Keren Shakhar

Attenuation of the Tumor-promoting Effect of Surgery by Spinal Blockade in Rats

Background The perioperative period is characterized by a state of immunosuppression, which was shown in animal studies to underlie the promotion of tumor metastasis by surgery. As this immunosuppression is partly ascribed to the neuroendocrine stress response, the authors hypothesized that spinal blockade, known to attenuate this response, may reduce the tumor-promoting effect of surgery. Methods Fischer-344 rats were subjected to a laparotomy during general halothane anesthesia alone or combined with either systemic morphine (10 mg/kg) or spinal block using bupivacaine (50 &mgr;g) with morphine (10 &mgr;g). Control groups were either anesthetized or undisturbed. Blood was drawn 5 h after surgery to assess number and activity of natural killer cells, or rats were inoculated intravenously with MADB106 adenocarcinoma cells, which metastasize only to the lungs. Metastatic development was assessed by quantifying lung retention of tumor cells 24 h after inoculation or by counting pulmonary metastases 3 weeks later. Results Laparotomy conducted during general anesthesia alone increased lung tumor retention up to 17-fold. The addition of spinal block reduced this effect by 70%. The number of metastases increased from 16.7 ± 10.5 (mean ± SD) in the control group to 37.2 ± 24.4 after surgery and was reduced to 10.5 ± 4.7 during spinal block. Systemic morphine also reduced the effects of surgery, but to a lesser degree. Natural killer cell activity was suppressed to a similar extent by surgery and by anesthesia alone. Conclusions The addition of spinal blockade to general halothane anesthesia markedly attenuates the promotion of metastasis by surgery.

Suppression of NK cell activity and of resistance to metastasis by stress: A role for adrenal catecholamines and β-adrenoceptors

Although acute stress has been reported to suppress natural killer cell activity (NKA) and host resistance to metastasis, it is unclear whether the sympathetic nervous system (SNS) has a role in these effects. The current study in Fischer 344 rats assessed the involvement of adrenal catecholamines and β1- and β2-adrenoceptors in mediating these deleterious effects of swim stress. In addition to assessing the number and activity of NK cells following swim stress, we used a tumor model based on the MADB106 mammary adenocarcinoma line: this syngeneic tumor metastasizes only to the lungs, and its lung tumor retention (LTR) and metastatic colonization are highly sensitive to NKA. The findings indicate that stress increased both LTR, assessed 24 h after inoculation, and the number of lung metastases, counted 3 weeks later. These effects were attenuated or completely abolished by the ganglionic blocker chlorisondamine (3 mg/kg i.p.), by adrenal demedullation, by a selective β-adrenergic antagonist (nadolol, 0.4 mg/kg), and additively by a selective β1- (atenolol, 1–6 mg/kg) and a selective β2-antagonist (either butoxamine 4–32 mg/kg or ICI-118,551 0.3–8 mg/kg). Stress also suppressed NKA, and adrenal demedullation prevented this suppression. Administration of adrenaline (0.1–1 mg/kg) or of a β-adrenergic agonist (metaproterenol, 0.8 mg/kg), in physiologically relevant doses, suppressed NKA in a dose-dependent manner, and increased LTR to levels characteristic of swim stress. Taken together, these findings suggest that acute stress, by releasing catecholamines from the adrenal glands and activating β1- and β2-adrenoceptors, suppresses NKA and consequently compromises resistance to NK-sensitive metastasis.

Marginating pulmonary-NK activity and resistance to experimental tumor metastasis: suppression by surgery and the prophylactic use of a β-adrenergic antagonist and a prostaglandin synthesis inhibitor☆

Surgery is imperative for cancer treatment, but was suggested to suppress immunity and facilitate metastasis. Here we study the involvement of catecholamines and prostaglandins (PG) in such outcomes, and the role played by marginating-pulmonary (MP)-NK cells in controlling MADB106 metastasis. Non-operated and laparotomized F344 rats were injected postoperatively with a PG synthesis inhibitor (indomethacin, 4 mg/kg i.p.), a beta-blocker (nadolol, 0.6 mg/kg s.c.), both drugs, or vehicle. Rats were then inoculated intravenously with non-immunogenic syngeneic MADB106 cells, and 24 h later lung tumor retention was assessed, or 3 weeks later lung metastases were counted. Additionally, 12 h after surgery we harvested MP-NK cells and circulating-NK cells and compared their numbers and cytotoxicity against MADB106 cells and standard YAC-1 target cells. Surgery significantly increased MADB106 metastasis. Nadolol and indomethacin reduced this effect by approximately 50% when used alone, and significantly more (75%) when used together. Only MP-leukocytes exhibited NK cytotoxicity against MADB106 cells. Surgery markedly suppressed it, and nadolol and indomethacin additively restored it. Similar effects were observed assessing MP-NK and circulating-NK cytotoxicity against YAC-1 target cells. Alterations in the numbers of NK cells were partly associated with alterations in total MP-NK activity, but not with circulating-NK activity. Last, administrating nai ve rats with physiologically relevant doses of a beta-adrenergic agonist (metaproterenol), and/or with PGE2, additively and independently of each other promoted MADB106 metastasis, simulating the effects of surgery. These findings point at potential prophylactic measures in cancer patients undergoing surgery, and suggest a role for MP-NK cells in resisting metastasis of apparently insensitive tumors.

