Detection of Adenocarcinoma of the Colon on 18 F-Fluciclovine PET/CT

ABSTRACT

An 85-year-old man with prostate cancer and de novo bone metastases was treated with hormonal therapy with resolution of bone lesions, improved primary disease, and improved serum tumor markers. Although on hormonal therapy, biochemical recurrence prompted performance of 18 F-fluciclovine PET/CT. Fluciclovine PET/CT revealed primary prostate cancer progression with incidental note of avid foci in the colon for which colonoscopy was recommended. Colonoscopy with biopsy was performed with pathology revealing primary colon adenocarcinoma. Before reinitiation of prostate cancer therapy, segmental colon resection was performed with pathology positive for additional sites of colon cancer.

PSMA-Avid Desmoid Tumor of the Abdominal Wall on 18F-Piflufolastat PET/CT

ABSTRACT

Prostate-specific membrane antigen (PSMA) PET/CT is widely used in the evaluation of suspected metastasis for initial definitive therapy and suspected recurrence of prostate cancer. We outline a case report of a 62-year-old man with history of prostate cancer treated with surgery, salvage radiation, and hormonal therapy presenting with rising PSA levels. There was incidental detection of a PSMA-avid subcutaneous abdominal wall mass on PSMA PET/CT study, which was consistent with desmoid fibromatosis on an ultrasound-guided biopsy.

Phase 1b/2 study of combination 177Lu girentuximab plus cabozantinib and nivolumab in treatment naïve patients with advanced clear cell RCC

TPS749

Background: Complete response (CR) is still a rare event in patients with advanced clear cell renal cell carcinoma (ccRCC). The combination of nivolumab plus cabozantinib was recently approved for the first-line treatment of ccRCC based on the CheckMate 9ER phase 3 study demonstrating improved progression-free survival (PFS) and objective response rate (ORR) in comparison to sunitinib. However, the CR rate was only 9%. Since the anti-tumor effects of immune checkpoint inhibitors are dependent on the presence of activated tumor-infiltrating T cells, drugs that could synergize with T cells’ anti-tumor activity can allow us to improve CR rates. Activation of the cGAS-STING pathway which is induced by radiation-induced DNA damage, is one promising mechanism that has been investigated. Many studies have shown that radiation treatment augments immune checkpoint inhibition. However, it is not always possible to radiate all metastatic lesions. Therefore, targeted peptide receptor radionuclide therapies, have been developed by conjugating radioisotopes to receptor binding analogs targeting specific cancer cell surface proteins, thereby delivering targeted radiation to cancer cells in the body with minimal damage to surrounding healthy cells. 177Lu girentuximab is the first antibody-radioisotope designed for ccRCC, targeting carbonic anhydrase 9-expressing cells, which includes >90% of ccRCC. It has been tested in metastatic ccRCC as a single agent and shown to be safe and effective in stabilizing disease in 57% of pts. In this study, we hypothesize that 177Lu girentuximab-induced DNA damage will potentiate the STING pathway, and this activation will synergize with nivolumab and cabozantinib to promote trafficking and infiltration of activated T cells to tumors and achieve higher CR rates. Methods: Up to 100 patients with treatment naïve, biopsy-proven ccRCC with adequate organ/marrow function with ≥1 evaluable lesion by RECIST 1.1 will be enrolled. A 5-patient safety lead-in will evaluate myelosuppression. Ongoing safety, and futility monitoring will employ a Bayesian approach. The sample size was chosen for reasonable operating characteristics to distinguish a CR rate (primary endpoint) of 18% as better than 9% using a beta(0.09, 0.91) prior. Secondary endpoints are ORR, PFS by RECIST 1.1, and overall survival. 177Lu-girentuximab 1480 MBq/m2 (61% of single agent MTD) will be administered every 12 weeks for up to 3 cycles. Starting with the second cycle, nivolumab and cabozantinib will be added at standard dose. To explore the effects of the treatment on inducing activated T cell infiltration, patients will undergo pre/post-treatment PET scan with [18F]F-AraG radiotracer as well as biopsies for single cell, spatial transcriptomics and proteomics studies. This investigator initiated trial is supported by Telix Pharmaceuticals and DOD grant W81XWH-22-1-0456.

