Lithium and the mitogenic response of human lymphocytes

The Potential Role of Lithium as an Antiviral Agent against SARS-CoV-2 via Membrane Depolarization: Review and Hypothesis

Studies on potential treatments of Coronavirus Disease 2019 (COVID-19) are important to improve the global situation in the face of the pandemic. This review proposes lithium as a potential drug to treat COVID-19. Our hypothesis states that lithium can suppress NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasome activity, inhibit cell death, and exhibit immunomodulation via membrane depolarization. Our hypothesis was formulated after finding consistent correlations between these actions and membrane depolarization induced by lithium. Eventually, lithium could serve to mitigate the NLRP3-mediated cytokine storm, which is allegedly reported to be the inciting event of a series of retrogressive events associated with mortality from COVID-19. It could also inhibit cell death and modulate the immune system to attenuate its release, clear the virus from the body, and interrupt the cycle of immune-system dysregulation. Therefore, these effects are presumed to improve the morbidity and mortality of COVID-19 patients. As the numbers of COVID-19 cases and deaths continue to rise exponentially without a clear consensus on potential therapeutic agents, urgent conduction of preclinical and clinical studies to prove the efficacy and safety of lithium is reasonable.

Proliferation and apoptosis of T lymphocytes in patients with bipolar disorder

The aim of the study was to evaluate proliferation capacity and susceptibility to apoptosis of T lymphocytes of patients with bipolar disorder (BD) and to investigate in vitro influence of two standard mood stabilizers: lithium and valproic acid on these parameters using flow cytometry. Our results show that T lymphocytes of BD patients, especially those treated with lithium, have reduced proliferation capacity compared to healthy people. In vitro studies showed that valproic acid reduces the number of cell divisions and percentages of proliferating cells regardless of health status but mainly in very high dose, while lithium has no significant influence on proliferation capacity of patients’ T lymphocytes. Lymphocytes of BD patients are also more prone to apoptosis compared with healthy individuals which is related to high expression of Bax, a pro-apoptotic protein. In vitro lithium protected patients’ lymphocytes from apoptosis proportionally to dose used. Valproic acid protected lymphocytes of patients from apoptosis mainly in therapeutic concentration. Our results show that mood stabilizers used to prevent relapses of the disease have anti-apoptotic effect on T lymphocytes of BD patients but they are not able to improve their proliferation capacity.

Variant-specific patterns and humoral regulation of HP1 proteins in human cells and tissues

We have examined the occurrence and distribution of HP1α and HP1β under in vivo, ex vivo and in vitro conditions. Consistent with a non-essential role in heterochromatin maintenance, both proteins are diminished or undetectable in several types of differentiated cells and are universally downregulated during erythropoiesis. Variant-specific patterns are observed in almost all human and mouse tissues examined. Yet, the most instructive example of HP1 plasticity is observed in the lymph nodes, where HP1α and HP1β exhibit regional patterns that are exactly complementary to one another. Furthermore, whereas HP1α shows a dispersed sub-nuclear distribution in the majority of peripheral lymphocytes, it coalesces into large heterochromatic foci upon stimulation with various mitogens and IL-2. The effect of inductive signals on HP1α distribution is reproduced by coculture of immortalized T- and B-cells and can be confirmed using specific markers. These complex patterns reveal an unexpected plasticity in HP1 variant expression and strongly suggest that the sub-nuclear distribution of HP1 proteins is regulated by humoral signals and microenvironmental cues.

Cancer morbidity in psychiatric patients: influence of lithium carbonate treatment

The relationship between mental diseases and cancer development has been examined in a number of studies but the findings are still inconclusive and suffer from methodological problems. Studies conducted to examine the effect of lithium on malignant cells yielded inconsistent results. The study group included 609 patients treated by lithium carbonate and 2396 controls. A lower but non significant risk (RR = 0.79; CI = 0.17-3.60) to develop non-epithelial tumors was found among lithium carbonate treated psychiatric patients as compared to controls. A significantly (P = 0.05) inverse trend of cancer with lithium dose was observed. The risk of cancer development among each group of psychiatric patients was significantly lower than in the general population (RR = 0.68 for the lithium treated group versus 0.78 for controls). Mental patients have a lower cancer prevalence than the general population and lithium may have a protective effect.

