A Pivotal Role for CXCL12 Signaling in HPV-Mediated Transformation of Keratinocytes: Clues to Understanding HPV-Pathogenesis in WHIM Syndrome

ACKR3 in Skin Homeostasis, an Overlooked Player in the CXCR4/CXCL12 Axis

CXCL12 and its receptor CXCR4 emerge as critical regulators within the intricate network of processes ensuring skin homeostasis. In this review, we discuss their spatial distribution and function in steady-state skin; delve into their role in acute wound healing, with emphasis on fibrotic and regenerative responses; and explore their relevance in skin responses to commensals and pathogens. Given the lack of knowledge surrounding ACKR3, the atypical receptor of CXCL12, we speculate whether and how it might be involved in the processes mentioned earlier. Is ACKR3 the (a)typical friend who enjoys missing the party, or do we need to take a closer look?

Increased Susceptibility of WHIM Mice to Papillomavirus-induced Disease is Dependent upon Immune Cell Dysfunction

Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) syndrome is a rare primary immunodeficiency disease in humans caused by a gain of function in CXCR4, mostly due to inherited heterozygous mutations in CXCR4. One major clinical symptom of WHIM patients is their high susceptibility to human papillomavirus (HPV) induced disease, such as warts. Persistent high risk HPV infections cause 5% of all human cancers, including cervical, anogenital, head and neck and some skin cancers. WHIM mice bearing the same mutation identified in WHIM patients were created to study the underlying causes for the symptoms manifest in patients suffering from the WHIM syndrome. Using murine papillomavirus (MmuPV1) as an infection model in mice for HPV-induced disease, we demonstrate that WHIM mice are more susceptible to MmuPV1-induced warts (papillomas) compared to wild type mice. Namely, the incidence of papillomas is higher in WHIM mice compared to wild type mice when mice are exposed to low doses of MmuPV1. MmuPV1 infection facilitated both myeloid and lymphoid cell mobilization in the blood of wild type mice but not in WHIM mice. Higher incidence and larger size of papillomas in WHIM mice correlated with lower abundance of infiltrating T cells within the papillomas. Finally, we demonstrate that transplantation of bone marrow from wild type mice into WHIM mice normalized the incidence and size of papillomas, consistent with the WHIM mutation in hematopoietic cells contributing to higher susceptibility of WHIM mice to MmuPV1-induced disease. Our results provide evidence that MmuPV1 infection in WHIM mice is a powerful preclinical infectious model to investigate treatment options for alleviating papillomavirus infections in WHIM syndrome.

CXCR4 WHIM syndrome is a cancer predisposition condition for virus-induced malignancies

Warts, hypogammaglobulinaemia, infections and myelokathexis syndrome (WHIMS) is a rare combined primary immunodeficiency caused by the gain of function of the CXCR4 chemokine receptor. We present the prevalence of cancer in WHIMS patients based on data from the French Severe Chronic Neutropenia Registry and an exhaustive literature review. The median follow-up of the 14 WHIMS 'patients was 28.5 years. A central review and viral evaluation of pathological samples were organized, and we conducted a thorough literature review to identify all reports of WHIMS cases. Six French patients were diagnosed with cancer at a median age of 37.6 years. The 40-year risk of malignancy was 39% (95% confidence interval [CI]: 6%-74%). We observed two human papillomavirus (HPV)-induced vulvar carcinomas, three lymphomas (two Epstein-Barr virus [EBV]-related) and one basal cell carcinoma. Among the 155 WHIMS cases from the literature, 22 cancers were reported in 16 patients, with an overall cancer 40-year risk of 23% (95% CI: 13%-39%). Malignancies included EBV-associated lymphoproliferative disorders and HPV-positive genital and anal cancers as in the French cohort. Worldwide, nine cases of malignancy were associated with HPV and four with EBV. Immunocompromised WHIMS patients appear to be particularly susceptible to developing early malignancy, mainly HPV-induced carcinomas, followed by EBV-related lymphomas.

The human Papillomavirus twilight zone - Latency, immune control and subclinical infection

The incorporation of HPV DNA testing into cervical screening programs has shown that many HPV-positive women are cytologically normal, with HPV-positivity fluctuating throughout life. Such results suggest that papillomaviruses may persist in a latent state after disease clearance, with sporadic recurrence. It appears that virus latency represents a narrow slot in a wider spectrum of subclinical and possibly productive infections. Clinical studies, and animal model infection studies, suggested a key role for host immune surveillance in maintaining such asymptomatic infections, and although infections may also be cleared, most studies have used the term 'clearance' to describe a situation where the presence of HPV DNA falls below the clinical detection level. Given our knowledge of papillomavirus immune evasion strategies and the restricted pattern of viral gene expression required for 'basal cell' persistence, the term 'apparent clearance' and 'subclinical persistence' of infection may better summarise our understanding. Subclinical infection also encompasses the lag phase, which occurs between infection and lesion development. This is dependent on infection titre, with multifocal infections developing more rapidly to disease. These concepts can usefully influence patient management where HPV-positivity occurs sometime after the onset of sexual activity, and where vertical transmission is suspected despite a lag period.

A phase III randomized crossover trial of plerixafor versus G-CSF for treatment of WHIM syndrome

BACKGROUNDWarts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a primary immunodeficiency disorder caused by heterozygous gain-of-function CXCR4 mutations. Myelokathexis is a kind of neutropenia caused by neutrophil retention in bone marrow and in WHIM syndrome is associated with lymphopenia and monocytopenia. The CXCR4 antagonist plerixafor mobilizes leukocytes to the blood; however, its safety and efficacy in WHIM syndrome are undefined.METHODSIn this investigator-initiated, single-center, quadruple-masked phase III crossover trial, we compared the total infection severity score (TISS) as the primary endpoint in an intent-to-treat manner in 19 patients with WHIM who each received 12 months treatment with plerixafor and 12 months treatment with granulocyte CSF (G-CSF, the standard of care for severe congenital neutropenia). The treatment order was randomized for each patient.RESULTSPlerixafor was nonsuperior to G-CSF for TISS (P = 0.54). In exploratory endpoints, plerixafor was noninferior to G-CSF for maintaining neutrophil counts of more than 500 cells/μL (P = 0.023) and was superior to G-CSF for maintaining lymphocyte counts above 1,000 cells/μL (P < 0.0001). Complete regression of a subset of large wart areas occurred on plerixafor in 5 of 7 patients with major wart burdens at baseline. Transient rash occurred on plerixafor, and bone pain was more common on G-CSF. There were no significant differences in drug preference or quality of life or the incidence of drug failure or serious adverse events.CONCLUSIONPlerixafor was not superior to G-CSF in patients with WHIM for TISS, the primary endpoint. Together with wart regression and hematologic improvement, the infection severity results support continued study of plerixafor as a potential treatment for WHIM syndrome.TRIAL REGISTRATIONClinicaltrials.gov NCT02231879.FUNDINGThis study was funded by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases.