Nivolumab-Induced Subcutaneous Fat Necrosis: Another FDG-Avid Immune-Related Adverse Event

A 59-year-old woman with history of metastatic melanoma, currently on nivolumab, presents for a restaging FDG PET/CT scan. New subcutaneous hypermetabolic foci are seen in bilateral lower extremities, suggestive of recurrent melanoma. She is referred for percutaneous image-guided biopsy for definitive diagnosis of progressive disease. Ultrasound shows the subcutaneous foci to be hyperechoic (fat density), and biopsy of the right thigh nodule shows fat necrosis with no evidence of tumor. Fat necrosis, an immune-related adverse event, can be FDG-avid and mimic malignancy on PET/CT scan.

18F-FDG PET/CT in the Evaluation of Bing-Neel Syndrome

Waldenström macroglobulinemia is an indolent B-cell lymphoproliferative disorder. When there is involvement of the central nervous system, Waldenström macroglobulinemia is known as Bing-Neel syndrome. We present a case of Bing-Neel syndrome in a patient who presented with confusion and left orbital pain. ¹⁸F-FDG PET/CT was utilized in making the diagnosis.

Implications of Ambient Glucose Variation on the Target-to-Background Ratio of Hepatic Tumors By (18)FDG-PET Imaging

Objectives:

To investigate the effects of ambient glucose on quantitative analysis of hepatic tumors on 2-deoxy-2-(¹⁸F)-fluoro-D-glucose (¹⁸FDG) positron emission tomography (PET) and to establish a method for glucose correction.

Patients and Methods:

Eighty-six patients with hepatic lesions identified on ¹⁸FDG PET/computed tomography (CT) were analyzed. The serum glucose level (Glc) was recorded prior to imaging, and the maximum standardized uptake value (SUV) in the hepatic tumors and the average SUV in normal liver were determined. The inverse relationship of SUV to glucose can be defined as d (SUV)/d (Glc) = g*SUV/(Glc), where g is the glucose sensitivity. Simulations using glucose level from 70 to 250 mg/dl were performed to evaluate the effects of Glc on the maximum SUV of malignant hepatic lesions and normal liver.

Results:

By logarithmic transformation and linear regression, g for metastasis was significantly higher than that for normal liver (−0.636 ± 0.144 vs. −0.0536 ± 0.0583; P = 0.00092). Simulation studies showed that the SUV in malignant lesions will decrease rapidly when Glc level is >120 mg/dl, while background liver remains relatively constant up to 250 mg/dl.

Conclusion:

The tumor FDG uptake is much more sensitive to ambient glucose level variation than the background liver. Therefore, correction by the glucose sensitivity factor will result in more accurate SUV measurements and make semi-quantitative analysis of ¹⁸FDG PET scans more reliable.

17-year-old runner with shin pain

Stress injury is a common cause of exercise-induced anterior shin pain. It is important to distinguish between the various causes of stress injury in a timely manner in order to optimize favorable treatment outcomes. Here, we will discuss a case of medial tibial stress syndrome, or shin splints, as one of the causes of shin pain, as well as how to approach shin pain for a successful diagnosis.

Anti-inflammatory effects of thiazolidinediones in human airway smooth muscle cells

Airway smooth muscle (ASM) cells have been reported to contribute to the inflammation of asthma. Because the thiazolidinediones (TZDs) exert anti-inflammatory effects, we examined the effects of troglitazone and rosiglitazone on the release of inflammatory moieties from cultured human ASM cells. Troglitazone dose-dependently reduced the IL-1β-induced release of IL-6 and vascular endothelial growth factor, the TNF-α-induced release of eotaxin and regulated on activation, normal T expressed and secreted (RANTES), and the IL-4-induced release of eotaxin. Rosiglitazone also inhibited the TNF-α-stimulated release of RANTES. Although TZDs are known to activate peroxisome proliferator-activated receptor-γ (PPARγ), these anti-inflammatory effects were not affected by a specific PPARγ inhibitor (GW 9662) or by the knockdown of PPARγ using short hairpin RNA. Troglitazone and rosiglitazone each caused the activation of adenosine monophosphate-activated protein kinase (AMPK), as detected by Western blotting using a phospho-AMPK antibody. The anti-inflammatory effects of TZDs were largely mimicked by the AMPK activators, 5-amino-4-imidazolecarboxamide ribose (AICAR) and metformin. However, the AMPK inhibitors, Ara A and Compound C, were not effective in preventing the anti-inflammatory effects of troglitazone or rosiglitzone, suggesting that the effects of these TZDs are likely not mediated through the activation of AMPK. These data indicate that TZDs inhibit the release of a variety of inflammatory mediators from human ASM cells, suggesting that they may be useful in the treatment of asthma, and the data also indicate that the effects of TZDs are not mediated by PPARγ or AMPK.