Depressed natural killer cell activity in schizophrenic patients

Factors that suppress natural killer (NK) cell activity were examined in a random sample of 73 schizophrenic patients. NK activity in these patients were compared with 25 healthy age, sex and race matched controls. The mean percent of NK activity was 21% in the schizophrenic group compared with 30% percent in the controls. The difference between these two groups was statistically significant. The mean percent of NK activity in the chronic undifferentiated schizophrenic subgroup and schizoaffective subgroup were 20% and 22% respectively. The degree of suppression of NK activity in the chronic undifferentiated subgroup was higher than in the schizoaffective one, but the difference was not statistically significant. The two subgroups were comparable regarding other immune related variables such as total white cell count, neutrophils, lymphocytes, total protein, albumin, globulin, immunoglobulins and stress. The lower impairment of NK activity in the schizoaffective subgroup may be due to their exposure to lithium which can enhance immune functions. Factors associated with significant suppression of NK activity in schizophrenic patients were physical restraint, number of psychotropic medications, number of chronic non-psychiatric diagnoses and race. Psychosocial stressors were associated with suppression of NK activity but it was not statistically significant. Our results identify factors associated with reduced NK activity observed in certain schizophrenic patients and NK activity in these patients may be the result of interaction between various factors.

Lithium chloride potentiates tumor necrosis factor-mediated cytotoxicity in vitro and in vivo

Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the presence of LiCl, the murine fibrosarcoma cell lines L929 and WEHI 164 clone 13 became greater than 10 times more sensitive to TNF-mediated cytotoxicity. The human tumor cell lines BT20 and HeLa D98/AH2 were also responsive to the cytotoxicity-enhancing effect of LiCl. Other monovalent or divalent cations did not affect TNF-mediated cytotoxicity. The potentiating effect of LiCl on TNF cytotoxicity was largely independent of transcription, and LiCl could be added to the cells as early as 2 hr before or as late as 4 hr after TNF without loss of effectiveness. The mechanism by which LiCl increases the cytotoxic response seems to differ from the sensitizing effect of actinomycin D or interferon gamma, since the latter treatments overcame TNF resistance of several cell lines, whereas LiCl did not. Evidence is presented that LiCl acts, either directly or indirectly, via the TNF-activated phospholipase A2 pathway. In nude mice, a combination of TNF and LiCl led to hemorrhagic necrosis and growth inhibition of L929 tumors, whereas little effect was observed when TNF was administered alone. HeLa D98/AH2 tumors also were sensitive to the potentiating effect of LiCl in vivo. We conclude that LiCl enhances the effectiveness of TNF in vitro and in vivo, results that may have therapeutic implications.

The effect of antidepressants on immune function in mice

Depression or its treatment with antidepressant agents may have an impact on the normal function of the immune system. To address this issue in an animal model, we studied the effect of maprotiline and desipramine treatment of mice on several immunological activities associated with host resistance to cancer and infections. Our results indicate that chronic maprotiline treatment depressed natural killer (NK) cell function, measured in vivo as clearance of tumor cells from the lung or in vitro as cytolytic activity. Cell-mediated immunity, measured as delayed hypersensitivity in vivo and T and B lymphocyte proliferative responses in vitro, was largely unaffected. Although antidepressant toxicity at high concentrations inhibited T, B, and NK cell activity, it is unlikely that this is the basis for the in vivo effects.

Lithium potentiates antigen-dependent stimulation of lymphocytes only under suboptimal conditions

