Thyroid and COVID-19: a review on pathophysiological, clinical and organizational aspects.

BACKGROUND: Thyroid dysfunction has been observed in patients with COVID-19, and endocrinologists are requested to understand this clinical issue. Pandemic-related restrictions and reorganization of healthcare services may affect thyroid disease management. OBJECTIVE AND METHODS: To analyze and discuss the relationship between COVID-19 and thyroid diseases from several perspectives. PubMed/MEDLINE, Google Scholar, Scopus, ClinicalTrial.gov were searched for this purpose by using free text words and medical subject headings as follows: "sars cov 2", "covid 19", "subacute thyroiditis", "atypical thyroiditis", "chronic thyroiditis", "hashimoto's thyroiditis", "graves' disease", "thyroid nodule", "differentiated thyroid cancer", "medullary thyroid cancer", "methimazole", "levothyroxine", "multikinase inhibitor", "remdesivir", "tocilizumab". Data were collected, analyzed, and discussed to answer the following clinical questions: "What evidence suggests that COVID-19 may induce detrimental consequences on thyroid function?"; "Could previous or concomitant thyroid diseases deteriorate the prognosis of COVID-19 once the infection has occurred?"; "Could medical management of thyroid diseases influence the clinical course of COVID-19?"; "Does medical management of COVID-19 interfere with thyroid function?"; "Are there defined strategies to better manage endocrine diseases despite restrictive measures and in-hospital and ambulatory activities reorganizations?". RESULTS: SARS-CoV-2 may induce thyroid dysfunction that is usually reversible, including subclinical and atypical thyroiditis. Patients with baseline thyroid diseases are not at higher risk of contracting or transmitting SARS-CoV-2, and baseline thyroid dysfunction does not foster a worse progression of COVID-19. However, it is unclear whether low levels of free triiodothyronine, observed in seriously ill patients with COVID-19, may worsen the disease's clinical progression and, consequently, if triiodothyronine supplementation could be a tool for reducing this burden. Glucocorticoids and heparin may affect thyroid hormone secretion and measurement, respectively, leading to possible misdiagnosis of thyroid dysfunction in severe cases of COVID-19. High-risk thyroid nodules require a fine-needle aspiration without relevant delay, whereas other non-urgent diagnostic procedures and therapeutic interventions should be postponed. DISCUSSION: Currently, we know that SARS-CoV-2 could lead to short-term and reversible thyroid dysfunction, but thyroid diseases seem not to affect the progression of COVID-19. Adequate management of patients with thyroid diseases remains essential during the pandemic, but it could be compromised because of healthcare service restrictions. Endocrine care centers should continuously recognize and classify priority cases for in-person visits and therapeutic procedures. Telemedicine may be a useful tool for managing patients not requiring in-person visits.

Nanoparticle delivery of grape seed-derived proanthocyanidins to airway epithelial cells dampens oxidative stress and inflammation.