Allergic airway responses in obese mice

RATIONALE

Epidemiologic data indicate an increased incidence of asthma in the obese.

OBJECTIVES

To determine whether obese mice exhibit augmented pulmonary responses after allergen sensitization and challenge.

METHODS

Lean, wild-type (C57BL/6), obese ob/ob, and obese db/db mice were sensitized to ovalbumin (OVA), and then challenged with aerosolized OVA or phosphate-buffered saline (PBS). Changes in total pulmonary resistance (Rl) induced by intravenous methacholine were measured by forced oscillation. Blood was collected, bronchoalveolar lavage (BAL) was performed, and lungs were harvested for measurement of cytokine expression by real-time reverse transcription-polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

OVA challenge increased baseline Rl in ob/ob, but not wild-type, mice, and airway responsiveness was greater in ob/ob than wild-type mice, regardless of the challenge. Compared with PBS, OVA challenge caused an increase in the number of BAL fluid (BALF) cells, an increase in lung Th2 cytokine expression, and an increase in serum IgE. Significantly fewer BALF cells were recovered from OVA-challenged ob/ob versus wild-type mice, whereas serum IgE levels were elevated significantly more in ob/ob versus wild-type mice. BALF and lung Th2 cytokine expression was not different in ob/ob versus wild-type mice. Airway responsiveness was greater in db/db versus wild-type mice, regardless of the challenge, and OVA caused airway hyperresponsiveness in db/db but not wild-type mice, despite reduced BALF cells in OVA-challenged db/db versus wild-type mice.

CONCLUSIONS

These results demonstrate that obesity enhances OVA-induced changes in pulmonary resistance and serum IgE and that these changes are not the result of increased Th2 type airway inflammation.

Type I interleukin-1 receptor is required for pulmonary responses to subacute ozone exposure in mice

Interleukin (IL)-1, a proinflammatory cytokine, is expressed in the lung after ozone (O(3)) exposure. IL-1 mediates its effects through the type I IL-1 receptor (IL-1RI), the only signaling receptor for both IL-1alpha and IL-1beta. The purpose of this study was to determine the role of IL-1RI in pulmonary responses to O(3.) To that end, wild-type, C57BL/6 (IL-1RI(+/+)) mice and IL-1RI-deficient (IL-1RI(-/-)) mice were exposed to O(3) either subacutely (0.3 ppm for 72 h) or acutely (2 ppm for 3 h). Subacute O(3) exposure increased bronchoalveolar lavage fluid (BALF) protein, interferon-gamma-inducible protein (IP)-10, soluble tumor necrosis factor receptor 1 (sTNFR1), and neutrophils in IL-1RI(+/+) and IL-1RI(-/-) mice. With the exception of IP-10, all outcome indicators were reduced in IL-1RI(-/-) mice. Furthermore, subacute O(3) exposure increased IL-6 mRNA expression in IL-1RI(+/+), but not IL-1RI(-/-) mice. Acute (2 ppm) O(3) exposure increased BALF protein, IL-6, eotaxin, KC, macrophage inflammatory protein (MIP)-2, IP-10, monocyte chemotactic protein-1, sTNFR1, neutrophils, and epithelial cells in IL-1RI(+/+) and IL-1RI(-/-) mice. For IL-6, eotaxin, MIP-2, and sTNFR1, there were small but significant reductions of these outcome indicators in IL-1RI(-/-) versus IL-1RI(+/+) mice at 6 hours after exposure, but not at other time points, whereas other outcome indicators were unaffected by IL-1RI deficiency. These results suggest that IL-1RI is required for O(3)-induced pulmonary inflammation during subacute O(3) exposure, but plays a more minor role during acute O(3) exposure. In addition, these results suggest that the induction of IL-6 via IL-1RI may be important in mediating the effects of O(3) during subacute exposure.

Adiponectin attenuates allergen-induced airway inflammation and hyperresponsiveness in mice

BACKGROUND

Epidemiologic data indicate an increased incidence of asthma in the obese.

OBJECTIVE

Because serum levels of the insulin-sensitizing and anti-inflammatory adipokine adiponectin are reduced in obese individuals, we sought to determine whether exogenous adiponectin can attenuate allergic airway responses.

