Cytokines can make you sick—Or keep you well

536 SELECTED SUMMARIES

GASTROENTEROLOGY

Overall, the work on the CF gene heralds a new era for the many sufferers from this disease, and for the possibilities of therapy and prevention. The findings are also of fundamental importance to investigators in cell physiology, to whom the identification, in CFTR, of either the Cll channel protein itself, or its essential regulator, are of obvious relevance. K. E. BARREm, K. DHARMSATHAPHORN,

Ph.D. M.D.

CYTOKINES CAN MAKE YOU SICK-OR KEEP YOU WELL Heinzel FP, Sadick MD, H&day EJ, et al. (Division of Infectious Diseases, Department of Medicine, University of California San Francisco Medical Center, San Francisco, CA; DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA) Reciprocal expression of interferon gamma or Interleukin 4 during the resolution or progression of murine leishmaniasis: Evidence for expansion of distinct helper T cell subsets. J Exp Med 1989;169:59-72. At designated times after infection with Leishmania major, poly(A)+ mRNA was isolated from spleen and lymph nodes of mice of the genetically susceptible BALB/c strain and of the genetically resistant C57Bl/6 strain. The steady state levels of IL-Z, IFN-y, IL-4, and IL-@ mRNA were determined using Northern hybridizations. IL-2 mRNA levels in the infected organs of BALB/c and C57BI/6 mice were comparable after infection. However, IFN-7 and IL-4 mRNA levels differed between these two strains. Levels of IFN-y mRNA in C57Bl/6 draining nodes in spleen were significantly greater than those in BALB/c mice. In contrast, IL-4 mRNA was apparent only in BALB/c mice and not in C57Bl/6 lymph nodes or spleen. Tissue levels of IL-l@ mRNA were lo-20 fold greater in BALB/c mice. BALB/c mice were pretreated with the monoclonal antibody GK1.5, which is directed at the CD4 antigen on helper T cells. This manipulation promoted healing of subsequent infection by transiently depleting CD4 T cells. At 8 weeks of infection, by which time lymphoid organs were repopulated with CD4’ T cells, GK1.5 pretreated BALB/c mice produced IFN-y, but not IL-4 mRNA. Serum levels of IgE were markedly elevated in infected BALB/c mice but not in infected C57Bl/6 or GKl.S-pre-treated BALB/c mice, consistent with in vivo biologic activity of IL-4 in nonhealing mice. Treatment of infected BALB/c mice with neutralizing anti-IL-4 antibody abolished the elevation of serum IgE and significantly attenuated the progression of disease as assessed by size and ulceration of the lesions, and by reduction in the number of tissue parasites. Both productive and deleterious responses to Leishmania infection have previously been shown to be dependent on CD4+ T cells. These findings are consistent with the differential expansion of protective, IFN-yproducing Thl cells in healing or resistant mice, and the expansion of deleterious, IL-4-producing Th2 cells in nonhealing or sensitive strains of mice. The inverse relationship of IFN-7 and IL-4 gene expression during leishmaniasis may underlie the divergence of cellular and humoral immunity that occurs during chronic infection with Leishmania and possibly other intracellular parasites.