The Chemokine System in Oncogenic Pathways Driven by Viruses: Perspectives for Cancer Immunotherapy

Simple Summary

Oncoviruses are viruses with oncogenic potential, responsible for almost 20% of human cancers worldwide. They are from various families, some of which belong to the microbial communities that inhabit several sites in the body of healthy humans. As a result, they most often establish latent infections controlled by the arsenal of human host responses that include the chemokine system playing key roles at the interface between tissue homeostasis and immune surveillance. Yet, chemokines and their receptors also contribute to oncogenic processes as they are targeted by the virus-induced deregulations of host responses and/or directly encoded by viruses. Thus, the chemokine system offers a strong rationale for therapeutic options, some few already approved or in trials, and future ones that we are discussing in view of the pharmacological approaches targeting the different functions of chemokines operating in both cancer cells and the tumor microenvironment.

Abstract

Chemokines interact with glycosaminoglycans of the extracellular matrix and activate heptahelical cellular receptors that mainly consist of G Protein-Coupled Receptors and a few atypical receptors also with decoy activity. They are well-described targets of oncogenic pathways and key players in cancer development, invasiveness, and metastasis acting both at the level of cancer cells and cells of the tumor microenvironment. Hence, they can regulate cancer cell proliferation and survival and promote immune or endothelial cell migration into the tumor microenvironment. Additionally, oncogenic viruses display the potential of jeopardizing the chemokine system by encoding mimics of chemokines and receptors as well as several products such as oncogenic proteins or microRNAs that deregulate their human host transcriptome. Conversely, the chemokine system participates in the host responses that control the virus life cycle, knowing that most oncoviruses establish asymptomatic latent infections. Therefore, the deregulated expression and function of chemokines and receptors as a consequence of acquired or inherited mutations could bias oncovirus infection toward pro-oncogenic pathways. We here review these different processes and discuss the anticancer therapeutic potential of targeting chemokine availability or receptor activation, from signaling to decoy-associated functions, in combination with immunotherapies.

Protease-Triggered Release of Stabilized CXCL12 from Coated Scaffolds in an Ex Vivo Wound Model

Biomaterials are designed to improve impaired healing of injured tissue. To accomplish better cell integration, we suggest to coat biomaterial surfaces with bio-functional proteins. Here, a mussel-derived surface-binding peptide is used and coupled to CXCL12 (stromal cell-derived factor 1α), a chemokine that activates CXCR4 and consequently recruits tissue-specific stem and progenitor cells. CXCL12 variants with either non-releasable or protease-mediated-release properties were designed and compared. Whereas CXCL12 was stabilized at the N-terminus for protease resistance, a C-terminal linker was designed that allowed for specific cleavage-mediated release by matrix metalloproteinase 9 and 2, since both enzymes are frequently found in wound fluid. These surface adhesive CXCL12 derivatives were produced by expressed protein ligation. Functionality of the modified chemokines was assessed by inositol phosphate accumulation and cell migration assays. Increased migration of keratinocytes and primary mesenchymal stem cells was demonstrated. Immobilization and release were studied for bioresorbable PCL-co-LC scaffolds, and accelerated wound closure was demonstrated in an ex vivo wound healing assay on porcine skin grafts. After 24 h, a significantly improved CXCL12-specific growth stimulation of the epithelial tips was already observed. The presented data display a successful application of protein-coated biomaterials for skin regeneration.

CXCR4 signaling controls dendritic cell location and activation at steady state and in inflammation

Dendritic cells (DCs) encompass several cell subsets that collaborate to initiate and regulate immune responses. Proper DC localization determines their function and requires the tightly controlled action of chemokine receptors. All DC subsets express CXCR4, but the genuine contribution of this receptor to their biology has been overlooked. We addressed this question using natural CXCR4 mutants resistant to CXCL12-induced desensitization and harboring a gain of function that cause the warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS), a rare immunodeficiency associated with high susceptibility to the pathogenesis of human papillomavirus (HPV). We report a reduction in the number of circulating plasmacytoid DCs (pDCs) in WHIM patients, whereas that of conventional DCs is preserved. This pattern was reproduced in an original mouse model of WS, enabling us to show that the circulating pDC defect can be corrected upon CXCR4 blockade and that pDC differentiation and function are preserved, despite CXCR4 dysfunction. We further identified proper CXCR4 signaling as a critical checkpoint for Langerhans cell and DC migration from the skin to lymph nodes, with corollary alterations of their activation state and tissue inflammation in a model of HPV-induced dysplasia. Beyond providing new hypotheses to explain the susceptibility of WHIM patients to HPV pathogenesis, this study shows that proper CXCR4 signaling establishes a migration threshold that controls DC egress from CXCL12-containing environments and highlights the critical and subset-specific contribution of CXCR4 signal termination to DC biology.

Inborn Errors of Immunity and Cancer

Simple Summary

Inborn Errors of Immunity (IEI) are a heterogeneous group of disorders characterized by a defect in the function of at least one, and often more, components of the immune system. The overall risk for cancer in children with IEI ranges from 4 to 25%. Several factors, namely, age of the patient, viral infection status and IEI type can influence the development of different cancer types. Immunologists and oncologists should interact to monitor and promptly diagnose the potential development of cancer in known IEI patients, as well as an underlying IEI in newly diagnosed cancers with suggestive medical history or high rate of therapy-related toxicity. The creation of an international registry of IEI cases with detailed information on the occurrence of cancer is fundamental to optimizing the diagnostic process and to evaluating the outcomes of new therapeutic options, with the aim of improving prognosis and reducing comorbidities.