METHODS

We sensitized and challenged BALB/cJ mice with ovalbumin (OVA). Alzet micro-osmotic pumps were implanted in the mice to deliver continuous infusions of buffer or adiponectin (1.0 microg/g/d), which resulted in an approximate 60% increase in serum adiponectin levels. Two days later, mice were challenged with aerosolized saline or OVA once per day for 3 days. Mice were examined 24 hours after the last challenge.

RESULTS

OVA challenge increased airway responsiveness to intravenous methacholine, bronchoalveolar lavage fluid cells, and T(H)2 cytokine levels. Importantly, each of these responses to OVA was reduced in adiponectin- versus buffer-treated mice. OVA challenge caused a 30% reduction in serum adiponectin levels and a corresponding decrease in adipose tissue adiponectin mRNA expression. OVA challenge also decreased pulmonary mRNA expression of each of 3 proposed adiponectin-binding proteins, adiponectin receptor 1, adiponectin receptor 2, and T-cadherin.

CONCLUSION

Our results indicate that serum adiponectin is reduced during pulmonary allergic reactions and that adiponectin attenuates allergic airway inflammation and airway hyperresponsiveness in mice.

CLINICAL IMPLICATIONS

The data suggest that adiponectin might play a role in the relationship between obesity and asthma.

Increased pulmonary responses to acute ozone exposure in obese db/db mice

Epidemiological studies indicate the incidence of asthma is increased in obese and overweight humans. Responses to ozone (O(3)), an asthma trigger, are increased in obese (ob/ob) mice lacking the satiety hormone leptin. The long form of leptin receptor (Ob-R(b)) is required for satiety; mice lacking this receptor (db/db mice) are also substantially obese. Here, wild-type (WT) and db/db mice were exposed to air or O(3) (2 ppm) for 3 h. Airway responsiveness, measured by the forced oscillation technique, was greater in db/db than WT mice after air exposure. O(3)-induced increases in pulmonary resistance and airway responsiveness were also greater in db/db mice. BALF eotaxin, IL-6, KC, and MIP-2 increased 4 h after O(3) exposure and subsided by 24 h, whereas protein and neutrophils continued to increase through 24 h. For each outcome, the effect of O(3) was significantly greater in db/db than WT mice. Previously published results obtained in ob/ob mice were similar except for O(3)-induced neutrophils and MIP-2, which were not different from WT mice. O(3) also induced pulmonary IL-1beta and TNF-alpha mRNA expression in db/db but not ob/ob mice. Leptin was increased in serum of db/db mice, and pulmonary mRNA expression of short form of leptin receptor (Ob-R(a)) was similar in db/db and WT mice. These data confirm obese mice have innate airway hyperresponsiveness and increased pulmonary responses to O(3). Differences between ob/ob mice, which lack leptin, and db/db mice, which lack Ob-R(b) but not Ob-R(a), suggest leptin, acting through Ob-R(a), can modify some pulmonary responses to O(3).

Interleukin-13 and interleukin-4 induce vascular endothelial growth factor release from airway smooth muscle cells: role of vascular endothelial growth factor genotype

Th2 cytokines induce the release of vascular endothelial growth factor (VEGF) from cultured human airway smooth muscle cells. The objective of this study was to examine the mechanistic basis for IL-4- and IL-13-induced VEGF release and to determine whether genetic differences are responsible for donor-to-donor variability in VEGF release. We measured VEGF mRNA expression by real-time PCR, mRNA stability using actinomycin D, and promoter activity with a VEGF-promoter luciferase reporter construct. We measured IL-4- and IL-13-induced VEGF release in cells from 21 donors by ELISA, genotyped the cells for common single nucleotide polymorphisms in the IL-4R alpha (Ile50Val, Ser478Pro, and Gln551Arg) and VEGF (-460T/C, -160C/T, -152G/A, +405C/G and +936 C/T) genes, and stratified the data by IL-4R alpha and VEGF genotype. IL-4 and IL-13 increased VEGF release and VEGF mRNA expression. IL-4 also increased mRNA stability but did not affect VEGF promoter activity. There was marked donor-to-donor variability in VEGF release from smooth muscle cells. The presence of Val50, Pro478/Arg551, or the Val50/Pro478/Arg551 IL-4R alpha haplotype had little effect on VEGF release. VEGF genotype at +405 or +936 alone had no effect on VEGF release, whereas cells bearing at least one -460C/-152A/+405G VEGF allele had lower release of VEGF in response to IL-13 or IL-4 than cells with other genotypes. Our data suggest that IL-4 and IL-13 mediate their effects on VEGF expression post-transcriptionally and indicate that polymorphisms in the VEGF, but not the IL-4R alpha, gene affect VEGF release from smooth muscle cells.