Prostaglandin E2 Suppresses NK Activity In Vivo and Promotes Postoperative Tumor Metastasis in Rats

AbstractBackground: Prostaglandins (PGs) were shown in vitro to suppress several functions of cellular immunity. It is unclear, however, whether physiological levels of PGs can suppress cellular immunity in vivo and whether such suppression would compromise postoperative host resistance to metastasis. Methods: Fischer 344 rats were administered PGE2 in doses (18 to 300 μg/kg subcutaneously) that increased the serum levels approximately 2- to 4-fold. We then assessed the number and activity of circulating natural killer (NK) cells, as well as rats’ resistance to experimental metastasis of a syngeneic NK-sensitive tumor (MADB106). To study whether endogenously released PGs after surgery compromise these indices, we tested whether laparotomy adversely affects them and whether a cyclooxygenase-synthesis inhibitor, indomethacin (4 mg/kg), attenuates these effects. Results: PGE2 dose-dependently suppressed NK activity per NK cell and dose-dependently increased 4- and 24-hour MADB106 lung tumor retention (LTR); 240 μg/kg of PGE2 quadrupled the number of lung metastases counted 3 weeks later. Selective depletion of NK cells abrogated the promotion of LTR by PGE2. Surgery significantly suppressed NK activity and increased MADB106 LTR, and indomethacin halved these effects without affecting nonoperated rats. Conclusions:PGE2 is a potent in vivo suppressor of NK activity, and its postoperative release may promote tumor recurrence.

Differences in number and activity of peripheral natural killer cells in primary versus secondary recurrent miscarriage

OBJECTIVE To compare peripheral natural-killer (NK) cell numbers and activity in women with primary recurrent miscarriage, secondary recurrent miscarriage and controls. DESIGN Observational study. Academic medical center. PATIENT(S) Thirty-eight women with primary recurrent miscarriage, 29 women with secondary recurrent miscarriage, and 25 control women. INTERVENTION(S) None.[1] The proportion of NK cells in the total lymphocyte population, [2] the concentration of NK cells per microliter of blood, and [3] NK activity (NKA), using both standard and whole-blood assays. RESULT(S) Primary aborters had the highest proportion and concentration of NK cells and had the highest activity using the standard assay. Secondary aborters had an intermediate level of these NK cell indices, whereas the control patients had the lowest levels. Using the whole-blood NKA assay, the differences between primary and secondary aborters were most apparent: primary aborters had significantly higher NKA than did either secondary aborters or control women (72, 40, and 35 lytic units, respectively). Approximately 50% of the variability in NKA could be attributed to differences in concentrations of NK cell per microliter of blood. CONCLUSION(S) The higher NKA evident in primary recurrent miscarriage and the reported higher efficacy of immunotherapy in primary aborters support the involvement of NK cells in the etiology of primary recurrent miscarriage.

Timing within the menstrual cycle, sex, and the use of oral contraceptives determine adrenergic suppression of NK cell activity

Physiological responses that involve adrenergic mechanisms, such as stress-induced changes in cardiovascular indices, were reported to fluctuate along the menstrual cycle. Metastatic development following surgery was also reported to vary according to the menstrual phase during which a primary breast tumour was removed. Natural killer (NK) cells are believed to play an important role in controlling metastases. Our recent studies in rats demonstrated that adrenergic suppression of NK activity and of resistance to metastasis is more profound during oestrous phases characterized by high levels of oestradiol. In the current study in humans, we examined the in vitro impact of a β-adrenergic agonist, metaproterenol (MP), on NK activity, comparing blood drawn from (a) women tested at 3–4 different phases of their menstrual cycle (n = 10), (b) women using oral contraceptives (OC) (n = 10), and (c) men (n = 7). NK activity in each blood sample was assessed in the presence of 5 different concentrations of MP (10–8M to 10–6M), and in its absence (baseline). The results indicated marked group differences in the magnitude of NK suppression by MP: EC50was 2.6-fold lower in the luteal phase compared to the follicular phase, and 1.8-fold lower in OC users compared to men, who were least susceptible to the effects of MP. No significant group differences or menstrual effects in baseline levels of NK activity were evident. These findings provide the first empirical evidence for menstrual regulation of adrenergic impact on cellular immune competence. Relevance of these findings to the relation between the timing of breast cancer excision within the menstrual cycle and survival rates is discussed.

The effects of a Chinese herb formula, anti-cancer number one (ACNO), on NK cell activity and tumor metastasis in rats.

