigate whether the spatial knowledge preserved in the hippocampal animals can be expressed flexibly under conditions different from those of the acquisition period. Rats with neurotoxic lesions to the dorsal hippocampus and sham-operated subjects were trained to reach the goal arm in a four-arm plus-shaped maze using a constant starting arm. During the training a transparent plexiglas barrier divided the maze in two equal halves in such a way that the animals could only travel from the starting arm to the goal arm, not having access to the remaining 50% of the maze. After seven days of training, a transfer test was used in which the starting arms were the two arms from which the animals had not started during the training phase. Results indicated that the lesioned rats made significantly more errors than the control subjects. But the most interesting results revealed that the kind of error made by the lesioned animals was congruent with the turn that they had to make during the acquisition phase in order to access the goal arm (reinforced). These results suggest that when the hippocampus is damaged a preserved highly inflexible egocentric strategy is employed to solve the spatial problem.

Extensive characterization of the immunophenotype and pattern of cytokine production by distinct subpopulations of normal human peripheral blood MHC II+/lineage- cells

Dendritic cells (DC) represent the most powerful professional antigen-presenting cells (APC) in the immune system. The aim of the present study was to analyse, on a single-cell basis by multiparametric flow cytometry with simultaneous four-colour staining and a two-step acquisition procedure, the immunophenotypic profile and cytokine production of DC from 67 normal whole peripheral blood (PB) samples. Two clearly different subsets of HLA-II+/lineage- were identified on the basis of their distinct phenotypic characteristics: one DC subset was CD33strong+ and CD123dim+ (0.16 +/- 0.06% of the PB nucleated cells and 55.9 +/- 11. 9% of all PB DC) and the other, CD33dim+ and CD123strong+ (0.12 +/- 0.04% of PB nucleated cells and 44.53 +/- 11.5% of all PB DC). Moreover, the former DC subpopulation clearly showed higher expression of the CD13 myeloid-associated antigen, the CD29 and CD58 adhesion molecules, the CD2, CD5 and CD86 costimulatory molecules, the CD32 IgG receptor and the CD11c complement receptor. In addition, these cells showed stronger HLA-DR and HLA-DQ expression and a higher reactivity for the IL-6 receptor alpha-chain (CD126) and for CD38. In contrast, the CD123strong+/CD33dim+ DC showed a stronger reactivity for the CD4 and CD45RA molecules, whereas they did not express the CD58, CD5, CD11c and CD13 antigens. Regarding cytokine production, our results show that while the CD33strong+/CD123dim+ DC are able to produce significant amounts of inflammatory cytokines, such as IL-1beta (97 +/- 5% of positive cells), IL-6 (96 +/- 1.1% of positive cells), IL-12 (81.5 +/- 15.5% of positive cells) and tumour necrosis factor-alpha (TNF-alpha) (84 +/- 22.1% of positive cells) as well as chemokines such as IL-8 (99 +/- 1% of positive cells), the functional ability of the CD123strong+/CD33dim+ DC subset to produce cytokines under the same conditions was almost null. Our results therefore clearly show the presence of two distinct subsets of DC in normal human PB, which differ not only in their immunophenotype but also in their functionality, as regards cytokine production.