BACKGROUND: Chronic respiratory diseases, whose one of the hallmarks is oxidative stress, are still incurable and need novel therapeutic tools and pharmaceutical agents. The phenolic compounds contained in grape are endowed with well-recognized anti-oxidant, anti-inflammatory, anti-cancer, and anti-aging activities. Considering that natural anti-oxidants, such as proanthocyanidins, have poor water solubility and oral bioavailability, we have developed a drug delivery system based on solid lipid nanoparticles (SLN), apt to encapsulate grape seed extract (GSE), containing proanthocyanidins. METHODS: Plain, 6-coumarin (6-Coum), DiR- and GSE-loaded SLN were produced with the melt-emulsion method. Physicochemical characterization of all prepared SLN was determined by photon correlation spectroscopy and laser Doppler anemometry. MTT assay (spectrophotometry) and propidium iodide (PI) assay (cytofluorimetry) were used to assess cell viability. Flow cytometry coupled with cell imaging was performed for assessing apoptosis and necrosis by Annexin V/7-AAD staining (plain SLE), cell internalization (6-Coum-SLN) and reactive oxygen species (ROS) production (SLN-GSE). NF-κB nuclear translocation was studied by immunofluorescence. In vivo bio-imaging was used to assess lung deposition and persistence of aerosolized DiR-loaded SLN. RESULTS: Plain SLN were not cytotoxic when incubated with H441 airway epithelial cells, as judged by both PI and MTT assays as well as by apoptosis/necrosis evaluation. 6-Coum-loaded SLN were taken up by H441 cells in a dose-dependent fashion and persisted into cells at detectable levels up to 16 days. SLN were detected in mice lungs up to 6 days. SLN-GSE possessed 243 nm as mean diameter, were negatively charged, and stable in size at 37 °C in Simulated Lung Fluid up to 48 h and at 4 °C in double distilled water up to 2 months. The content of SLN in proanthocyanidins remained unvaried up to 2 months. GSE-loaded SLN determined a significant reduction in ROS production when added 24-72 h before the stimulation with hydrogen peroxide. Interestingly, while at 24 h free GSE determined a higher decrease of ROS production than SLN-GSE, the contrary was seen at 48 and 72 h. Similar results were observed for NF-κB nuclear translocation. CONCLUSIONS: SLN are a biocompatible drug delivery system for natural anti-oxidants obtained from grape seed in a model of oxidative stress in airway epithelial cells. They feature stability and long-term persistence inside cells where they release proanthocyanidins. These results could pave the way to novel anti-oxidant and anti-inflammatory therapies for chronic respiratory diseases.

Liver melanomacrophage centres as indicators of Atlantic bluefin tuna, Thunnus thynnus L. well-being.

Melanomacrophage centres (MMCs), located in different organs of non-mammalian vertebrates, play a role in the destruction, detoxification or recycling of endogenous and exogenous materials. Cytochrome P450 monoxygenase 1A (CYP1A) is involved in xenobiotics biotransformation, and its liver expression is considered as a biomarker for detecting exposure to environmental pollutants. Atlantic bluefin tuna (ABFT), Thunnus thynnus L., liver samples were collected from: wild animals caught in the eastern Atlantic; juveniles reared in the central Adriatic; juveniles reared in the northern Adriatic; adults reared in the western Mediterranean. The samples were processed for basic histology, histochemistry and for CYP1A immunodetection. An unexpected high density of MMCs, containing ferric iron and lipofuscin-ceroids, was detected in the juveniles sampled in the northern Adriatic Sea. These individuals showed also a strong anti-CYP1A immunopositivity in hepatocytes and in the epithelium of bile ducts. This study supports the utility of MMCs as biomarkers of fish 'health status' and gives concern for a potential contaminant accumulation in ABFT.

Chronic Stress as a Risk Factor for Type 2 Diabetes: Endocrine, Metabolic, and Immune Implications.

BACKGROUND: Chronic stress is a condition of pressure on the brain and whole body, which in the long term may lead to a frank disease status, even including type 2 diabetes (T2D). Stress activates the hypothalamus-pituitary-adrenal axis with release of glucocorticoids (GCs) and catecholamines, as well as activation of the inflammatory pathway of the immune system, which alters glucose and lipid metabolism, ultimately leading to beta-cell destruction, insulin resistance and T2D onset. Alteration of the glucose and lipid metabolism accounts for insulin resistance and T2D outcome. Furthermore, stress-related subversion of the intestinal microbiota leads to an imbalance of the gut-brain-immune axis, as evidenced by the stress-related depression often associated with T2D. Inflammatory mechanisms: A condition of generalized inflammation and subversion of the intestinal microbiota represents another facet of stress-induced disease. In fact, chronic stress acts on the gut-brain axis with multi-organ consequences, as evidenced by the association between depression and T2D. Novel Therapeutic Options: Oxidative stress with the production of reactive oxygen species and cytokine-mediated inflammation represents the main hallmarks of chronic stress. ROS production and pro-inflammatory cytokines represent the main hallmarks of stress-related disorders, and therefore, the use of natural antioxidant and anti-inflammatory substances (nutraceuticals) may offer an alternative therapeutic approach to combat stress-related T2D. Single or combined administration of nutraceuticals would be very beneficial in targeting the neuro-endocrine-immune axis, thus, regulating major pathways involved in T2D onset. However, more clinical trials are needed to establish the effectiveness of nutraceutical treatment, dosage, time of administration and the most favorable combinations of compounds. Therefore, in view of their antioxidant and anti-inflammatory properties, the use of natural products or nutraceuticals for the treatment of stress-related diseases, even including T2D, will be discussed. Several evidences suggest that chronic stress represents one of the main factors responsible for the outcome of T2D.