Vol. 98, No. 2

Comment. Lymphokines are secreted products of lymphocytes that have a wide range of biologic effects. For many years, these biologic activities of lymphokines were used to describe each “factor” as it was identified. Over the years, the number of different biologic activities multiplied to very large and confusing numbers. A decade ago a conference was held of investigators interested in lymphokines and it became apparent that a relatively smaller number of molecules, each having multiple activities, were responsible for these many biologic activities. The term interleukin was coined at this conference to denote a molecule produced by one leukocyte and acting on another. Sufficient data seemed available at the time to firmly establish the existence of at least 2 interleukins that were designated lnterleukin-1 and Interleukin-2. A major effort was initiated to biochemically characterize these lymphokine or interleukin molecules and to clone the genes encoding them. By general agreement the genes must be cloned and thus the protein sequence identified before a molecule can receive an interleukin designation. The progress over this past decade in this area of immunology has been astounding. Seven distinct interleukins have been identified, several more candidates are in the wings, and probably more are yet to be identified. Many of these substances are pleiotropic, i.e., they have effects on cells outside the immune system that has generated the term “cytokine” as an alternate descriptor, one that can include various colony stimulating factors, interferons, etc. besides the interleukins. However, the terms “lymphokine, ” “interleukin,” and “cytokine” are frequently used interchangeably. These molecules clearly mediate the many effects of the immune system and many of them can be generated by multiple different cell types. The challenge for the future is the solution of how the synthesis of this complex array of molecules is coordinated and regulated. In a previous Selected Summary, the existence of murine helper T cells that make a restricted pattern of cytokines was discussed. These cell types were initially identified in T cell clones and hybridomas that had been cultured in vitro for long periods. Thl-type helper T cells produced IFN--, and IL-2 whereas Th2-type helper T cells produced IL-4 and IL-5. A major question has been whether this is an artifact of the long-term culture or whether this applies physiologically to T cell function in vivo. The present work supports the latter idea. In this experimental model of lesihmaniasis, not only were Thl-like and Th2-like cell types identified, but also the predominance of one cell type or the other in different mouse strains correlated with disease susceptibility. Mouse strains that had a predominant Thl-like response were resistant to leishmaniasis, whereas mouse strains with a predominant ThL-like response were sensitive. Moreover, manipulation of the CD4 subset or administration of antibody inhibitors of IL-4 were able to convert the cytokine pattern with the result that the sensitive strains became resistant. The implication of this interesting study is that the pattern of cytokines produced to a given agent or antigen may be a crucial factor in determining health vs. disease. Thl and Th2-type helper T cells have not yet been identified in humans in whom the situation appears more complex. However, it’s intriguing to speculate that a disordered pattern of cytokine expression may be involved in chronic inflammatory diseases of the intestine and other organs. Regardless of whether that turns out to be the case, the cytokines are almost certainly involved in and mediate chronic inflammation wherever it occurs. This is of more than theoretical interest. Purified interleukins produced by recombinant DNA technology are becoming available for therapeutic use. Some, such as IL-z, have already been applied to human disease. In addition, inhibitors of the interleukins, either in the form of natural substances, recombinant DNA-drive competitive inhibitors, or antibodies will also be available for use in humans in the not-too-distant future, given the rapid progress being made in this area. Studies such as this one on leishmaniasis are laying the groundwork for an

SELECTED SUMMARIES

February 1990

entirely

new form of therapy in which the body’s own natural

substances are used to treat or modifv disease. CO. ELSON. M.D.

ESWL FOR BILE DUCT STONES: MAKING WAVES IN ESTABLISHED THERAPY Bland KI, /ones RS, Maher JW, et al. [Multi-institutional study). Extracorporeal shock-wave lithotripsy of bile duct calculi. Ann Surg 1989;209:743-53. This paper

a multicenter study in the United shock wave lithotripsy (ESWL) for fragmentation of bile duct stones. Patients were treated under an investigational protocol after it was determined that the stones could not be removed using conventional nonsurgical measures such as endoscopic sphincterotomy or percutaneous extraction. Forty-two patients were treated, 55L70 were men and 45% were women; the mean (&SD) age was 73.8 t 13.8 yr. Most had significant concurrent medical illnesses. Two thirds had previously undergone cholecystectomy. Stones were located in the common bile duct in 79% of patients, in the common hepatic duct in 24~0, in lobar ducts in 1770, and in the papilla in 9%. Thirty-three percent had 1 stone, 26% had 2.12% had 3, and 29% had 4 or more at entry. Coincidental gallbladder stones were present in 31(r0. Mean stone diameter was States

reports

using extracorporeal

18.5 -i 6.4 mm, with the largest stone having a diameter of l-10 mm in 1770, 31-20 mm in 5270, and 21-30 mm in 29%. No stones >3O mm were treated. Prior to ESWL, patients had a mean of 2.3 nonsurgical attempts at stone extraction.

Seventy-six percent of patients had undergone no correlation between the number of stones and the need for retreatment. There was, however, a direct relationship between the stone number and the rate of duct clearance at discharge. Of the patients with solitary stones, 93% were stone-free at discharge. There were no procedure-related deaths in this relatively elderly high-risk population. Complications during ESWL occurred in 14% of total treatments, with hemobilia (5%), respiratory depression due to anesthesia (3.5%). and biliary pain (2%) being most frequent. Following ESWL, complications were seen in 47% of treatments, with hemobilia and biliary symptoms evident in 21%. ESWL-related pulmonary complications were seen in 5%. At the time of discharge, 93% of all complications had resolved. The authors conclude that ESWL appears to be a safe and effective modality for the fragmentation of bile duct stones. Comments. The management of bile duct stones has undergone a dramatic change during the past IO years. Surgical common bile duct exploration, the standard therapy until recently, carries significant risk, even in the nonemergent setting. Two large British studies reported the morbidity of common duct exploration to be 11% in the elective setting (Surg Gynecol Obstet 1987;164:245-51) and an alarming 46% overall (Br J Surg 1987:74:1095-9). The surgical mortality in several studies was roughly 2% overall. This had prompted the search for an effective nonsurgical approach to bile duct stones. Percutaneous transhepatic cholangiography has been a useful diagnostic tool in patients with dilated bile ducts. However,