Abstract

Inborn Errors of Immunity (IEI) are a heterogeneous group of disorders characterized by a defect in the function of at least one, and often more, components of the immune system. The aim of this narrative review is to discuss the epidemiology, the pathogenesis and the correct management of tumours in patients with IEI. PubMed was used to search for all of the studies published over the last 20 years using the keywords: “inborn errors of immunity” or “primary immunodeficiency” and “cancer” or “tumour” or “malignancy”. Literature analysis showed that the overall risk for cancer in children with IEI ranges from 4 to 25%. Several factors, namely, age of the patient, viral infection status and IEI type can influence the development of different cancer types. The knowledge of a specific tumour risk in the presence of IEI highlights the importance of a synergistic effort by immunologists and oncologists in tracking down the potential development of cancer in known IEI patients, as well as an underlying IEI in patients with newly diagnosed cancers. In the current genomic era, the creation of an international registry of IEI cases integrated with malignancies occurrence information is fundamental to optimizing the diagnostic process and to evaluating the outcomes of new therapeutic options, with the hope to obtain a better prognosis for these patients.

CXCR4/ACKR3/CXCL12 axis in the lymphatic metastasis of vulvar squamous cell carcinoma

Aims

Vulvar squamous cell carcinoma (VSCC) spreads early and mainly locally via direct expansion into adjacent structures, followed by lymphatic metastasis to the regional lymph nodes (LNs). In the lymphatic metastasis, cancer cells bearing CXCR4 and ACKR3 (CXCR7) receptors are recruited to the LNs that produce the CXCL12 ligand. Our study aimed to assess the role of the CXCR4/ACKR3/CXCL12 axis in VSCC progression.

Methods

Tumour and LN tissue samples were obtained from 46 patients with VSCC and 51 patients with premalignant vulvar lesions. We assessed CXCR4, ACKR3 and CXCL12 by immunohistochemistry (IHC) in the tissue samples. Additionally, CXCL12 levels were determined by ELISA in the sera of 23 patients with premalignant lesions, 37 with VSCC and 16 healthy volunteers.

Results

CXCR4 and ACKR3 proteins were virtually absent in vulvar precancers, while in VSCC samples the IHC staining was strong. In the LNs of patients with VSCC, 98% of metastatic cells expressed CXCR4 and 85% expressed ACKR3. Neither CXCR4 nor ACKR3 presence was correlated with tumour human papilloma virus status. Few CXCL12-positive cells were found in the analysed tissue samples, but serum CXCL12 levels were significantly increased in both patients with premalignant vulvar lesions and with VSCC compared with healthy volunteers.

Conclusions

It appears that during progression and lymphatic spread of VSCC, the CXCR4/ACKR3/CXCL12 axis is activated. Moreover, our data suggest that CXCR4 antagonists merit further attention as a possible therapeutic option in patients with VSCC.

Molecular pathways in the development of HPV-induced cervical cancer

Recently, human papillomavirus (HPV) has gained considerable attention in cervical cancer research studies. It is one of the most important sexually transmitted diseases that can affect 160 to 289 out of 10000 persons every year. Due to the infectious nature of this virus, HPV can be considered a serious threat. The knowledge of viral structure, especially for viral oncoproteins like E6, E7, and their role in causing cancer is very important. This virus has different paths (PI3K/Akt, Wnt/β-catenin, ERK/MAPK, and JAK/STAT) that are involved in the transmission of signaling paths through active molecules like MEK (pMEK), ERK (pERK), and Akt (pAkt). It's eventually through these paths that cancer is developed. Precise knowledge of these paths and their signals give us the prognosis to adopt appropriate goals for prevention and control of these series of cancer.

Results of a phase 2 trial of an oral CXCR4 antagonist, mavorixafor, for treatment of WHIM syndrome

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare primary immunodeficiency caused by gain-of-function mutations in the CXCR4 gene. We report the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of mavorixafor from a phase 2 open-label dose-escalation and extension study in 8 adult patients with genetically confirmed WHIM syndrome. Mavorixafor is an oral small molecule selective antagonist of the CXCR4 receptor that increases mobilization and trafficking of white blood cells from the bone marrow. Patients received escalating doses of mavorixafor, up to 400 mg once daily. Five patients continued on the extension study for up to 28.6 months. Mavorixafor was well tolerated with no treatment-related serious adverse events. At a median follow-up of 16.5 months, we observed dose-dependent increases in absolute neutrophil count (ANC) and absolute lymphocyte count (ALC). At doses ≥300 mg/d, ANC was maintained at >500 cells per microliter for a median of 12.6 hours, and ALC was maintained at >1000 cells per microliter for up to 16.9 hours. Continued follow-up on the extension study resulted in a yearly infection rate that decreased from 4.63 events (95% confidence interval, 3.3-6.3) in the 12 months prior to the trial to 2.27 events (95% confidence interval, 1.4-3.5) for patients on effective doses. We observed an average 75% reduction in the number of cutaneous warts. This study demonstrates that mavorixafor, 400 mg once daily, mobilizes neutrophil and lymphocytes in adult patients with WHIM syndrome and provides preliminary evidence of clinical benefit for patients on long-term therapy. The trial was registered at www.clinicaltrials.gov as #NCT03005327.

The CXCL12/CXCR4/ACKR3 Axis in the Tumor Microenvironment: Signaling, Crosstalk, and Therapeutic Targeting

Elevated expression of the chemokine receptors CXCR4 and ACKR3 and of their cognate ligand CXCL12 is detected in a wide range of tumors and the tumor microenvironment (TME). Yet, the molecular mechanisms by which the CXCL12/CXCR4/ACKR3 axis contributes to the pathogenesis are complex and not fully understood. To dissect the role of this axis in cancer, we discuss its ability to impinge on canonical and less conventional signaling networks in different cancer cell types; its bidirectional crosstalk, notably with receptor tyrosine kinase (RTK) and other factors present in the TME; and the infiltration of immune cells that supporttumor progression. We discuss current and emerging avenues that target the CXCL12/CXCR4/ACKR3 axis. Coordinately targeting both RTKs and CXCR4/ACKR3 and/or CXCL12 is an attractive approach to consider in multitargeted cancer therapies. In addition, inhibiting infiltrating immune cells or reactivating the immune system along with modulating the CXCL12/CXCR4/ACKR3 axis in the TME has therapeutic promise.

TLR2/CXCR4 coassociation facilitatesChlamydia pneumoniaeinfection-induced atherosclerosis

Toll-like receptor 2 (TLR2) and C-X-C motif chemokine receptor 4 (CXCR4) have both been shown to be involved in atherosclerosis. We demonstrate for the first time the presence of TLR2/CXCR4 coassociation during C. pneumoniae infection-induced atherosclerosis. Amazingly, blocking of both TLR2 and CXCR4 significantly retards and even almost reverses this infection-induced atherosclerosis. Our work reveals new mechanisms about C. pneumoniae infection-induced atherosclerosis and identifies potential new therapeutic targets for the prevention and treatment of atherosclerosis.