Effects of herbal supplements on the immune system in relation to exercise.

Athletes who undergo strenuous exercise, especially in endurance sports, frequently use herbal supplements in order to have a better performance. In this review we try to find out if the most common herbal supplements (Echinacea, Rhodiola, Ginseng) are effective in the empowerment of performance or in the modulation of the immune system. It seems that the prevalent effect is adaptogenic rather than ergogenic, with a better tolerance of the exercise induced stress, related to enhancement of the whole immune system and decrease of the oxidative damage.

Characterization of myocardial lesions associated with cardiomyopathy syndrome in Atlantic salmon, Salmo salar L., using laser capture microdissection.

Cardiomyopathy syndrome (CMS) in Atlantic salmon, Salmo salar L., is characterized by focal infiltration in the spongy myocardium and endocardium of the heart. The origin of the mononuclear infiltrate is unknown. Using experimentally infected fish, we investigated localization of the causative agent, piscine myocarditis virus (PMCV), within the heart and characterized the cell population associated with myocardial lesions. Cellular and transcriptional characteristics in the lesions were compared with adjacent non-infiltrated tissues using laser capture microdissection, RT-qPCR and immunohistochemistry. Our results reveal that PMCV is almost exclusively present in myocardial lesions. The inflammatory infiltrate comprises a variety of leucocyte populations, including T cells, B cells, MHC class II(+) and CD83(+) cells, most likely of the macrophage line. Correlation analyses demonstrated co-ordinated leucocyte activity at the site of the virus infection. Cellular proliferation and/or DNA repair was demonstrated within the myocardial lesions. Different cell populations, mainly myocytes, stained positive for proliferating cell nuclear antigen (PCNA). Densities of endothelial cells and fibroblasts were not significantly increased. The simultaneous presence of PMCV and various inflammatory cells in all myocardial lesions analysed may indicate that both viral lytic and immunopathological effects may contribute to the pathogenesis of CMS.

Oral but not parenteral interleukin (IL)-12 redirects T helper 2 (Th2)-type responses to an oral vaccine without altering mucosal IgA responses.

Our past studies have shown that the mucosal adjuvant cholera toxin (CT) induces T helper type 2 (Th2) responses with systemic IgG1, IgE and mucosal secretory IgA (S-IgA) antibodies (Abs). In this study, recombinant murine IL-12 (rmIL-12) was given either parenterally or orally to mice orally immunized with tetanus toxoid (TT) and CT to determine whether this cytokine could redirect the CT-induced Th2-type responses and what effect this shift would have on S-IgA Ab responses. Intraperitoneal administration of rmIL-12 shifted TT-specific responses toward Th1-type and resulted in CD4+ T cells producing IFN-gamma and IL-2 with markedly reduced levels of Th2-type cytokines. This cytokine profile was accompanied by increased delayed-type hypersensitivity (DTH) and shifts in serum IgG1 to IgG2a and IgG3 anti-TT Ab responses. Further, serum IgE and S-IgA Ab responses were markedly reduced by parenteral IL-12. When IL-12 complexed to liposomes was given orally both shifts to IgG2a and IgG3 and low IgE Abs again occurred concomitant with enhanced serum IFN-gamma and DTH responses. Interestingly, oral rmIL-12 did not result in significant levels of serum IL-12 nor altered S-IgA Ab responses and resulted in higher levels of some Th2-type cytokines both in vitro and in vivo when compared with parenteral IL-12. Our results show that the shifts in systemic immune responses with intact S-IgA Abs which occur after oral delivery of IL-12-liposomes are due to cytokine effects in the Peyer's patches and suggest new strategies for the targeted manipulation of Th1- and Th2-type responses to mucosal vaccines.

