Gut and airway microbiota dysbiosis and their role in COVID-19 and long-COVID

The gut microbiota plays a crucial role in human health and disease. Gut dysbiosis is known to be associated with increased susceptibility to respiratory diseases and modifications in the immune response and homeostasis of the lungs (the so-called gut-lung axis). Furthermore, recent studies have highlighted the possible role of dysbiosis in neurological disturbances, introducing the notion of the "gut-brain axis." During the last 2 years, several studies have described the presence of gut dysbiosis during coronavirus disease 2019 (COVID-19) and its relationship with disease severity, SARS-CoV-2 gastrointestinal replication, and immune inflammation. Moreover, the possible persistence of gut dysbiosis after disease resolution may be linked to long-COVID syndrome and particularly to its neurological manifestations. We reviewed recent evidence on the association between dysbiosis and COVID-19, investigating the possible epidemiologic confounding factors like age, location, sex, sample size, the severity of disease, comorbidities, therapy, and vaccination status on gut and airway microbial dysbiosis in selected studies on both COVID-19 and long-COVID. Moreover, we analyzed the confounding factors strictly related to microbiota, specifically diet investigation and previous use of antibiotics/probiotics, and the methodology used to study the microbiota (α- and β-diversity parameters and relative abundance tools). Of note, only a few studies focused on longitudinal analyses, especially for long-term observation in long-COVID. Lastly, there is a lack of knowledge regarding the role of microbiota transplantation and other therapeutic approaches and their possible impact on disease progression and severity. Preliminary data seem to suggest that gut and airway dysbiosis might play a role in COVID-19 and in long-COVID neurological symptoms. Indeed, the development and interpretation of these data could have important implications for future preventive and therapeutic strategies.

The cytokine storm and thyroid hormone changes in COVID-19

BACKGROUND

COVID-19 is now a worldwide pandemic. Among the many extra-pulmonary manifestations of COVID-19, recent evidence suggested a possible occurrence of thyroid dysfunction.

PURPOSE

The Aim of the present review is to summarize available studies regarding thyroid function alterations in patients with COVID-19 and to overview the possible physio-pathological explanations.

CONCLUSIONS

The repercussions of the thyroid of COVID-19 seem to be related, in part, with the occurrence of a "cytokine storm" that would, in turn, induce a "non-thyroidal illness". Some specific cytokines and chemokines appear to have a direct role on the hypothalamus-pituitary-thyroid axis. On the other hand, some authors have observed an increased incidence of a destructive thyroiditis, either subacute or painless, in patients with COVID-19. The hypothesis of a direct infection of the thyroid by SARS-Cov-2 stems from the observation that its receptor, ACE2, is strongly expressed in thyroid tissue. Lastly, it is highly probable that some pharmaceutical agents largely used for the treatment of COVID-19 can act as confounding factors in the laboratory evaluation of thyroid function parameters.

Long-Term Suppressive cART Is Not Sufficient to Restore Intestinal Permeability and Gut Microbiota Compositional Changes

Background: We explored the long-term effects of cART on markers of gut damage, microbial translocation, and paired gut/blood microbiota composition, with a focus on the role exerted by different drug classes.

Methods: We enrolled 41 cART naïve HIV-infected subjects, undergoing blood and fecal sampling prior to cART (T0) and after 12 (T12) and 24 (T24) months of therapy. Fifteen HIV-uninfected individuals were enrolled as controls. We analyzed: (i) T-cell homeostasis (flow cytometry); (ii) microbial translocation (sCD14, EndoCab, 16S rDNA); (iii) intestinal permeability and damage markers (LAC/MAN, I-FABP, fecal calprotectin); (iv) plasma and fecal microbiota composition (alpha- and beta-diversity, relative abundance); (v) functional metagenome predictions (PICRUSt).