WHIM Syndrome: from Pathogenesis Towards Personalized Medicine and Cure

WHIM syndrome is a rare combined primary immunodeficiency disease named by acronym for the diagnostic tetrad of warts, hypogammaglobulinemia, infections, and myelokathexis. Myelokathexis is a unique form of non-cyclic severe congenital neutropenia caused by accumulation of mature and degenerating neutrophils in the bone marrow; monocytopenia and lymphopenia, especially B lymphopenia, also commonly occur. WHIM syndrome is usually caused by autosomal dominant mutations in the G protein-coupled chemokine receptor CXCR4 that impair desensitization, resulting in enhanced and prolonged G protein- and β-arrestin-dependent responses. Accordingly, CXCR4 antagonists have shown promise as mechanism-based treatments in phase 1 clinical trials. This review is based on analysis of all 105 published cases of WHIM syndrome and covers current concepts, recent advances, unresolved enigmas and controversies, and promising future research directions.

Cutaneous Papillomaviruses and Non-melanoma Skin Cancer: Causal Agents or Innocent Bystanders?

There is still controversy in the scientific field about whether certain types of cutaneous human papillomaviruses (HPVs) are causally involved in the development of non-melanoma skin cancer (NMSC). Deciphering the etiological role of cutaneous HPVs requires - besides tissue culture systems - appropriate preclinical models to match the obtained results with clinical data from affected patients. Clear scientific evidence about the etiology and underlying mechanisms involved in NMSC development is fundamental to provide reasonable arguments for public health institutions to classify at least certain cutaneous HPVs as group 1 carcinogens. This in turn would have implications on fundraising institutions and health care decision makers to force - similarly as for anogenital cancer - the implementation of a broad vaccination program against "high-risk" cutaneous HPVs to prevent NMSC as the most frequent cancer worldwide. Precise knowledge of the multi-step progression from normal cells to cancer is a prerequisite to understand the functional and clinical impact of cofactors that affect the individual outcome and the personalized treatment of a disease. This overview summarizes not only recent arguments that favor the acceptance of a viral etiology in NMSC development but also reflects aspects of causality in medicine, the use of empirically meaningful model systems and strategies for prevention.

Multisystem multitasking by CXCL12 and its receptors CXCR4 and ACKR3

Chemokines are named and best known for their chemotactic cytokine activity in the hematopoietic system; however, their importance extends far beyond leukocytes, cell movement and immunoregulation. CXCL12, the most protean of chemokines, regulates development in multiple systems, including the hematopoietic, cardiovascular and nervous systems, and regulates diverse cell functions, including differentiation, distribution, activation, immune synapse formation, effector function, proliferation and survival in the immune system alone. The broad importance of CXCL12 is revealed by the complex lethal developmental phenotypes in mice lacking either Cxcl12 or either one of its two known 7-transmembrane domain receptors Cxcr4 and Ackr3, as well as by gain-of-function mutations in human CXCR4, which cause WHIM syndrome, a multisystem and combined immunodeficiency disease and the only Mendelian condition caused by a chemokine system mutation. In addition, wild type CXCR4 is important in the pathogenesis of HIV/AIDS and cancer. Thus, CXCL12 and its receptors CXCR4 and ACKR3 provide extraordinary examples of multisystem multitasking in the chemokine system in both health and disease.

CXCR4-Specific Nanobodies as Potential Therapeutics for WHIM syndrome

WHIM syndrome is a rare congenital immunodeficiency disease, named after its main clinical manifestations: warts, hypogammaglobulinemia, infections, and myelokathexis, which refers to abnormal accumulation of mature neutrophils in the bone marrow. The disease is primarily caused by C-terminal truncation mutations of the chemokine receptor CXCR4, giving these CXCR4-WHIM mutants a gain of function in response to their ligand CXCL12. Considering the broad functions of CXCR4 in maintaining leukocyte homeostasis, patients are panleukopenic and display altered immune responses, likely as a consequence of impairment in the differentiation and trafficking of leukocytes. Treatment of WHIM patients currently consists of symptom relief, leading to unsatisfactory clinical responses. As an alternative and potentially more effective approach, we tested the potency and efficacy of CXCR4-specific nanobodies on inhibiting CXCR4-WHIM mutants. Nanobodies are therapeutic proteins based on the smallest functional fragments of heavy chain antibodies. They combine the advantages of small-molecule drugs and antibody-based therapeutics due to their relative small size, high stability, and high affinity. We compared the potential of monovalent and bivalent CXCR4-specific nanobodies to inhibit CXCL12-induced CXCR4-WHIM-mediated signaling with the small-molecule clinical candidate AMD3100. The CXCR4-targeting nanobodies displace CXCL12 binding and bind CXCR4-wild type and CXCR4-WHIM (R334X/S338X) mutants and with (sub-) nanomolar affinities. The nanobodies' epitope was mapped to extracellular loop 2 of CXCR4, overlapping with the binding site of CXCL12. Monovalent, and in particular bivalent, nanobodies were more potent than AMD3100 in reducing CXCL12-mediated G protein activation. In addition, CXCR4-WHIM-dependent calcium flux and wound healing of human papillomavirus-immortalized cell lines in response to CXCL12 was effectively inhibited by the nanobodies. Based on these in vitro results, we conclude that CXCR4 nanobodies hold significant potential as alternative therapeutics for CXCR4-associated diseases such as WHIM syndrome.

Pathogenesis, diagnosis and therapeutic strategies in WHIM syndrome immunodeficiency

21 INTRODUCTION

WHIM syndrome is a rare combined primary immunodeficiency disorder caused by autosomal dominant gain-of-function mutations in the chemokine receptor CXCR4. It is the only Mendelian condition known to be caused by mutation of a chemokine or chemokine receptor. As such, it provides a scientific opportunity to understand chemokine-dependent immunoregulation in humans and a medical opportunity to develop mechanism-based treatment and cure strategies.

22 AREAS COVERED

This review covers the clinical features, genetics, immunopathogenesis and clinical management of WHIM syndrome. Clinical trials of targeted therapeutic agents and potential cure strategies are also included.