Taking advantage of viral immune evasion: virus-derived proteins represent novel biopharmaceuticals.

In healthy individuals, natural and adaptive immune responses are able to control virus entry into the host. In particular, CD8(+)-mediated cytotoxicity, sustained by the intervention of CD4+ cells, represents the major key event leading to virus eradication. On the other hand, viruses are able to evade from host immune response via several mechanisms, and special emphasis will be placed on hepatitis C virus and chronic Epstein-Barr infections also in view of personal data. Virokines, viroreceptors, and serpins greatly contribute to viral immune escape, and, among virokines, interleukin (IL)-10 has been object of intensive studies. Finally, all these products have been used as biopharmaceuticals, and, for instance, viral IL-10, chemokine-binding proteins, and serpins exhibit in animal models immunosuppressive, anti-inflammatory, and antiatherogenic activities. As far as their use in human trials is concernded, many cautions are required in order to avoid deleterious side effects and, in particular, the purity of the product, its route and frequency of administration, as well as the immune status of the patient should be taken into serious account.

Ablation of T-helper 1 cell derived cytokines and of monocyte-derived tumor necrosis factor-alpha in hereditary hemorrhagic telangiectasia: immunological consequences and clinical considerations.

Experimental evidences on the adaptive immune response in patients with hereditary hemorragic telagiectasia (HHT) are lacking. Here, we report in 9 patients with HHT a multiple deficit involving the intracellular expression of T helper (h)1-derived cytokines [Interferon (IFN)-gamma, Interleukin (IL)-2 and Tumor Necrosis Factor (TNF)-alpha] and of monocyte-derived TNF-alpha. On the other hand, percentages of Th2-derived cytokines (IL-4, IL-5 and IL-10) were normal or, in some cases, above normality. Quite interestingly, monocyte-derived IL-10 was detectable in 5 out of 9 patients in a percentage of cells comparable to controls or exceeding normal levels. Taken together, these data point out, in HHT, an ablation of Th1-responses, while Th2-type cytokines are preserved, thus exerting either a suppressive effect on Th1-cells (via IL-4 and IL-10) or an antiinflammatory response on monocyte-derived TNF-alpha (via IL-10). Furthermore, monocyte-derived IL-10 may also contribute to the antiinflammatory activity seen in HHT. According to current literature even if patients with HHT do not exhibit certain diseases, such as autoimmune diseases, cancer and abnormal responses to pathogens, the observed immune deficits need to be diagnosed and therapeutically corrected.

Involvement of the transforming growth factor beta in the pathogenesis of hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is characterized by vessel alterations such as dilatation of postcapillary venules and arterio-venous communications, which account for the major clinical manifestations of the disease. Two types of HHT have been characterized HHT-1 and HHT-2, respectively, depending the former on endoglin mutations and the latter on activin receptor-like kinase 1 (ALK-1) mutations. Both endoglin and ALK-1 bind to the transforming growth factor (TGF) superfamily which, physiologically, regulates the activities of endothelial cells and also those related to the extracellular matrix. In this review, the salient features of TGF-beta will be outlined with special reference to its activity on the immune system and on tumorigenesis. Furthermore, the involvement of TGF-beta in the pathogenesis of some gastrointestinal diseases will be discussed and, in particular, in the course of liver disease, Helicobacter pylori infection and inflammatory bowel disease. In the light of these data and of animal model of HHT, the potential risk of developing other diseases in HHT patients will be discussed.

Expression and function of the early activation antigen CD69 in murine macrophages.