The effects of anti-cancer number one (ACNO), a 19-herb Chinese formula used to treat cancer patients, were studied in F344 rats. In the first study, the number and activity of circulating NK cells were evaluated following 18 days of oral consumption of 0.1, 0.5, or 2 g/kg/day. The second study assessed the effect of ACNO on resistance to metastasis of the MADB106 tumor line, a syngeneic mammary adenocarcinoma that metastasizes only to the lungs and is highly sensitive to NK activity (NKA) in vivo. Resistance to metastasis was assessed under baseline conditions and following the administration of a beta-adrenergic agonist, metaproterenol (MP). MP was used to simulate sympathetic response to stressful conditions, and was previously shown to suppress resistance to MADB 106 metastasis. The results of the first study indicated a dose-dependent increase in NKA per ml of blood and per NK cell, with no significant changes in blood concentration of NK cells. In the second study, whereas MP caused a 4.5-fold increase in the number of metastases in untreated rats, only a 2.3-fold increase occurred in rats treated with ACNO. No significant improvement in baseline levels of resistance to metastasis was observed. These findings indicate the importance of studying ACNO under stressful conditions in patients with potentially metastasizing tumors. This may prove particularly important during the perioperative period, spanning from the detection of the primary tumor to postoperative treatment. During this critical period, psychological and physiological stress responses are known to cause massive immunosuppression, which was suggested to promote metastatic development.

Timing within the oestrous cycle modulates adrenergic suppression of NK activity and resistance to metastasis: possible clinical implications

Clinical observations suggest that the rate of metastatic development and long-term mortality following surgery in breast cancer patients is influenced by the menstrual phase during which surgery is conducted. The menstrual cycle is known to modulate various physiological responses and medical conditions that involve adrenergic mechanisms (e.g., asthma). Natural killer activity (NKA), an immune function controlling metastasis, is suppressed following surgery, and in vitro by adrenaline. We therefore hypothesize that the clinical observation may be partly attributable to surgery-induced adrenergic suppression of NK-dependent resistance to metastasis, a suppression that depends on menstrual phase during surgery. To test this hypothesis in rats, 140 F344 females at different phases of their oestrous cycle were injected with a β-adrenergic agonist, metaproterenol (MP) (0.4 or 0.8 mg kg–1, s.c.), or with vehicle, before i.v. inoculation with MADB106 tumour cells. This syngeneic mammary adenocarcinoma line metastasizes only to the lungs, and is highly sensitive to NKA. In a second experiment, the suppression of NKA by MP was studied in vitro in blood drawn at different phases of the oestrous cycle (n = 36). Finally, the effects of stress on the number and activity of NK cells were assessed along the oestrous cycle (n = 71). The findings indicate that the suppressive effects of MP on resistance to metastasis and on NKA, are significantly greater during the oestrous phase characterized by high oestradiol levels (D3/proestrus/oestrus). Similarly, NKA per cell was suppressed by stress only during this phase. In untreated animals, in which inadvertent stress was minimized, no effects of the oestrous cycle on NKA or on resistance to metastasis were evident. These findings indicate that the oestrous cycle modulates adrenergic suppression of NKA and of resistance to metastasis. The relevance of these findings to the above clinical observation, as well as that of our related findings in women from a parallel study, is discussed.

Sleep, fatigue, and NK cell activity in healthy volunteers : Significant relationships revealed by within subject analyses

Poor sleep is thought to compromise health partially through its effect on immune function. Although experimental studies have shown that sleep deprivation reduces natural killer cell activity (NKCA) within individuals, cross-sectional studies of individuals in ordinary life have often failed to find such a relationship. The current study compared cross-sectional and longitudinal approaches to explore the association between sleep and NKCA. The relationship between NKCA and fatigue was also studied since individuals who are highly fatigued due to various clinical conditions often exhibit reduced NKCA. In the present study, fatigue and amount of sleep were assessed by self-report, and NKCA was assessed in peripheral blood samples collected from each of 45 healthy women at two time points approximately one month apart. Using cross-sectional analysis for each of the two sessions, sleep was related to NKCA only in the second session. Fatigue was not related to NKCA at either session. A within-subject design, however, revealed that an increase in the amount of sleep and decrease in levels of fatigue were related to an increase in NKCA. The current findings suggest that NKCA varies with amount of sleep or fatigue within an individual, and that this relationship may often be masked by large interpersonal differences in cross-sectional studies.

Why Do We Feel Sick When Infected--Can Altruism Play a Role?

When we contract an infection, we typically feel sick and behave accordingly. Symptoms of sickness behavior (SB) include anorexia, hypersomnia, depression, and reduced social interactions. SB affects species spanning from arthropods to vertebrates, is triggered nonspecifically by viruses, bacteria, and parasites, and is orchestrated by a complex network of cytokines and neuroendocrine pathways; clearly, it has been naturally selected. Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities. How could SB persist? Former explanations focused on individual fitness, invoking improved resistance to pathogens. Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?