Results: Twelve and twenty four-month successful cART resulted in a rise in EndoCAb (p = 0.0001) and I-FABP (p = 0.039) vis-à-vis stable 16S rDNA, sCD14, calprotectin and LAC/MAN, along with reduced immune activation in the periphery. Furthermore, cART did not lead to substantial modifications of microbial composition in both plasma and feces and metabolic metagenome predictions. The stratification according to cART regimens revealed a feeble effect on microbiota composition in patients on NNRTI-based or INSTI-based regimens, but not PI-based regimens.

Conclusions: We hereby show that 24 months of viro-immunological effective cART, while containing peripheral hyperactivation, exerts only minor effects on the gastrointestinal tract. Persistent alteration of plasma markers indicative of gut structural and functional impairment seemingly parallels enduring fecal dysbiosis, irrespective of drug classes, with no effect on metabolic metagenome predictions.

The importance of patients' case-mix for the correct interpretation of the hospital fatality rate in COVID-19 disease

OBJECTIVE

We aimed to document data on the epidemiology and factors associated with clinical course leading to death of patients hospitalised with COVID-19.

METHODS

Prospective observational cohort study on patients hospitalised with COVID-19 disease in February-24th/May-17th 2020 in Milan, Italy. Uni-multivariable Cox regression analyses were performed. Death's percentage by two-weeks' intervals according to age and disease severity was analysed.

RESULTS

A total of 174/539 (32.3%) patients died in hospital over 8228 person-day follow-up; the 14-day Kaplan-Meier probability of death was 29.5% (95%CI: 25.5-34.0). Older age, burden of comorbidities, COVID-19 disease severity, inflammatory markers at admission were independent predictors of increased risk, while several drug-combinations were predictors of reduced risk of in-hospital death. The highest fatality rate, 36.5%, occurred during the 2nd-3rd week of March, when 55.4% of patients presented with severe disease, while a second peak, by the end of April, was related to the admission of older patients (55% ≥80 years) with less severe disease, 30% coming from long-term care facilities.

CONCLUSIONS

The unusual fatality rate in our setting is likely to be related to age and the clinical conditions of our patients. These findings may be useful to better allocate resources of the national healthcare system, in case of re-intensification of COVID-19 epidemics.

Patients with chronic autoimmune thyroiditis are not at higher risk for developing clinically overt thyroid cancer: a 10-year follow-up study

OBJECTIVE

The association between chronic autoimmune thyroiditis (CAT) and differentiated thyroid cancer (DTC) remains controversial. The incidence of DTC increases when screening procedures are implemented, as typically occurs in CAT patients being routinely submitted to thyroid ultrasound (US). The aim of this study was to longitudinally evaluate the long-term development of DTC in patients with CAT.

DESIGN AND METHODS

A retrospective longitudinal cohort study was designed. For the study, 510 patients with chronic autoimmune thyroiditis (CAT) with a 10-year follow-up were enrolled. Patients were divided in two groups according to the presence (CAT+ NOD+; n = 115) or absence (CAT+ NOD-; n = 395) of co-existent nodules at diagnosis. The main outcome measures were appearance of new thyroid-nodules and development of DTC during follow-up.

RESULTS

During a 10-year median follow-up period, new thyroid-nodules were detected in 34/115 (29.5%) patients in the CAT+ NOD+ group and in 41/395 (10.3%) in the CAT+ NOD- group (P < 0.001). Logistic regression analysis showed that thyroid-volume at diagnosis and belonging to the CAT+ NOD+ group significantly predicted the appearance of a new thyroid nodule during follow-up, independently of baseline age and sex. Among the 75 patients experiencing the appearance of a new nodule, 27 (39%) met the criteria for fine-needle-aspiration-cytology (FNAC). A benign cytological diagnosis was rendered in all cases.

CONCLUSIONS

In our series of CAT patients, the appearance of new thyroid-nodules was frequent, but none of them were found to be malignant. The presence of CAT appears to be associated with a negligible risk of developing clinically overt DTC.

