Characterization of biological response modifier release by human monocytes cultured in suspension in serum-free medium

Tofacitinib versus methotrexate in rheumatoid arthritis

BACKGROUND

Methotrexate is the most frequently used first-line antirheumatic drug. We report the findings of a phase 3 study of monotherapy with tofacitinib, an oral Janus kinase inhibitor, as compared with methotrexate monotherapy in patients with rheumatoid arthritis who had not previously received methotrexate or therapeutic doses of methotrexate.

METHODS

We randomly assigned 958 patients to receive 5 mg or 10 mg of tofacitinib twice daily or methotrexate at a dose that was incrementally increased to 20 mg per week over 8 weeks; 956 patients received a study drug. The coprimary end points at month 6 were the mean change from baseline in the van der Heijde modified total Sharp score (which ranges from 0 to 448, with higher scores indicating greater structural joint damage) and the proportion of patients with an American College of Rheumatology (ACR) 70 response (≥70% reduction in the number of both tender and swollen joints and ≥70% improvement in three of five other criteria: the patient's assessment of pain, level of disability, C-reactive protein level or erythrocyte sedimentation rate, global assessment of disease by the patient, and global assessment of disease by the physician).

RESULTS

Mean changes in the modified total Sharp score from baseline to month 6 were significantly smaller in the tofacitinib groups than in the methotrexate group, but changes were modest in all three groups (0.2 points in the 5-mg tofacitinib group and <0.1 point in the 10-mg tofacitinib group, as compared with 0.8 points in the methotrexate group [P<0.001 for both comparisons]). Among the patients receiving tofacitinib, 25.5% in the 5-mg group and 37.7% in the 10-mg group had an ACR 70 response at month 6, as compared with 12.0% of patients in the methotrexate group (P<0.001 for both comparisons). Herpes zoster developed in 31 of 770 patients who received tofacitinib (4.0%) and in 2 of 186 patients who received methotrexate (1.1%). Confirmed cases of cancer (including three cases of lymphoma) developed in 5 patients who received tofacitinib and in 1 patient who received methotrexate. Tofacitinib was associated with increases in creatinine levels and in low-density and high-density lipoprotein cholesterol levels.

CONCLUSIONS

In patients who had not previously received methotrexate or therapeutic doses of methotrexate, tofacitinib monotherapy was superior to methotrexate in reducing signs and symptoms of rheumatoid arthritis and inhibiting the progression of structural joint damage. The benefits of tofacitinib need to be considered in the context of the risks of adverse events. (Funded by Pfizer; ORAL Start ClinicalTrials.gov number, NCT01039688.).

Proatherogenic and proinflammatory properties of immune complexes prepared with purified human oxLDL antibodies and human oxLDL

Immune complexes (IC) prepared with human low density lipoprotein (LDL) and rabbit LDL antibodies induce foam cell transformation of human macrophages and activate the release of proinflammatory mediators by human macrophages and THP-1 cells. Because the affinity of human oxidized LDL (oxLDL) antibodies is lower than that of rabbit antibodies, IC formed with human antibodies could have limited pathogenic potential. Immune complexes prepared with human oxidized LDL (oxLDL) and purified human oxLDL antibodies (predominantly of the IgG1 and IgG3 isotypes) were presented to THP-1 cells using two protocols previously described in studies of the properties of LDL-IC prepared with rabbit antibodies. OxLDL/human oxLDL antibody IC immobilized by adsorption to red blood cells (RBC) induced the release of significantly higher levels of TNF from THP-1 cells (872-313 pg/ml) than oxLDL adsorbed to RBC (461-75.6 pg/ml) and caused a higher degree of cholesterol ester accumulation in the same cells (5.4-0.77 in cells incubated with IC-coated RBC vs 1.99-1.16 in oxLDL-coated RBC). Insoluble IC prepared with oxLDL/human oxLDL antibody were even more effective in promoting intracellular accumulation of cholesterol in THP-1 cells (total cholesterol = 53.8-13.5 and cholesterol esters = 24.0-7.2 mg/l in THP-1 cells incubated with insoluble IC (200 micrograms) vs total cholesterol = 32.4-8.2 and cholesterol esters = 7.7 +/- 2.8 micrograms/l in THP-1 cells incubated with an identical concentration of oxLDL) and also induced the release of TNF. Thus we have demonstrated that IC prepared with human oxLDL and human oxLDL antibodies have the same atherogenic and proinflammatory properties as IC prepared with human LDL and rabbit LDL antibodies. This strongly supports the concept that modified LDL-IC present in circulation and/or tissues play an important pathogenic role in arteriosclerosis.