23 EXPERT OPINION

WHIM syndrome may be particularly amenable to mechanism-based therapeutics for three reasons: 1) CXCR4 has been validated as the molecular target in the disease by Mendelian genetics; 2) the biochemical abnormality is excessive CXCR4 signaling; and 3) antagonists selective for CXCR4 have been developed. Plerixafor is FDA-approved for hematopoietic stem cell (HSC) mobilization and has shown preliminary safety and efficacy in phase I clinical trials in WHIM syndrome. Gene editing may represent a viable cure strategy, since chromothriptic deletion of the disease allele in HSCs resulted in clinical cure of a patient and because CXCR4 haploinsufficiency enhances engraftment of transplanted HSCs in mice.

Modern management of phagocyte defects

Phagocytic neutrophil granulocytes are among the first immune cells active at sites of infection, forming an important first-line defense against invading microorganisms. Congenital immune defects concerning these phagocytes may be due to reduced neutrophil numbers or function. Management of affected patients depends on the type and severity of disease. Here, we provide an overview of causes and treatment of diseases associated with congenital neutropenia, as well as defects of the phagocytic respiratory burst.

Effect of human cytomegalovirus (HCMV) US27 on CXCR4 receptor internalization measured by fluorogen-activating protein (FAP) biosensors

Human cytomegalovirus (HCMV) is a widespread pathogen and a member of the Herpesviridae family. HCMV has a large genome that encodes many genes that are non-essential for virus replication but instead play roles in manipulation of the host immune environment. One of these is the US27 gene, which encodes a protein with homology to the chemokine receptor family of G protein-coupled receptors (GPCRs). The US27 protein has no known chemokine ligands but can modulate the signaling activity of host receptor CXCR4. We investigated the mechanism for enhanced CXCR4 signaling in the presence of US27 using a novel biosensor system comprised of fluorogen activating proteins (FAPs). FAP-tagged CXCR4 and US27 were used to explore receptor internalization and recovery dynamics, and the results demonstrate that significantly more CXCR4 internalization was observed in the presence of US27 compared to CXCR4 alone upon stimulation with CXCL12. While ligand-induced endocytosis rates were higher, steady state internalization of CXCR4 was not affected by US27. Additionally, US27 underwent rapid endocytosis at a rate that was independent of either CXCR4 expression or CXCL12 stimulation. These results demonstrate that one mechanism by which US27 can enhance CXCR4 signaling is to alter receptor internalization dynamics, which could ultimately have the effect of promoting virus dissemination by increasing trafficking of HCMV-infected cells to tissues where CXCL12 is highly expressed.

Dysplasia of Granulocytes in a Patient with HPV Disease, Recurrent Infections, and B Lymphopenia: A Novel Variant of WHIM Syndrome?

WHIM syndrome is a condition in which affected persons have chronic peripheral neutropenia, lymphopenia, abnormal susceptibility to human papilloma virus infection, and myelokathexis. Myelokathexis refers to the retention of mature neutrophils in the bone marrow (BM), which accounts for degenerative changes and hypersegmentation. Most patients present heterozygous autosomal dominant mutations of the gene encoding CXCR4. Consequently, aberrant CXCL12/CXCR4 signaling impairs the receptor downregulation causing hyperactivation (gain-of-function) that affects BM homing for myelopoiesis and lymphopoiesis and the release of neutrophils in the bloodstream. We report the case of a 26-year-old female with severe foot and hand cutaneous warts since childhood, recalcitrant genital condylomatas, bacterial infections, and intraepithelial cervical neoplasia. Laboratory tests revealed severe B lymphopenia and HPV high and low risk types. HIV testing was negative. Not only CXCR4 but also GATA2, NEMO, and CD40L gene mutations were excluded. BM smears revealed, in the presence of a normal cellularity, hyperplasia of myeloid cells (MPO positive) and karyorrhexis, especially in neutrophils and eosinophils. Of note, neutrophils with altered lobation of nuclei connected by long thin chromatin filaments were observed. Our patient presented a clinical and histological picture reminiscent of WHIM in the presence of normal peripheral neutrophil counts and wild-type CXCR4 gene. Although the BM did not reveal a classical pattern of myelokathexis, the observation of consistent signs of neutrophil dysplasia has fuelled the hypothesis of a novel WHIM variant or a novel immunodeficiency. We speculate that abnormalities that affect CXCR4/CXCL12 pair, including GRK levels or activity, might be responsible for this WHIM-like disorder.

The CXCL12/CXCR4 Signaling Pathway: A New Susceptibility Factor in Human Papillomavirus Pathogenesis

The productive human papillomavirus (HPV) life cycle is tightly linked to the differentiation and cycling of keratinocytes. Deregulation of these processes and stimulation of cell proliferation by the action of viral oncoproteins and host cell factors underlies HPV-mediated carcinogenesis. Severe HPV infections characterize the wart, hypogammaglobulinemia, infection, and myelokathexis (WHIM) immunodeficiency syndrome, which is caused by gain-of-function mutations in the CXCR4 receptor for the CXCL12 chemokine, one of which is CXCR4¹⁰¹³. We investigated whether CXCR4¹⁰¹³ interferes in the HPV18 life cycle in epithelial organotypic cultures. Expression of CXCR4¹⁰¹³ promoted stabilization of HPV oncoproteins, thus disturbing cell cycle progression and proliferation at the expense of the ordered expression of the viral genes required for virus production. Conversely, blocking CXCR4¹⁰¹³ function restored virus production and limited HPV-induced carcinogenesis. Thus, CXCR4 and its potential activation by genetic alterations in the course of the carcinogenic process can be considered as an important host factor for HPV carcinogenesis.

Human papillomaviruses (HPV) are epitheliotropic tumor viruses causing mostly benign warts but that have developed strategies to establish persistent infections. Although host immune responses clear most infections, persistence of some HPV types causes ~5% of human cancers and severe pathogenesis in immunosuppressed individuals. How early events in HPV infection, determined by the interaction between viral and host proteins, might lead to viral persistence and pathogenesis is unknown. Here, we thought to investigate this issue by providing mechanistic insights into the selective susceptibility to HPV pathogenesis displayed by patients who are immunosuppressed as a consequence of mutations in the CXCR4 gene encoding for the receptor of the CXCL12 chemokine (WHIM syndrome). We previously unraveled the existence of a general interplay between the CXCL12/CXCR4 axis and HPV, which is hijacked toward cell transformation upon expression of the CXCR4 mutant. Here, using three dimensional epithelial cell cultures to analyze the HPV life cycle, we found that the CXCR4 mutant promotes cell hyperproliferation and stabilization of viral oncoprotein expression at the expense of virus production. Our results, which identify CXCR4 as an important gatekeeper of keratinocyte proliferation and as a new susceptibility factor in HPV pathogenesis, may be translated into anti-viral and anti-cancer strategies.