Disseminated cytomegalovirus disease after bendamustine: a case report and analysis of circulating B- and T-cell subsets

Background

Bendamustine, used for the treatment of indolent B-cell non-Hodgkin lymphoma and chronic lymphocytic leukemia, is known to cause prolonged myelosuppression and lymphocytopenia and has been associated with the risk of developing serious and fatal infections. While reports of localized CMV infections in asymptomatic patients exist, disseminated CMV disease has not been described.

Case presentation

We report the first case of disseminated CMV infection in a 75-year-old male diagnosed with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia with massive bone marrow infiltration. Despite 6-cycle R-bendamustine chemotherapy resulted in a good partial response, the patient developed persistent fever and severe weight loss. Analysis of cerebrospinal fluid and peripheral blood revealed the presence of CMV-DNA, while the fundus oculi examination revealed bilateral CMV retinitis. Treatment with induction and maintenance drugs was complicated by neutropenia and deterioration of renal function with electrolyte imbalance. From an immunological standpoint, we observed a profound imbalances in phenotype and function of B- and T-cell subsets, with a high proportion of circulating total, activated CD69+ and CD80+ B-cells, a low γ/δ T-cell frequency with a high proportion of CD69- and CD38-expressing cells, and hyperactivated/exhausted CD4+ and CD8+ T-cell phenotypes unable to face CMV challenge.

Conclusions

We hereby describe a severe form of disseminated CMV disease after R-bendamustine treatment. Our observations strongly support the careful clinical monitoring of CMV reactivation/infection in oncologic patients undergoing this therapeutic regimen.

Mucosal cell populations may contribute to peripheral immune abnormalities in HIV-infected subjects introducing cART with moderate immune-suppression

HIV infection causes the progressive depletion of CD4+ T-lymphocytes and profound modifications of T-cell homeostasis, which persist despite virologically-suppressive treatment and have been linked to a worse clinical outcome. Enduring alterations of the gastrointestinal tract may represent the underlying pathogenic mechanisms of these phenomena. Twenty-six HIV-infected subjects were assessed over a 12-month period following the introduction of antiretroviral therapy. 18 uninfected individuals were enrolled as controls. Parameters of peripheral T-cell homeostasis (activation, maturation), gastrointestinal function (microbial translocation, gut inflammation, fecal microbiota composition) and mucosal immunity (CD4+CCR6+CD161+, CD4+CCR9+α4β7+, stem cell memory CD4+/CD8+ T-cells) were assessed. CD4+CCR6+CD161+ cells were depleted in HIV-infected untreated subjects and maintained significantly lower levels compared to controls, despite the introduction of effective antiviral treatment. The frequency of gut-homing CD4+CCR9+α4β7+ cells was also impaired in untreated infection and correlated with the HIV RNA load and CD4+HLADR+CD38+; during therapy, we observed a contraction of this pool in the peripheral blood and the loss of its correlation with antigenic exposure/immune activation. A partial correction of the balance between stem cell memory pools and T-cell homeostasis was registered following treatment. In HIV-infected subjects with moderate immune-suppression, antiretroviral therapy has a marginal impact on mucosal immune populations which feature distinctive kinetics in the periphery, possibly reflecting their diverse recruitment from the blood to the mucosa. The persistent defects in mucosal immunity may fuel peripheral T-cell abnormalities through diverse mechanisms, including the production of IL-17/IL-22, cellular permissiveness to infection and regulation of T-lymphocyte maturation.