Nonadherent cultures of human monocytes kill Mycobacterium smegmatis, but adherent cultures do not

Human peripheral blood monocytes are permissive for the growth of Mycobacterium tuberculosis, but the fate of nonpathogenic Mycobacterium smegmatis in these cells is not known. Since M. smegmatis may be used as a host with which to express and screen for M. tuberculosis genes needed for survival in monocytes, we determined whether human peripheral blood monocytes could restrict the growth of Mycobacterium smegmatis. Adherent human peripheral blood monocytes were permissive for the growth of M. smegmatis, as measured by ex vivo [3H]uracil uptake. However, human peripheral blood monocytes which were cultured nonadherently in Teflon wells were able to restrict the growth of M. smegmatis while remaining permissive for the growth of M. tuberculosis H37Ra. The loss of viability of M. smegmatis in nonadherent cells was correlated with an increase in nonspacious phagocytic vacuoles. The killing of M. smegmatis was not blocked by NG-monomethyl-L-arginine, suggesting that it was not due to the production of reactive nitrogen intermediates. Incubation of the monocytes for 1 to 7 days before infection had no effect on the fate of M. smegmatis, suggesting that adherence versus nonadherence, and not differentiation, was the key determinant for the difference in functional ability. Nonadherent human peripheral blood monocytes may be a more appropriate model than adherent cells for the study of factors employed by bacterial to survive within monocytes and for selection screening of bacterial genes needed for intracellular survival.

Characterization of inhibition of Mycobacterium avium replication in macrophages by normal human serum

Serum from some AIDS patients permits the rapid multiplication of Mycobacterium avium in cultured human macrophages. Serum from human immunodeficiency virus-negative individuals inhibits replication. The characteristics of the serum-induced inhibition were examined here. M. avium 7497 serovar 4 grew exponentially in macrophages when they were cultured in serumless medium. Growth was measured by determining the CFU after infected macrophages were lysed at 0 to 7 days after infection. Normal AB serum (5 to 10%) added to infected macrophages resulted in an initial 4-day lag of bacterial growth followed by rapid replication from 4 to 7 days. Serum also inhibited bacterial replication in medium without macrophages. This inhibition was not biphasic but was sustained over 7 days. Macrophage-associated M. avium became less responsive to serum inhibitor within 24 h after infection of macrophages. Within 2 days of culture, M. avium no longer responded to inhibitor. Replication of macrophage-derived M. avium (Vi) was in some instances serum inhibitable and at other times was enhanced by serum, when it was used to infect fresh macrophages. The Vi phenotype remained serum inhibitable without macrophages. Preinfection of macrophages with heat-killed M. avium did not alter serum-induced bacterial inhibition or escape from inhibition.

Long term cultures of human monocytes in vitro. Impact of GM-CSF on survival and differentiation

In vitro differentiation of human monocytes (Mo) provides large amounts of mature and functionally competent macrophages (M phi) which may be used as potentially powerful anticancer agents for adoptive immunotherapy. Granulocyte macrophage-colony stimulating factor (GM-CSF) was evaluated for its ability to influence long term cultures of Mo-derived M phi. Large quantities of Mo isolated by leukapheresis and elutriation were cultured in non-adherent cell culture bags or in plastic flasks with or without GM-CSF. At various stages of differentiation, GM-CSF treated M phi were recovered and assayed for survival, morphology, surface antigens, functional properties and proliferation in comparison with control M phi. In the present paper, we demonstrate that GM-CSF at a concentration of 50 U/ml (5 ng/ml) promotes better cell survival and the differentiation of Mo into M phi displaying certain morphological differences as compared to control M phi such as an increased expression of Max-1 antigen, CR3 and Fc gamma II receptors, higher phagocytic properties and increased capacities of cytotoxicity and TNF secretion when the cells are further activated by IFN-gamma. Furthermore, GM-CSF treated cells exhibit a low-grade proliferation although the nature of the proliferating cells has not been entirely elucidated. We conclude that the GM-CSF treated M phi would be particularly suitable for adoptive immunotherapy.

Inhibition by normal human serum of Mycobacterium avium multiplication in cultured human macrophages

Normal human serum used as a protein supplement in RPMI 1640 medium inhibited growth in blood-derived human macrophages (MP) of virulent Mycobacterium avium serovars 4 and 8, derived from patients with acquired immunodeficiency syndrome, but not virulent Mycobacterium tuberculosis. A defined serum substitute (SS) promoted the intramacrophage growth of M. avium but not of M. tuberculosis. The effects of serum or SS were measured by counting viable bacteria in lysates of the MP at 0, 4, and 7 days after their infection by the bacteria. Neither serum nor SS inhibited or enhanced M. avium growth in the absence of MP. The results suggest that a nutrient essential for intracellular replication of M. avium is made by MP from a pronutrient present in both SS and serum and that something in serum inhibits MP conversion of the pronutrient to nutrient. This inhibition may be an important mechanism of native resistance against M. avium in normal people.