Immunization of hamsters with DNP-BSA in either Freund's complete or incomplete adjuvant led to the induction of antigen reactive lymph node cells. As assessed by in vitro lymphocyte stimulation assays, antigen in complete adjuvant was more effective than antigen in incomplete adjuvant in inducing immunity. Supplementing antigen-stimulated cultures from animals 14 days post-immunization with LiCl led to no enhancement of tritiated thymidine incorporation into cells from animals immunized with antigen in complete adjuvant, but did enhance antigen-dependent stimulation of cells from animals immunized with antigen + incomplete adjuvant. LiCl was, however, able to enhance stimulation of cells from animals immunized with antigen + complete adjuvant at 22 and 29 days post-immunization, when in vitro responsiveness was declining. Lymph node cells from animals optimally immunized antigen + complete adjuvant were fractionated by passage over Sephadex G-10 columns. Sephadex G-10 non-adherent cells, deficient in cells such as macrophages, exhibited a depressed responsiveness to antigen, compared to unfractionated cells, and responsiveness was not restored by LiCl. Stimulation of cells by antigen was found to be inhibited by supplementing the cultures with theophylline or dibutyryl cyclic AMP and this inhibition could be reversed by LiCl. Lithium would, therefore, appear to be able to influence lymphocyte adenylate cyclase. Thus, LiCl can exert an immunopharmacologic effect on in vitro antigen stimulation primarily when conditions are suboptimal, possibly through an influence on cyclic AMP metabolism.

Mechanism of lithium-induced augmentation of T-cell proliferation

The mechanism whereby lithium augments mitogen-stimulated T-cell proliferation was investigated. Lithium in a concentration of 5mM caused a significant increase in interleukin 2 (IL-2) production after phytohemagglutinin (PHA) stimulation. Lithium also caused an increase in interleukin 1 production from peripheral blood monocytes. Lithium did not influence the expression of IL-2 receptors on T-cells. However, lithium did result in increased proliferative response to IL-2 in an IL-2 responsive cell line. Thus, lithium influences the T-cell proliferation response to mitogens in several ways, by stimulation of lymphokine and monokine production as well as by augmenting the response of IL-2 responsive cells to IL-2.

The anti-proliferative effect of lithium chloride on melanoma cells and its reversion by myo-inositol

The effect of LiCl on melanoma cell growth and differentiation was studied in mouse and human melanoma cell lines. LiCl markedly inhibited B16 and HT-144 melanoma cell growth in vitro. Clonogenicity in soft agar of the melanoma cells was also markedly inhibited by LiCl. Pretreatment of B16 mouse melanoma cells with LiCl delayed the appearance of melanoma tumours in syngeneic mice. Growth inhibition of cells was accompanied by morphological and biochemical alterations. LiCl induced cell enlargement and formation of dendrite-like structures. The activity of NADPH cytochrome c reductase, an enzymatic marker of endoplasmic reticulum was significantly (2-3 fold) increased. Addition of myo-inositol to cell cultures partially reversed the anti-proliferative and morphological effects of LiCl on melanoma cells. This finding may suggest that the anti-proliferative effect of LiCl is related to its effect on phosphatidylinositol metabolism.

Lymphocytes from patients receiving lithium do not inhibit CFU-C growth

Lymphocyte subset levels and function were examined in 12 patients on lithium therapy and in 11 healthy hospital personnel. Co-culture of allogeneic human bone marrow cells with monocyte-depleted lymphocyte preparations revealed that CFU-C formation was significantly reduced (mean 43% inhibition) in the presence of normal lymphocytes but not with the patients' lymphocytes (less than 5% inhibition). This did not reflect numerical changes in lymphocyte subsets, since these were similar for control and lithium subjects. T colony formation was significantly depressed in the patient group (P less than 0.05), whereas B colony numbers were similar in both groups (P greater than 0.1). The possible role of HLA-incompatibility affecting CFU-C growth was investigated in co-culture experiments, using lymphocytes from HLA-identical twins, one of whom was receiving lithium. In four separate co-culture experiments, the inhibitory effect was shown with lymphocytes from the non-lithium twin but was not demonstrated by the lithium subject. Addition of lithium in vitro to co-cultures of normal marrow and lymphocytes was found to negate the inhibitory phenomenon in a dose-related manner. It is postulated that granulocytosis induced by the administration of lithium may be a manifestation of changes in a lymphocytic control system.

A controlled study of cellular immune function in affective disorders before and during somatic therapy

Lymphocyte blastogenesis induced by lectins (PHA, Con A, and PWM) was assessed in 27 drug-free patients with unipolar (n = 21) or bipolar (n = 5) depression and 13 normal controls. Fifteen patients were restudied after clinical remission. Symptomatic patients did not differ from controls nor did endogenous and nonendogenous depressions differ in their lymphocyte blastogenesis response to any of the three lectins. However, a significant reduction in lymphocyte blastogenesis with both PHA and Con A stimulation was found following somatic treatment. Cellular immune function appears to be normal in depressed patients, although the somatic therapies are associated with a reduction in this function.