An objective method for detecting time-dependent effects in graft survival

The proportional hazards model has become increasingly important in the analysis of censored survival data after transplantation. Neverthless, in clinical transplantation it is still undefined how the influence of covariates changes over time. The additive regression model is an alternative (or extension) to the Cox model. It results in plots (Aalen plots) that may give information on the effect of covariates over time by way of the cumulative regression function plots. A total of 386 primary cadaveric kidney transplants performed between 1984 and 1996 were included in our analysis. The follow-up period ranged from 24 to 156 months. According to Aalen, an additive regression model was used and plots for the detection of time-dependent effects of covariates were determined. Patients dying with functioning grafts were classed as graft failures. Factors potentially affecting graft outcome, such as sex, donor and recipient's age, HLA A-B match, cold ischaemia time (CIT), delayed graft function (DGF), serum creatinine at 1 month (Cr1), rejection episodes within 3 months (R3), and type of brain death (BD), were considered. The slopes of the plots by donor age, DGF, HLA A-B match, R3, Cr1 and BD appear to have a significant influence throughout the observation period, with different time-dependent effects on graft survival. Slopes for DGF, Cr1, and age of donor are positive (increased hazard), while slopes for HLA match and BD are negative (decreased hazard). Estimated regression functions for DGF, donor age and Cr1 show a prompt slope (within 3 months); the covariate R3 has a clear influence for about 5 years, and then seems to disappear; and BD appears to have a consistent effect over the entire period. The additive regression model with Aalen plots represents a useful technique in the analysis of survival data after kidney transplantation. Some covariates, such as R3, may often lose their effects on graft survival, with a relevant clinical impact. Others have a clear and additive influence over the entire period (BD), while the effects of donor age, DGF and CR1 each appear to have a prompt effect in the outcome.

Tumour necrosis factor-alpha gene polymorphism: implications in kidney transplantation

In this study we have analysed the TNFA biallelic polymorphism at the -308 position, in 169 kidney recipients that received the graft in a single Italian transplantation facility and we have then correlated the TNFA genotypes with the post-transplant outcome. To assess the cytokine genotypes, a polymerase chain reaction-sequence specific primer (PCR-SSP) methodology has been utilised. By the analysis of the different genotypes, the corresponding TNF-alpha phenotypes and the level of the TNF-alpha production, were deduced: the TNF(*)1/TNF(*)1 genotype gives a low TNF-alpha production level, TNF(*)1/TNF(*) 2 and TNF(*)2/TNF(*)2 genotypes give a high TNF-alpha production level. Out of the one hundred and sixty-nine patients studied, one hundred and twenty-one recipients (72%) had a low TNF-alpha producer phenotype, whereas forty-eight (28%) had a high TNF-alpha producer phenotype. These frequencies were not statistically different from those of the control group. The incidence of acute rejection episodes, vascular damage (grade III degrees of Banff classification), and serum creatinine levels at 1 month, were significantly greater in high TNF-alpha producers (P=0. 048, 0.031 and 0.007 respectively). The logistical regression model indicated that only the high producer genotype and donor age were significantly and independently correlated with acute graft failure (P=0.02 and P=0.013 respectively). This analysis shows that recipient TNFA polymorphism, previously associated with differential production TNF-alpha by in vitro studies could be related to the clinical outcome of kidney transplantation.

Compensation for increase in respiratory workload during mechanical ventilation. Pressure-support versus proportional-assist ventilation

Variation in respiratory impedance may occur in mechanically ventilated patients. During pressure-targeted ventilatory support, this may lead to patient-ventilator asynchrony. We assessed the hypothesis that during pressure-support ventilation (PSV), preservation of minute ventilation (V E) consequent to added mechanical loads would result in an increase in respiratory rate (RR) due to the large reduction in tidal volume (VT). WITH proportional-assist ventilation (PAV), preservation of V E would occur through the preservation of VT, with a smaller effect on RR. We anticipated that this compensatory strategy would result in greater patient comfort and a reduce work of breathing. An increase in respiratory impedance was obtained by chest and abdominal binding in 10 patients during weaning from mechanical ventilation. V E remained constant in both ventilatory modes after chest and abdominal compression. During PSV, this maintenance of VE was obtained through a 58 +/- 3% increase in RR that compensated for a 29 +/- 2% reduction in VT. The magnitudes of the reduction in VT (10 +/- 3%) and of the increase in RR (14 +/- 2%) were smaller (p < 0. 001) during PAV. During both PSV and PAV, chest and abdominal compression caused increases in both the pressure-time product (PTP) of the diaphragm per minute (142.9 +/- 26.9 cm H(2)O. s/min, PSV, and 117.6 +/- 16.4 cm H(2)O. s/min, PAV) and per liter (13.4 +/- 2.5 cm H(2)O. s/L, PSV, and 9.6 +/- 0.7 cm H(2)O. s/L, PAV). These increments were greater (p < 0.001) during PSV than during PAV. The capability of keeping VT and V E constant through increases in inspiratory effort after increases in mechanical loads is relatively preserved only during PAV. The ventilatory response to an added respiratory load during PSV required greater muscle effort than during PAV.