Effect of leptin on allergic airway responses in mice

BACKGROUND

Epidemiologic data indicate that the incidence of asthma is increased in obese patients.

OBJECTIVE

Because the serum levels of the satiety hormone and proinflammatory cytokine leptin are increased in obese individuals, we sought to determine whether leptin can augment allergic airway responses.

METHODS

We sensitized and challenged BALB/cJ mice with ovalbumin. Alzet micro-osmotic pumps were implanted in the mice to deliver a continuous infusion of either saline or leptin (1.75 mug/g/d). Two days later, the mice were challenged with either aerosolized saline or ovalbumin once per day for 3 days. We measured airway responsiveness, performed bronchoalveolar lavage, and obtained blood to measure serum leptin and IgE 24 or 48 hours after the last challenge.

RESULTS

Leptin infusion increased serum leptin concentrations, which were increased further after ovalbumin sensitization and challenge. Ovalbumin challenge increased bronchoalveolar lavage fluid cells and cytokines, serum IgE, lung cytokine mRNA expression, and responses to inhaled, aerosolized methacholine. It is important to note that the changes in methacholine responsiveness and IgE were augmented in leptin- versus saline-infused mice.

CONCLUSIONS

These results indicate that serum leptin is increased during allergic reactions in the airways and may play a role in the relationship between obesity and asthma.

Oncostatin M causes eotaxin-1 release from airway smooth muscle: Synergy with IL-4 and IL-13

BACKGROUND

Eotaxin is implicated in asthmatic eosinophilia. Oncostatin M (OSM) causes eotaxin release from fibroblasts.

OBJECTIVE

We sought to examine the effects and mechanism of action of OSM and other IL-6 family cytokines on eotaxin release from human airway smooth muscle cells.

METHODS

Eotaxin 1 release was measured by means of ELISA. Western blotting was used to examine mitogen-activated protein kinase and signal transducer and activator of transcription 3 (STAT-3) phosphorylation. Eotaxin promoter activity was analyzed in cells transfected with wild-type STAT-3, a mutant form of STAT-3 that cannot be phosphorylated, and a constitutively active form of STAT-3. The mRNA and protein expression of IL-4R alpha, the signaling receptor for IL-4 and IL-13, was evaluated by means of real-time PCR and flow cytometry, respectively.

RESULTS

OSM increased eotaxin 1 release and augmented IL-4- or IL-13-induced eotaxin release, whereas other IL-6 family cytokines did not. OSM caused a greater increase in STAT-3 phosphorylation and STAT-3-mediated gene transcription than other IL-6 family cytokines. OSM increased eotaxin promoter activity and augmented IL-13- and IL-4-induced increases in promoter activity. The constitutively active form of STAT-3 increased eotaxin promoter activity, whereas the mutant form of STAT-3 that cannot be phosphorylated significantly reduced eotaxin promoter activity induced by OSM or IL-4 plus OSM. OSM increased IL-4R alpha mRNA and protein levels.

CONCLUSIONS

OSM induces eotaxin 1 expression in human airway smooth muscle cells by a mechanism involving STAT-3. OSM synergizes with IL-13 and IL-4 to increase eotaxin 1 expression, possibly as a result of effects on IL-4R alpha expression.

Oncostatin M causes VEGF release from human airway smooth muscle: synergy with IL-1beta