CD69, a member of the natural killer cell gene complex family of signal transducing receptors, represents one of the earliest activation antigens in human and murine lymphocytes. In contrast, human monocytes may express CD69 in a constitutive fashion. We have evaluated the expression and function of CD69 in murine bone marrow-derived macrophages. CD69 expression as determined by flow cytometry was not constitutive but was induced by stimulation with interferon-gamma (IFN-gamma) plus bacterial lipopolysaccharide (LPS) or tumor necrosis factor a (TNF-alpha). Stimulation with LPS alone was equally effective. Infection with the protozoan parasite Leishmania did not induce CD69 expression nor influence CD69 up-regulation by IFN-gamma plus LPS. Induction of CD69 expression was significantly inhibited in the presence of prostaglandin E2 or dibutyryl-cAMP. Stimulation of macrophages with anti-CD69 monoclonal antibody in the presence of IFN-gamma induced both nitric oxide production and TNF-alpha release. Moreover, anti-CD69 stimulation of Leishmania-infected macrophages resulted in elimination of the intracellular parasite. These results suggest that CD69 is an activation antigen for murine macrophages and may serve as a signaling receptor for an as yet uncharacterized ligand.

L-carnitine deficiency in AIDS patients.

OBJECTIVE: To evaluate carnitine (3-hydroxy-4-N-trimethyl-ammoniobutanoate) deficiency in AIDS patients by measuring serum total, free and short-chain carnitine concentrations. DESIGN: We conducted an open study. SETTING: All patients were seen at the Infectious Diseases Clinic, Università 'La Sapienza', Rome, Italy. PATIENTS, PARTICIPANTS: Twenty-nine AIDS patients, aged 27-41 years, with a previous history of drug use; and 14 healthy age- and sex-matched controls were studied. INTERVENTIONS: Study subjects were administered 500-800 mg zidovudine daily for 2 to 28 months (8 +/- 6 months). MAIN OUTCOME MEASURES: Carnitine deficiency was suspected in study participants prior to data collection because of previously reported cardiac symptoms, muscle weakness, hypometabolism and/or cachexia. RESULTS: A marked decrease in total and free carnitine was observed in 21 (72%) subjects. Nine of these patients also had low levels of short-chain carnitine. CONCLUSIONS: AIDS patients may become carnitine-depleted and therefore at risk for alterations in fatty-acid oxidation and energy supply.

MALP-2, a Mycoplasma lipopeptide with classical endotoxic properties: end of an era of LPS monopoly?

Although some activities of LPS are shared by other bacterial components, for half a century LPS has been regarded as unique in displaying many pathophysiological activities. Here we report on a synthetic lipopeptide, MALP-2 from Mycoplasma fermentans, which expresses potent endotoxin-like activity and whose lethal toxicity is comparable to that of LPS. With the exception of the Limulus lysate gelation test, in which MALP-2 was approximately 1000-fold less active than LPS, the synthetic lipopeptide induced all activities tested for, and in most cases to an extent comparable to that of LPS. Unlike LPS, the biological activities of MALP-2 were expressed both in LPS-responder and in LPS-non-responder mice (BALB/c/l, C57BL10/ScCr), indicating that MALP-2 signaling, unlike that of LPS, is not transduced via the Toll-like receptor (Tlr) 4 protein.MALP-2 expressed no toxicity in normal or sensitized Tlr2 knockout (Tlr2(-/-)) mice indicating that its toxic activity is induced via Tlr2 signaling. The phenomenology of the lethal shock induced by MALP-2 in normal or sensitized mice, i.e. the kinetics of its development and symptoms of illness exhibited by the treated animals, was very reminiscent of the lethal shock induced by LPS.

The role of the liver in the response to LPS: experimental and clinical findings.