Oral granisetron as prophylaxis for nausea and vomiting during fluorescein angiography. A multicentre, double-blind, randomised, parallel group, placebo-controlled study

BACKGROUND

Prophylaxis with oral Granisetron was assessed in patients undergoing fluorescein angiography (FAG) in order to evaluate its efficacy in reducing patients' discomfort due to nausea and vomiting (4% > 20%) and to ensure completion of the investigation.

EXPERIMENTAL PLAN

Multicentre, randomised, double-blind, placebo-controlled study, with a follow-up visit performed 24 hrs after FAG.

ENVIRONMENT

Five Anaesthesia/Resuscitation and Ophthalmology operational units participated in the study.

PATIENTS

120 patients (24 from each Centre) of both sexes and aged > 18 years, suffering from retinal disorders, were enrolled after informed consent. Pregnancy, lactation, anti-neoplastic treatment, ASA status IV/V were main exclusion criteria. All recruired patients completed the study.

INTERVENTIONS

Ophthalmological evaluation was performed 30 days before and the same day as FAG. Anaesthesiological assessment on the same day as FAG, recording, BP, HR, ASA status, allergic diathesis, allergy to medications and contrast media, concomitant treatments. Oral Granisetrom 1 mg or placebo was given on an empty stomach 1 hr before the injection of 5 ml 20% fluorescein in 3 sec. A follow-up examination was done 24 hrs after FAG.

SURVEY

In both groups nausea, retching and vomiting were seen after fluorescein injection.

RESULTS

The study demonstrated that Granisetron is more active than placebo in controlling nausea (3 cases vs 4), and retching (2 vs 6). It was significantly more effective than placebo in the prevention of vomiting (0 vs 3). Efficacy was evaluated with chi 2, p < or = 0.05).

CONCLUSIONS

The results suggest that Granisetron may be indicated as prophylaxis in patients undergoing FAG in order to prevent or control emesis, improve patients' comfort and ensure successful outcome of the investigation.

Renal needle biopsy of the transplant kidney: vascular and urologic complications

The authors reviewed the complications of 114 needle biopsies performed in 103 transplant kidneys. The diagnostic and therapeutic approach has changed markedly as a result of the introduction of Doppler ultrasound and the possibility of selectively embolizing fistula tracts. Macroscopic haematuria was the most frequent complication (5%); in one case it appeared 1 week after biopsy and was complicated with obstructive anuria due to a pyeloureteric clot. The incidence of arteriovenous fistulae was fairly low (0.9%); a selective renal angiography was performed, confirming the vascular lesion and allowing its selective embolization. Perirenal blood collections were also rare and the amounts were small.

[Urologic complications in kidney transplants: experience in 274 transplants]

The urological complications after a renal transplantation still represent an event anything but rare, ranging, according to the different statistics, from 0.9% up to 23%, with a mortality between 0 and 25%. In this work done by the Verona Centre the experience on 274 transplantations is reported. The urological complications weighed with 6.2% and absence of mortality among the patients. The importance of the prevention and precocious diagnosis is confirmed.