Vascular endothelial growth factor (VEGF), a potent angiogenesis factor, likely contributes to airway remodeling in asthma. We sought to examine the effects and mechanism of action of IL-6 family cytokines on VEGF release from human airway smooth muscle (HASM) cells. Oncostatin M (OSM), but not other IL-6 family cytokines, increased VEGF release, and IL-1beta enhanced OSM-induced VEGF release. OSM increased VEGF mRNA expression and VEGF promoter activity, whereas IL-1beta had no effect. IL-1beta did not augment the effects of OSM on VEGF promoter activity but did augment OSM-induced VEGF mRNA expression and mRNA stability. The STAT3 inhibitor piceatannol decreased both OSM-induced VEGF release and synergy between OSM and IL-1beta, without affecting responses to IL-1beta alone. Piceatannol also inhibited OSM-induced VEGF mRNA expression. In contrast, inhibitors of MAPK pathway had no effect on OSM or OSM plus IL-1beta-induced VEGF release. OSM increased type 1 IL-1 receptor (IL-1R1) mRNA expression, as measured by real-time PCR, and piceatannol attenuated this response. Consistent with the increase in IL-1R1 expression, OSM markedly augmented IL-1beta-induced VEGF, MCP-1, and IL-6 release. In summary, our data indicate OSM causes VEGF expression in HASM cells by a transcriptional mechanism involving STAT3. IL-1beta also synergizes with OSM to increase VEGF release, likely as a result of effects of IL-1beta on VEGF mRNA stability as well as effects of OSM on IL-1R1 expression. This is the first description of a role for OSM on IL-1R1 expression in any cell type. OSM may contribute to airway remodeling observed in chronic airway disease.

Role of interleukin-6 in murine airway responses to ozone

This study sought to examine the role of interleukin-6 (IL-6) in ozone (O(3))-induced airway injury, inflammation, and hyperresponsiveness (AHR). Subacute (72 h) exposure to 0.3 ppm O(3) significantly elevated bronchoalveolar lavage fluid (BALF) protein, neutrophils, and soluble TNF receptors (sTNFR1 and sTNFR2) in wild-type C57BL/6 (IL-6(+/+)) mice; however, all four outcome indicators were significantly reduced in IL-6-deficient (IL-6(-/-)) compared with IL-6(+/+) mice. Acute O(3) exposure (2 ppm for 3 h) increased BALF protein, KC, macrophage inflammatory protein(MIP)-2, eotaxin, sTNFR1, and sTNFR2 in IL-6(+/+) mice. However, MIP-2 and sTNFR2 were not significantly increased following O(3) exposure in IL-6(-/-) mice. Increases in BALF neutrophils induced by O(3) (2 ppm for 3 h) were also significantly reduced in IL-6(-/-) vs. IL-6(+/+) mice. Airway responsiveness to methacholine was measured by whole body plethysmography before and following acute (3 h) or subacute (72 h) exposure to 0.3 ppm O(3). Acute O(3) exposure caused AHR in both groups of mice, but there was no genotype-related difference in the magnitude of O(3)-induced AHR. AHR was absent in mice of either genotype exposed for 72 h. Our results indicate that IL-6 deficiency reduces airway neutrophilia, as well as the levels of BALF sTNFR1 and sTNFR2 following acute high dose and/or subacute low-dose O(3) exposure, but has no effect on O(3)-induced AHR.

IL-13 and IL-4 promote TARC release in human airway smooth muscle cells: role of IL-4 receptor genotype

The chemokine thymus- and activation-regulated chemokine (TARC) induces selective migration of Th2, but not Th1, lymphocytes and is upregulated in the airways of asthmatic patients. The purpose of this study was to determine whether human airway smooth muscle (HASM) cells produce TARC. Neither IL-4, IL-13, IL-1beta, IFN-gamma, nor TNF-alpha alone stimulated TARC release into the supernatant of cultured HASM cells. However, both IL-4 and IL-13 increased TARC protein and mRNA expression when administered in combination with TNF-alpha but not IL-1beta or IFN-gamma. Macrophage-derived chemokine was not expressed under any of these conditions. TARC release induced by TNF-alpha + IL-13 or TNF-alpha + IL-4 was inhibited by the beta-agonist isoproterenol and by other agents that activate protein kinase A, but not by dexamethasone. To determine whether polymorphisms of the IL-4Ralpha have an impact on the ability of IL-13 or IL-4 to induce TARC release, HASM cells from multiple donors were genotyped for the Ile50Val, Ser478Pro, and Gln551Arg polymorphisms of the IL-4Ralpha. Our data indicate that cells expressing the Val50/Pro478/Arg551 haplotype had significantly greater IL-13- or IL-4-induced TARC release than cells with other IL-4Ralpha genotypes. These data indicate that Th2 cytokines enhance TARC expression in HASM cells in an IL-4Ralpha genotype-dependent fashion and suggest that airway smooth muscle cells participate in a positive feedback loop that promotes the recruitment of Th2 cells into asthmatic airways.