Altered chemotactic response to CXCL12 in patients carrying GATA2 mutations

GATA2 deficiency-formerly described as MonoMAC syndrome; dendritic cells, monocytes, B cells, and natural killer cell deficiency; familial myelodysplastic syndrome/acute myeloid leukemia; or Emberger syndrome-encompasses a range of hematologic and nonhematologic anomalies, mainly characterized by monocytopenia, B lymphopenia, natural killer cell cytopenia, neutropenia, immunodeficiency, and a high risk of developing acute myeloid leukemia. Herein, we present 7 patients with GATA2 deficiency recruited into the French Severe Chronic Neutropenia Registry, which enrolls patients with all kinds of congenital neutropenia. We performed extended immunophenotyping of their whole blood lymphocyte populations, together with the analysis of their chemotactic responses. Lymphopenia was recorded for B and CD4(+) T cells in 6 patients. Although only 3 patients displayed natural killer cell cytopenia, the CD56(bright) natural killer subpopulation was nearly absent in all 7 patients. Natural killer cells from 6 patients showed decreased CXCL12/CXCR4-dependent chemotaxis, whereas other lymphocytes, and most significantly B lymphocytes, displayed enhanced CXCL12-induced chemotaxis compared with healthy volunteers. Surface expression of CXCR4 was significantly diminished in the patients' natural killer cells, although the total expression of the receptor was found to be equivalent to that of natural killer cells from healthy individual controls. Together, these data reveal that GATA2 deficiency is associated with impaired membrane expression and chemotactic dysfunctions of CXCR4. These dysfunctions may contribute to the physiopathology of this deficiency by affecting the normal distribution of lymphocytes and thus potentially affecting the susceptibility of patients to associated infections.

Symptomatic Improvement in Human Papillomavirus-Induced Epithelial Neoplasia by Specific Targeting of the CXCR4 Chemokine Receptor

Human papillomavirus (HPV) infection is estimated to be the causal agent in 5% of all human cancers and is the leading cause of genital warts, which is the most common sexually transmitted viral disease. Currently, there are no medications to treat HPV infection, and therapeutic strategies primarily target HPV-related cancer rather than viral infection. HPV infection has severe effects on patients who display selective susceptibility to the virus in the context of primary immunodeficiencies, such as the warts, hypogammaglobulinemia, infections, and myelokathexis syndrome, which is caused by dysfunctions of CXCR4, the receptor for the CXCL12 chemokine. In this study we showed in a transgenic mouse model of HPV-induced epidermal neoplasia the beneficial effects of Cxcl12/Cxcr4 pathway blockade with the selective CXCR4 antagonist AMD3100. Daily treatment with AMD3100 for 28 days potently reduced the abnormal ear epidermal thickening in all mice. This effect was associated with reductions in keratinocyte hyperproliferation and immune cell infiltration, both of which are linked to neoplastic progression. Moreover, we observed the abnormal coordinate expression of Cxcl12 and p16INK4a (a surrogate marker of HPV-induced cancers) in dysplastic epidermal keratinocytes, which was inhibited by AMD3100 treatment. These results provide strong evidence for the therapeutic potential of CXCL12/CXCR4 pathway blockade in HPV-induced pathogenesis.

Immunodeficiency-associated viral oncogenesis

Several viruses with different replication mechanisms contribute to oncogenesis by both direct and indirect mechanisms in immunosuppressed subjects after solid organ transplantation, after allogeneic stem cell transplantation, or with human immunodeficiency virus (HIV) infection. Epstein-Barr virus (EBV), human papillomavirus (HPV), Kaposi sarcoma herpesvirus (KSHV), human T-cell lymphotropic virus type 1 (HTLV-1) and Merkel cell polyoma virus (MCV) are the main viruses associated with the development of cancer in immunosuppressed patients. Besides being a main cause of immunodeficiency, HIV1 has a direct pro-oncogenic effect. In this review, we provide an update on the association between the condition of acquired immunodeficiency and cancer risk, specifically addressing the contributions to oncogenesis of HPV, MCV, KSHV, HTLV-1, and EBV.

Molecular transitions from papillomavirus infection to cervical precancer and cancer: Role of stromal estrogen receptor signaling

To study the multistep process of cervical cancer development, we analyzed 128 frozen cervical samples spanning normalcy, increasingly severe cervical intraepithelial neoplasia (CIN1- CIN3), and cervical cancer (CxCa) from multiple perspectives, revealing a cascade of progressive changes. Compared with normal tissue, expression of many DNA replication/repair and cell proliferation genes was increased in CIN1/CIN2 lesions and further sustained in CIN3, consistent with high-risk human papillomavirus (HPV)-induced tumor suppressor inactivation. The CIN3-to-CxCa transition showed metabolic shifts, including decreased expression of mitochondrial electron transport complex components and ribosomal protein genes. Significantly, despite clinical, epidemiological, and animal model results linking estrogen and estrogen receptor alpha (ERα) to CxCa, ERα expression declined >15-fold from normalcy to cancer, showing the strongest inverse correlation of any gene with the increasing expression of p16, a marker for HPV-linked cancers. This drop in ERα in CIN and tumor cells was confirmed at the protein level. However, ERα expression in stromal cells continued throughout CxCa development. Our further studies localized stromal ERα to FSP1+, CD34+, SMA- precursor fibrocytes adjacent to normal and precancerous CIN epithelium, and FSP1-, CD34-, SMA+ activated fibroblasts in CxCas. Moreover, rank correlations with ERα mRNA identified IL-8, CXCL12, CXCL14, their receptors, and other angiogenesis and immune cell infiltration and inflammatory factors as candidates for ERα-induced stroma-tumor signaling pathways. The results indicate that estrogen signaling in cervical cancer has dramatic differences from ERα+ breast cancers, and imply that estrogen signaling increasingly proceeds indirectly through ERα in tumor-associated stromal fibroblasts.

The relevance of the chemokine receptor ACKR3/CXCR7 on CXCL12-mediated effects in cancers with a focus on virus-related cancers

Recent studies have highlighted the importance of understanding the molecular determinants of CXCL12-mediated effects in cancers. Once previously thought to interact exclusively with CXCR4, CXCL12 also binds with high affinity to CXCR7 (recently renamed ACKR3), which belongs to an atypical chemokine receptor family whose members fail to activate Gαi proteins but interact with β-arrestins. In addition to its capacity to control CXCL12 bioavailability, ACKR3 can either enhance or dampen CXCR4-mediated signaling and activity. In light of the most recent findings, we have examined the role of ACKR3 in cancer, including a subset of virus-related cancers.