Low density lipoprotein metabolism by human macrophages activated with low density lipoprotein immune complexes. A possible mechanism of foam cell formation

Human macrophages play a key role in atherogenesis and are believed to be the progenitors of the cholesteryl ester (CE)-laden foam cells present in early atherosclerotic lesions. Several mechanisms by which macrophages accumulate CE have been recently described. One involves a perturbation in LDL metabolism subsequent to macrophage activation. Thus, we decided to study the effect of macrophage activation by immune complexes on N-LDL metabolism. Initially, LDL-containing immune complexes (LDL-IC) were chosen, since increased plasma levels of these IC have been reported in patients with coronary heart disease. Human macrophages stimulated for 22 h with LDL-IC (250 micrograms/ml) and incubated afterwards for 20 h with 10 micrograms/ml 125I-N-LDL showed a six- and fourfold increase in the accumulation and degradation, respectively, of 125I-N-LDL over the values observed in nonstimulated cells. Scatchard analysis of 125I-N-LDL-specific binding suggests an increase (20-fold) in the number of LDL receptors in macrophages stimulated with LDL-IC. We studied other immune complexes varying in size and antigen composition. Some of the IC were able to stimulate, although to a lesser degree, the uptake of N-LDL by macrophages. Lipoprotein IC are more efficient and have the greatest capacity to increase N-LDL uptake and CE accumulation. We conclude that human macrophage activation by LDL-IC leads to an increase in LDL receptor activity and promotes in vitro foam cell formation.

Inhibition by 1,25(OH)2-vitamin D3 of the multiplication of virulent tubercle bacilli in cultured human macrophages

Historically, sunlight has seemed to fortify antituberculosis resistance. Evidence is presented here suggesting a role for vitamin D in this effect. The active metabolite of this photosynthesized vitamin, 1,25-dihydroxy-vitamin D3 (1,25D), promotes maturation and activation of human monocytes and macrophages (MPs). Therefore, it was tested for ability to protect MPs against virulent tubercle bacilli. MPs were derived by 7-day culture from blood monocytes, infected with the bacilli, and exposed to 1,25D in several regimens. Their inhibition of bacilli was measured by lysing samples of the cultures at 0, 4, and 7 days after infection and making bacillary CFU counts from serial dilutions of the lysates. 1,25D enabled MPs to slow or stop bacillary replication. Autologous serum supported the 1,25D-induced protection because the vitamin was not effective in medium supplemented with a serum substitute and was less effective in a heterologous AB serum than in autologous serum. The protection developed rapidly and could be induced even when 1,25D was added 3 days after infection. A concentration on the order of 4 micrograms/ml was needed for protection by the regimens used in these experiments. That is considerably higher than normal circulating concentrations of 1,25D but could be reached in infectious granulomas, because MPs can make 1,25D from precursor 25-hydroxyvitamin D3. The precursor circulates at levels 10(3) higher than those of 1,25D and is directly influenced by dietary intake or photosynthetic production of vitamin D. These results identify 1,25D as an immunomodulator which can reproducibly activate human MPs to express tuberculoimmunity. They connect vitamin D, sunlight, and tuberculoimmunity and suggest that vitamin D should be considered a vital factor in the practical control of tuberculosis.

Low density lipoprotein metabolism in human macrophages stimulated with microbial or microbial-related products

To determine whether stimulation of macrophages with products related to, or released as a consequence of, infectious processes could play a role in inducing the formation of foam cells, we studied the metabolism of native and acetylated low density lipoprotein (LDL) by human macrophages stimulated with lipopolysaccharide (LPS), muramyl dipeptide (MDP), polyinosinic:polycytidilic acid (Poly I:Poly C) and gamma-interferon. Cholesteryl ester (CE) synthesis by macrophages stimulated with LPS, MDP and Poly I:Poly C was markedly increased when the cells were incubated with native LDL (p less than 0.05). When incubated with acetylated LDL, LPS-stimulated macrophages showed a depression in CE synthesis (p less than 0.05). When incubated with acetyl-LDL, macrophages stimulated with Poly I:Poly C and gamma interferon showed a significant increase (p less than 0.05) in CE synthesis. The increase in CE synthesis by LPS-stimulated macrophages exposed to native LDL and by gamma-interferon-stimulated macrophages exposed to acetylated LDL was paralleled by an increase in cholesterol ester mass. The increase in CE synthesis and accumulation observed in LPS-stimulated macrophages incubated with native LDL seems to be due to an increase in the receptor mediated uptake of LDL. LPS inhibited and gamma-interferon activated the expression of the scavenger pathway in human macrophages. This may explain the changes observed in CE synthesis and accumulation when macrophages activated by the above stimuli were incubated with acetylated LDL. In conclusion, activation of human macrophages by some products released during, or as a consequence of, infectious processes led to an increase in CE synthesis and accumulation that may be relevant to the formation of "foam cells".