The liver plays an important physiological role in lipopolysaccharide (LPS) detoxification and, in particular, hepatocytes are involved in the clearance of endotoxin of intestinal derivation. In experimental shock models, tumor necrosis factor (TNF)-alpha induces hepatocyte apoptosis and lethal effects are due to secreted TNF-alpha and not to cell-associated TNF-alpha. An exaggerated production of TNF-alpha has been reported in murine viral infections, in which mice become sensitized to low amounts of LPS and both interferon (IFN)-gamma and IFN-alpha/beta are involved in the macrophage-induced release of TNF-alpha. The prominent role of LPS and TNF-alpha in liver injury is also supported by studies of ethanol-induced hepatic damage. In humans, evidence of LPS-induced hepatic injury has been reported in cirrhosis, autoimmune hepatitis, and primary biliary cirrhosis and a decreased phagocytic activity of the reticulo-endothelial system has been found in these diseases. The origin of endotoxemia in hepatitis C virus (HCV) infected patients seems to be multifactorial and LPS may be of exogenous or endogenous derivation. In endotoxemic HCV-positive patients responsive to a combined treatment with IFN-alpha/ribavirin (RIB), endotoxemia was no longer detected at the end of the therapeutic regimen. By contrast, 48% of the non-responders to this treatment were still endotoxemic and their monocytes displayed higher intracellular TNF-alpha and interleukin (IL)-1beta levels than responders. Moreover, in responders, an equilibrium between IFN-gamma and IL-10 serum levels was attained. In the non-responders, serum levels of IL-10 did not increase following treatment. This may imply that an imbalance between T helper (Th)1 and Th2 derived cytokines could be envisaged in the non-responders.

Enteric bacteria, lipopolysaccharides and related cytokines in inflammatory bowel disease: biological and clinical significance.

Ulcerative colitis (UC) and Crohn's disease (CD) [inflammatory bowel disease (IBD)] are both characterized by an exaggerated immune response at the gut associated lymphoreticular tissue level. Such an abnormal and dysregulated immune response may be directed against luminal and/or enteric bacterial antigens, as also supported by murine models of inflammatory bowel disease (IBD) caused by organisms such as Citrobacter rodentium and Helicobacter hepaticus. Bacterial endotoxins or lipopolysaccharides (LPS) have been detected in the plasma of IBD patients and an abnormal microflora and/or an increased permeability of the intestinal mucosa have been invoked as cofactors responsible for endotoxemia. At the same time, the evidence that phagocytosis and killing exerted by polymorphonuclear cells and monocytes and the T-cell dependent antibacterial activity are decreased in IBD patients may also explain the origin of LPS in these diseases. In IBD, pro-inflammatory cytokines and chemokines have been detected in elevated amounts in mucosal tissue and/or in peripheral blood, thus suggesting a monocyte/macrophage stimulation by enteric bacteria and/or their constituents (e.g. LPS). On these grounds, in experimental models and in human IBD, anti-cytokine monoclonal antibodies and interleukin receptor antagonists are under investigation for their capacity to neutralize the noxious effects of immune mediators. Finally, the administration of lactobacilli is beneficial in human IBD and, in murine colitis, this treatment leads to a normalization of intestinal flora, reducing the number of colonic mucosal adherent and translocated bacteria.

The gamma subunit of F1 and the PVP protein of F0 (F0I) are components of the gate of the mitochondrial F0F1 H(+)-ATP synthase.

The gamma subunit of the F1 moiety of the bovine mitochondrial H(+)-ATP synthase is shown to function as a component of the gate. Addition of purified gamma subunit to F0-liposomes inhibits transmembrane proton conduction. This inhibition can be removed by the bifunctional thiol reagent diamide. Immunoblot analysis shows that the diamide effect is likely due to disulphide bridging of the gamma subunit with the PVP protein of the F0 sector.

Mitochondrial F0F1 H+-ATP synthase. Characterization of F0 components involved in H+ translocation.

The membrane F0 sector of mitochondrial ATP synthase complex was rapidly isolated by direct extraction with CHAPS from F1-depleted submitochondrial particles. The preparation thus obtained is stable and can be reconstituted in artificial phospholipid membranes to result in oligomycin-sensitive proton conduction, or recombined with purified F1 to give the oligomycin-sensitive F0F1-ATPase complex. The F0 preparation and constituent polypeptides were characterized by SDS-polyacrylamide gel electrophoresis and immunoblot analysis. The functional role of F0 polypeptides was examined by means of trypsin digestion and reconstitution studies. It is shown that, in addition to the 8 kDa DCCD-binding protein, the nuclear encoded protein [(1987) J. Mol. Biol. 197, 89-100], characterized as an intrinsic component of F0 (F0I, PVP protein [(1988) FEBS Lett. 237,9-14]) [corrected] is involved in H+ translocation and the sensitivity of this process to the F0 inhibitors, DCCD and oligomycin.

