Effect of cations and cation channel blockers on human natural killer cells

Electrolyte imbalance causes suppression of NK and T cell effector function in malignant ascites

BACKGROUND

Malignant ascites commonly occurs in advanced or recurrent stages of epithelial ovarian cancer during peritoneal carcinomatosis and is correlated with poor prognosis. Due to its complex composition of cellular and acellular components malignant ascites creates a unique tumor microenvironment, which mediates immunosuppression and promotes progression of disease. However, the immunosuppressive mechanisms remain poorly understood.

METHODS

In the present study, we explored the antitumor activity of healthy donor NK and T cells directed against ovarian cancer cells in presence of malignant ascites derived from patients with advanced or recurrent peritoneal carcinomatosis. A wide range of methods was used to study the effect of ascites on NK and T cells (FACS, ELISA, EliSpot, qPCR, Live-cell and confocal microscopy, Western blot and electrolyte flux assays). The ascites components were assessed using quantitative analysis (nephelometry, potentiometry and clinical chemistry) and separation methods (dialysis, ultracentrifugal filtration and lipid depletion).

RESULTS

Ascites rapidly inhibited NK cell degranulation, tumor lysis, cytokine secretion and calcium signaling. Similarly, target independent NK and T cell activation was impaired in ascites environment. We identified imbalanced electrolytes in ascites as crucial factors causing extensive immunosuppression of NK and T cells. Specifically, high sodium, low chloride and low potassium content significantly suppressed NK-mediated cytotoxicity. Electrolyte imbalance led to changes in transcription and protein expression of electrolyte channels and impaired NK and T cell activation. Selected inhibitors of sodium electrolyte channels restored intracellular calcium flux, conjugation, degranulation and transcript expression of signaling molecules. The levels of ascites-mediated immunosuppression and sodium/chloride/potassium imbalance correlated with poor patient outcome and selected molecular alterations were confirmed in immune cells from ovarian cancer patients.

CONCLUSION

Our data suggest a novel electrolyte-based mechanism of immunosuppression in malignant ascites of patients with peritoneal carcinomatosis. We show for the first time that the immunosuppression of NK cytotoxicity in coculture assays is correlated to patient poor survival. Therapeutic application of sodium channel inhibitors may provide new means for restoring immune cell activity in ascites or similar electrolyte imbalanced environments.

The Ca2+ Channel Blocker Verapamil Inhibits the In Vitro Activation and Function of T Lymphocytes: A 2022 Reappraisal

Ca²⁺ channel blockers (CCBs) are commonly used to treat different cardiovascular conditions. These drugs disrupt the intracellular Ca²⁺ signaling network, inhibiting numerous cellular functions in different cells, including T lymphocytes. We explored the effect of the CCB verapamil on normal human peripheral blood T cell activation, proliferation, and cytokine production. Cells were activated by ligating CD3 or CD3/CD28 in the presence or absence of verapamil, and the expression of activation-induced cell surface molecules (CD25, CD40L, CD69, PD-1, and OX40), cell proliferation, and cytokine release were assessed by flow cytometry. Verapamil exerted a dose-dependent inhibitory effect on the expression of all the activation-induced cell surface molecules tested. In addition, verapamil diminished T cell proliferation induced in response to CD3/CD28 stimulation. Likewise, the production of Th1/Th17 and Th2 cytokines was also reduced by verapamil. Our data substantiate a potent in vitro suppressive effect of verapamil on T lymphocytes, a fact that might be relevant in patients receiving CCBs.

[Could anaesthesia, analgesia and sympathetic modulation affect neoplasic recurrence after surgery? A systematic review centred over the modulation of natural killer cells activity]

OBJECTIVE

The Natural Killer cells (NK) are an important part of non-specific cellular-mediated and antitumoral immunity. The goal of this review is to recapitulate data published over NK activity during the perioperative period and the influence of anaesthesia, analgesia and modulation of sympathetic system.

DATA SOURCES

Pubmed/Medline database.

STUDY SELECTION AND DATA EXTRACTION

Keywords-based selection, without limit of date: fundamental studies, randomized controlled trials and non-randomized comparative studies.