Effect of serum on the metabolism of exogenous arachidonic acid by phagocytic cells of the mouse thymic reticulum

Phagocytic cells derived from the mouse thymic reticulum (P-TR) were used to study the effect of serum on the metabolism of arachidonic acid (AA). After labeling with (14C)-AA in the presence of 10% serum, we failed to detect in the culture medium the presence of significant amounts of radiolabeled prostaglandins. In contrast, when the labeling period was carried out in serum-free medium, we observed the secretion of both cyclooxygenase and lipoxygenase derivatives. In addition, the pattern of arachidonate incorporation into cell lipids was different in the two culture conditions. In the presence of serum, the great majority of the radioactivity was found associated with phospholipids, whereas in serum-free medium, almost 50% of the incorporated fatty acid was associated with triglycerides. Since serum albumin is known to play a major role in the control of fatty acid uptake, we have studied the effect of the addition of 2% BSA to cells prelabeled in the absence of serum. This treatment switches the patterns of metabolite release and lipid labeling towards those of serum-treated cells. In addition, we showed that the effects of glucocorticoids on AA release differ markedly according to the composition of the culture medium.

Regulation of prostaglandin E2 and plasminogen activator by various immunomodulators in human monocytes

Mononuclear phagocyte populations and monocytes are able to produce, among numerous substances, a neutral protease, i.e. plasminogen activator (PA) and prostaglandins. Since it has been shown that prostaglandins (PGs) and particularly PGE2 could exert an inhibitory effect on PA production by macrophages, we have measured the in vitro production of PA and PGE2 by monocytes isolated from healthy donors. These monocytes were cultured either in the absence or the presence of various immunomodulators: lipopolysaccharide from E. coli, concanavalin A and RU 41740 or Biostim a broad spectrum immunostimulating agent isolated from Klebsiella pneumoniae (Cassenne Laboratories, France). The production of PGE2 was proportional to the number of monocytes per incubation, and at a given cell concentration varied greatly from one subject to another. When considering PGE2 productions, the type of the response to the different immunomodulators varied from subject to subject and ranged from stimulation to no effect, or even inhibition. Moreover, a statistically significant, inverse relationship exists between the spontaneous production of PGE2 and the effect of each immunomodulator. For a given subject, all agents always acted in the same way and there was an inverse relationship between the effects of the immunomodulators on plasminogen activator and PGE2 production.

Analysis of human blood monocyte activation at the level of gene expression. Expression of alpha interferon genes during activation of human monocytes by poly IC/LC and muramyl dipeptide

Human monocytes were activated to secrete alpha interferon (IFN-alpha) by poly IC/LC but not by other monocyte activators, such as muramyl dipeptide (MDP). In contrast, monocytes were activated to secrete fibroblast growth factor (FGF) release by MDP but not by poly IC/LC. The amount of total RNA present in unactivated and activated human monocytes was similar. Using two 32P-labeled cDNA probes (pLM001 and HuIFN-alpha 2) for human IFN-alpha genes in hybridization studies, we analyzed messenger RNA species from this gene family in activated human monocytes. After activation with poly IC/LC, two other mRNA species (2.8 and 5.5 kb) were detected in addition to the 1.0 kb mRNA normally associated with IFN-alpha secretion. Unexpectedly, monocytes activated with MDP also contained 2.8 kb IFN-alpha mRNA. There was associated with this 2.8 kb IFN-alpha mRNA, found in MDP-activated monocytes, appreciable levels of intracellular IFN-alpha activity in the absence of detectable secreted IFN-alpha. Thus the secretion of IFN-alpha in activated human monocytes can be correlated with the appearance of a 1.0 kb mRNA species after poly IC/LC exposure. Secretion appears to be defective in MDP-stimulated monocytes even though they contain active intracellular IFN-alpha apparently translated from the 2.8 kb mRNA.