CXCR4: a virus's best friend?

Viruses are dependent on their hosts for replication and dispersal in the environment; thus, the most successful viruses are those that co-evolve with their hosts. CXCR4 is a cellular chemokine receptor that plays central roles in development, hematopoiesis, and immune surveillance through signaling induced by its ligand, CXCL12. The CXCR4-CXCL12 axis has been besieged by many pathogens that employ a range of strategies to modify or exploit CXCR4 activity. While CXCR4 was identified as a critical co-factor for entry of HIV into CD4+ T cells early on, other viruses may utilize CXCR4 to gain cell entry as well. Moreover, several viruses have been found to modulate CXCR4 expression or alter its functional activity, with direct effects on cell trafficking, immune responses, cell proliferation, and cell survival. Because CXCR4 is targeted by a diverse group of viral pathogens, modification of host CXCR4 signaling activity is emerging as a common theme in virus persistence and is likely to be important for subversion of the host immune system. This review highlights major viral pathogens that use and abuse CXCR4 and explores the possible reasons why this chemokine receptor has become "a virus's best friend".

A phase 1 clinical trial of long-term, low-dose treatment of WHIM syndrome with the CXCR4 antagonist plerixafor

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare immunodeficiency disorder caused by gain-of-function mutations in the G protein-coupled chemokine receptor CXCR4. The CXCR4 antagonist plerixafor, which is approved by the US Food and Drug Administration (FDA) for stem cell mobilization in cancer and administered for that indication at 0.24 mg/kg, has been shown in short-term (1- to 2-week) phase 1 dose-escalation studies to correct neutropenia and other cytopenias in WHIM syndrome. However, long-term safety and long-term hematologic and clinical efficacy data are lacking. Here we report results from the first long-term clinical trial of plerixafor in any disease, in which 3 adults with WHIM syndrome self-injected 0.01 to 0.02 mg/kg (4% to 8% of the FDA-approved dose) subcutaneously twice daily for 6 months. Circulating leukocytes were durably increased throughout the trial in all patients, and this was associated with fewer infections and improvement in warts in combination with imiquimod; however, immunoglobulin levels and specific vaccine responses were not fully restored. No drug-associated side effects were observed. These results provide preliminary evidence for the safety and clinical efficacy of long-term, low-dose plerixafor in WHIM syndrome and support its continued study as mechanism-based therapy in this disease. The ClinicalTrials.gov identifier for this study is NCT00967785.

Genetics on a WHIM

We initially described the WHIM syndrome based on the combination of Warts, Hypogammaglobulinaemia, Infections and Myelokathexis (neutrophil retention in the bone marrow). Translational research led to the discovery that this rare immunodeficiency disease is caused by a heterozygous mutation in the CXCR4 gene. Recently, Plerixafor has been suggested as a treatment for WHIM syndrome due to its efficacy as a CXCR4 antagonist, closing the translational research loop. In this review, we will focus on the clinical manifestations, pathophysiology, diagnosis and possible therapies for this rare entity.

CXCR4 in epidermal keratinocytes: crosstalk within the skin

In this issue, Takekoshi et al. investigated the role of CXCR4 in IL-23-induced keratinocyte hyperproliferation using an epidermal-specific knockout mouse model and found that CXCR4 limited keratinocyte proliferation. Some reports in the literature support this idea, whereas others contradict it; this disparity may be related to the differential roles of CXCR4 in various cell types or to a recently identified second receptor (CXCR7). Nevertheless, CXCR4 and its ligand SDF-1 have been implicated in skin wound healing, systemic lupus erythematosus, and basal cell carcinoma tumor angiogenesis. Further study is merited.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

The CXCR4 mutations in WHIM syndrome impair the stability of the T-cell immunologic synapse

WHIM (warts, hypogammaglobulinemia, infections, myelokathexis) syndrome is a rare disease characterized by diverse symptoms indicative of aberrantly functioning immunity. It is caused by mutations in the chemokine receptor CXCR4, which impair its intracellular trafficking, leading to increased responsiveness to chemokine ligand and retention of neutrophils in bone marrow. Yet WHIM symptoms related to adaptive immunity, such as delayed IgG switching and impaired memory B-cell function, remain largely unexplained. We hypothesized that the WHIM-associated mutations in CXCR4 may affect the formation of immunologic synapses between T cells and antigen-presenting cells (APCs). We show that, in the presence of competing external chemokine signals, the stability of T-APC conjugates from patients with WHIM-mutant CXCR4 is disrupted as a result of impaired recruitment of the mutant receptor to the immunologic synapse. Using retrogenic mice that develop WHIM-mutant T cells, we show that WHIM-mutant CXCR4 inhibits the formation of long-lasting T-APC interactions in ex vivo lymph node slice time-lapse microscopy. These findings demonstrate that chemokine receptors can affect T-APC synapse stability and allow us to propose a novel mechanism that contributes to the adaptive immune response defects in WHIM patients.

Autocrine CCL3 and CCL4 induced by the oncoprotein LMP1 promote Epstein-Barr virus-triggered B cell proliferation

Epstein-Barr virus (EBV) alters the regulation and expression of a variety of cytokines in its host cells to modulate host immune surveillance and facilitate viral persistence. Using cytokine antibody arrays, we found that, in addition to the cytokines reported previously, two chemotactic cytokines, CCL3 and CCL4, were induced in EBV-infected B cells and were expressed at high levels in all EBV-immortalized lymphoblastoid cell lines (LCLs). Furthermore, EBV latent membrane protein 1 (LMP1)-mediated Jun N-terminal protein kinase activation was responsible for upregulation of CCL3 and CCL4. Inhibition of CCL3 and CCL4 in LCLs using a short hairpin RNA approach or by neutralizing antibodies suppressed cell proliferation and caused apoptosis, indicating that autocrine CCL3 and CCL4 are required for LCL survival and growth. Importantly, significant amounts of CCL3 were detected in EBV-positive plasma from immunocompromised patients, suggesting that EBV modulates this chemokine in vivo. This study reveals the regulatory mechanism and a novel function of CCL3 and CCL4 in EBV-infected B cells. CCL3 might be useful as a therapeutic target in EBV-associated lymphoproliferative diseases and malignancies.