DATA SYNTHESIS

In human as in animal studies, an important correlation exists between NK activity and prognosis linked to the development of metastasis. The great depression of this cytotoxicity during the perioperative period could be able to compromise host defenses. The influence of anaesthetics and analgesics is important. The effects of the opioids, the agonists and the antagonists of the sympathetic nervous system, the prostaglandins, the NSAIDs, the ketamine, the hypnotics and the locoregional anaesthesia are systematically reviewed. The limits of experimental model presented are covered.

CONCLUSION

The effects of anaesthetic/analgesic drugs and techniques, the consequences of sympathomodulation on NK activity are numerous and sometimes opposite. It is important for the anaesthesiologist to keep in mind that the long term consequences of his techniques on the patients' outcome must be clarified.

Infiltration anesthetic lidocaine inhibits cancer cell invasion by modulating ectodomain shedding of heparin-binding epidermal growth factor-like growth factor (HB-EGF)

Although the mechanism is unknown, infiltration anesthetics are believed to have membrane-stabilizing action. We report here that such a most commonly used anesthetic, lidocaine, effectively inhibited the invasive ability of human cancer (HT1080, HOS, and RPMI-7951) cells at concentrations used in surgical operations (5-20 mM). Ectodomain shedding of heparin-binding epidermal growth factor-like growth factor (HB-EGF) from the cell surface plays an important role in invasion by HT1080 cells. Lidocaine reduced the invasion ability of these cells by partly inhibiting the shedding of HB-EGF from the cell surface and modulation of intracellular Ca2+ concentration contributed to this action. The anesthetic action of lidocaine (sodium channel blocking ability) did not contribute to this anti-invasive action. In addition, lidocaine (5-30 mM), infiltrated around the inoculation site, inhibited pulmonary metastases of murine osteosarcoma (LM 8) cells in vivo. These data point to previously unrecognized beneficial actions of lidocaine and suggest that lidocaine might be an ideal infiltration anesthetic for surgical cancer operations.

Effect of procaine hydrochloride on cyanide intoxication and its effect on neuronal calcium in mice

Cyanide intoxication in mice can be antagonized by the local anesthetic, procaine HCI, either alone or in combination with sodium nitrite and/or sodium thiosulfate. Antitoxic potency, derived from LD50 values, was compared in groups of mice pretreated with sodium nitrite (43.9 mg/kg i.p.), sodium thiosulfate (1 g/kg i.p.), and procaine HCI (37.0 mg/kg i.p.) either alone or in various combinations. The results of present study indicated that procaine HCI provides a significant protection against the lethal effects of potassium cyanide. Dose-response studies revealed procaine hydrochloride pretreated 3 min before KCN, at doses of 18.48-73.9 mg/kg, produced significant elevation of KCN LD50, moreover it has a good dose-effect relationship, but its antidotal effect was weaker than sodium nitrite or sodium thiosulfate when they were administered alone. The protective effect of sodium nitrite and sodium thiosulfate was enhanced with procaine HCI. When procaine was administered in combination both with sodium nitrite and sodium thiosulfate, its protective effects were further enhanced. Its antitoxic potency is 6.22. The effects of procaine on antagonizing the cyanide-induced whole-brain total calcium increase were also studied. KCN (7 mg/kg i.p.) significantly increased whole-brain total calcium level from 28.37 +/- 0.75 to 48.05 +/- 1.06 mg/g dry wt within 30 min, which can be prevented by procaine pretreated 15 min before KCN. One of the possible mechanism of procaine on antagonizing cyanide toxicity seems, at least, related to its effect on inhibiting the cyanide-induced neuronal calcium increase and maintaining the homeostasis of neuronal calcium.