537

endoscopic sphincterotomy, 87% had placement of a nasobiliary catheter, 17% had T-tube and/or percutaneous catheter placement, and 14% had undergone an unsuccessful attempt at intracorporeal mechanical lithotriusv. All patients weIe”treated with the Dornier HM3 water bath lithotripter under flouroscopic guidance. A maximum of 2,400 shocks (mean 1,924 5 289) were delivered per patient at 12-22 kv (mean 18.5 i 1.9). General anesthesia was used in 31% of treatments and epidural in 39%; the remainder were given regional/ local anesthesia with i.v. sedation. Prophylactic antibiotics were administered and continued until stone debris was cleared (3 days or less in 67%,12 days or more in 10%). ESWL treatment was halted

when there was cholangiographic evidence of stone disintegration or when a maximum of 2,400 shocks had been delivered [mean treatment time 53 f 21 min). Initial fragmentation was achieved in over 90% of treatments. Following fragmentation, half of the patients required additional nonsurgical procedures to achieve complete stone clearance. Percutaneous extraction and endoscopic sphincterotomy with stone extraction were the most common procedures performed. Two patients required surgical intervention. Retreatment was performed in 15 of 42 patients (36%) either because of incomplete fragmentation, or because fragments remaining in the ducts 4 days after initial ESWL were thought to be too large for spontaneous passage or endoscopic extraction. At the time of discharge, 74% of patients were stonefree, 19% had fragmented debris, 2% had unfragmented stones, and 5% could not be determined radiographically. There was therapeutic efforts, until recently, were limited to attempts at pushing the stone antegrade through the often edematous Sphincter of Oddi, or to extracting those stones small enough to pass through the catheter. Endoscopic sphincterotomy made possible the extraction of larger stones via a less invasive route, with a substantially lower morbidity rate and a somewhat lower mortality rate than surgery (Br J Surg 1987;74:209-II). Within the last 2 years, there have emerged a plethora of even newer approaches and revisions to these now established techniques. Dissolution agents, such as monooctanoin and methyl-tertbutyl ether (MTBE) have shown some potential for therapeutic efficacy. While minimally successful in completely dissolving duct stones in initial trials, monooctanoin has facilitated subsequent extraction by noninvasive means [AJR 1987:148:185-8). MTBE may have even greater efficacy, although therapy may be limited by complications resulting from intestinal contact with this agent (AJR 1987;148:372-4). Other investigational modalities that appear promising include mechanical, electrohydraulic, and laser lithotripsy via the percutaneous or endoscopic route, ultrasonic jet cutting, and ESWL. The largest experience of ESWL for bile duct stones was with the Dornier HM3 kidney lithotripter in Munich (Gastroenterology 1989;96:146-52). These authors reported that following failure of routine endoscopic measures, stone fragmentation was achieved in 103 of 113 patients (91%). Furthermore, with prior sphincterotomy, complete stone clearance from the bile ducts occurred in 86% of patients within a median of 4 days after therapy. This included 23 patients (20% Jwith spontaneous clearance, 71 patients (63%] with endoscopic extraction, and 3 patients (3%) following instillation of solvents. Multiple ESWL treatments were required in 14%. Complications were seen in 36% of patients, with skin hematoma, mild hematuria. and mild biliary/abdominal pain being the most common adverse effects. In this high-risk population. the 30-day mortality rate was 0.9%. An earlier paper from Canada (AJR 1988;151:9236) reported results with 16 patients using the same device. In 15 of 16 patients (94%) the stones were successfully fragmented. As in the German study, complete bile duct clearance was achieved in 87% of patients following ESWL. This included spontaneous duct clearance in 9 patients (56%) and endoscopic extraction in another 5