Relationship between respiratory burst and adhesiveness capacity in elderly polymorphonuclear cells.

Polymorphonuclear cell (PMN) activation was assessed in 30 aged donors, in terms of either adherence to different substrates or superoxide anion (O2-) generation by adhering and suspended cells in response to several agonists. Results showed that PMN in suspension from elderly individuals displayed a phorbol 12-myristate 13-acetate (PMA)-triggered O2- responsiveness which overlapped that seen in the younger counterpart, while a significant decrease of respiratory burst was observed in the presence of formyl-methionyl-leucine-phenylalanine (FMLP). Moreover, in spite of a normal nylon fiber adhesiveness, aged individuals exhibited a reduced PMN adherence to foetal calf serum (FCS)-coated plastic surfaces by using either PMA or FMLP as stimulant. However, elderly adhering cells produced higher amounts of O2- than homologous neutrophils in suspension. Cell pretreatment with anti-CD11b, anti-CD11c and anti-CD18 antibodies led to a further inhibition of PMN adhesion to FCS-coated plates. By contrast, under the same experimental conditions, O2- generation from adhering cells was reduced by using anti-CD18 antibody only. Altogether, these findings provide additional evidence for an imbalance of PMN-mediated functions in the elderly.

Age-related effects of oxidative metabolism and cyclic AMP signaling on neutrophil apoptosis.

Spontaneous as well as Fas-induced polymorphonuclear cell apoptosis is unchanged in the elderly. However, a weak responsiveness to antiapoptotic signals elicited by proinflammatory molecules has been reported in neutrophils isolated from aged humans. To gain insight into this field, here we have evaluated the role of oxidative metabolism and cyclic AMP (cAMP) signaling on age-related neutrophil apoptotic cell death. Results show that although superoxide dismutase (SOD), added exogenously to cell cultures, is able to prolong neutrophil survival in both young and aged individuals, high amounts of the enzyme are further effective in cell cultures of young donors only. Notably, the addition of catalase gives rise to a more striking, yet comparable, inhibition of neutrophil-programmed cell death in both groups of subjects. Furthermore, even low amounts of catalase are enough to restore a normal apoptotic outcome in SOD-treated cell cultures of old donors. Unlike the oxidative metabolism, cAMP signaling activation does not reveal any difference in the apoptotic response of neutrophils isolated from young and aged donors. Thus, supplementation of cell cultures with prostaglandin E2, dibutyryl cAMP or, to a lesser degree, forskolin results in a dose-dependent inhibition of DNA cleavage product appearance in both groups of subjects. The data outline that an impairment of neutrophil antioxidant shield, leading to an augmented cell oxidative load, is likely to occur as a feature of age. This may increase the apoptotic rate of stimulated cells, which may in turn account for the increased susceptibility of elderly individuals to life-threatening infections.

Impairment of T immunoregulatory activities in the induction of antibody specific response in aged humans.

T helper (Th) and T suppressor (Ts) functions on the induction of specific antibody response have been studied in 80 aged individuals by means of a plaque-forming cell assay. Of the subjects 45.2% exhibited a reduction of Ts activity on Ig production by adding Concanavalin A (Con A) to cultures on day 0, while 35.7% of aged donors showed a decrease of Th functions by supplementation of Con A on day 2. A small number of individuals displayed a combined deficit (Th + Ts). Furthermore, these defects seem to be related to soluble suppressive factors which might adhere to cell surface. In fact, preincubation of peripheral blood mononuclear cells (PBMC) before their addition to cultures and resuspension in fresh medium normalized the immunoregulatory defects. On the other hand, overnight supernatants from old PBMC transferred to young PBMC cultures induced the same deficit observed in the aged cell suspensions. Finally, Zinc chloride supplementation to cultures was able to correct the deficient Th activity only. These data suggest an additional defect of immunoregulation in the elderly.