Ropivacaine and lidocaine inhibit proliferation of non-transformed cultured adult human fibroblasts, endothelial cells and keratinocytes

Local anaesthetics are known to affect a variety of cell functions, many of which are involved in the inflammatory response. Local anaesthetics have also been shown to influence cell proliferation. The aim of this study was to examine the effect of two local anaesthetics (ropivacaine and lidocaine) on cell proliferation of cultured human fibroblasts, vascular endothelial cells and epithelial cells, i.e. keratinocytes, as earlier studies have not included primary human cell types. Significant inhibition of fibroblast proliferation was observed with concentrations of 50 microM ropivacaine or 100 microM lidocaine in 1% newborn calf serum and 500 microM ropivacaine or lidocaine in 10% newborn calf serum. The proliferation of endothelial cells was significantly inhibited by 1 mM ropivacaine in 5% human serum and 500 microM ropivacaine or 100 microM lidocaine in 40% human serum. Significant inhibition was not obtained with lidocaine when these cells were cultured in 5% HS. Significant inhibition of keratinocytes was obtained with 100 microM ropivacaine and 500 microM lidocaine. The effective concentrations are within the range of therapeutical concentrations in vivo and there seems to be a general correlation between the local anaesthetic potency and the inhibiting effect on cell proliferation. This suggest a mechanism by which local anaesthetics may exhibit anti-hyperproliferative effects in clinical situations.

Opposite effects of amiloride and amiloride analogues on activation of natural killer cytotoxicity by the phorbol ester TPA and gamma-interferon

Amiloride, a K(+)-sparing diuretic used as an Na+/H+ exchange inhibitor, blocked the activation of human natural killer (NK) activity against K562 cells by either the phorbol ester TPA or gamma-interferon. However, this stimulation was not blocked by 5-(N,N-hexamethylene)amiloride, a potent inhibitor of Na+/H+ exchange. Spontaneous NK activity was inhibited by this amiloride analogue as well as by 5-(N-methyl-N-guanidinocarbonylmethyl) amiloride, another potent inhibitor of exchange, but only in concentrations 30-80 times higher than those used to inhibit Na+/H+ exchange. The analogue phenamil amiloride blocked NK activity in concentrations found to inhibit epithelial Na+ channels, whereas tetrodotoxin, the specific inhibitor of voltage-dependent Na+ channels, had no effect. These results indicate that Na+/H+ exchange is not essential either for spontaneous NK activity or for its activation by TPA and gamma-interferon. They also suggest the involvement of voltage-independent Na+ channels in NK activity.

Responses of murine natural killer cells to binding of the fungal target Cryptococcus neoformans

Natural killer (NK) cells bind to and inhibit the growth of the fungal target Cryptococcus neoformans. Since C. neoformans is structurally and chemically distinct from the standard tumor cell target used in the model of NK cell-mediated cytotoxicity, this study was designed to investigate the NK cell response after binding to cryptococci. Transmission electron micrographs and three-dimensional reconstructions of NK cell-cryptococci conjugates demonstrated focusing of the NK cell centrioles and Golgi apparatus toward the cryptococcal attachment site. NK cell cytoskeletal changes after cryptococcal binding were confirmed by immunofluorescence studies in which NK cells were allowed to bind to cryptococci in Mg2(+)-containing, Ca2(+)-free medium. One hour after the addition of Ca2+ to the preformed conjugates, the bound NK cells demonstrated a significant increase in the percentage of microtubule organizing centers focused toward the cryptococcal binding site. Colchicine, a drug that inhibits microtubule assembly, did not affect NK cell-cryptococci binding but abrogated NK cell-mediated cryptococcal growth inhibition, indicating that microtubule assembly, an important prerequisite for the secretory process, is not required for NK cell-cryptococci binding but is essential for inhibition of cryptococcal growth. In addition, the Ca2+ channel-blocking reagents, lidocaine and verapamil, did not affect NK cell-cryptococci binding but blocked the NK cell-mediated anticryptococcal activity, suggesting that a Ca2+ flux is essential for inhibition of cryptococcal growth. Considered together, these data indicate that NK cells respond to binding of a target cell that has a capsule and cell wall, in addition to a cell membrane, in a manner similar to that seen following binding to target cells that are surrounded by only a cell membrane; however, the response of the NK cells to the binding of C. neoformans is slower and possibly less efficient than the response after tumor cell binding.