[Significance of mixed lymphocyte culture (MLC) in renal transplants from living donors]

Results of MLC were correlated with kidney-graft survival of recipients of living related donor. The 56 patients tested by MLC were divided into two groups according as the stimulation index was more or less than 5. In 20 of these patients transplanted, renal allograft survival correlated better with low stimulation in MLC, suggesting more histocompatibility.

[Diagnosis and therapy of lymphocele as a complication of renal transplantation]

Of 165 renal transplanted patients, three (1.8%) developed a pelvic lymphocele. Decreased renal function, leg edema, a lower quadrant abdominal mass and fluid retention represented suspicion as the possibility of lymph collection in the perirenal space. Excretory urography associated with pelvic tomography, Computerized Tomography and B scan ultrasound confirmed diagnosis and were helpful in the post-operative follow-up. Drainage procedure restored normal renal function and morphology. External drainage and marsupialization into the peritoneum have been used successfully.

[Relation between cytomegalovirus infection and the so-called intolerance to azathioprine in renal transplantation]

Renal transplant recipients can develop hepatic function abnormalities or severe leucopenia after transplantation. Generally it is thought to be due to azathioprine intolerance and patients are treated by curtailment of immunosuppressive therapy, being subsequently at risk to lose their allograft because of rejection. Evidence of Cytomegalovirus (CMV) infection is also common after renal transplantation. It is generally thought that the majority of these infections are asymptomatic, but they can be accompanied by leucopenia and/or hepatic function abnormalities. Sixty-nine renal transplant recipients have been studied for at least three months in order to investigate the relationship between CMV and azathioprine intolerance after transplantation. Twenty-five out of 58 patients who underwent seroconversion to CMV (a fourfold or greater rise in titer of CMV antibodies) after transplantation or who had a high CMV titer (greater than or equal to 1 : 16) prior to transplant, developed azathioprine intolerance. None of 11 patients who before renal transplantation had low CMV titers and who did'nt underwent seroconversion did not tolerate azathioprine. Therefore the Authors advance the hypothesis that azathioprine intolerance following renal transplantation can be often due to an asymptomatic and unknown CMV infection.

[HLA and rejection of renal transplants from cadavers]

Seventy-two patients were typed for HLA-A and HLA-B. Kidney-graft survival, reversibility and time of appearance of reject episodes were comparated with matching level. Matching level had double classification: NIT and Verona; the validity of tissue-typing as prediction of the best result of transplantation and major reversibility of reject episodes.

[Aseptic osseous necrosis after renal transplantation]

Of 165 renal Transplantated patients, 12 developed aseptic bone necrosis in the femoral head (6 patients), in the femoral condyle (5 patients), in the astragalus (1 patient). The onset of symptoms was 6 to 23 months after transplantation. 99mTc-O4-MDP bone scintigraphy and radiological examination associated with clinical signs confirmed the diagnosis. Unresolved hyperparathyroidism, phosforus depletion, ponderal increase, total i.v. prednisolone-boluses and trauma represented conditions which might predispose to the development of lesion. 8 patients were managed with conservative treatment. 4 patients required a total of 8 operations: head replacement arthroplasty and articular cartilage reimplant in two patients with disease involving femoral head; articular cartilage reimplant and condyle replacement arthroplasty in two patients with disease involving femoral condyle.

[Internal arteriovenous fistula in the antecubital region]

An assessment was made of the anterior cubital region as a vascular approach for primary and alternative dialysis. Reference is made to 36 fistulae in this area within 44 months' survival in the drawing of various conclusions with regard to surgical technique. End anastomosis of the median, cephalic or basilic vein laterally on the brachial or radial artery is recommended as a means of preventing or cutting down the more common complications associated with internal arteriovenous fitulae. The anastomosis should not exceed 6 mm in diameter. Complications led to loss of fistula function. In many cases, however, they did not prevent employment of the region for alternative approaches, such as superficialisation of the basilic vein or prosthesis.