Circulating T-cell subpopulations in lithium-associated granulocytosis

Granulocytosis is a common feature in patients undergoing lithium therapy. With increasing evidence that T lymphocytes play a role in the control of granulopoiesis, we have investigated the effect of lithium administration on circulating levels of T helper and T suppressor cells, as identified by monoclonal antibodies, to determine whether lithium-induced granulocytosis is mediated through changes in peripheral blood T cell subsets. Lithium carbonate was administered to 10 subjects over a 2 week period. Differential leucocyte counts and T, B, T helper and T suppressor lymphocyte enumerations were performed prior to administration of lithium (Day 1) and on 2 occasions (Day 7 and 14) during ingestion of the drug. Ten healthy control subjects were similarly investigated. Small, but significant elevation (p less than 0.05) in neutrophil counts at 7 and 14 days were observed in subjects taking lithium, serum lithium levels at these times were 0.56 +/- 0.27 and 0.68 +/- 0.17 mmol/l, respectively; lymphocyte and monocyte levels were unaffected. The percentages and absolute numbers of circulating T, B, T helper and T suppressor lymphocytes were not significantly altered (p greater than 0.05) during lithium administration and did not differ significantly (p greater than 0.05) from those recorded for the control group. We were thus unable to demonstrate that short-term lithium administration induced changes in the circulating levels of T helper (OKT4+) or T suppressor (OKT8+) cells.

The effects of prostaglandins on the proliferation of cultured human T lymphocytes

The effects of PGE2 on cultured T lymphocytes (CTC) stimulated by either Con A, PHA, or lectin-free IL-2 were studied. PGE2, in a concentration ranging from 100 to 1 ng/ml, consistently and significantly inhibited the proliferation of CTC induced by either PHA or Con A. PGF2 alpha was essentially without effect. Although the degree of inhibition of PHA-treated CTC was increased with suboptimal amounts of PHA, significant inhibition still resulted with optimal PHA concentrations. PGE2, but not PGF2 alpha, was also effective in significantly inhibiting the proliferation of IL-2-treated CTC in a dose-related fashion; however, the addition of suboptimal amounts of IL-2 did not result in greater increases in the degree of inhibition by PGE2. Depleting the CTC of either OKT-4 or OKT-8 phenotypic cells did not abrogate this PGE2 inhibitory effect, indicating that PGE2 does not suppress the proliferative response solely by the activation of suppressor cells with the OKT-8 phenotype. PGE2 also was found to inhibit the production of IL-2 by fresh lymphocytes treated by either optimal or suboptimal amounts of PHA, however, this decrease in production by PGE2 was not necessarily associated with a decrease in the proliferation of these stimulated lymphocytes. Only with low PHA concentrations, where IL-2 production was markedly reduced and barely detectable, was lymphocyte proliferation appreciably reduced by PGE2. In additional experiments, LiCl was added to PGE2 containing cultures to determine whether LiCl could modulate the inhibitor effect of PGE2 of either PHA- or IL-2-stimulated CTC. In these studies, LiCl, in concentrations of 1-10 mM was found to lessen or completely abrogate the reduced PHA proliferative response induced by PGE2. This effect was more pronounced with suboptimal concentrations of PHA than with optimal PHA amounts. In contrast, the PGE2-induced inhibition of IL-2-stimulated CTC was not modified or altered by the addition of LiCl. Thus, these results suggest that LiCl acts at the level of IL-2 production instead of IL-2 action, and that PGE2 inhibits IL-2-induced proliferation of CTC by a different or additional mechanism than for PHA-treated cells. In conclusion, these results, taken as a whole, indicate that PGE2 suppresses the proliferation of stimulated CTC by at least two different mechanisms: 1) by reducing the production of IL-2 by stimulated lymphocytes; and 2) by directly acting on the responding CTC.(ABSTRACT TRUNCATED AT 400 WORDS)