An antedrug of the CXCL12 neutraligand blocks experimental allergic asthma without systemic effect in mice

The chemokine receptor CXCR4 and its chemokine CXCL12 are involved in normal tissue patterning but also in tumor cell growth and survival as well as in the recruitment of immune and inflammatory cells, as successfully demonstrated using agents that block either CXCL12 or CXCR4. In order to achieve selectivity in drug action on the CXCR4/CXCL12 pair, in particular in the airways, drugs should be delivered as selectively as possible in the treated tissue and should not diffuse in the systemic circulation, where it may reach undesired organs. To this end, we used a previously unexploited Knoevenagel reaction to create a short lived drug, or soft drug, based on the CXCL12-neutralizing small molecule, chalcone 4, which blocks binding of CXCL12 to CXCR4. We show that the compound, carbonitrile-chalcone 4, blocks the recruitment of eosinophils to the airways in ovalbumin-sensitized and challenged mice in vivo when administered directly to the airways by the intranasal route, but not when administered systemically by the intraperitoneal route. We show that the lack of effect at a distant site is due to the rapid degradation of the molecule to inactive fragments. This approach allows selective action of the CXCL12 neutraligands although the target protein is widely distributed in the organism.

Coxsackievirus B3 infects the bone marrow and diminishes the restorative capacity of erythroid and lymphoid progenitors

Coxsackievirus B3 (CVB3) is known to infect stem cells in the neonatal central nervous system. Here, we evaluated the effects of CVB3 infection on the major source and repository of stem cells, the bone marrow (BM). Viral genome was detectable in BM within 24 h of infection, and productive infection of BM cells was evident, peaking at 48 h postinfection (p.i.), when ∼1 to 2% of BM cells produced infectious virus particles. Beginning at 2 to 3 days p.i., a dramatic and persistent loss of immature erythroid cells, B and T lymphocytes, and neutrophils was observed in BM and, by day 3 to 4 p.i., the femoral BM stroma was largely destroyed. Analysis of peripheral blood revealed a modest neutrophilia, a loss of reticulocytes, and a massive lymphopenia. The abundance of multipotent progenitor cells (Lin(-)/c-kit(+)/Flt3(+)) in BM declined ∼10-fold during CVB3 infection and, consistent with a deficiency of primitive hematopoietic progenitors, serum levels of the hematopoietic growth factor Flt3 ligand were dramatically elevated. Therefore, we analyzed the regenerative capacity of BM from CVB3-infected mice. Granulocyte/macrophage progenitors displayed a relatively normal proliferative ability, consistent with the fact that the peripheral blood level of neutrophils-which are very short-lived cells-remained high throughout infection. However, erythroid and lymphoid hematopoietic progenitors in BM from CVB3-infected mice showed a markedly reduced colony-forming capacity, consonant with the observed loss of both lymphocytes and immature erythroid cells/reticulocytes from the BM and peripheral blood. In summary, CVB3 infects the BM and exerts differential effects on the various hematopoietic progenitor populations.

The biology and life-cycle of human papillomaviruses

Human papillomaviruses (HPVs) comprise a diverse group, and have different epithelial tropisms and life-cycle strategies. Many HPVs are classified as low-risk, as they are only very rarely associated with neoplasia or cancer in the general population. These HPVs typically cause inapparent/inconspicuous infections, or benign papillomas, which can persist for months or years, but which are eventually resolved by the host's immune system. Low-risk HPVs are difficult to manage in immunosuppressed people and in individuals with genetic predispositions, and can give rise to papillomatosis, and in rare instances, to cancer. The high-risk HPV types are, by contrast, a cause of several important human cancers, including almost all cases of cervical cancer, a large proportion of other anogenital cancers and a growing number of head and neck tumours. The high-risk HPV types constitute a subset of the genus Alphapapillomavirus that are prevalent in the general population, and in most individuals cause only inconspicuous oral and genital lesions. Cancer progression is associated with persistent high-risk HPV infection and with deregulated viral gene expression, which leads to excessive cell proliferation, deficient DNA repair, and the accumulation of genetic damage in the infected cell. Although their life-cycle organisation is broadly similar to that of the low-risk HPV types, the two groups differ significantly in their capacity to drive cell cycle entry and cell proliferation in the basal/parabasal cell layers. This is thought to be linked, at least in part, to different abilities of the high- and low-risk E6 proteins to modulate the activity of p53 and PDZ-domain proteins, and the differential ability of the E7 proteins to target the several different members of the retinoblastoma protein family. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Description and outcome of a cohort of 8 patients with WHIM syndrome from the French Severe Chronic Neutropenia Registry

BACKGROUND

WHIM syndrome (WS), a rare congenital neutropenia due to mutations of the CXCR4 chemokine receptor, is associated with Human Papillomavirus (HPV)-induced Warts, Hypogammaglobulinemia, bacterial Infections and Myelokathexis. The long term follow up of eight patients highlights the clinical heterogeneity of this disease as well as the main therapeutic approaches and remaining challenges in the light of the recent development of new CXCR4 inhibitors.

OBJECTIVE

This study aims to describe the natural history of WS based on a French cohort of 8 patients.

METHODS

We have reviewed the clinical, biological and immunological features of patients with WS enrolled into the French Severe Chronic Neutropenia Registry.

RESULTS

We identified four pedigrees with WS comprised of eight patients and one foetus. Estimated incidence for WS was of 0.23 per million births. Median age at the last visit was 29 years. Three pedigrees encompassing seven patients and the fetus displayed autosomal dominant heterozygous mutations of the CXCR4 gene, while one patient presented a wild-type CXCR4 gene. Two subjects exhibited congenital conotruncal heart malformations. In addition to neutropenia and myelokathexis, all patients presented deep monocytopenia and lymphopenia. Seven patients presented repeated bacterial Ears Nose Throat as well as severe bacterial infections that were curable with antibiotics. Four patients with late onset prophylaxis developed chronic obstructive pulmonary disease (COPD). Two patients reported atypical mycobacteria infections which in one case may have been responsible for one patient's death due to liver failure at the age of 40.6 years. HPV-related disease manifested in five subjects and progressed as invasive vulvar carcinoma with a fatal course in one patient at the age of 39.5 years. In addition, two patients developed T cell lymphoma skin cancer and basal cell carcinoma at the age of 38 and 65 years.

CONCLUSIONS

Continuous prophylactic anti-infective measures, when started in early childhood, seem to effectively prevent further bacterial infections and the consequent development of COPD. Long-term follow up is needed to evaluate the effect of early anti-HPV targeted prophylaxis on the development of skin and genital warts.